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    Introduction to OrganicSpectoscopy

    Dr. Joy Granada HofilenaAugust 7, 2010

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    Review of Some BasicsReview of Some Basics c = R x P

    Angular resolution: U = 1.22 P / D radians

    206,265 in a radian

    E = h R

    F = L / 4 T d2

    AZ, El, RA, Dec, Ecliptic, Galactic

    Siderial time, Hour AngleG = 6.67 x 10-8 (c.g.s)

    c = 3 x 1010 cm/sec,

    k = 1.38 x 10-16

    h = 6.626 x 10-27

    mH ~ mproton = 1.67 x 10-24 gramsme = 0.91 x 10

    -27 grams

    eV = 1.602 x 10-12 erg

    Luminosity of Sun = 4 x 1033 erg/sec

    Mass of the Sun = 2 x 1033 grams

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    The Physics of EM RadiationThe Physics of EM Radiation

    Light: PR- PR = c = 2.998 x 1010 cm/s (in vacuum)

    - E = hR

    Photon energy (erg)

    1 erg sec-1 = 10-7 Watt

    h = 6.626 x 10-27 (c.g.s)

    1 eV = 1.602 x 10-12 erg

    - p = E / c = h / PPhoton momentum- P = h / p = h / mv deBroglie wavelength

    Planck Function: BR(T)

    Emission, absorption, continua

    Discrete energy levels: Hydrogen

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    Telescope

    Focal Plane

    Slit

    Spectrograph

    SpectrographSpectrograph

    collimator

    Dispersing element

    camera

    detector

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    Refraction:Refraction:

    Snells Law: n1 sin(H1) = n2 sin(H2)

    H2

    H1 n1

    n2

    n1 = refractive index in region 1

    n2 = refractive index in region 2

    n = c / v = Pvacuum / Pmedium

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    Diffraction:Diffraction:

    Light spreads as U = P / dIn the far field given by L = d2 / P

    d

    L

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    2 slit interference

    Constructive

    Destructive

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    Types of Spectra:

    Nebulae

    Stars

    Hot,

    Opaquemedia

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    EMR

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    Materials responseto radiation or particles

    Valence electrons

    Core electrons

    Atoms/molecules

    E&M radiation interacts with materials becauseelectrons and molecules in materials are polarizable:

    (refraction, absorption)

    = n+ i k

    n = refraction, k= absorption

    Ions, electrons and atoms incident on materials can interact with materials because

    they are either charged or can scatter from atomic cores

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    Techniques and information content

    Molecular

    Libration

    (hindered rotations)

    Molecular

    vibrations

    Electronic

    Absorption

    Valence band and

    shallow electronic

    levels (atoms)

    Deep electronic

    core levels (atoms)

    Microwave,

    THz

    Infrared,

    Raman,

    EELSVisible

    Fluorescence

    Luminescence

    UV absorption

    UV photoemission

    Electron lossX-ray photoemission

    (XPS, ESCA)

    Auger Electron (AES)

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    No. of molecular vibrations:

    Where : n = no. of atoms

    C3H8= 3(11) - 6

    = 27

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    Fundamental vibrations

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    Linear CO2

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    For CH2groups

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    Other linear molecules

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    HookesL

    aw

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    Harmonic oscillator

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    Energy curve of a vibrating bond:

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    T

    he IR

    spectrum:

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    A

    nimations:

    Introduction to IRspectroscopy

    The theory of IRspectroscopy

    Sample IRspectra of molecules

    E:\Organic Chemistry Software\PC_IR_Tutor

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    octane

    CH3CH2CH2CH2CH2CH2CH2CH3

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    CH3CH2CH2CH2C CH

    1-hexyne

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    sec-butyl alcohol

    benzyl alcohol

    A Comparison of Aliphatic and Aromatic Alcohols

    CH3CHCH2CH3

    OH

    CH2-OH