ABSORPTION SPECTRUM OF SILICON DIFLUORIDE
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Date
1966
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Emission spectra of the $SiF_{2}$ molecule in the ultraviolet have been obtained by Johns, Chantry and Barrow, [Trans, Far. Soc. 54, 1589 (1958)] and by Rao and Venkateswarlu (Jour. Mol. Spectroscopy 7, 287 (1961)]. Infrared absorption spectra of $SiF_{2}$ isolated in rare-gas matrices at $20-50^{\circ}K$ have been reported [J. M. Bassler, P. L. Timms and J. L. Margrave, Inorg, Chem. 5, 729 (1966)] and also, the microwave absorption spectrum [V. M. Rao, R. F. Curl, P. L. Timms and J. L. Margrave, J. Chem. Phys, 43, 2557 (1965)]. The analysis of the emission bands seemed, however, to be in error and thus, a detailed investigation of the ultraviolet absorption spectrum in the region 2400-2100\AA was undertaken. In the present studies the compound was generated at high temperatures and pumped continuously through the absorption cell during the measurements. The absorption spectrum recorded clearly shows the existence of a progression and extends further on the high frequency side than the detection limit of $2178{\AA}$ reported by earlier workers. The bands are found to fit into a series of progressions from the ground level (000) to (0v1/20), i.e., a progression with successive excitation of the bending vibration in the upper electronic state. Also a number of weak bands arising from the vibrationally-excited lower state are observed. This existence of a long progression involving bending frequency suggests that the apex angle of the molecule has changed considerably during transition. The bending frequency obtained for the lower electronic state is $345 cm^{-1}$, while that for the upper electronic state is $253 cm^{-1}$ in contrast to the values of $427 cm^{-1}$ and $342 cm^{-1}$ for the lower and upper states reported by Rao and Venkateswarlu. The microwave spectrum led to a bending frequency of $343 cm^{-1}$.
Description
Author Institution: Department of Chemistry, Rice University Houston, Texas, 77001