CO2and CO laser microwave double resonance spectroscopy of OCS: Precise measurement of dipole moment and polarizability anisotropy

摘要

Laserndash;microwave double resonance (LMDR) with high electric field was applied to the OCS molecule. Stark Lambhyphen;dip spectra due to the infrared transitions of the 2ngr;2(0200ndash;0000, 9.6 mgr;m), 2ngr;1(2000ndash;0000, 5.8 mgr;m), and ngr;1+2ngr;2(1200ndash;0000, 5.3 mgr;m) bands were observed with the CO2and CO lasers. The spectra due to the corresponding hot bands; 0310ndash;0110, 0400ndash;0200, 1200ndash;1000, 1310ndash;1110; 2110ndash;0110, 3000ndash;1000; 1400ndash;0200, 1420ndash;0220, 1510ndash;0310, 2200ndash;1000; and a few bands of OC34S and O13CS were also identified. Associated with these infrared transitions, more than 90 LMDR signals were detected and assigned to rotational transitions in the 11 vibrational states 0000, 1000, 2000, 0110, 0200, 0220, 0310, 0400, 1200, 1420, and 2200 of the normal species, and in the two vibrational states 0000 and 0200 of both OC34S and O13CS. Dipole moments were determined with accuracies (2.5sgr;) better than 2times;10minus;5D for all these vibrational states. Polarizability anisotropies were also obtained for some states. The data for the ground ngr;1and ngr;2vibrational states are, with the 2.5sgr; uncertainties in parentheses.From the Stark Lambhyphen;dip spectra the origins of various vibrational bands were determined, among which those for the 0200ndash;0000 and 0310ndash;0110 bands are 31thinsp;389thinsp;530.4(25) and 31thinsp;566thinsp;477.57(67) MHz, respectively. The dipole moments and band origins obtained in the present study agree well with the available accurate values from molecular beam electric resonance and heterodyne measurement, respectively. A procedure for the calibration of electric field in laser Stark and double resonance spectroscopy, in which the dipole moment of OCS is used as the standard, is described.