We report the determination of the absolute rate constant of ${\mathrm{Na}}_{2}^{+}$ production by associative ionization collisions between crossed beams of Na $3^{2}P_{\frac{3}{2}}$ atoms. New measurement techniques greatly improve the accuracy of rate-constant determinations in crossed-beam experiments. We find the rate constant to be (1.8\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}11}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\ensuremath{-}1}$. This value is appreciably larger than many of those previously reported.We report the determination of the absolute rate constant of ${\mathrm{Na}}_{2}^{+}$ production by associative ionization collisions between crossed beams of Na $3^{2}P_{\frac{3}{2}}$ atoms. New measurement techniques greatly improve the accuracy of rate-constant determinations in crossed-beam experiments. We find the rate constant to be (1.8\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}11}$ ${\mathrm{cm}}^{3}$${\mathrm{sec}}^{\ensuremath{-}1}$. This value is appreciably larger than many of those previously reported.

Physical Review AAug 1, 198345 citations

Coherence studies of atomic collisions

R. Hippler

Springer eBooksApr 7, 20080 citations

Cold collisions in an atomic beam

H. R. Thorsheim, Yanping Wang, J. Weiner

We report a measurement of the rate constant for associative ionization (AI) between excited Na(3p) atoms colliding within a single beam at a velocity of 11.9 ${\mathrm{msec}}^{\mathrm{\ensuremath{-}}1}$, corresponding to a temperature of 65 mK. The collisions take place in a narrow velocity class of excited atoms produced by crossing the collimated Na beam with a monomode dye laser at an angle of 45\ifmmode^\circ\else\textdegree\fi{}. Light polarized linearly in the collision plane yields an AI rate constant greater than that for circular polarization by a factor of 2. We find ${K}_{65\mathrm{m}\mathrm{K}{}^{\mathrm{lin}}}$ =(12.2\ifmmode\pm\else\textpm\fi{}4.3)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$ and ${K}_{65\mathrm{m}\mathrm{K}{}^{\mathrm{cir}}}$ =(6.1\ifmmode\pm\else\textpm\fi{}1.8)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$. The experimental arrangement also permits absolute calibration of earlier crossed-beam measurements of the excitation function (cross section versus velocity) at conventional thermal beam kinetic energies. Present results together with earlier work show that the cross-sectional temperature dependence is in qualitative accord with theory.We report a measurement of the rate constant for associative ionization (AI) between excited Na(3p) atoms colliding within a single beam at a velocity of 11.9 ${\mathrm{msec}}^{\mathrm{\ensuremath{-}}1}$, corresponding to a temperature of 65 mK. The collisions take place in a narrow velocity class of excited atoms produced by crossing the collimated Na beam with a monomode dye laser at an angle of 45\ifmmode^\circ\else\textdegree\fi{}. Light polarized linearly in the collision plane yields an AI rate constant greater than that for circular polarization by a factor of 2. We find ${K}_{65\mathrm{m}\mathrm{K}{}^{\mathrm{lin}}}$ =(12.2\ifmmode\pm\else\textpm\fi{}4.3)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$ and ${K}_{65\mathrm{m}\mathrm{K}{}^{\mathrm{cir}}}$ =(6.1\ifmmode\pm\else\textpm\fi{}1.8)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$. The experimental arrangement also permits absolute calibration of earlier crossed-beam measurements of the excitation function (cross section versus velocity) at conventional thermal beam kinetic energies. Present results together with earlier work show that the cross-sectional temperature dependence is in qualitative accord with theory.

Physical Review AMar 1, 199025 citations

Crossed-beam studies of aluminum atom cooling via inelastic collisions with O2 molecules

Dong Yan, Yujie Ma, Ang Xu +5 more

The pioneering works have demonstrated that the method of single collisions in crossed molecular beams is an important technique for achieving kinetic cool-ing of atoms or molecules in specific rotational states. In this study, we investigated the elastic and inelastic collisions between Al(2P1/2) metal atoms and O2 molecules at high collision energies in the range of 6.4–14.8 kcal/mol, utilizing the laser-ablation crossed beams in conjunction with time-sliced ion velocity map imaging tech-nique. We observed kinetic cooling of Al(2P1/2) atoms with an upper-limit laboratory-frame root-mean-square velocity of 24±3 m/s, corresponding to a translational temperature of 0.9±0.2 K in the laboratory frame, facilitated by the vibrational excitation of O2 (v′ = 1) in inelastic collisions. The translational cooling of Al atoms in the lab frame enhanced detection probability in the transformation of density-to-flux, as evidenced by the scattering images obtained during the experiments.The pioneering works have demonstrated that the method of single collisions in crossed molecular beams is an important technique for achieving kinetic cool-ing of atoms or molecules in specific rotational states. In this study, we investigated the elastic and inelastic collisions between Al(2P1/2) metal atoms and O2 molecules at high collision energies in the range of 6.4–14.8 kcal/mol, utilizing the laser-ablation crossed beams in conjunction with time-sliced ion velocity map imaging tech-nique. We observed kinetic cooling of Al(2P1/2) atoms with an upper-limit laboratory-frame root-mean-square velocity of 24±3 m/s, corresponding to a translational temperature of 0.9±0.2 K in the laboratory frame, facilitated by the vibrational excitation of O2 (v′ = 1) in inelastic collisions. The translational cooling of Al atoms in the lab frame enhanced detection probability in the transformation of density-to-flux, as evidenced by the scattering images obtained during the experiments.

Chinese Journal of Chemical PhysicsJun 3, 20251 citation

We report the determination of the absolute rate constant of

{\mathrm{Na}}_{2}^{+}

production by associative ionization collisions between crossed beams of Na

3^{2}P_{\frac{3}{2}}

atoms. New measurement techniques greatly improve the accuracy of rate-constant determinations in crossed-beam experiments. We find the rate constant to be (1.8\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}11}$

{\mathrm{cm}}^{3}

${\mathrm{sec}}^{\ensuremath{-}1}$. This value is appreciably larger than many of those previously reported.

{K}_{65\mathrm{m}\mathrm{K}{}^{\mathrm{lin}}}

=(12.2\ifmmode\pm\else\textpm\fi{}4.3)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$

{\mathrm{cm}}^{3}

${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$ and

{K}_{65\mathrm{m}\mathrm{K}{}^{\mathrm{cir}}}

=(6.1\ifmmode\pm\else\textpm\fi{}1.8)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$

{\mathrm{cm}}^{3}

${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$. The experimental arrangement also permits absolute calibration of earlier crossed-beam measurements of the excitation function (cross section versus velocity) at conventional thermal beam kinetic energies. Present results together with earlier work show that the cross-sectional temperature dependence is in qualitative accord with theory.