Effect of polarization of the atomic residue on excitation cross sections of optical transitions of alkali atoms

G. A. Delone, Nikolai L. Manakov, М. А. Преображенский +1 more

Victor A. Kartoshkin

This work is devoted to the calculation of complex cross sections for the spin exchange collisions between polarized alkali atoms. This is of interest for two reasons. First, knowledge of the cross sections allows one to quantitatively analyze spin-exchange collisions. Second, the obtained results can be used in practice to create quantum electronic devices with optical orientation based on the spin-exchange principle.

P. Rudecki, Stanisław Chwirot, S. Łęgowski

The dependence of the circular polarization of the fluorescence of alkali atoms on the intensity and spectral composition of the σ+-polarized exciting D1 line has been investigated by considering the stationary solutions of rate equations for populations of the Zeeman sublevels. The calculations were performed for pumping-light intensities corresponding to those of classical light sources, e.g., radio frequency or microwave discharge lamps, and commonly accepted values of cross sections for collisional relaxation of ground-state and excited atoms. The systematic errors of cross sections for collisional disorientation of 2P1/2 alkali atoms due to the neglect of intensity and spectral composition of the exciting light are estimated.

E. I. Dashevskaya

Jochen Fricke, J. Haas, E. Lüscher +1 more

Cross sections for random collisional reorientation of J within the sublevels of the $6^{2}P_{\frac{3}{2}}$ excited state of cesium have been measured using the ${D}_{2}$ optical-pumping technique. The measured cross sections ${{\ensuremath{\sigma}}_{M}}^{2}$ are: Cs-He (3.2\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}15}$ ${\mathrm{cm}}^{2}$, Cs-Ne (2.9\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}15}$ ${\mathrm{cm}}^{2}$, Cs-Ar (6.0\ifmmode\pm\else\textpm\fi{}1.2)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}15}$ ${\mathrm{cm}}^{2}$, Cs-Kr (9.2\ifmmode\pm\else\textpm\fi{}1.9)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}15}$ ${\mathrm{cm}}^{2}$, Cs-Xe (11.3\ifmmode\pm\else\textpm\fi{}2.3)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}15}$ ${\mathrm{cm}}^{2}$. Simplified equations for ${\mathrm{D}}_{1}$ and ${\mathrm{D}}_{2}$ pumping with zero, partial, and complete excited-state mixing are derived for a hypothetical alkali atom with zero nuclear spin. The calculations are extended to cesium atoms with nuclear spin $\frac{7}{2}$ pumped by ${\ensuremath{\sigma}}^{+}$ ${\mathrm{D}}_{2}$ radiation. The equilibrium value ${〈{S}_{z}〉}_{0}$ and the time dependence $〈{S}_{z}(t)〉$ of the electronic spin polarization are computed for various degrees of excited-state mixing. $〈{S}_{z}(t)〉$ is found to be nearly single-exponential in the zero- and the complete-mixing cases, but shows a distinct double-exponential behavior in the intermediate region. ${〈{S}_{z}〉}_{0}$ is shown to be dependent on the degree of mixing, and to change sign as the degree of mixing increases. Measurements were performed with a new transmission technique by passing a separate ${\ensuremath{\sigma}}^{+}$-polarized ${\mathrm{D}}_{2}$ pumping beam and an alternately ${\ensuremath{\sigma}}^{+}$- and ${\ensuremath{\sigma}}^{\ensuremath{-}}$-polarized ${\mathrm{D}}_{1}$ testing beam through the cesium absorption cell. The cross sections for collisionally induced mixing were evaluated by measuring the buffer pressure at which ${〈{S}_{z}〉}_{0}$ passed through zero.

Alexander F. Shestakov, S.V. Kristenko, S. I. Vetchinkin