Resonance transfer of excitation in the collision of identical atoms

The excitation transfers through collision between hydrogen atoms and between other simple identical atoms are considered theoretically by an impact parameter method. A rotating atom approximation and a fixed atom approximation (concerned with the direction of electronic polarization) are applied to the problem. The cross-section for the transfer of the excitation (2 p 2 P ) of a hydrogen atom with thermal velocity (kinetic energy of 0.025 ev) to the other hydrogen atom in the ground state is estimated to be 3065 Å 2 with the rotating atom approximation and 680 Å 2 with the fixed atom approximation. In the case of helium atoms, the cross-section for the transfer of the excitation (2 p 1 P ) is also estimated to be 606.7 Å 2 with thermal velocity.The excitation transfers through collision between hydrogen atoms and between other simple identical atoms are considered theoretically by an impact parameter method. A rotating atom approximation and a fixed atom approximation (concerned with the direction of electronic polarization) are applied to the problem. The cross-section for the transfer of the excitation (2 p 2 P ) of a hydrogen atom with thermal velocity (kinetic energy of 0.025 ev) to the other hydrogen atom in the ground state is estimated to be 3065 Å 2 with the rotating atom approximation and 680 Å 2 with the fixed atom approximation. In the case of helium atoms, the cross-section for the transfer of the excitation (2 p 1 P ) is also estimated to be 606.7 Å 2 with thermal velocity.

Journal of the Physical Society of JapanMar 1, 196420 citations

Excitation-Transfer Collisions between Rubidium and Helium Atoms

T. J. Beahn, W. J. Condell, Hirsch I. Mandelberg

An experiment is described which measures the collision cross section for transfer of excitation in rubidium by helium. Rubidium atoms are pumped to either the $^{2}P_{\frac{1}{2}}$ or $^{2}P_{\frac{3}{2}}$ state by irradiation with one of the resonance lines. Some excited rubidium atoms are transferred to the other $P$ state by collisions with helium atoms. The rubidium atoms then radiate both resonance lines. Measurements of the intensities of both resonance lines as a function of helium pressure are used to calculate the collision cross section. The cross section for $^{2}P_{\frac{1}{2}}$ to $^{2}P_{\frac{3}{2}}$ is 1.0\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$ \ifmmode\pm\else\textpm\fi{}10% and for $^{2}P_{\frac{3}{2}}$ to $^{2}P_{\frac{1}{2}}$ is 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$ \ifmmode\pm\else\textpm\fi{}10%.An experiment is described which measures the collision cross section for transfer of excitation in rubidium by helium. Rubidium atoms are pumped to either the $^{2}P_{\frac{1}{2}}$ or $^{2}P_{\frac{3}{2}}$ state by irradiation with one of the resonance lines. Some excited rubidium atoms are transferred to the other $P$ state by collisions with helium atoms. The rubidium atoms then radiate both resonance lines. Measurements of the intensities of both resonance lines as a function of helium pressure are used to calculate the collision cross section. The cross section for $^{2}P_{\frac{1}{2}}$ to $^{2}P_{\frac{3}{2}}$ is 1.0\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$\ifmmode\pm\else\textpm\fi{}10% and for $^{2}P_{\frac{3}{2}}$ to $^{2}P_{\frac{1}{2}}$ is 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$\ifmmode\pm\else\textpm\fi{}10%.

Physical ReviewJan 7, 196628 citations

An experiment is described which measures the collision cross section for transfer of excitation in rubidium by helium. Rubidium atoms are pumped to either the

^{2}P_{\frac{1}{2}}

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

state by irradiation with one of the resonance lines. Some excited rubidium atoms are transferred to the other

P

state by collisions with helium atoms. The rubidium atoms then radiate both resonance lines. Measurements of the intensities of both resonance lines as a function of helium pressure are used to calculate the collision cross section. The cross section for

^{2}P_{\frac{1}{2}}

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

is 1.0\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}17}$

{\mathrm{cm}}^{2}

\ifmmode\pm\else\textpm\fi{}10% and for

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

^{2}P_{\frac{1}{2}}

is 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}17}$

{\mathrm{cm}}^{2}

\ifmmode\pm\else\textpm\fi{}10%.