Experimental Study of Hyperfine State Changing Collisions in the Cs(6\textit{P}
1/2) State using Argon Perturbers
A two-step excitation experiment has been employed to measure the collisional rate coefficients and to study the velocity distribution of
Cs(6P1∕2) atoms that have undergone a single hyperfine state-changing collision with Ar. In addition, argon pressure broadening rates and shifts of the cesium $6{P}_{1∕2}({F}^{\ensuremath{'}})\ensuremath{\rightarrow}8{S}_{1∕2}({F}^{\ensuremath{''}})$ transitions have been determined. In the experiment, a single mode, cw Ti:sapphire laser is tuned to line center of the $6{S}_{1∕2}(F=4)\ensuremath{\rightarrow}6{P}_{1∕2}$(${F}^{\ensuremath{'}}=3$ or 4) transition. Then, the frequency of a single mode cw dye laser is scanned over the $6{P}_{1∕2}\ensuremath{\rightarrow}8{S}_{1∕2}$ manifold to probe the populations of the
6P1∕2 hyperfine levels. Absorption of probe laser photons is monitored by detecting $8{S}_{1∕2}\ensuremath{\rightarrow}6{P}_{3∕2}$ fluorescence. The experiment is conducted at room temperature, where the Cs density is low $(n\ensuremath{\sim}3.4\ifmmode\times\else\texttimes\fi{}{10}^{10}\phantom{\rule{0.3em}{0ex}}\mathrm{atoms}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3})$, and thus the probability of a $\mathrm{Cs}\text{\ensuremath{-}}\mathrm{Cs}$ collision is negligible during the
Cs(6P1∕2) radiative lifetime. The Ar pressure is varied from 0 to
1.52Torr, and $\mathrm{Cs}\text{\ensuremath{-}}\mathrm{Ar}$ collisions cause population to be transferred from the directly excited $6{P}_{1∕2}({F}^{\ensuremath{'}})$ level to the other
6P1∕2 hyperfine level. The data are analyzed using a density matrix formalism to yield the rate coefficients for $\mathrm{Cs}(6{P}_{1∕2})\text{\ensuremath{-}}\mathrm{Ar}$ hyperfine state-changing collisions. In addition, the one-dimensional velocity changing collision kernel for
Cs(6P1∕2) atoms prepared with
vz=0 that undergo ${F}^{\ensuremath{'}}=3\ensuremath{\leftrightarrow}{F}^{\ensuremath{'}}=4$ hyperfine state-changing collisions with argon is reported.
An experimental investigation of the Cs 6s 2S1/2→6p 2P3/2→10s 2S1/2 double-resonance two-photon polar-ization spectrum has been made. In the investigation, a linear polarization degree was measured to extract the alignment depolarization cross section in the cesium 6p 2P3/2 level due to collisions between ground-level argon and excited 6p 2P3/2 cesium atoms over the Zeeman coherences. The spectra show strong depolarization of the Cs 6p 2P3/2 level. The measured alignment depolarization cross section value of 186 58 Å2 is in good agreement with the experiment and theoretical predictions. DOI: 10.1103/PhysRevA.73.042713 PACS numbers: 32.80.t, 32.70.n I.
An experimental investigation of the Cs 6s {sup 2}S{sub 1/2}{yields}6p {sup 2}P{sub 3/2}{yields}10s {sup 2}S{sub 1/2} double-resonance two-photon polarization spectrum has been made. In the investigation, a linear polarization degree was measured to extract the alignment depolarization cross section in the cesium 6p {sup 2}P{sub 3/2} level due to collisions between ground-level argon and excited 6p {sup 2}P{sub 3/2} cesium atoms over the Zeeman coherences. The spectra show strong depolarization of the Cs 6p {sup 2}P{sub 3/2} level. The measured alignment depolarization cross section value of 186 (58) A{sup 2} is in good agreement with the experiment and theoretical predictions.