INFRARED-MICROWAVE TWO-PHOTON SPECTRA IN THE $\nu_{4}$ AND $\nu_{6}$ BANDS OF $CD_{2}CO^{*}$
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Date
1983
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Ohio State University
Abstract
Infrared-microwave two-photon spectra in the $980 cm^{-1}$ region have been obtained for the asymmetric tip molecule $CD_{2}CO$. The radiation sources are a $CO_{2}/N_{2}O$ cw laser and backward wave oscillators operating in the 8-18 GHz region. The microwave radiation is amplified to $\sim$20 watts by means of a traveling wave tube amplifier. The microwave frequency is stepped and the spectrum is recorded by a laboratory computer. Two-photon transitions have been observed for the $\nu_{4}$ and $\nu_{6}$ bands of $CD_{2}CO$. Initial assignments were based on the results of an infrared laser Stark $study.^{1}$ The $\nu_{6}$ two-photon transitions have been observed in a sample cell outside the laser cavity. The $\nu_{4}$ transitions are considerably weaker and were observed with an in-cavity cell. A computer program has been implemented for theoretical calculation of the intensities of infrared-microwave two-photon transitions for an asymmetric top molecule. The calculation is complicated by the existence of many possible intermediate states and by the necessity of many summations over M components. The computational procedure will be described briefly. $^{*}$This work was supported by the National Science $Foundation.^{1}$D. Coffey, JR., C. Yamada, and E. Hirota, J. Mol. Spectrosc. 64, 98-108 (1977).
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Author Institution: Department of Chemistry, Michigan State University East Lansing