11

33 :: Principles of Instrumental AnalysisPrinciples of Instrumental Analysis:: Douglas A. Douglas A. SkoogSkoog -- : :

22

Power PointPower Point

. . Principles of Instrumental AnalysisPrinciples of Instrumental Analysis Douglas A. Douglas A. SkoogSkoog

. .

33

ContentsContents Chapter 1Chapter 1: Atomic and Emission Spectrometry: Atomic and Emission Spectrometry Chapter 2Chapter 2: Molecular Fluorescence, Phosphorescence, and : Molecular Fluorescence, Phosphorescence, and

ChemiluminescenceChemiluminescence SpectroscopySpectroscopy Chapter 3Chapter 3: X: X--Ray SpectroscopyRay Spectroscopy Chapter 4Chapter 4:: Electron SpectroscopyElectron Spectroscopy Chapter 5Chapter 5: Thermal methods of analysis: Thermal methods of analysis Chapter 6Chapter 6: Mass Spectrometry (MS): Mass Spectrometry (MS) Chapter 7Chapter 7: High Performance Liquid Chromatography : High Performance Liquid Chromatography

(HPLC)(HPLC)

44

Chapter 1:Chapter 1:Atomic and Emission Atomic and Emission

SpectrometrySpectrometry

55

.. .. .. .. .. .. .. ) ) (( .. .. ICPICP

..

66

Atomic Absorption ProcessesAtomic Absorption Processes

AA: When radiation passes : When radiation passes through an atomic vapor, it through an atomic vapor, it may be partially absorbed. may be partially absorbed.

BB: Absorption can occur : Absorption can occur only at specific wavelength.only at specific wavelength.

CC: These wavelength : These wavelength corresponds to the energies corresponds to the energies required to arise the atom required to arise the atom from one state to another from one state to another ((E) E)

77

Emission Emission vsvs AbsorptionAbsorptionSince the energy spacing (Since the energy spacing (E), are identical to E), are identical to

those in emission transitions, absorption those in emission transitions, absorption wavelength wavelength 11, , 22, etc. are exactly the same as , etc. are exactly the same as emission wavelength. emission wavelength.

88

Emission Emission vsvs AbsorptionAbsorption

While emission lines must originated from the While emission lines must originated from the excited state, absorption lines can originate excited state, absorption lines can originate from the ground state.from the ground state.

99

Atomic Absorption SpectrometerAtomic Absorption Spectrometer

The essential components of an AAS:The essential components of an AAS: a light source (1)a light source (1) a a monochromatormonochromator (2)(2) a detector, amplifier a detector, amplifier readout system readout system

(3)(3) a atomizer (4) a atomizer (4)

1010

Atomic absorption spectrometerAtomic absorption spectrometer

1111

AAS operationsAAS operations Radiation is directed through the Radiation is directed through the atomized sampleatomized sample

and into and into monochromatormonochromator.. The The analytical resonance lineanalytical resonance line is isolated from is isolated from

radiation of other wavelengths and sent to detector.radiation of other wavelengths and sent to detector.Measurements are made with and without sample Measurements are made with and without sample

present to provide an present to provide an intensity ratiointensity ratio.. The amplifier converts the ratio signal into The amplifier converts the ratio signal into

absorbanceabsorbance or or concentrationconcentration, which is displayed on , which is displayed on the readout device.the readout device.

1212

Flame AtomizerFlame AtomizerMost atomic absorption Most atomic absorption

measurements are made with measurements are made with Laminar flow or Premix burner.Laminar flow or Premix burner.

There are three main elements:There are three main elements:The The nebulizernebulizerThe spray chamberThe spray chamberThe burnerThe burner

1313

Spray Spray ChamberChamber

To reduce drop size, To reduce drop size, obstacles such as a glass obstacles such as a glass or baffles are placed in the or baffles are placed in the spray path.spray path.

Large drops tend to Large drops tend to disintegrated upon impact, disintegrated upon impact, increasing the number of increasing the number of more desirable fine more desirable fine droplets.droplets.

The remaining large drops The remaining large drops condense and are condense and are eliminated through the eliminated through the drain. drain.

1414

Flame atomization and LimitationFlame atomization and Limitation

The smaller droplets are entrained in the The smaller droplets are entrained in the stream of fuel and oxidant gases and proceed stream of fuel and oxidant gases and proceed through the spray chamber. through the spray chamber.

The mixture emerges in a quiet laminar flow The mixture emerges in a quiet laminar flow when it finally passes into the flame.when it finally passes into the flame.

The loss, a large part of the sample is a major The loss, a large part of the sample is a major limitation of the flame atomizers. limitation of the flame atomizers.

1515

Composition of the flameComposition of the flame

Atomization depends on the Atomization depends on the compositioncomposition or or stoichiometrystoichiometry of the of the fuelfuel--oxidant mixture.oxidant mixture.

At least for some elements, the ratio of At least for some elements, the ratio of fuel to oxidant in the gas mixture fuel to oxidant in the gas mixture influences, where the free atoms are influences, where the free atoms are concentrated in the flame.concentrated in the flame.

1616

Concentration profile exampleConcentration profile example

AirAir--Acetylene Acetylene Flame Flame

A: Fuel rich, A: Fuel rich, ReducingReducing

B: Lean, B: Lean, OxidizingOxidizing

1717

Molybdenum in different airMolybdenum in different air--acetylene acetylene flamesflames

Deeper red colors represent higher atomic Deeper red colors represent higher atomic concentrations.concentrations.

With With reducing flamereducing flame, free , free analyteanalyte atoms persist up atoms persist up to to 4 Cm above4 Cm above the burner tip. The the burner tip. The highest highest concentrationconcentration is found about is found about 1 Cm1 Cm above the above the burner.burner.

In In oxidizing flamoxidizing flam, free atoms are confined to a , free atoms are confined to a smaller zone, almost entirely below the smaller zone, almost entirely below the 1 Cm level1 Cm level. .

1818

Grating Grating MonochromatorMonochromator

Typical Typical configuration of a configuration of a grating grating monochromatormonochromator..

Radiation focused Radiation focused on the entrance slit on the entrance slit is reflected by is reflected by spherical mirror (Mspherical mirror (M--1), as a collimated 1), as a collimated beam.beam.

1919

Grating Grating MonochromatorMonochromator

This beam, then goes to the grating, where it is This beam, then goes to the grating, where it is dispereddispered at different angles according to at different angles according to wavelength.wavelength.

When the grating is rotated to the proper angle, the When the grating is rotated to the proper angle, the resonance line (resonance line (RR, green), is directed by the , green), is directed by the second mirror (Msecond mirror (M--2), through the exit slit.2), through the exit slit.

Other wavelengths (blue and red), are Other wavelengths (blue and red), are dispereddispered, at , at angles which prevent passage from exit slit. angles which prevent passage from exit slit.

2020

Graphite Tube FurnaceGraphite Tube FurnaceThe furnace tube is The furnace tube is

usually usually pyrolyticallypyrolytically coated coated graphite. graphite.

It is surrounded by It is surrounded by and filled with a and filled with a protective sheath of protective sheath of an inert gas such as an inert gas such as argon or nitrogen.argon or nitrogen.

2121

Procedure of GFProcedure of GF

The sample solution is introduced through a The sample solution is introduced through a small injection port in the graphite tube by small injection port in the graphite tube by means of a micropipette. means of a micropipette.

Sample volume is normally in the rang of 1 Sample volume is normally in the rang of 1 to 100 to 100 micrilitersmicriliters..

During measurements, the sample is totally During measurements, the sample is totally vaporized within a few seconds.vaporized within a few seconds.

2222

Absorbance signal of GFAbsorbance signal of GF

A transient A transient absorption absorption signal is signal is produced, produced, because the because the sample is sample is totally totally vaporized vaporized rapidly.rapidly.

2323

Delves Cup methodDelves Cup method The Delves The Delves

Cup is one Cup is one useful variant useful variant of the flame of the flame technique.technique.

As small as As small as 100100l sample .l sample .

Precision Precision about 5%about 5%

CdCd and and PbPb in in blood.blood.

2424

Procedure of Delves Cup methodProcedure of Delves Cup method Sample solution is dispensed by micropipette into a Sample solution is dispensed by micropipette into a

nickel cup.nickel cup.Mild heating near the flame is used to dry the sample.Mild heating near the flame is used to dry the sample. The cup is rapidly inserted directly into the flame.The cup is rapidly inserted directly into the flame. The sample is converted into an atomic vapor which The sample is converted into an atomic vapor which

flows into an elongated tube.flows into an elongated tube. The light beam is directed through the tube for The light beam is directed through the tube for

measurement of the transient absorption signal.measurement of the transient absorption signal.

2525

Applications of Delves Cup methodApplications of Delves Cup method

Samples as small as 100 Samples as small as 100 l can be analyzed with l can be analyzed with the Delves Cup method, a significant improvement the Delves Cup method, a significant improvement over conventional flame operation.over conventional flame operation.

Precision is on the order of 5%.Precision is on the order of 5%.A typical application is the determination of A typical application is the determination of

volatile elements such as volatile elements such as cadmiumcadmium and and leadlead in in blood.blood.

2626

Cold Vapor Mercury TechniquesCold Vapor Mercury Techniques Vapor generation methods Vapor generation methods

represent another approach represent another approach to atomization.to atomization.

In this method the In this method the apparatus is used in the apparatus is used in the cold vapor mercury cold vapor mercury technique.technique.

