MICROWAVE DOUBLE RESONANCE COLLISIONAL SPECTRA FOR OCS $J = 2\leftarrow 1$ FOUR-LEVEL SYSTEMS

$^{1}$T. Oka, Adv. At. Mol. Phys. 9. 127 (1973)Author Institution:Collisional transfer of rotational energy in OCS has been investigated by microwave double resonance for various M-resolved and zero-field four-level systems involving the $J = 2\leftarrow 1$ transition in the ground and first excited bending states. As reported $previously,^{1}$ the signs of the fractional signal intensity changes $\Delta I/I$ for the pure gas show that dipolar, parity-changing collisional transitions are preferred. For mixtures of OCS with excess $He, H_{2}$ and $D_{2}, \Delta I \simeq 0$ for the ground vibrational state, indicating no collisional preferences. For the $\ell$-doubled $v_{2}=1$ excited bending state, $\Delta I/I$ changes sign for the zero-field system in going from the pure gas to the $He, H_{2}$ and $D_{2}$ mixtures, revealing that parity-conserving $\Delta J = \pm 1$ transitions are preferred over the $\Delta J = 0$ intra-doublet parity-changing transitions