Studies of collisional selection rules in thioformaldehyde (H2CS) by microwave-optical double resonance.
Individual rotational levels in the A 1A2,v4=1 state of thioformaldehyde (H2CS) are excited by a cw laser and microwave transitions in the region of 8-12 GHz are measured. Some of the microwave frequencies are found to be characteristic of rotational levels other than the level being pumped. Since the microwave frequencies are characteristic of individual rotational levels in the excited state and the excited-state lifetime is approximately 170 micros, information is obtained concerning rotational selection rules during collisions. It is found that J can change by several units and Ka by 0, +/-2, +/-4, and +/-6. The latter result confirms that o-H2CS is not converted to p-H2CS by collisions. Observation of Ka doublets indicates that there are no appreciable differences between the two components.
Barnett
M
M
Steacie Institute of Molecular Sciences, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada. mbarn@superaje.com
Ramsay
D A
DA
Zhu
Q
Q