Time-resolved UV-IR Pump-stimulated Emission Pump Spectroscopy: Probing Collisional Relaxation of $8p^{2}P_{3/2}$ 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 $8p^{2}P_{3/2}$ cesium atoms were produced by a pump laser. A second laser, the stimulated emission pump, promoted the population exclusively to the $5d^{2}D_{5/2}$ level. The intensity of the $5d^{2}D_{5/2}\rightarrow6s^{2}S_{1/2}$ cascade fluorescence at $852.12\: nm$ was monitored. The linear polarization dependence of the $6s^{2}S_{1/2}\rightarrow8p^{2}P_{3/2}\rightarrow5d^{2}D_{5/2}$ transition was measured in the presence of argon gas at various pressures. From the measurement, we obtained the disalignment cross section value for the $8p^{2}P_{3/2}$ level due to collisions with ground-level argon atoms.