Reaction:Reaction: HgHg2+2++Sn+Sn2+2+ HgHg00+Sn+Sn4+4+

2727

Cold Vapor Mercury TechniquesCold Vapor Mercury Techniques When stannous chloride When stannous chloride

is added to the sample is added to the sample solution, mercury is solution, mercury is reduced to the free reduced to the free metallic state.metallic state.

A flow of air or A flow of air or nitrogen is used to nitrogen is used to sweep the mercury sweep the mercury vapor into a quartz cell vapor into a quartz cell which is positioned in which is positioned in the light beam.the light beam.

2828

Advantages of CVMTAdvantages of CVMT

No flame is required with this method since No flame is required with this method since the the analyteanalyte, mercury, is already converted to , mercury, is already converted to the atomic state.the atomic state.

A transient absorption signal is obtained as A transient absorption signal is obtained as the vapor passes through the cell.the vapor passes through the cell.

A fast chart recorder or a peak integration A fast chart recorder or a peak integration device is used to register the absorbance device is used to register the absorbance value.value.

2929

Volatile Metal Hydride Technique Volatile Metal Hydride Technique (VMHT)(VMHT)

Vapor generation methods are applicable to the As, Se, Vapor generation methods are applicable to the As, Se, Te, Te, SbSb, Bi, , Bi, SnSn, and , and GeGe elements, which form volatile elements, which form volatile hydrides.hydrides.

An apparatuses like that described for mercury is used An apparatuses like that described for mercury is used for the vapor releasing reaction. for the vapor releasing reaction.

3030

Procedure of VMHTProcedure of VMHT

When sodium When sodium borohydrideborohydride is added to acidified is added to acidified sample solution, free hydrogen is produced, and sample solution, free hydrogen is produced, and the the analyteanalyte is reduced to the metal hydride.is reduced to the metal hydride.

The volatile hydride is then swept into a cool flame The volatile hydride is then swept into a cool flame (A), or into a heated quartz cell (B).(A), or into a heated quartz cell (B).

Free atoms of the Free atoms of the analyteanalyte are produced, giving a are produced, giving a transient signal similar to that described for transient signal similar to that described for mercury. mercury.

3131

Advantages of VMHTAdvantages of VMHT

Many of the element such as Many of the element such as AsAs, Se, Te, , Se, Te, SbSb, Bi, , Bi, SnSn, and , and GeGe are troublesome when are troublesome when conventional flame methods are used.conventional flame methods are used.

Vapor generation methods overcome the Vapor generation methods overcome the experimental problem and greatly improve experimental problem and greatly improve the AA measurements of these elements. the AA measurements of these elements.

3232

Advantages of vapor generation methodsAdvantages of vapor generation methods

Matrix effects reducedMatrix effects reducedAnalyteAnalyte distilled away from other componentsdistilled away from other components

Improved precisionImproved precisionLow NoiseLow Noise

High sensitivityHigh sensitivity10001000--fold improvement for some elementsfold improvement for some elementsDetection Limits down to Detection Limits down to ngng levellevel

3333

Flame Flame vsvs FurnaceFurnace

FlameFlameFasterFasterMore preciseMore preciseLess troubled Less troubled

by matrix by matrix effectseffects

FurnaceFurnaceMore sensitiveMore sensitiveBetter suited to Better suited to

micro samplesmicro samplesMore convenient More convenient

for difficult for difficult materialsmaterials

3434

Background Correction in AASBackground Correction in AAS

Two methods are general for Two methods are general for background correction:background correction:Continuum SourceContinuum SourceZeemanZeeman effecteffect

3535

BC based on continuum sourceBC based on continuum source Two sources are used, the normal line source (a Two sources are used, the normal line source (a

hollow cathode lamp) and a continuum source.hollow cathode lamp) and a continuum source.

3636

Procedure of BCProcedure of BC

Radiation from the two is alternately cycled Radiation from the two is alternately cycled through the atomizer zone, this is shown as a through the atomizer zone, this is shown as a broken line in the figure.broken line in the figure.

This This choppingchopping also produces an AC signal at the also produces an AC signal at the detector.detector.

When the sample is introduced, the absorbance When the sample is introduced, the absorbance difference for two sources is measured.difference for two sources is measured.

The difference represents true atomic absorption The difference represents true atomic absorption for background. for background.

3737

ApplicationsApplications

Although the system shown, is that Although the system shown, is that used in a singleused in a single--beam instrument, a beam instrument, a comparable method can be applied to comparable method can be applied to doubledouble--beam units.beam units.

3838

Background Correction based on the Background Correction based on the ZeemanZeeman effecteffect

Splitting of electronic energy levels in strong Splitting of electronic energy levels in strong magnetic fieldmagnetic field (1 to 10 KG)(1 to 10 KG)

The sublevels differ from one another by about The sublevels differ from one another by about 0.01 nm0.01 nm

This phenomenon is called This phenomenon is called ZeemanZeeman effecteffect Provide a more accurate Provide a more accurate BCBC than othersthan others

3939

Electro thermal AA with Electro thermal AA with ZeemanZeeman effect effect BCBC

4040

Effects of lamp powerEffects of lamp power

selfself--absorptionabsorptionselfself--reversalreversal decrease in the measured absorbancedecrease in the measured absorbance increased curvature of the calibration plotincreased curvature of the calibration plot

4141

SelfSelf--absorption broadeningabsorption broadening The intensity of the emitted The intensity of the emitted

resonance line usually resonance line usually increases with lamp power.increases with lamp power.

However, the line also However, the line also broadens due to an effect broadens due to an effect known as known as selfself--absorptionabsorption..

It is due to generating too It is due to generating too high a concentration of high a concentration of element vapor in the lamp.element vapor in the lamp.

4242

SelfSelf--reversalreversal

In some case, there is a In some case, there is a special absorption special absorption effect known as effect known as selfself--reversal.reversal.

This results in severe This results in severe broadening and a broadening and a selective loss of selective loss of intensity at the center intensity at the center of the line.of the line.

4343

Effect of broadeningEffect of broadening Such broadening Such broadening

effects result in a effects result in a decrease in the decrease in the measured measured absorbance, and absorbance, and increased increased curvature of the curvature of the calibration plot.calibration plot.

4444

AAS operating procedureAAS operating procedure

(1) Preparation of solutions(1) Preparation of solutions (2) Selection of lamp, Set power(2) Selection of lamp, Set power (3) Set (3) Set RR, adjust , adjust bandpassbandpass (4) (4) AdjustationAdjustation of atomizerof atomizer (5) measurement of absorbance(5) measurement of absorbance (6) Calibration, determination of (6) Calibration, determination of CCxx

4545

AAS operating procedureAAS operating procedure

4646

Atomic Fluorescence ProcessesAtomic Fluorescence Processes

When radiation from a light source falls on an When radiation from a light source falls on an atomic vapor, it may stimulate emission of atomic vapor, it may stimulate emission of radiation, called atomic fluorescence.radiation, called atomic fluorescence.

4747

fluorescence spectrumfluorescence spectrum

Fluorescence process gives a Fluorescence process gives a fluorescence emission spectrum.fluorescence emission spectrum.

Fluorescence lines appear at the same Fluorescence lines appear at the same wavelengths as emission and absorption wavelengths as emission and absorption lines.lines.

4848

Kind of fluorescenceKind of fluorescence (A) (A) DirectDirect--line fluorescenceline fluorescence, radiation emitted has the same , radiation emitted has the same

wavelength as that absorbed.wavelength as that absorbed. (B) (B) StepStep--wise fluorescencewise fluorescence, the atom returns to the ground , the atom returns to the ground

state via an intermediate state. state via an intermediate state. The stepThe step--wise produces emission lines which have longer wise produces emission lines which have longer

wavelengths than absorbed radiation. wavelengths than absorbed radiation.

4949

Intensity of linesIntensity of lines Resonance lines (Resonance lines (RR) are most sensitive.) are most sensitive.

5050

Spectral Characteristics of AA compared Spectral Characteristics of AA compared to emissionto emission

AA spectrum of any given AA spectrum of any given element is relatively element is relatively simple.simple.

AA transitions must AA transitions must originate from the ground originate from the ground state (A).state (A).

The resulting resonance The resulting resonance lines, are quite few in lines, are quite few in number (B).number (B).

More transition are More transition are possible for emission (C).possible for emission (C).

Since the emission Since the emission originate from several originate from several excited states.excited states.

The emission spectrum is The emission spectrum is more complex (D). more complex (D).

5151

Spectral Characteristics of AA compared Spectral Characteristics of AA compared to emissionto emission

5252

Atomic EmissionAtomic Emission EE11, , ultraviolet, ultraviolet, below 400 below 400 nm.nm.

EE22, , 22, blue, blue EE33, , 33, green, green EE44, , 44, ,

yellowyellow EE55, , 55, red, red

5353

SpectrographySpectrography

A spectrograph, which uses photographic A spectrograph, which uses photographic recording of the spectra, is used for recording of the spectra, is used for measuring emission spectra.measuring emission spectra.

It has three major components:It has three major components:The excitation sourceThe excitation sourceThe spectrographThe spectrographPhotographic platePhotographic plate

5454

Emission SpectrographEmission Spectrograph The excitation source, converts a small quantity of sample The excitation source, converts a small quantity of sample

into a hot atomic vapor containing excited atoms.into a hot atomic vapor containing excited atoms. In spectrograph, the emitted radiation is separated into its In spectrograph, the emitted radiation is separated into its

analytical wavelengths by a disperser such as a concave analytical wavelengths by a disperser such as a concave grating.grating.

The photographic plate, registers line intensities.The photographic plate, registers line intensities.

5555

Application of SpectrographApplication of Spectrograph

Determine presence of elements from Determine presence of elements from wavelengths of lines.wavelengths of lines.

