Molecular Orbitals for Polyatomic Molecules Polyatomic Spectroscopy

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Molecular Orbitals for Polyatomic
MoleculesPolyatomic Spectroscopy

• Fred J. Grieman

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CH4 Previous Localized Model
? - delocalized orbitals
2 different energies
not 4 localized bonds
of equal energy
4 equivalent bonds sCH C(sp3) H(1s) All of
the same energy. What would the Photoelectron
Spectrum look like? 1 band at 1 energy.
CH4 Photoelectron Spectrum
Spartan Calculation
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Some other molecules showing delocalized orbitals

• BeH2
• H3
• Ethene
• Allyl
• Benzene
• Water

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Polyatomic Spectroscopy
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(vi ½) ??i
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Normal Coordinates in Diatomic Molecules
Q
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CO2 Example

• Spartan Vibrational Mode Calculation

Higher resolution spectra
Notice in Spartan spectrum No symmetric
stretch!!
Asymmetric stretch Bends
Change in dipole moment with respect to molecular
axis
Parallel Band Perpendicular Band
?J 1
?J 1, 0
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