Time-resolved UV-IR pump-stimulated emission pump spectroscopy to probe collisional relaxation of $8p{}^2{P}_{3\mathrm{/}2}$ Cs I

We describe and use a time-resolved pump-stimulated emission pump spectroscopic technique to measure collisional relaxation in a high-lying energy level of atomic cesium. Aligned $8p{}^2{P}_{3\mathrm{/}2}$ cesium atoms were produced by a pump laser. A second laser, the stimulated emission pump, promoted the population exclusively to the $5d{}^2{D}_{5\mathrm{/}2}$ level. The intensity of the $5d{}^2{D}_{5\mathrm{/}2}\to 6s{}^2{S}_{1\mathrm{/}2}$ cascade fluorescence at 852.12 nm was monitored. The linear polarization dependence of the $6s{}^2{S}_{1\mathrm{/}2}\to 8p{}^2{P}_{3\mathrm{/}2}\to 5d{}^2{S}_{5\mathrm{/}2}$ transition was measured in the presence of argon gas at various pressures. From the measurement, we obtained the disalignment cross section value for the $8p{}^2{P}_{3\mathrm{/}2}$ level due to collisions with ground-level argon atoms.