Collisional disalignment of caesium Rydberg states
Leslie Pendrill, George William Series
Cross sections for the disalignment of excited caesium atoms, by collision with atoms in ground states, have been determined by studying the damping of quantum beats in fluorescence. Atoms in a sealed cell were excited selectively to 122D3/2 and 132S3/2 by a pulsed tunable laser and discharge lamp. Alignment was induced by linear polarisation of the exciting light and monitored correspondingly. The quantum beats originate in the coherent excitation of hyperfine states whose structures have been determined in previous work. Collisional damping is investigated studying the quantum-beat signal over a range of atomic densities. The fluorescence contains a component representing the decay of population as well as of alignment, and extraction of the alignment cross sections relies on previous measurements of the depopulation cross sections. The results for disalignment cross sections are: sigma (2)(122D3/2)=4.1+or-0.8*10-16 m2, sigma (2)(132D3/2)=5.3+or-0.9*10-16 m2, about three times larger than the depopulation cross sections. Radiative lifetimes obtained from the analysis agree with previous determinations.
Journal of Physics B Atomic and Molecular Physics•Dec 14, 1978•6 citations