Vibrational spectroscopy: structure determination

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Vibrational spectroscopy structure determination
Marisa Monreals office hours are changed today
only to 3 - 4 pm in 3515 MSB.
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Centrosymmetric point groups
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Spectroscopy and the structure of non-linear
molecules
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General observations

• IR-active modes can be distributed among no more
  than 3 symmetrical species. Raman-active modes
  can be distributed among as many as 4 symmetrical
  species.
• The rule of mutual exclusion In
  centrosymmetrical point groups (have i), unit
  vectors transform as ungerade and direct products
  as gerade IR-active modes will be Raman inactive
  and vice-versa.
• It is possible to have some NMVs that cannot be
  observed as fundamentals in either IR or Raman
  silent modes.
• The totally symmetrical representation is
  associated in every point group with one or more
  direct product transformations NMVs that are
  totally symmetrical will always be Raman active.

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mer and fac-ML3(CO)3
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XeO3F2
The IR spectrum of XeO3F2 shows one Xe-O stretch
and one Xe-F stretch. Propose a shape for this
molecule consistent with these observations.
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