Concentration determined from line Concentration determined from line densities.densities.

It is a fast method for qualitative and It is a fast method for qualitative and quantitative analysis of soils, minerals and quantitative analysis of soils, minerals and rocks.rocks.

5656

Advantages of Emission SpectrographAdvantages of Emission Spectrograph

The entire spectrum can be recorded in a The entire spectrum can be recorded in a single exposure, thus the spectrograph is an single exposure, thus the spectrograph is an excellent qualitative tool, as we can excellent qualitative tool, as we can determine the presence of various elements determine the presence of various elements from the wavelengths of lines.from the wavelengths of lines.

Do not need any pretreatment of solid Do not need any pretreatment of solid samples and the concentration of elements samples and the concentration of elements determined from line densities, after determined from line densities, after comparison with a standard. comparison with a standard.

5757

Emission SourcesEmission Sources

FlamesFlamesAirAir-- AcetyleneAcetyleneAcetyleneAcetylene--Nitrous oxideNitrous oxide

Electrical dischargesElectrical dischargesDC and AC arcsDC and AC arcsHigh voltage sparksHigh voltage sparks

PlasmaPlasmaInductivelyInductively--Coupled Plasma (ICP)Coupled Plasma (ICP)

5858

Flames sourcesFlames sources Flames produce simple Flames produce simple

spectra because of their spectra because of their relatively low relatively low temperatures, 2000K to temperatures, 2000K to 3000K.3000K.

Low temperatures sources Low temperatures sources do not produce efficient do not produce efficient excitation for many excitation for many elements.elements.

It is for solution samples.It is for solution samples.

5959

Electrical discharge sourcesElectrical discharge sources

Higher temperatures, Higher temperatures, about 5000K, are attained about 5000K, are attained with electrical discharges with electrical discharges sources.sources.

These include, simple DC These include, simple DC and AC arcs and high and AC arcs and high voltage sparks.voltage sparks.

It is for solid samples.It is for solid samples.

6060

ICPICP InductivelyInductively--Coupled and Coupled and

DC plasmas use electronic DC plasmas use electronic excitation of a rare gas to excitation of a rare gas to generate high temperature generate high temperature atomic vapors, up to atomic vapors, up to 8000K.8000K.

They provide excellent They provide excellent sensitivities and high sensitivities and high precision for a wide rang precision for a wide rang of elements.of elements.

It is for solution samples.It is for solution samples.

6161

Typical Typical nebulizernebulizer for sample injection into for sample injection into plasma sourceplasma source

Sample is Sample is introduced introduced with argon with argon flowing at flowing at about 1 about 1 1it/min.1it/min.

6262

Resolution requirements for emissionResolution requirements for emission

(A) with a low temperature flame, such as air(A) with a low temperature flame, such as air--propane at propane at 2000K, only alkali metals emit strongly. Their spectra are 2000K, only alkali metals emit strongly. Their spectra are so simple that even a filter with a 10 nm resolution is so simple that even a filter with a 10 nm resolution is adequate.adequate.

6363

Resolution requirements for emissionResolution requirements for emission (B) the hotter (B) the hotter

nitrous oxidenitrous oxide--acetylene flame acetylene flame at 3000K, gives at 3000K, gives more complex more complex spectra.spectra.

Resolution of Resolution of emission lines emission lines as close as 0.1 as close as 0.1 nm.nm.

6464

Resolution requirements for emissionResolution requirements for emission ((C)AtC)At

temperatures temperatures near 5000K, near 5000K, arcs and sparks arcs and sparks produce very produce very complex complex spectra.spectra.

Resolution as Resolution as good as 0.03 good as 0.03 nm may be nm may be necessary.necessary.

6565

Resolution requirements for emissionResolution requirements for emission

((D)FinallyD)Finally, , plasma sources, plasma sources, with with temperatures to temperatures to 8000K, may 8000K, may require a require a resolution of resolution of 0.01 nm.0.01 nm.

6666

Chapter 2:Chapter 2:Molecular Fluorescence, Molecular Fluorescence,

Phosphorescence, and Phosphorescence, and ChemiluminescenceChemiluminescence

SpectroscopySpectroscopy

6767

.. .. .. .. ((

.. ...) ...) pHpH

..

.. .. ..

6868

Molecular Fluorescence, Molecular Fluorescence, Phosphorescence, and Phosphorescence, and

ChemiluminescenceChemiluminescence SpectroscopySpectroscopy

The methods are known collectively as The methods are known collectively as luminescenceluminescence..

Fluorescence and Phosphorescence are often Fluorescence and Phosphorescence are often referred to referred to photoluminescencephotoluminescence..

6969

Principles of Fluorescence and Principles of Fluorescence and PhosphorescencePhosphorescence

In each, molecules of the In each, molecules of the analyteanalyte are are excited to give a species whose emission excited to give a species whose emission spectrum provides information for spectrum provides information for qualitativequalitative or or quantitativequantitative analyses.analyses.

7070

Different of Fluorescence and Different of Fluorescence and PhosphorescencePhosphorescence

The electronic energy transitions responsible for The electronic energy transitions responsible for the photoluminescence do not involve a change on the photoluminescence do not involve a change on electron spinelectron spin in fluorescence, but in in fluorescence, but in phosphorescence the spin is changed.phosphorescence the spin is changed.

Fluorescence radiation is Fluorescence radiation is shortshort--livedlived (10(10--55 sec.)sec.) Phosphorescence radiation is Phosphorescence radiation is longlong--livedlived (several (several

seconds or longer)seconds or longer)

7171

Principles of Principles of ChemiluminescenceChemiluminescence

This method is based upon an excited species This method is based upon an excited species that is formed in the course of a that is formed in the course of a chemical chemical reactionreaction..

The excited particles are the products of a The excited particles are the products of a reaction between the reaction between the analyteanalyte and a and a suitable suitable reagentreagent (usually a strong oxidant).(usually a strong oxidant).

The result is a spectrum characteristic of the The result is a spectrum characteristic of the oxidation productoxidation product of the of the analyteanalyte rather than rather than the the analyteanalyte itself.itself.

7272

Theory of Fluorescence and Theory of Fluorescence and PhosphorescencePhosphorescence

Fluorescence behavior occurs in complex gaseous, liquid, Fluorescence behavior occurs in complex gaseous, liquid, and solid chemical systems.and solid chemical systems.

The type of fluorescence, in which the absorbed radiation The type of fluorescence, in which the absorbed radiation is reemitted without alteration, is known as is reemitted without alteration, is known as resonance resonance fluorescencefluorescence (3s to 3p and reverse).(3s to 3p and reverse).

Often, the fluorescence and phosphorescence lines are Often, the fluorescence and phosphorescence lines are

longer thanlonger than the resonance line (the resonance line (Stokes shiftStokes shift). ).

7373

Fluorescence and PhosphorescenceFluorescence and PhosphorescenceExcited StatesExcited States

Electron spinElectron spin Spectroscopic Spectroscopic

multiplicity(2S+1)multiplicity(2S+1) Singlet state Singlet state Doublet state (free Doublet state (free

radicals)radicals) Triplet stateTriplet state SingletSinglet--singlet transitions singlet transitions

are allowed, but singletare allowed, but singlet--triplet or reverse are triplet or reverse are forbidden.forbidden.

7474

Partial energyPartial energy-- level diagram for a typical level diagram for a typical photoluminescence moleculephotoluminescence molecule

7575

Photoluminescence ProcessesPhotoluminescence Processes

Absorption of two bands of radiation,Absorption of two bands of radiation,11(S(S00 SS11) and ) and 22(S(S00 SS22) )

VibrationalVibrational relaxationrelaxationDeactivation processes:Deactivation processes: 33(S(S11 SS00) Fluorescence (10) Fluorescence (10--66 to 10to 10--55 Sec.)Sec.) 44(T(T11 SS00) Phosphorescence(10) Phosphorescence(10--44 to 10 Sec.)to 10 Sec.)

7676

Internal ConversionInternal ConversionIt is a intermolecular processes by which It is a intermolecular processes by which

a molecule passes to a lower energy a molecule passes to a lower energy electronic state without emission of electronic state without emission of radiation.radiation.

It appears when two electronic energy It appears when two electronic energy levels are close for an overlap in levels are close for an overlap in vibrationalvibrational energy levels in two energy levels in two excited excited singletsinglet states states

7777

Intersystem CrossingIntersystem CrossingIt is a process in which the spin of an It is a process in which the spin of an

excited electron is reversed, and a excited electron is reversed, and a change in multiplicity of the molecule change in multiplicity of the molecule results.results.

It is a It is a singletsinglet--triplettriplet transition.transition.There are most common in molecules There are most common in molecules

that contain heavy atoms, such as iodine that contain heavy atoms, such as iodine or bromine (the or bromine (the heavyheavy-- atom effectatom effect) )

7878

Variables that affect fluorescence and Variables that affect fluorescence and phosphorescencephosphorescence

Quantum yieldQuantum yield Transition types in fluorescenceTransition types in fluorescenceQuantum efficiency and Transition typesQuantum efficiency and Transition types Fluorescence and structureFluorescence and structure Effect of structural rigidityEffect of structural rigidity Temperature and solvent effectsTemperature and solvent effects Effect of pH on fluorescenceEffect of pH on fluorescence Effect of dissolved oxygenEffect of dissolved oxygen Effect of concentration on fluorescence intensityEffect of concentration on fluorescence intensity

7979

Quantum yieldQuantum yield ( (quantum efficiency) quantum efficiency)

It is the ratio of the number of molecules that It is the ratio of the number of molecules that fluorescefluoresce to the total number of excited to the total number of excited molecules.molecules.

