[MOS] MOS Seminar Tuesday, October 21, 2014 ( Schedule Change )

[Luis H Galindo]

MOS seminar with Barratt Park, originally scheduled for October 21, has been moved to a Physical Chemistry Seminar for this day only. So the seminar will take place at 4:30 PM in Room 6-120 with refreshments at 4:00 PM in the Amdur Room, 6-233.

Seminar on
Modern Optics and Spectroscopy

 "Princesses and Peas: Why are molecules in a tizzy about subtle bumps and curves along the reaction coordinate?"
Barratt Park,
Massachusetts Institute of Technology

Tuesday, October 21, 2014
4:30 p.m.
How does a change in molecular point group accompanying an electronic excitation allow the molecule to tell us what it is up to? My talk will focus on the high-resolution laser spectroscopy of sulphur dioxide (SO2) and acetylene (C2H2). The C̃ state of SO2 has a small barrier at the C2v geometry, so it prefers non-equivalent bond lengths (Csgeometry). The barrier causes a staggering in the antisymmetric stretch overtones with even vs. odd vibrational quanta. We have made the first direct observation of the odd (b2) levels, which allows us to directly characterize the asymmetry. The results are analyzed in terms of a diabatic vibronic coupling model, and the relevance to the SO2 photodissociation dynamics will be discussed. Acetylene also undergoes a change of point group upon excitation from the linear X̃ state (D∞h) to trans-bent à state (C2h). A simplified (and more restrictive!) set of Franck-Condon propensity rules for the Ã→X̃ emission spectrum will be discussed. When understood using a simple model, the intensity patterns in the spectra are a direct observation of the bright state wavepacket and the interactions that arise from the acetylene ⇄ vinylindene and cis ⇄ trans isomerizations that occur on the X̃ and à potential energy surfaces, respectively.

 MIT, Bldg 6-120
Refreshments served after the lecture
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This is an email distribution list for regular email announcements regarding the Modern Optics and Spectroscopy lecture series (MOS).
This series is co-sponsored by the MIT Laser Biomedical Research Center, the Department of Chemistry, the Department of Electrical Engineering and Computer Science, and School of Science, MIT.
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