Velocity changing collisions in the laser saturation spectra of 87Rb D 2 F″ = 2

Abstract

The saturation absorption technique is applied to the 87Rb 2S 1/2 F″ = 2 → 2P 3/2 F′ = 1, 2 and 3 transitions to study the effect of velocity changing collisions (VCC). The VCC caused Doppler pedestal increases with argon pressure from 0 to 110 mTorr and decreases with modulation frequencies of 700–3200 Hz. The resonances of the velocity selective, saturated optical pumping are washed out for pressure of 110 mTorr. The magnitude of the Doppler pedestal relative to the homogeneous features, yields a rate for velocity changing collisions of 6.5 ± 0.2 × 10 −10 cm 3 s −1.