INFRARED-MICROWAVE TWO-PHOTON SPECTROSCOPY OF THE $\nu_{2}$ BAND OF $NH_{3}$ AND THE $\nu_{3}$ BAND OF $CH_{3}F.^{*}$
Loading...
Date
1981
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
A computer-controlled infrared-microwave two-photon spectrometer with sample cells outside the laser cavity has been used to record two-photon transitions in the $\nu_{2}$ bands of $^{14}NH_{3}$ and $^{15}H_{3}$ and in the $\nu_{3}$ band of $CH_{3}F$. By fitting the lineshapes to an approximate lineshape expression, it has been found possible to determine the line centers to a precision of a few tenths of a MHz $(\sim 0.00001 \mbox{cm}^{-1})$. The absolute accuracy of the frequencies is approximately 10 times poorer as a result of fluctuations in the frequency of the laser stabilized to the maximum of the laser gain curve. Because of the broad-band characteristics of the sample cells and phase-locked microwave sources, the spectra are close to theoretical lineshapes. The $^{14}NH_{3}$ data have been fit separately and together with previous two-photon $data^{1,2}$ to a simple rotation vibration Hamiltonian. Inversion frequencies in the lower state obtained by microwave $spectroscopy^{3}$ and in the upper state obtained by millimeter-wave $spectroscopy^{4}$ were assumed. The results of a number of fitting procedures will be reported. The two-photon frequencies obtained for $CH_{3}F$ and the parameters obtained by fitting to a simple Hamiltonian will also be presented.
Description
$^{*}$This work was supported by the National Science Foundation. $^{1}$ S. M. Freund and T. Oka, Phys. Rev. A13, 2178 (1976). $^{2}$ H. Jones, Appl. Phys. 15, 261-264 (1978). $^{3}$ R. L. Poynter and R. K. Kakar, Astrophysical J. Supp. Ser. 29, 87 (1975). $^{4}$ S. Urban, V. Spirko, D. Papousek, R. S. McDowell, N. G. Nereson, S .P. Belov, L. I. Gershstein, A. V. Maslovsky, A. F. Krupnov, J. Curtis and K. Narahari Rao, J. Mol. Spectrosc. 79, 455-495 (1980).
Author Institution:
Author Institution: