An experimental investigation of the Cs $6s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}\ensuremath{\rightarrow}6p\phantom{\rule{0.2em}{0ex}}^{2}P_{3∕2}\ensuremath{\rightarrow}10s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}$ 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
6p2P3∕2 level due to collisions between ground-level argon and excited
6p2P3∕2 cesium atoms over the Zeeman coherences. The spectra show strong depolarization of the Cs
6p2P3∕2 level. The measured alignment depolarization cross section value of 186
(58)A˚2 is in good agreement with the experiment and theoretical predictions.
We studied the effect of depolarization of the atomic cesium in the 6p 2 P 3/2 level by using two-photon two-color nano-second pulse lasers in collision with krypton buffer gas at various pressures.We used linearly polarized dye lasers at 852.112 nm and at 603.409 nm wavelengths for the 6s 2 S 1/2 → 6p 2 P 3/2 → 10s 2 S 1/2 transition.Excitation of the ground state cesium atoms by linearly polarized light produces an electric quadrupole moment in the excited state.The polarization degree of the emission spectra was measured and was used to calculate the alignment (electric quadrupole moment) in the 6p 2 P 3/2 state.Further,the collisional depolarization effect on the linear polarization was measured at various buffer gas pressures from the spectra and it showed a strong pressure dependence on the polarization spectrum.Finally, we extracted the collisional depolarization cross-section of the 6p 2 P 3/2 Cs atoms in collision with Kr from the measured linear polarization spectrum.
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.