It is the ratio of the number of molecules that It is the ratio of the number of molecules that phosphorescephosphoresce to the total number of excited to the total number of excited molecules.molecules.

8080

EquationEquation of Quantum yieldof Quantum yield = = KKff / / KKff + + KKii + + KKecec + + KKicic + + KKpdpd + + KKdd = Quantum yield= Quantum yieldK = the relative rate constants:K = the relative rate constants:

KKff for fluorescencefor fluorescenceKKii for intersystem crossingfor intersystem crossingKKecec for external crossingfor external crossingKKicic for internal crossingfor internal crossingKKpdpd for for predissociationpredissociationKKdd for for disscociationdisscociation

8181

Transition types in fluorescenceTransition types in fluorescenceFluorescence seldom results from Fluorescence seldom results from

absorption of UVabsorption of UV--radiation lower than radiation lower than 250 nm (high energy, 250 nm (high energy, predissociationpredissociationand dissociation).and dissociation).

Fluorescence due to Fluorescence due to ** transitions is seldom observed.transitions is seldom observed.

** and and ** nn are common are common (longer wavelength).(longer wavelength).

8282

Quantum efficiency and Transition typesQuantum efficiency and Transition types

Quantum efficiency is greater forQuantum efficiency is greater for** than than ** nn..

First, the molar First, the molar absorptivityabsorptivity (() of ) of ,,* transitions (100 to * transitions (100 to 1000) is greater than n,1000) is greater than n,* transitions.* transitions.

Second, the rate constant for intersystem crossing (Second, the rate constant for intersystem crossing (KKii) is ) is smaller for smaller for ,,* excited states, because the energy * excited states, because the energy difference between the singletdifference between the singlet--triplet states is larger. triplet states is larger.

8383

Fluorescence and structureFluorescence and structure

Compounds containing aromatic functional groups Compounds containing aromatic functional groups with lowwith low--energyenergy ** transition levels have most intensive transition levels have most intensive fluorescence lines.fluorescence lines.

Compounds containing aliphatic and aliphatic Compounds containing aliphatic and aliphatic carbonyl or highly conjugated doublecarbonyl or highly conjugated double--bond may bond may also exhibit fluorescence ( number of these are also exhibit fluorescence ( number of these are small compared with aromatics). small compared with aromatics).

8484

Effect of structural rigidityEffect of structural rigidity

Rigid structures have Rigid structures have intense fluorescence.intense fluorescence.

Quantum efficiency for Quantum efficiency for fluorenefluorene is 1.0 but for is 1.0 but for biphenylbiphenyl is 0.2, under is 0.2, under similar conditions.similar conditions.

Rigidity, decrease internal Rigidity, decrease internal conversion rate (conversion rate (KKicic).).

8585

Temperature and solvent effectsTemperature and solvent effects

Quantum efficiency decreases with increasing Quantum efficiency decreases with increasing temperature (deactivation by external conversion, temperature (deactivation by external conversion, KKecec, is improved)., is improved).

A decrease in solvent A decrease in solvent viscosityviscosity also increase the also increase the external conversion and decrease the quantum external conversion and decrease the quantum efficiency.efficiency.

PolarityPolarity of solvent ( nof solvent ( n * * blue shiftblue shift and and * * red shiftred shift with polar solvents) with polar solvents)

8686

Effect of pH on fluorescenceEffect of pH on fluorescence

Aromatic compounds with Aromatic compounds with acidic or basic functional acidic or basic functional groups are pH dependent.groups are pH dependent.

8787

Effect of dissolved oxygenEffect of dissolved oxygen

Dissolved oxygen often Dissolved oxygen often reducesreduces emission intensity emission intensity of a fluorescence in solution (of a fluorescence in solution (photochemicallyphotochemicallyinduced oxidation of the fluorescent species).induced oxidation of the fluorescent species).

Quenching takesQuenching takes place as a consequence of the place as a consequence of the paramagnetic properties of molecular oxygen. paramagnetic properties of molecular oxygen.

8888

Effect of concentration on fluorescence Effect of concentration on fluorescence intensityintensity

F = power of fluorescence radiationF = power of fluorescence radiation.. F = KF = K(P(P00 P)P)

P = power after traveling from a P = power after traveling from a bb length of solutionlength of solutionPP00 = power of incident beam= power of incident beamKK depends upon the quantum efficiencydepends upon the quantum efficiency

BeerBeers law : P/Ps law : P/P00 = 10= 10--bcbcF = KF = KPP00(1(1--10 10 bcbc))F = 2.3KF = 2.3KbcPbcP00F = F = KcKc

8989

Emission and Excitation SpectraEmission and Excitation Spectra

Three types of Three types of photoluminescence photoluminescence spectra for spectra for phenathrenephenathrene..

9090

InstrumentsInstruments All All fluorometersfluorometers and and

spectrofluorometesspectrofluorometes employ employ doubledouble--beam optics. beam optics.

FluorometersFluorometers are same as are same as Photometers, that filters are Photometers, that filters are employed.employed.

SpectrofluorometersSpectrofluorometers are same are same as Spectrophotometers, that as Spectrophotometers, that grating or prism grating or prism monochromatorsmonochromators are are employed.employed.

9191

Components of InstrumentsComponents of Instruments

The components differ only in detail The components differ only in detail from those of photometers or from those of photometers or spectrophotometersspectrophotometers..

9292

SourcesSources

A more intense source is needed than tungsten or A more intense source is needed than tungsten or hydrogen lamp.hydrogen lamp.

A A mercury mercury or or xenonxenon arc lamp is commonly employed.arc lamp is commonly employed. The spectrum of xenon lamp is continuous between 250 to The spectrum of xenon lamp is continuous between 250 to

600 nm, 600 nm, Mercury lamps produce an intense spectrum with lines at Mercury lamps produce an intense spectrum with lines at

366, 405, 436, 546, 577, 691, and 773 nm.366, 405, 436, 546, 577, 691, and 773 nm. LasersLasers are used recently. are used recently.

9393

Filters and Filters and monochromatorsmonochromators

InterferenceInterference and and absorptionabsorption filters have filters have been employed in been employed in fluorometersfluorometers..

Most Most spectrofluorometersspectrofluorometers are employed are employed with with gratinggrating monochromatorsmonochromators..

9494

DetectorsDetectors

The typical fluorescent signal is The typical fluorescent signal is low low intensityintensity..

Photomultiplier tubesPhotomultiplier tubes are used in sensitive are used in sensitive fluorescence instruments.fluorescence instruments.

Diode arrayDiode array detectors have also been used.detectors have also been used.

9595

Cell and cell componentsCell and cell components

CylindricalCylindrical and and rectangularrectangular cells cells fabricated of fabricated of glassglass and and quartsquarts are are used.used.

9696

FluorometersFluorometers designsdesigns Mercury lampMercury lamp Single Single

photomultiplier photomultiplier detectordetector

9797

SpectrofluorometersSpectrofluorometers designsdesigns

Typical designTypical design

9898

phosphorometersphosphorometers designdesign

PhosphorescencePhosphorescence

9999

Sensitivity of fluorescence and Sensitivity of fluorescence and phosphorescencephosphorescence

These methods are inherently applicable to lower These methods are inherently applicable to lower concentration than concentration than spectrophotometricspectrophotometric methods.methods.

This high sensitivity arise from the fact that the This high sensitivity arise from the fact that the concentration of concentration of analyteanalyte is related to is related to FF that can be that can be measured independently of the power of the source measured independently of the power of the source (p(p00), thus P), thus P00 can be increased.can be increased.

100100

Applications of Applications of FluorometersFluorometers

Determination of inorganic species (two methods):Determination of inorganic species (two methods):Direct methods involve the formation of a fluorescent Direct methods involve the formation of a fluorescent chelatechelate

and the measurements of its emission.and the measurements of its emission.Diminutions of fluorescence resulting from quenching actions Diminutions of fluorescence resulting from quenching actions

of the of the analyteanalyte. .

Determination of organic speciesDetermination of organic species

101101

Applications of Applications of phosphorometersphosphorometers

Condensed ring aromatics hydrocarbons containing Condensed ring aromatics hydrocarbons containing heavy atomsheavy atoms such as halogens or sulfur.such as halogens or sulfur.

Organic and biochemical species such as Organic and biochemical species such as nucleic nucleic acids, amino acids, acids, amino acids, pyrinepyrine andand pyrimidinepyrimidine, , petroleum hydrocarbons petroleum hydrocarbons andand pesticides. pesticides.

102102

Chapter 3:Chapter 3:XX--Ray SpectroscopyRay Spectroscopy

103103

.. . . .. .. .. ((

. . . . ..

104104

XX--Ray SpectroscopyRay SpectroscopyAbsorptionAbsorptionEmissionEmissionScatteringScatteringFluorescenceFluorescenceAnd Diffraction of radiationAnd Diffraction of radiation

105105

Fundamental PrinciplesFundamental Principles

Short wavelength Short wavelength electromagnetic radiationelectromagnetic radiation

1010--5 to 100 5 to 100 0.1 to 250.1 to 25 is common Xis common X--RayRay Under some conditions, only Under some conditions, only

continuous spectrum (a) continuous spectrum (a) ((BremsstralungBremsstralung) )

Under other, line spectrum is Under other, line spectrum is superimposed upon continuum superimposed upon continuum (b)(b)

106106

Emission of XEmission of X--RayRayBombardment of a metal target with a Bombardment of a metal target with a

beam of highbeam of high--energy electrons.energy electrons.Exposure of a substance to a primary Exposure of a substance to a primary

beam of Xbeam of X--RaysRaysEmployment of a radioactive source Employment of a radioactive source

whose decay process results in Xwhose decay process results in X--Ray Ray emission.emission.

