C566lecture10_000

C566lecture10_000 - C566 Master Lecture Notes Lecture 10...

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C566 Master Lecture Notes Lecture 10 Bottom line vibrational selection Rules 1. (Q i ) = (T x ), (T y ) or (T z ) 2.  = 1 (harmonic oscillator) 3. One mode changes at a time (normal coordinates) Example : NH 3 (T z ) = a 1 (so NH 3 has a permanent dipole); (T y , T x ) = e. For a 1 stretch absorption, what is the direction of the transition moment? For e stretch, what is the direction of the transition moment? Brief Raman overview: Many vibrational modes are “dark” with respect to IR absorption, but “bright” with respect to Raman. [Raman is a low-signal technique, but much easier to handle visible light than IR] induced =  E where is a 3 x 3 tensor Transforms as xx, xy, xz, etc. in character table H = E induced = E  E Bottom line selection rules: Diatomics 1.  = 1 (+1 are stokes, -1 are antistokes lines) 2. J = 0, 2 3. No permanent dipole moment required Polyatomics 1.  i = 1 (+1 are stokes, -1 are antistokes lines) for symmetry allowed vibrations
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This note was uploaded on 01/18/2012 for the course C 566 taught by Professor Carolinechickjarroll during the Spring '11 term at Indiana.

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C566lecture10_000 - C566 Master Lecture Notes Lecture 10...

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