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.