HIGH RESOLUTION ROVIBRATIONAL SPECTRA OF FIVE-MEMBERED RINGS WITH HETEROATOMS: NEW RESULTS FROM THE FAR-INFRARED BEAMLINE OF THE CANADIAN LIGHT SOURCE
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Date
2007
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Ohio State University
Abstract
The ground state spectra and structures of five-membered ring molecules like pyrrole, furan and thiophene are well established via microwave spectroscopy. Some rotationally-resolved studies of the vibrational bands of these molecules have previously been conducted at high resolution by Fourier transform and infrared diode laser spectroscopy; however, the data obtained via Fourier transform spectroscopy suffers in quality due to the low light flux of conventional light sources (particularly at frequencies lower than 600 cm$^{-1}$), and due to the requirement that the entrance iris be very small to obtain spectra at high resolution. We report new rotationally-resolved vibrational spectra of five-membered ring molecules using the intense, spatially-confined infrared light produced by the Canadian Light Source synchrotron, which we have coupled into a Bruker IFS125 Fourier transform spectrometer. Spectra of exceptionally high quality were taken at the full resolution of the instrument (0.001 cm$^{-1}$), both with the synchrotron source (400-700 cm$^{-1}$) and the internal globar source (700-1000 cm$^{-1}$). Comparisons of the 400-700 cm$^{-1}$ spectra with those taken with a conventional globar source are given, and analysis of the rotational structure of these bands is presented.
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Author Institution: Department of Physics and Centre for Laser, Atomic, and Molecular Sciences, University of New Brunswick, Fredericton, Canada E3B 5A3; Department of Chemistry, University of Manitoba, Winnipeg, MB, Canada R3T 2N2