The resonant transfer of energy from the inversion sublevels in NH 3 to He atoms in triplet Rydberg states with principal quantum number n = 38 has been controlled using electric fields below 15 V/cm in intrabeam collisions at translational temperatures of ∼1 K. The experiments were performed in pulsed supersonic beams of NH 3 seeded in He at a ratio of 1:19. The He atoms were prepared in the metastable 1s2s 3 S 1 level in a pulsed electric discharge in the trailing part of the beams. The velocity slip between the heavy NH 3 and the lighter metastable He was exploited to perform collision studies at center-of-mass collision speeds of ∼70 m/s. Resonant energy transfer in the atom–molecule collisions was identified by Rydberg-state-selective electric-field ionization. The experimental data have been compared to a theoretical model of the resonant dipole–dipole interactions between the collision partners based on the impact parameter method.The resonant transfer of energy from the inversion sublevels in NH 3 to He atoms in triplet Rydberg states with principal quantum number n = 38 has been controlled using electric fields below 15 V/cm in intrabeam collisions at translational temperatures of ∼1 K. The experiments were performed in pulsed supersonic beams of NH 3 seeded in He at a ratio of 1:19. The He atoms were prepared in the metastable 1s2s 3 S 1 level in a pulsed electric discharge in the trailing part of the beams. The velocity slip between the heavy NH 3 and the lighter metastable He was exploited to perform collision studies at center-of-mass collision speeds of ∼70 m/s. Resonant energy transfer in the atom–molecule collisions was identified by Rydberg-state-selective electric-field ionization. The experimental data have been compared to a theoretical model of the resonant dipole–dipole interactions between the collision partners based on the impact parameter method.

arXiv:2001.08440The Journal of Physical Chemistry LettersDec 10, 201920 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%.