107107

Frequency of XFrequency of X--Ray and atomic numberRay and atomic number hhvv00 = = hchc//00 = = VeVe

VeVe = product of accelerating = product of accelerating voltage and electron chargevoltage and electron charge

h = Plankh = Planks constants constant c = velocity of lightc = velocity of light vv0 0 = maximum frequency = maximum frequency

that can produced at voltage that can produced at voltage V, while V, while 0 0 is the lowis the low--wavelength wavelength

00 = 12.398/V= 12.398/V 00 ( ( ) and V (volt)) and V (volt)

108108

Partial energy levelsPartial energy levels

109109

Absorption of XAbsorption of X--RayRay XX--Ray absorption spectra for Ray absorption spectra for

PbPb and Agand Ag Like emission spectrum, it is Like emission spectrum, it is

simple and consist of a few simple and consist of a few wellwell--defined absorption peaks.defined absorption peaks.

The wavelength of peaks are The wavelength of peaks are characteristic of the elementcharacteristic of the element

Sharp discontinuities called Sharp discontinuities called absorption edges. absorption edges.

110110

Diffraction of XDiffraction of X--RayRay BraggBraggs lows low (1912)(1912)

AP + PC = nAP + PC = n AP = PC = d SinAP = PC = d Sin nn = 2d Sin= 2d Sin SinSin = n= n / 2d/ 2d

111111

Instrument componentsInstrument components

SourceSourceDevice for restricting the wavelength range Device for restricting the wavelength range

to be employed.to be employed.Sample holderSample holderRadiation detector or transducerRadiation detector or transducerSignal processor Signal processor Read out deviceRead out device

112112

Source (XSource (X--Ray Tube)Ray Tube)

Coolidge tubeCoolidge tube Targets: W, Cr, Cu, Targets: W, Cr, Cu,

Mo, Mo, RhRh, Ag, Fe and , Ag, Fe and CoCo

113113

Commercial XCommercial X--Ray tubeRay tube

114114

Filter for XFilter for X--Ray beamsRay beams

Use of a filter to produce Use of a filter to produce monochromatic radiationmonochromatic radiation

KK line is then available line is then available for analytical purposes.for analytical purposes.

Continuous radiation is Continuous radiation is also feasible with thin also feasible with thin strips of metal.strips of metal.

115115

Wavelength dispersion with Wavelength dispersion with monochromatorsmonochromators

Consists of:Consists of: A pair of beam collimators A pair of beam collimators

(as slits in optical (as slits in optical instruments)instruments)

A dispersing element A dispersing element

Dispersive element is a Dispersive element is a single crystal mounted on single crystal mounted on a a goniometergoniometer or or rotatablerotatable tabletable

116116

XX--Ray DetectorsRay Detectors

Photographic emulsions (early XPhotographic emulsions (early X--Ray equipments)Ray equipments) In modern equipments, for high speed and In modern equipments, for high speed and

accuracy:accuracy:GasGas--filled detectorsfilled detectorsScintillation detectorsScintillation detectorsSemiconductor detectorsSemiconductor detectors

117117

GasGas--Filled DetectorsFilled Detectors

Three types:Three types: Ionization chambersIonization chambers Proportional countersProportional counters Geiger tubesGeiger tubes

118118

Gas amplification for various types of gasGas amplification for various types of gas--filled detectorsfilled detectors

In ionization chamber (VIn ionization chamber (V11 to Vto V22), the ), the number of electrons reaching the number of electrons reaching the anode is reasonably constant and anode is reasonably constant and represent the total number formed by represent the total number formed by a single photon.a single photon.

In proportional counter (VIn proportional counter (V33 to Vto V44), ), the number of electrons increase the number of electrons increase rapidly with applied potential rapidly with applied potential (secondary ion(secondary ion--pair production by pair production by collisions of electrons and gas collisions of electrons and gas molecules), molecules), gas amplificationgas amplification..

In Geiger tube (VIn Geiger tube (V55 to vto v66), ), amplification of the electrical pulse is amplification of the electrical pulse is enormous. enormous.

119119

Semiconductor DetectorsSemiconductor Detectors Lithium drifted Lithium drifted

silicon silicon (or(orgermaniumgermanium))detectors.detectors.

Is formed by Is formed by depositing lithium on depositing lithium on the surface of a pthe surface of a p--doped silicon crystal.doped silicon crystal.

120120

Signal ProcessorsSignal ProcessorsPulsePulse--Height SelectorsHeight SelectorsPulsePulse--Height AnalyzersHeight AnalyzersScalersScalers and Countersand Counters

121121

Typical signalTypical signal--height selectorheight selector

122122

XX--Ray FluorescenceRay Fluorescence

Instruments:Instruments:Wavelength DispersiveWavelength Dispersive

Single Single Channel or SequentialChannel or SequentialMulti Multi Channel or SimultaneousChannel or Simultaneous

Energy DispersiveEnergy DispersiveNondispersiveNondispersive instrumentsinstruments

ApplicationsApplications:: QualitativeQualitative SemiquantitativeSemiquantitative

123123

Energy dispersive XRF, (a) XEnergy dispersive XRF, (a) X--Ray tube Ray tube source, (b) Radioactive sourcesource, (b) Radioactive source

124124

NondispersiveNondispersive InstrumentsInstruments

Routine Routine determination determination of S and of S and PbPb in in gasoline. gasoline.

125125

Typical XRF spectrumTypical XRF spectrum

126126

Chapter 4:Chapter 4:Electron Electron

SpectroscopySpectroscopy

127127

.. .. (ESCA)(ESCA)

.. ESCAESCA

.. ESCAESCA

..

.. ESCAESCA . . ..

DU1

Slide 127

DU1 Dear User!, 25/01/2007

128128

Electron SpectroscopyElectron Spectroscopy

ESCA: Electron Spectroscopy for Chemical AnalysisESCA: Electron Spectroscopy for Chemical Analysis XPS: XXPS: X--Ray Photoelectron SpectroscopyRay Photoelectron Spectroscopy UPS: Ultraviolet Photoelectron SpectroscopyUPS: Ultraviolet Photoelectron Spectroscopy PES: Photoelectron SpectroscopyPES: Photoelectron Spectroscopy AES: Auger Electron SpectroscopyAES: Auger Electron Spectroscopy INS: Ion Neutralization SpectroscopyINS: Ion Neutralization Spectroscopy EIS: Electron Impact SpectroscopyEIS: Electron Impact Spectroscopy PIS: Penning Ionization SpectroscopyPIS: Penning Ionization Spectroscopy

129129

principlesprinciples

hh= 1/2mv= 1/2mvee22 + + EEbb + q+ q= Frequency of emitted electrons= Frequency of emitted electronsh = Plank constanth = Plank constant1/2mv1/2mvee22 = Kinetic energy of emitted electron= Kinetic energy of emitted electronEEbb = Binding energy of emitted electron= Binding energy of emitted electronq = Charge of targetq = Charge of target= Working function of emitting material = Working function of emitting material

130130

ESCAESCA S + hS + h11(X(X--Ray)Ray) SS+*+* + e+ e--

Kinetic energy of emitted electros are measured Kinetic energy of emitted electros are measured and intensity of these electrons as a function of and intensity of these electrons as a function of kinetic energy is plotted.kinetic energy is plotted.

SS+*+* SS++ + h+ h2 2 (X(X--Ray Fluorescence)Ray Fluorescence) SS+* +* SS++++ + e+ e-- (Auger electron) (Auger electron) M. Pierre AugerM. Pierre Auger

131131

Energy diagram for ESCA ProcessEnergy diagram for ESCA Process

132132

Primary and satellite peaks for NeonPrimary and satellite peaks for Neon

133133

Parameters in ESCAParameters in ESCA

Chemical ShiftChemical ShiftSpectral SplintingSpectral SplintingKinetic energy of emitted electronsKinetic energy of emitted electronsBonding energy of electronsBonding energy of electrons

134134

Representative chemical shift dataRepresentative chemical shift dataElementElement Oxidation state and Oxidation state and

compoundcompoundPrincipal Principal Metal ESCA Metal ESCA PeakPeak

BE and selected BE and selected line widths for line widths for PMEPPMEP

OxideOxideBE O(1S)BE O(1S)

Hydroxide Hydroxide BE O(1S)BE O(1S)

PdPd

NiNi

CuCu

PdPdPdOPdOPdOPdO22Pd(OH)Pd(OH)44PdSOPdSO44NiNiNiONiONiNi22OO33Ni(OH)Ni(OH)22NiSiONiSiO33CuCuCuOCuOCuCu22OO

Pd(3dPd(3d5/25/2))Pd(3dPd(3d5/25/2))Pd(3dPd(3d5/25/2))Pd(3dPd(3d5/25/2))Pd(3dPd(3d5/25/2))Ni(2pNi(2p3/23/2))Ni(2pNi(2p3/23/2))Ni(2pNi(2p3/23/2))Ni(2pNi(2p3/23/2))Ni(2pNi(2p3/23/2))Cu(2pCu(2p3/23/2))Cu(2pCu(2p3/23/2))Cu(2pCu(2p3/23/2))

335.45(1.00)335.45(1.00)336.9336.9??338.55338.55338.7338.7852.75852.75854.6854.6855.7855.7856.45856.45856.9856.9932.47(1.01)932.47(1.01)933.7933.7932.5(1.2)932.5(1.2)

530.1530.1

530.0530.0530.0530.0

529.7529.7530.3530.3

531.7531.7531.95531.95

531.7531.7

135135

Binding energy for electrons emitted from 1S orbital of N or Binding energy for electrons emitted from 1S orbital of N or

