A microwave double resonance study of collision-induced transitions between the M components of a rotational transition of OCS

Four-level MW–MW double resonance experiments on the rotational Stark levels M=0 and M±1 of the OCS j=1→2 transition have been performed to investigate collision-induced population transfer due to OCS self-collisions. A MW bridge has been used as a filter in order to discriminate between the pump and signal radiation and the relative change of signal line intensity η has been determined for both M components by means of a double modulation technique. A two-level Bloch-type description of the signal transition is given to estimate additional effects of the off-resonant pump radiation in the absence of collisions.