Experimental, polarization-dependent excitation spectra for excited-state-Mg--rare-gas-atom optical collisions are reported. In these first studies of the process, polarized Mg atoms in the 3p $^{1}$ ${\mathit{P}}_{1}$ level are produced by absorption of linearly polarized light tuned to the 3s $^{1}$ ${\mathit{S}}_{0}$ \ensuremath{\rightarrow}3p $^{1}$ ${\mathit{P}}_{1}$ resonance transition at 285.2 nm. Detuning-dependent, collision-induced polarization spectra are measured in a \ifmmode\pm\else\textpm\fi{}200-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ range around the Mg 3p $^{1}$ ${\mathit{P}}_{1}$ \ensuremath{\rightarrow}5s $^{1}$ ${\mathit{S}}_{0}$ transition at 571.2 nm. The spectra correspond to probing transient Mg-Ne and Mg-Ar molecules on 3p $^{1}\mathrm{\ensuremath{\Pi}}_{1}$\ensuremath{\rightarrow}5s $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$ and 3p $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$\ensuremath{\rightarrow}5s $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$ electronic transitions. Measurements of these excited-state polarization spectra for Mg-Ne optical collisions reveal that for detunings to the red of the atomic Mg 3p $^{1}$ ${\mathit{P}}_{1}$ \ensuremath{\rightarrow}5s $^{1}$ ${\mathit{S}}_{0}$ transition, electronic linear polarization greater than 50% survives far into the molecular regime. This represents a direct measure of the polarization important to alignment-dependent inelastic processes in alkaline-earth-metal--rare-gas-atom collisions. The polarization spectra are discussed in terms of existing information on the interatomic potentials and through an axial recoil limit for the polarization degree for parallel and perpendicular molecular transitions. Rate coefficients k for disalignment of Mg 3p $^{1}$ ${\mathit{P}}_{1}$ atoms by collisions with Ar [k=9.4(5)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$ /s] and with Ne [k=6.5(7)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$ /s] are also extracted from the data.Experimental, polarization-dependent excitation spectra for excited-state-Mg--rare-gas-atom optical collisions are reported. In these first studies of the process, polarized Mg atoms in the 3p $^{1}$${\mathit{P}}_{1}$ level are produced by absorption of linearly polarized light tuned to the 3s $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}3p $^{1}$${\mathit{P}}_{1}$ resonance transition at 285.2 nm. Detuning-dependent, collision-induced polarization spectra are measured in a \ifmmode\pm\else\textpm\fi{}200-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ range around the Mg 3p $^{1}$${\mathit{P}}_{1}$\ensuremath{\rightarrow}5s $^{1}$${\mathit{S}}_{0}$ transition at 571.2 nm. The spectra correspond to probing transient Mg-Ne and Mg-Ar molecules on 3p $^{1}\mathrm{\ensuremath{\Pi}}_{1}$\ensuremath{\rightarrow}5s $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$ and 3p $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$\ensuremath{\rightarrow}5s $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$ electronic transitions. Measurements of these excited-state polarization spectra for Mg-Ne optical collisions reveal that for detunings to the red of the atomic Mg 3p $^{1}$${\mathit{P}}_{1}$\ensuremath{\rightarrow}5s $^{1}$${\mathit{S}}_{0}$ transition, electronic linear polarization greater than 50% survives far into the molecular regime. This represents a direct measure of the polarization important to alignment-dependent inelastic processes in alkaline-earth-metal--rare-gas-atom collisions. The polarization spectra are discussed in terms of existing information on the interatomic potentials and through an axial recoil limit for the polarization degree for parallel and perpendicular molecular transitions. Rate coefficients k for disalignment of Mg 3p $^{1}$${\mathit{P}}_{1}$ atoms by collisions with Ar [k=9.4(5)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$/s] and with Ne [k=6.5(7)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$/s] are also extracted from the data.

Physical Review AJul 1, 19949 citations

Production of highly polarized vapors using laser optical pumping with velocity-changing collisions

W. W. Quivers

Experiments have shown the novel combination of laser optical pumping and velocity-changing collisions (between active- and buffer-gas atoms) to be very effective in producing vapors with high atomic or nuclear polarizations. This paper presents a theory which has proven successful in analyzing these experiments. The theory predicts the amount of polarization attainable for particular experimental conditions and establishes the general criteria for optimum polarization. The theory is based on sets of coupled rate equations, which contain terms describing the pumping process (i.e., stimulated absorption or emission), radiative branching, relaxation, and velocity-changing collisions. The collision terms are written in the strong-collision approximation, which assumes that a single collision, on average, thermalizes the velocity distribution. Expressions are derived for the polarization and level populations.Experiments have shown the novel combination of laser optical pumping and velocity-changing collisions (between active- and buffer-gas atoms) to be very effective in producing vapors with high atomic or nuclear polarizations. This paper presents a theory which has proven successful in analyzing these experiments. The theory predicts the amount of polarization attainable for particular experimental conditions and establishes the general criteria for optimum polarization. The theory is based on sets of coupled rate equations, which contain terms describing the pumping process (i.e., stimulated absorption or emission), radiative branching, relaxation, and velocity-changing collisions. The collision terms are written in the strong-collision approximation, which assumes that a single collision, on average, thermalizes the velocity distribution. Expressions are derived for the polarization and level populations.

Physical Review ANov 1, 198627 citations

Light scattering by polarized atoms

M. Ya. Agre, Л. П. Рапопорт, M. E. Alferieff

Journal of Experimental and Theoretical PhysicsSep 1, 19931 citation

Experimental, polarization-dependent excitation spectra for excited-state-Mg--rare-gas-atom optical collisions are reported. In these first studies of the process, polarized Mg atoms in the 3p

^{1}

{\mathit{P}}_{1}

level are produced by absorption of linearly polarized light tuned to the 3s

^{1}

{\mathit{S}}_{0}

\ensuremath{\rightarrow}3p

^{1}

{\mathit{P}}_{1}

resonance transition at 285.2 nm. Detuning-dependent, collision-induced polarization spectra are measured in a \ifmmode\pm\else\textpm\fi{}200-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ range around the Mg 3p

^{1}

{\mathit{P}}_{1}

\ensuremath{\rightarrow}5s

^{1}

{\mathit{S}}_{0}

transition at 571.2 nm. The spectra correspond to probing transient Mg-Ne and Mg-Ar molecules on 3p $^{1}\mathrm{\ensuremath{\Pi}}_{1}$\ensuremath{\rightarrow}5s $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$ and 3p $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$\ensuremath{\rightarrow}5s $^{1}\mathrm{\ensuremath{\Sigma}}_{0}^{+}$ electronic transitions. Measurements of these excited-state polarization spectra for Mg-Ne optical collisions reveal that for detunings to the red of the atomic Mg 3p

^{1}

{\mathit{P}}_{1}

\ensuremath{\rightarrow}5s

^{1}

{\mathit{S}}_{0}

transition, electronic linear polarization greater than 50% survives far into the molecular regime. This represents a direct measure of the polarization important to alignment-dependent inelastic processes in alkaline-earth-metal--rare-gas-atom collisions. The polarization spectra are discussed in terms of existing information on the interatomic potentials and through an axial recoil limit for the polarization degree for parallel and perpendicular molecular transitions. Rate coefficients k for disalignment of Mg 3p

^{1}

{\mathit{P}}_{1}

atoms by collisions with Ar [k=9.4(5)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$

{\mathrm{cm}}^{3}

/s] and with Ne [k=6.5(7)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$

{\mathrm{cm}}^{3}

/s] are also extracted from the data.