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