prashanth upadhya, yao-chun shen, giles davies & edmund linfield terahertz time-domain...

Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield Prashanth Upadhya, Yao-Chun Shen, Giles Davies & Edmund Linfield

Terahertz Time-Domain Spectroscopy ofTerahertz Time-Domain Spectroscopy ofGlucose and Uric Acid Glucose and Uric Acid

Cavendish Laboratory, Cambridge UniversityCavendish Laboratory, Cambridge University

IntroductionIntroduction

ExperimentExperiment

Far-infrared absorptionFar-infrared absorption

Glucose and sucroseGlucose and sucrose

Uric Acid & its derivativeUric Acid & its derivative

Temperature & structural dependent absorptionTemperature & structural dependent absorption

ConclusionsConclusions

ContentsContents

IntroductionIntroduction

many intrinsic resonances predicted in the THz regime many intrinsic resonances predicted in the THz regime vibrational modes in polynucleotidesvibrational modes in polynucleotides … …Powell et al Powell et al

base twisting and librational modes in DNA structurebase twisting and librational modes in DNA structure …… Young et alYoung et al

low frequency collective vibrational modes low frequency collective vibrational modes distinguish between different isomeric configurations in retinal moleculesdistinguish between different isomeric configurations in retinal molecules … …Walther et al Walther et al

finger print of conformational state – benzoic acidfinger print of conformational state – benzoic acid ……Walther et al Walther et al

Vacuum capable THz-TDS set-upVacuum capable THz-TDS set-up

useful bandwidth of 0.1- 3.0 THz useful bandwidth of 0.1- 3.0 THz

spectral resolution of better than 1 cmspectral resolution of better than 1 cm-1-1

Sample preparationSample preparation

pellets (1.2-1.4mm) with matrix for low temperature pellets (1.2-1.4mm) with matrix for low temperature measurements measurements (polyethylene:sample::8:1)(polyethylene:sample::8:1)

pure sample pellets ( 0.3- 0.7mm) for room temperaturepure sample pellets ( 0.3- 0.7mm) for room temperature measurement – to observe distinct peaks measurement – to observe distinct peaks

Particle size – ESEM measurementParticle size – ESEM measurement

Submicron particle size – minimise scattering effect on Submicron particle size – minimise scattering effect on observed spectraobserved spectra

Far-infrared absorption in GlucoseFar-infrared absorption in Glucose

0.5 1.0 1.5 2.0 2.5

0

10

20

30

40

50

60

Abs

orpt

ion

(a.u

.)

Frequency (THz)

D-Fructose L-Glucose D-Glucose

Far-infrared absorption in GlucoseFar-infrared absorption in Glucose

D-GlucoseD-Glucose

L-GlucoseL-Glucose

D-FructoseD-Fructose

0.5 1.0 1.5 2.0 2.5

0

10

20

30

40

50

60

Abs

orpt

ion

(a.u

.)

Frequency (THz)

D-Fructose L-Glucose D-Glucose

Dependence on crystallanityDependence on crystallanity

0.5 1.0 1.5 2.0 2.5 3.0

0

5

10

15

20

25

Abs

orpt

ion

(a.u

.)

Frequency (THz)

Crystalline Solution

Intermolecular vibrational modesIntermolecular vibrational modes

Absorption in molecule containing glucose Absorption in molecule containing glucose structurestructure

0.5 1.0 1.5 2.0 2.5 3.0

0

5

10

15

20

25

Abs

orpt

ion

(a.u

.)

Frequency (THz)

Sucrose L-Glucose

Absorption in molecule containing glucose Absorption in molecule containing glucose structurestructure

absorption tend to depend on molecular absorption tend to depend on molecular environmentenvironment

L-GlucoseL-Glucose

SucroseSucrose

0.5 1.0 1.5 2.0 2.5 3.0

0

5

10

15

20

25

Abs

orpt

ion

(a.u

.)

Frequency (THz)

Sucrose L-Glucose

0.0 0.5 1.0 1.5 2.0 2.5 3.00

5

10

15

20

25

30

35

300K

204K

103K

4K

Abs

orpt

ion

(a.u

.)

Frequency (THz)

L-Glucose - absorption peaks at low temperatureL-Glucose - absorption peaks at low temperature

many distinct absorption peaks at low temperaturemany distinct absorption peaks at low temperature

We observed terahertz absorption as a We observed terahertz absorption as a result of intermolecular interactionresult of intermolecular interaction

&&

also dependence on structural change in a also dependence on structural change in a moleculemolecule

……… ……… in other molecules? in other molecules?

Far-infrared absorption in Uric AcidFar-infrared absorption in Uric Acid

0.5 1.0 1.5 2.0 2.5 3.0

0

5

10

15

20

Abs

orpt

ion

(a.u

.)

Frequency (THz)

Uric Acid Allantoin

Far-infrared absorption in Uric AcidFar-infrared absorption in Uric Acid

Uric AcidUric Acid

AllantoinAllantoin

structural dependence of absorptionstructural dependence of absorption

0.5 1.0 1.5 2.0 2.5 3.0

0

5

10

15

20

Abs

orpt

ion

(a.u

.)

Frequency (THz)

Uric Acid Allantoin

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0

5

10

15

20

25 300K

205K

98K

4K

Abso

rptio

n (

a.u

.)Frequency (THz)

0.0 0.5 1.0 1.5 2.0 2.5 3.0-5

0

5

10

15

20

25

30

35

40

300K

200K

100K

4k

Abs

orpt

ion

(a.u

.)

Frequency (THz)

Temperature dependenceTemperature dependence

stronger temperature dependence in allantoinstronger temperature dependence in allantoin

change in energy surfaces of molecules at low temperaturechange in energy surfaces of molecules at low temperature

AllantoinAllantoinUric AcidUric Acid

Uric Acid - absorption line profileUric Acid - absorption line profile

change in position and width of peaks with change in position and width of peaks with temperature temperature

ConclusionsConclusions

Demonstrated use of THz-TDS to study far-infrared Demonstrated use of THz-TDS to study far-infrared response of some isomeric and derived structures of response of some isomeric and derived structures of glucose and uric acidglucose and uric acid

Observed absorption due to collective Observed absorption due to collective intermolecular modesintermolecular modes

Strong temperature and structural dependence of Strong temperature and structural dependence of absorptionabsorption

Theoretical model analysis required to understand Theoretical model analysis required to understand the underlying dynamics the underlying dynamics

AcknowledgementsAcknowledgements

EPSRCEPSRC

Royal Society Royal Society

Toshiba Research EuropeToshiba Research Europe

Association of Commonwealth UniversitiesAssociation of Commonwealth Universities

and thanks toand thanks to

Dr. M. B. JohnstonDr. M. B. Johnston

Dr. A. DowdDr. A. Dowd