O and 2S orbital of 2S in selected compounds.O and 2S orbital of 2S in selected compounds.Compound Compound Binding energy, Binding energy, eVeV Compound Compound Binding energy, Binding energy, eVeV

N CompoundN CompoundRNHRNHRCRC--NRNRRCONH2RCONH2RCRCNNRN=NRRN=NRRNHRNH++

RR44NN++

ArNHArNH++

ArNOHArNOH O CompoundO Compound

P(CHP(CH33))33OOSi(CHSi(CH33))33OO22POClPOCl33

397.1397.1--398.3398.3398398--399399398398--399.7399.7398.5398.5399399--399.5399.5400.3400.3--400.5400.5401401--402.3402.3401.1401.1402.9402.9--404404

535.9535.9537.7537.7537.8537.8

VOClVOCl33CrOCrO22ClCl22SOSO22ClCl22SOSO22FF22

S CompoundS CompoundSS22--

SS22OO3322--

RSHRSHArSHArSHRSSRRSSRSOSO3322--

RSORSO22RRSOSO4422--

538.7538.7538.9538.9539.3539.3540.3540.3

160.9160.9160.9160.9--166.9166.9161.8161.8--162.2162.2162.5162.5--162.9162.9162.7162.7--162.9162.9165.4165.4166.7166.7--167.3167.3167.8167.8--168.1168.1

136136

Chemical shifts reflecting Chemical shifts reflecting covalency/ionicitycovalency/ionicity changes in changes in complex oxides for complex oxides for MMxxOOyy AAzzMMssOOtt

ElementElement CompoundCompound Peak B.E. in Peak B.E. in eVeV

AlAl

SiSi

PP

SeSe

Al(2p)Al(2p)AlAl22OO33NaNa22AlAl22OO44Si(2p)Si(2p)SiOSiO22TalcTalcSoda glassSoda glassP(2p)P(2p)NaNa22HPOHPO44NaNa33POPO33Se(3dSe(3d5/25/2))(NH(NH44)SeO)SeO44NaNa22SeOSeO44HH22SeOSeO44

73.873.872.972.9

103.4103.4103.1103.1102.9102.9

133.1133.1134.7134.7

59.259.260.660.661.261.2

137137

ESCA ApparatusESCA Apparatus

138138

Spherical electrostatic field with a Spherical electrostatic field with a proceeding retarding potential plateproceeding retarding potential plate

139139

ESCA spectrometer with Cylindrical ESCA spectrometer with Cylindrical Mirror Analyzer (CMA)Mirror Analyzer (CMA)

140140

Retarding Potential Analyzer (RPA), top Retarding Potential Analyzer (RPA), top view (a) Cylindrical (b) Linearview (a) Cylindrical (b) Linear

141141

DoubleDouble--focusing magnetic field analyzerfocusing magnetic field analyzer

142142

Typical spectrumTypical spectrum

For a single energetic For a single energetic band of electrons band of electrons with a retarding with a retarding potential analyzer. (a) potential analyzer. (a) Intensity, (b) FirstIntensity, (b) First--derivativederivative

143143

Auger KLL from NeonAuger KLL from Neon

144144

Shifts induced in Shifts induced in zeoliteszeolites, (a) relative , (a) relative quantification, (b) Si(2p) Shiftsquantification, (b) Si(2p) Shifts

145145

ESCA analysis of Surface of ESCA analysis of Surface of BaOBaO and and BaCO3BaCO3

146146

Shifts in Shifts in zeoliteszeolites by Caby Ca2+2+ and Naand Na++substitutionsubstitution

147147

Chapter 5:Chapter 5:Thermal methods of Thermal methods of

analysisanalysis

148148

.. TGTG .. TGTG .. DTADTA .. DTADTA .. DSCDSC .. DSCDSC .. DSC DSC .. ETET .. ETET .. TMATMA ..

149149

DefinitionsDefinitions Thermal methods are based upon the measurement Thermal methods are based upon the measurement

of the dynamic relationship between temperature of the dynamic relationship between temperature and some property of a system such as mass, heat and some property of a system such as mass, heat of reaction, or volume.of reaction, or volume.

Five of the most important groups of these:Five of the most important groups of these:TGTG: : ThermogravimetryThermogravimetryDTADTA: Differential Thermal Analysis: Differential Thermal AnalysisDSCDSC: Differential Scanning : Differential Scanning CalorimetryCalorimetryEMEM: : EnthalpimetricEnthalpimetric MethodsMethodsTMATMA: Thermo Mechanical Analysis: Thermo Mechanical Analysis

150150

Thermal methods of analysis Thermal methods of analysis Differential Scanning Differential Scanning

CalorimetryCalorimetry ((DSCDSC)) Measure heat absorbed or Measure heat absorbed or

liberated during heating or liberated during heating or coolingcooling

Thermal Gravimetric Thermal Gravimetric Analysis (Analysis (TGATGA)) Measure change in weight Measure change in weight

during heating or coolingduring heating or cooling

Thermo Mechanical Thermo Mechanical Analysis (Analysis (TMATMA)) Measure change in Measure change in

dimensions during heating dimensions during heating or coolingor cooling

Differential Thermal Analysis Differential Thermal Analysis

((DTADTA), measure heat absorbed ), measure heat absorbed or emitted during heating, by or emitted during heating, by measuring the temperature measuring the temperature difference between the system and difference between the system and an inert sample. an inert sample.

151151

ThermogravimetryThermogravimetry ((TGTG))

In a TG the mass of sample is recorded In a TG the mass of sample is recorded continuously as its temperature is increased continuously as its temperature is increased linearly from ambient to as high as 1200linearly from ambient to as high as 1200C.C.

A A thermogramthermogram provides both quantitative and provides both quantitative and qualitative information qualitative information

152152

Apparatus of Apparatus of TGTGThe The TGTG systems includes:systems includes:

A sensitive recording analytical balanceA sensitive recording analytical balanceA furnaceA furnaceA furnace temperature controller and A furnace temperature controller and

programmerprogrammera recorder that provides a plot of sample a recorder that provides a plot of sample

mass as a function of temperaturemass as a function of temperature

153153

Thermal BalanceThermal Balance A: beamA: beam B: sample cup and B: sample cup and

holderholder C: counter weightC: counter weight D: lamp and D: lamp and

PhotodiodesPhotodiodes E: coilE: coil F: magnetF: magnet G: control amplifier G: control amplifier H: tare calculatorH: tare calculator I: amplifierI: amplifier J: recorderJ: recorder

154154

Applications of Applications of TGTG

QualitativeQualitative analysis of inorganic, analysis of inorganic, organic, polymeric and composite organic, polymeric and composite materialsmaterials

QuantitativeQuantitative analysis of Inorganic, analysis of Inorganic, organic, polymeric and composite organic, polymeric and composite materialsmaterials

155155

A A TGTG ThermogramThermogram

156156

a) Differential a) Differential ThermogramThermogram, b) Simple , b) Simple ThermogramThermogram

157157

Polymer Analysis with Polymer Analysis with TGTG PVC: Polyvinyl ChloridePVC: Polyvinyl Chloride PMMA: PMMA: PolymethylPolymethyl

methacrylatemethacrylate LDPE: Low Density LDPE: Low Density

Poly Poly EthylenEthylen PI: aromatic PI: aromatic

polypyromellitimidepolypyromellitimide PTFE: PTFE:

PolytetrafluoroethylenePolytetrafluoroethylene

158158

Differential Thermal Analysis (Differential Thermal Analysis (DTADTA))

In In DTADTA, the heat absorbed or emitted by a , the heat absorbed or emitted by a chemical system is observed by measuring chemical system is observed by measuring the temperature difference between that the temperature difference between that system and an system and an inert referenceinert reference compound compound (alumina or silicon carbide).(alumina or silicon carbide).

The temperature of sample and reference The temperature of sample and reference compound are increased at a constant rate.compound are increased at a constant rate.

159159

Apparatus of Apparatus of DTADTASample holder comprising

thermocouples, sample containers and a ceramic or metallic block

FurnaceTemperature programmerRecording system

160160

Apparatus of Apparatus of DTADTA

161161

Schematic illustration of a DTA cell

162162

Cell for DTA measurements

163163

Applications of Applications of DTADTAA DTA curve can be used as a finger print

for identifcation purposes.The area under a DTA peak can be to the

enthalpy change and is not affected by the heat capacity of the sample.

164164

Peak area in Peak area in DTADTA

The peak area (The peak area (AA), which is related to enthalpy ), which is related to enthalpy changes in the test sample, is determined from changes in the test sample, is determined from following equation:following equation:

A =mq/gK

where m is the sample mass, q is the enthalpy change per unit mass, g is a measured shape factor and K is the thermal conductivity of sample.

165165

Determination of CDetermination of Cp p by by DTADTA

It is possible to measure the heat capacity CP at constant pressure using DTA:

Cp = K(T2-T1)/mH where T1 and T2 are the differential temperatures

generated when the apparatus is first run without any sample at all and then with the test sample in position. H is the heating rate and the constant K is determined by calibration against standard substances.

166166

The sample will undergo endothermic (glass transition) and exothermic

(crystallization) processes that change its temperature relative to the reference.

167167

Differential Scanning Differential Scanning CalorimetryCalorimetry ((DSCDSC))

In DSC, the sample and a reference material are also In DSC, the sample and a reference material are also subjected to a continuously increasing temperature, subjected to a continuously increasing temperature, hence, however, heat is added to the sample or to the hence, however, heat is added to the sample or to the reference as necessary to maintain the two at identical reference as necessary to maintain the two at identical temperature.temperature.

