There will be a seminar this Monday for a Physical Chemistry teaching position. It's really important that they get student feed back, so please attend if you can! Thanks! Department of Chemistry Candidate –Physical Chemistry Position “Analysis of High-Resolution Vibrational-Rotational Spectra of Simple Polyatomic Molecules” by Dr. Tony Masiello, Postdoctoral Research Associate Pacific Northwest National Laboratory Monday, December 5, 2005 1:00 – 1:50 p.m. S2-108 Abstract Spectroscopy is the major experimental tool that allows for the precise determination of bond strengths, lengths and angles which in turn leads to an under-standing of molecular dimensions, shapes and reactivity. In addition to structural investigations, spectroscopy can be used to find the chemical composition of a sample, follow the changes in a chemical reaction or manipulate whole molecules or functional groups. Because the strength of the absorption features is dependent upon the tempera-ture at which the spectra are obtained, one can use modeling to deduce temperatures. This latter application requires knowledge of the rotational-vibrational quantum numbers for the observed transitions, one of the goals of spectroscopic research. This presentation will detail the results of a comprehensive investigation of the spectroscopic properties of sulfur trioxide, an important participant in reactions in the upper atmosphere. The fundamental vibrational modes and several hot bands of the 34S and 18O isotopic variants of SO3 have been investigated using high-resolution infrared spectroscopy and coherent anti-Stokes Raman scattering. For all of the isotopic variants, the Raman-active symmetric stretching mode 1 displays complex Q-branch patterns due to indirect couplings with infrared-inactive 2, 4 combination and overtone levels. Essential to modeling the interactions of these levels with 1 is the understanding of the fundamental vibrations that make up these levels.