State-Transfer Collisions

Energy transfer in atom-dimer collisions is analyzed using a model of loosely bound hard spheres. The results are compared with calculations for a real system. It is found that large energy transfer at a particular scattering angle is sensitive to the initial internal state of the dimer. A quantum theory of atom-dimer collisions is developed and it is found that resonances in the dissociation channel of the dimer are expected. The final rotational states of the dimer are also investigated. It is found that large energy transfer occurs with no change in the rotational state of the dimer.Energy transfer in atom-dimer collisions is analyzed using a model of loosely bound hard spheres. The results are compared with calculations for a real system. It is found that large energy transfer at a particular scattering angle is sensitive to the initial internal state of the dimer. A quantum theory of atom-dimer collisions is developed and it is found that resonances in the dissociation channel of the dimer are expected. The final rotational states of the dimer are also investigated. It is found that large energy transfer occurs with no change in the rotational state of the dimer.

Physical Review AApr 1, 19880 citations

Resonant Rydberg–Rydberg collisions

Thomas F. Gallagher

Resonant energy transfer collisions, those in which one atom or molecule transfers only internal energy, as oppposed to translational energy, to its collision partner require a precise match of the energy intervals in the two collision partners. Because of this energy specificity, resonant collisional energy transfer plays an important role in many laser applications, the He–Ne and CO 2 lasers being perhaps the best known examples. It is interesting to imagine an experiment in which we can tune the energy of the excited state of atom B through the energy of the excited state of atom A, as shown in Fig. 14.1. At resonance we would expect the cross section for collisionally transferring the energy from an excited A atom to a ground state B atom to increase sharply as shown in Fig. 14.1. In general, atomic and molecular energy levels are fixed, and the situation of Fig. 14.1 is impossible to realize. Nonetheless systematic studies of resonant energy transfer have been carried out by altering the collision partner, showing the importance of resonance in collisional energy transfer. The use of atomic Rydberg states, which have series of closely spaced levels, presents a natural opportunity for the study of resonant collisional energy transfer. One of the earliest experiments was the observation of resonant rotational to electronic energy transfer from NH 3 to Xe Rydberg atoms by Smith et al .Resonant energy transfer collisions, those in which one atom or molecule transfers only internal energy, as oppposed to translational energy, to its collision partner require a precise match of the energy intervals in the two collision partners. Because of this energy specificity, resonant collisional energy transfer plays an important role in many laser applications, the He–Ne and CO 2 lasers being perhaps the best known examples. It is interesting to imagine an experiment in which we can tune the energy of the excited state of atom B through the energy of the excited state of atom A, as shown in Fig. 14.1. At resonance we would expect the cross section for collisionally transferring the energy from an excited A atom to a ground state B atom to increase sharply as shown in Fig. 14.1. In general, atomic and molecular energy levels are fixed, and the situation of Fig. 14.1 is impossible to realize. Nonetheless systematic studies of resonant energy transfer have been carried out by altering the collision partner, showing the importance of resonance in collisional energy transfer. The use of atomic Rydberg states, which have series of closely spaced levels, presents a natural opportunity for the study of resonant collisional energy transfer. One of the earliest experiments was the observation of resonant rotational to electronic energy transfer from NH 3 to Xe Rydberg atoms by Smith et al .

Cambridge University Press eBooksSep 15, 19940 citations

Inelastic Collisions

Francis F. Chen, Jane P. Chang

Springer eBooksJan 1, 20031 citation

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

Scattering States

Stephen J. Gustafson, Israel Michael Sigal

UniversitextJan 1, 20200 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%.