The added heat, which is recorded, compensates for The added heat, which is recorded, compensates for that lost or gained as a consequence of that lost or gained as a consequence of ENDOTHERMICENDOTHERMIC or or EXOTHERMICEXOTHERMIC reactions reactions occurring in the sample. occurring in the sample.

168168

Schematic of Schematic of DSCDSC InstrumentInstrument

N2 flow

Pt thermopile

Sample Reference

Pt thermopile

T1 T2

heater heaterLow mass

1 gram

W

169169

Variants of Variants of DSCDSCHeat flux DSCHeat flux DSC

1955 1955 BoersmaBoersma 1 large (30 1 large (30 100 g) furnace100 g) furnace

Power compensated DSCPower compensated DSC Separate small (1 g) Separate small (1 g) microheatersmicroheaters for sample and for sample and

referencereferenceHyper DSCHyper DSC

Very fast scan rates 500Very fast scan rates 500C/minC/min Mimic processing conditionsMimic processing conditions

StepScanStepScan DSCDSC Short dynamic and isothermal scan stepsShort dynamic and isothermal scan steps Separate reversible and irreversible effectsSeparate reversible and irreversible effects

170170

Kinds of common Kinds of common DSCDSCThere are two types of DSC

systems in common use:Power - compensation DSCHeat - flux DSC

171171

Power-compensation DSCIn power-compensation DSC the

temperatures of the sample and reference are controlled independently using separate, identical furnaces. The temperatures of the sample and reference are made identical by varying the power input to the two furnaces; the energy required to do this is a measure of the enthalpy or heat capacity changes in the sample relative to the reference.

172172

Power-compensation DSC

173173

Heat-flux DSCIn heat-flux DSC, the sample and

reference are connected by a low-resistance heat-flow path (a metal disc). The assembly is enclosed in a single furnace. Enthalpy or heat capacity changes in the sample cause a difference in its temperature relative to the reference.

174174

Heat-flux DSC

175175

Output of Output of DSCDSC

Temperature, K

Thermogram

dH/d

t, m

J/s

Glass transition

crystallization

melting

exo

endo

176176

Glass TransitionGlass Transition

Step in Step in thermogramthermogram Transition from disordered Transition from disordered

solid to liquidsolid to liquid Observed in glassy solids, Observed in glassy solids,

e.g., polymerse.g., polymers TTgg, glass transition , glass transition

temperaturetemperature

Temperature, K

Thermogram

dH/d

t, m

J/s Glass transition

Tg

177177

CrystallizationCrystallization Sharp positive peakSharp positive peak Disordered to ordered Disordered to ordered

transitiontransition Material can crystallize!Material can crystallize! Observed in glassy solids, Observed in glassy solids,

e.g., polymerse.g., polymers TTcc, crystallization , crystallization

temperaturetemperature

Temperature, K

Thermogram

dH/d

t, m

J/s

Crystallization

Tc

178178

MeltingMelting Negative peak on Negative peak on

thermogramthermogram Ordered to disordered Ordered to disordered

transitiontransition TTmm, melting temperature, melting temperature NB: melting happens to NB: melting happens to

crystalline polymers; crystalline polymers; glassing happens to glassing happens to amorphous polymersamorphous polymers

Temperature, K

Thermogram

dH/d

t, m

J/s Melting

Tm

179179

AnalysisAnalysis

Sharp positive peakSharp positive peak Disordered to ordered Disordered to ordered

transitiontransition Observed in glassy solids, Observed in glassy solids,

e.g., polymerse.g., polymers TTcc, crystallization , crystallization

temperaturetemperature

Temperature, K

dH/d

t, m

J/s

Crystallization

Tc

180180

DSCDSC Thermal transition for Polyethylene Thermal transition for Polyethylene TerephethalateTerephethalate

181181

DSCDSC ThermogramThermogram for for solfursolfur Generation of Generation of

phase phase diagrams and diagrams and the study of the study of phase phase transitiontransition

182182

DSCDSC thermogramthermogram for benzoic acidfor benzoic acid

The first peak The first peak corresponds corresponds to the to the melting melting pointpoint and the and the second to the second to the boiling boiling pointpoint..

183183

DSCDSC study of study of PhenacetinPhenacetin drugdrug

Generally, Generally, curves curves provides provides purity data purity data

184184

DSCDSC thermogramthermogram of polymeric materialsof polymeric materials

185185

DSCDSC thermogramthermogram of mixed polymersof mixed polymers

186186

Heat CapacityHeat Capacity

dqdqpp/dt/dt = heat flow= heat flowdT/dtdT/dt = heating rate= heating rate((dqdqpp/dt/dt) / () / (dT/dtdT/dt) = ) = dqdqpp/dT/dT = c= cpp

187187

Peak area in Peak area in DSCDSC The peak areas for differential The peak areas for differential thermogramsthermograms depend depend

upon the mass of the sample m, the heat or enthalpy upon the mass of the sample m, the heat or enthalpy H of the chemical or physical process, and certain H of the chemical or physical process, and certain geometric and heat conductivity factors.geometric and heat conductivity factors.

These variables are related by the equation:These variables are related by the equation:A = A = --GmGmH/K = H/K = --KKmmHH

A = peak area(A = peak area(T T time)time)G = calibration factor depend on geometry of G = calibration factor depend on geometry of samplesampleK = constant, related to thermal conductivityK = constant, related to thermal conductivityH = the enthalpyH = the enthalpym = mass of samplem = mass of sample

188188

Sine of Sine of H in H in DTADTA and and DSCDSC

Negative sine for exothermicNegative sine for exothermicPositive sine for endothermicPositive sine for endothermic

189189

Applications of differential Applications of differential methods (methods (DTADTA and and DSCDSC))

Inorganic substancesInorganic substancesOrganic compoundsOrganic compoundsPolymersPolymers

190190

What Can You Measure with What Can You Measure with DSCDSC??Qualitative analysisQualitative analysis

Fingerprinting of minerals, clays, polymersFingerprinting of minerals, clays, polymers Sample puritySample purity

Melting pointsMelting pointsHeat capacity, cHeat capacity, cppGlass transition temperature, Glass transition temperature, TTgg Crystallization temperature, Crystallization temperature, TTcc Phase diagramsPhase diagrams

191191

Where DSC is Used?Where DSC is Used?

Pharmaceutical industryPharmaceutical industry PurityPurity

Food industryFood industry Characterization of fats and oilsCharacterization of fats and oils

Polymer industryPolymer industry Synthetic blendsSynthetic blends

192192

Inorganic substancesInorganic substancesDSC, has been widely used for studies involving DSC, has been widely used for studies involving

the thermal behavior such as:the thermal behavior such as:SilicatesSilicatesFerritesFerritesClaysClaysOxidesOxidesCeramicsCeramicsGlassesGlasses

193193

Organic compoundsOrganic compoundsFor determining of the: For determining of the:

Melting PointMelting PointBoiling PointBoiling PointDecomposition PointDecomposition PointPurity of drug samples, in Purity of drug samples, in

pharmaceutical industry.pharmaceutical industry.

194194

PolymersPolymersVarious types of transitions states:Various types of transitions states:

Glass transition temperatureGlass transition temperatureCrystalline transitionCrystalline transitionSoftening PointSoftening Point

Quantitative analysis of polymer Quantitative analysis of polymer mixtures.mixtures.

195195

EnthalpimetricEnthalpimetric Methods (Methods (EPEP))

EM are of two main types: EM are of two main types: Thermometric titrationThermometric titrationDirect injection enthalpy or Direct injection enthalpy or enthalpimetricenthalpimetric

titrationtitration

196196

Thermometric titrationThermometric titrationTemperature measurement is used to Temperature measurement is used to

establish the end point.establish the end point.The analytical parameter is the volume The analytical parameter is the volume

of standard solution.of standard solution.

197197

Direct Injection Enthalpy (Direct Injection Enthalpy (DIEDIE))

An excess of reagent is added as An excess of reagent is added as rapidly as possible and resulting rapidly as possible and resulting temperature change, which is temperature change, which is directly proportional to directly proportional to analyteanalyteconcentration, is then determined.concentration, is then determined.

198198

Advantages of thermometric Advantages of thermometric titrationtitration

Wide applicability to inorganic, organic and Wide applicability to inorganic, organic and biological samples.biological samples.

They can be applied to aqueous and nonThey can be applied to aqueous and non--aqueous aqueous solutions, to gases and to molten media.solutions, to gases and to molten media.

Their speed and their ability to provide Their speed and their ability to provide fundamental thermodynamic data (fundamental thermodynamic data (H, H, S and S and G).G).

The precision is 1% relative for quantities of The precision is 1% relative for quantities of analyteanalyte in the 1 to 50 in the 1 to 50 mmolmmol range. range.

199199

Advantages of Advantages of DIEDIE They are They are fasterfasterDonDont require t require standardized reagentsstandardized reagents Possibility of Possibility of multiple serialmultiple serial determinationsdeterminations

Disadvantage:Disadvantage:Less precisionLess precision than the than the titrimetrictitrimetric procedureprocedure

200200

Principles of thermometric titrationPrinciples of thermometric titration

The observed temperature change are the The observed temperature change are the consequence of the heat evolved or absorbed by consequence of the heat evolved or absorbed by the reaction between the the reaction between the analyteanalyte and the reagent.and the reagent.

H = H = G + TG + TSS The temperature change of reaction is plotted The temperature change of reaction is plotted vsvs

volume of volume of titranttitrant (such as (such as potentiometricpotentiometric titration). titration).

