Temperature and excitation power influence on the velocity-selective optical pumping resonances of Cs-133 atoms confined in an extremely thin cell

Linear and nonlinear absorption spectra of Cs-133 vapor confined in an extremely thin cell were computed via iterations with respect to the resonance radiation intensity. When the incident radiation intensity is low, the transient polarization of the atoms that undergo frequent collisions with the cell walls leads to sub-Doppler features in the absorption spectra. Higher incident radiation intensities result in the appearance of velocity-selective optical pumping resonances. The theory developed agrees quantitatively with the experimental findings.