Optical-optical double resonance circular polarization spectroscopy: Measurement of the disorientation cross section in 6p2P1/2 Cs atoms

We have measured the cross section for the disorientation of excited 6p2P1/2133Cs atoms by collisions with ground state Ar atoms by optical-optical double resonance circular polarization spectroscopy. Circular polarization spectra were measured for the 6s2S1/2→ 6p2P1/2→ 10s2S1/2 transition. Orientation was optically induced in the 2P1/2 state by circularly polarized light. A polarization degree was measured when two pulsed lasers were circularly polarized with the same helicities and opposite helicities, respectively. The intensity of the cascade fluorescence signal, monitored from the 9p2P1/2→ 6s2S1/2 transition at 361.73 nm, was analyzed in the presence of Ar pressures ranging from 7 mbar to 133 mbar. This is a direct measure of the importance of the orientation to inelastic process in alkali rare-gas collisions. A disorientation cross section value of 9.25 (1.4) Å2 was extracted from the measurements. Our result is in good agreement with the theoretical and experimental predictions within the error limits.

► Measured orientation-dependent circular polarization spectrum. ► Measured collisional cross section of the J=12 excited cesium atoms in collision with argon atoms. ► Experimentally investigate the orientation-dependent inelastic process in alkali rare-gas collisions. ► Used the first time a two-step pump-probe laser technique to make such measurements.