201201

Comparison of Comparison of PotentiometricPotentiometric and and Thermometric titrationThermometric titration

T = T = --nnH/H/kk = Q/= Q/kk Q = total amount of heat Q = total amount of heat

evolved or absorbedevolved or absorbed n = number of moles of n = number of moles of

reactantreactant k = effective heat capacity of k = effective heat capacity of

the system the system

202202

Principles of Direct Injection Principles of Direct Injection EnthalpimetryEnthalpimetry

A recorder data is shown.A recorder data is shown. Is based upon the Is based upon the

measurement of measurement of T as: T as: T T = = --nnH/H/kk = Q/= Q/kkfollowing the addition of a following the addition of a plugplug of reagent to the of reagent to the analyteanalyte solutionsolution

203203

ApparatusApparatus Reagent delivery Reagent delivery

systemsystem Screw Screw driven driven

syringessyringes The reagent 50 to 100 The reagent 50 to 100

time more time more concentratedconcentrated

Reaction vesselReaction vessel Adiabatic condition Adiabatic condition

Temperature Temperature measurementmeasurement

ThermistorsThermistors as sensorsas sensors

204204

ApplicationsApplications

Analysis of mixturesAnalysis of mixturesEDTA reaction with EDTA reaction with

Ca is exothermic but Ca is exothermic but with Mg is with Mg is endothermicendothermic

Determination of Determination of enzyme activityenzyme activity

Study of proteins and Study of proteins and lipidslipids

205205

ThermomechanicalThermomechanical Analysis (Analysis (TMATMA))All TMA instruments consist of a means of All TMA instruments consist of a means of

applying applying stressstress in a controlled way while in a controlled way while measuring measuring strainstrain. .

Isothermal method is called Isothermal method is called ThermomchanicalThermomchanical Analysis (TMA).Analysis (TMA).

Temperature programming method is called Temperature programming method is called Dynamic Mechanical Analysis (DMA). Dynamic Mechanical Analysis (DMA).

206206

Typical StressTypical Stress--Strain CurveStrain Curve Stress: Force/areaStress: Force/area Strain:Strain:

elongation/basic lengthelongation/basic length Increase in volume/basic Increase in volume/basic

volumevolume ectect..

207207

What determinedWhat determined TgTg (glass transition temperature)(glass transition temperature) Creep behaviorCreep behavior Cure behaviorCure behavior S.P. (Softening point)S.P. (Softening point) M.P. (Melting point)M.P. (Melting point) Tension strengthTension strength Torsion strengthTorsion strength ShearShear FlexureFlexure Kinds of modulusKinds of modulus

Modulus of elasticityModulus of elasticity Modulus of rigidityModulus of rigidity Modulus of torsionModulus of torsion Modulus ofModulus of youngyoungss

208208

TMATMA apparatusapparatus

209209

Measuring principles of Measuring principles of TMATMA

Metal furnace Metal furnace assemblyassembly

Sample (coated sheet Sample (coated sheet metal)metal)

Sample holderSample holder Measuring sensorMeasuring sensor

210210

TMATMA sensorssensors

(a) Penetration(a) Penetration (b) extension(b) extension (c) flexure(c) flexure (d) (d) torsionaltorsional

measurementsmeasurements

211211

Shape of Shape of TMATMAsensorssensors

212212

Chapter 6:Chapter 6:Mass Spectrometry Mass Spectrometry

(MS)(MS)

213213

.. MSMS ... ...

.. MSMS ..

.. FTFT--MSMS .. MSMS--MS, GCMS, GC--MS, ICPMS, ICP--

MSMS .. ..

214214

IntroductionIntroduction The components of sample The components of sample

are converted to rapidly are converted to rapidly moving gaseous ions and moving gaseous ions and resolving them on the basis resolving them on the basis of their of their massmasstotochargecharge((m/zm/z or or m/em/e) ratios. ) ratios.

The The high costhigh cost of instrument of instrument and maintaining is inhibited and maintaining is inhibited their more widetheir more wide--spread use. spread use.

MS is capable of MS is capable of providing providing qualitativequalitativeand and quantitativequantitativeinformation about both information about both the the atomicatomic and and molecularmolecular composition composition of inorganic and of inorganic and organic materialsorganic materials. .

215215

Definition of mass spectrometry Mass spectrometry is the study of systems causing the

formation of gaseous ions, with or without fragmentation, which are then characterized by their mass-to-charge ratios (m/z) and relative abundances.

Unlike other forms of spectroscopy/spectrometry, mass spec purposely induces destructive interactions between molecules and electromagnetic radiation

Mass Spec is the study of the effect of ionizing energy on molecules

Mass Spec depends upon chemical reactions in the gas phase in which sample molecules are consumed during the formation of ionic and neutral species

Although sample is consumed destructively by Mass Spec, the technique is very sensitive and only trace amounts (picomoles) of material are used in the analysis

216216

Historical DevelopmentHistorical Development

1906 J.J. Thomson (the 1906 J.J. Thomson (the behavior of positive ions behavior of positive ions in magnetic and in magnetic and electrostatic fields).electrostatic fields).

1940 commercial sources 1940 commercial sources were designed specially were designed specially for the quantitative for the quantitative determination of the determination of the components of the components of the complex hydrocarbon complex hydrocarbon mixtures in the mixtures in the petroleum petroleum industryindustry. .

1950 commercial MS 1950 commercial MS were developed for the were developed for the qualitative and qualitative and quantitative of the quantitative of the elements based on the elements based on the m/zm/zof elementary ions formed of elementary ions formed in an electric spark.in an electric spark.

1960, MS shifted towards 1960, MS shifted towards its use for the its use for the identification and identification and structural analysisstructural analysis of of complex molecules.complex molecules.

Recently, the MS is used Recently, the MS is used for for surfaces analysis.surfaces analysis.

Finally, Finally, detectordetector for GC for GC and LC. and LC.

217217

Components of MSComponents of MS

218218

The Components of a Mass Spectrometer

219219

General Description of MS componentsGeneral Description of MS components

Sample inlet system is Sample inlet system is introduced the sample into the introduced the sample into the ion source with minimal loss of ion source with minimal loss of vacuum.vacuum.

Batch inlet Batch inlet Direct probe inletDirect probe inletGC inletGC inletLC inletLC inlet

Ion source is served to convert Ion source is served to convert the sample into charged the sample into charged particles (positive and particles (positive and negative) but the negative ion negative) but the negative ion is removed.is removed.

Mass analyzer is a dispersive Mass analyzer is a dispersive device as same as device as same as prismprism or or gratinggrating in an optical in an optical spectrometerspectrometer. .

DetectorDetectorFaraday CupFaraday CupSolidSolid--state electron state electron

multipliermultiplierIonIon--Sensitive Sensitive

photographic plates.photographic plates. Signal ProcessorSignal Processor ReadRead--outout

220220

Fragmentation of Methane in Ionization Fragmentation of Methane in Ionization sourcesource

CHCH44 +e+e CHCH44++ + 2e+ 2eCHCH33++ + H+ H + 2e+ 2eCHCH22++ + 2H+ 2H + 2e+ 2eCHCH++ + 3H+ 3H + 2e+ 2eCC++ + 4H+ 4H + 2e+ 2eCHCH33 + H+ H++ + 2e+ 2e

221221

Batch inlet systemBatch inlet system

222222

The direct probe inletThe direct probe inletNonvolatile liquids, Nonvolatile liquids,

Thermally unstable Thermally unstable compounds, and Solids compounds, and Solids are introduced by a are introduced by a sample probe, which is sample probe, which is inserted through a inserted through a vacuum lock.vacuum lock.

Spectra can be Spectra can be obtained a few minutes obtained a few minutes after sample after sample introduction.introduction.

The sample is held on The sample is held on the surface of a glass the surface of a glass capillary tube, a fine capillary tube, a fine wire, or a small cap.wire, or a small cap.

Carbohydrates, Carbohydrates, steroids, metalsteroids, metal--organic organic species, and lowspecies, and low--molecular polymers molecular polymers can be analyzed. can be analyzed.

223223

Chromatographic Inlet SystemChromatographic Inlet System A chromatographic A chromatographic

column can conveniently column can conveniently serve as a sample source.serve as a sample source.

A major problem in A major problem in interfacing a GC with a interfacing a GC with a MS arises from the MS arises from the presence of the carrier gas, presence of the carrier gas, which dilutes the eluted which dilutes the eluted components. components.

224224

Sample Introduction Systems 1) Gas source (lighter elements) dual inlet - sample purified and

measured with standard gas at identical conditions precisions ~ 0.005% continous flow - sample volatized and purified (by EA or GC) and injected into mass spec in He carrier gas, standards measured before and after, precisions ~ 0.005-0.01%

2) Solid source (heavier elements) TIMS - sample loaded onto Re filament, heated to ~1500C, precisions ~0.001% laser ablation -sample surface sealed under vacuum, then sputtered with laser precisions ~0.01%?

3) Inductively coupled plasma (all elements, Li to U) ICPMS -sample converted to liquid form, converted to fine aerosol in nebulizer, injected into ~5000K plasma torch

225225

Ion sources for molecular studiesIon sources for molecular studiesNameName Abbr.Abbr. TypeType Ionizing AgentIonizing AgentElectron IonizationElectron IonizationField IonizationField IonizationChemical IonizationChemical IonizationField Field DesorptionDesorptionFast Atom BombardmentFast Atom BombardmentSecondary Ion MSSecondary Ion MSPlasma Plasma DesorptionDesorption

Thermal Thermal DesorptionDesorptionLaser Laser DesorptionDesorptionElectrohydrodynamicElectrohydrodynamicIoni