With the use of two-step laser excitation, it is shown that the state distributions of highly excited barium atoms are substantially altered by inelastic collisions with barium atoms. For ``pure'' Rydberg states the initially produced ns or nd eigenstates are rapidly mixed with nearly degenerate n'l' states. For initially produced states that may be viewed as admixtures of Rydberg and doubly excited independent-electron eigenstates, collisions convert the distribution to one with nearly pure, albeit state-mixed, Rydberg character. Broadening of the absorption profiles of the highly excited states is also observed. This effect results from quasistatic interaction between two highly excited atoms during the excitation. Beyond a critical excited-atom density, avalanche effects lead to an apparent narrowing of these profiles which subsequently broaden at still higher atom density.With the use of two-step laser excitation, it is shown that the state distributions of highly excited barium atoms are substantially altered by inelastic collisions with barium atoms. For ``pure'' Rydberg states the initially produced ns or nd eigenstates are rapidly mixed with nearly degenerate n'l' states. For initially produced states that may be viewed as admixtures of Rydberg and doubly excited independent-electron eigenstates, collisions convert the distribution to one with nearly pure, albeit state-mixed, Rydberg character. Broadening of the absorption profiles of the highly excited states is also observed. This effect results from quasistatic interaction between two highly excited atoms during the excitation. Beyond a critical excited-atom density, avalanche effects lead to an apparent narrowing of these profiles which subsequently broaden at still higher atom density.

Physical Review AOct 1, 19888 citations

Collisions of Rydberg Atoms with Molecules

F. B. Dunning, R. F. Stebbings

Annual Review of Physical ChemistryOct 1, 198240 citations

Collision Spectroscopy of Rydberg Atoms

James Veale

Jan 1, 19950 citations

Giant cross sections for L changing in Rydberg-Rydberg collisions

S. Yoshida, Joachim Burgdörfer, G. Fields +2 more

State changing in thermal-energy collisions between strontium atoms in very-high- $n$ , $n\ensuremath{\approx}300$, $n{\phantom{\rule{0.16em}{0ex}}}^{1}{F}_{3}$ Rydberg states is studied. In collisions between Rydberg atoms, the dipole-dipole interaction generates an effective electric field at each atom, which triggers Stark precession and the evolution of their angular momenta, $L$ . Such $L$ -changing collisions are examined using both quantum and classical theory. The theoretical predictions are experimentally verified by monitoring the damping of quantum beats induced by the sudden application of a DC ``pump'' field. The present work shows that, due to the long-range nature of the interactions, the cross sections, $\ensuremath{\sigma}$, for $L$ changing are considerably larger than the geometric collision cross section. For thermal collisions the cross section $\ensuremath{\sigma}$ for $n{\phantom{\rule{0.28em}{0ex}}}^{1}{F}_{3}$ Rydberg states with $n\ensuremath{\simeq}300$ is $\ensuremath{\approx}8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}$. Scaling rules derived in this paper predict that for cold collisions $\ensuremath{\sigma}$ may increase by a further factor of 4.State changing in thermal-energy collisions between strontium atoms in very-high-$n$, $n\ensuremath{\approx}300$, $n{\phantom{\rule{0.16em}{0ex}}}^{1}{F}_{3}$ Rydberg states is studied. In collisions between Rydberg atoms, the dipole-dipole interaction generates an effective electric field at each atom, which triggers Stark precession and the evolution of their angular momenta, $L$. Such $L$-changing collisions are examined using both quantum and classical theory. The theoretical predictions are experimentally verified by monitoring the damping of quantum beats induced by the sudden application of a DC ``pump'' field. The present work shows that, due to the long-range nature of the interactions, the cross sections, $\ensuremath{\sigma}$, for $L$ changing are considerably larger than the geometric collision cross section. For thermal collisions the cross section $\ensuremath{\sigma}$ for $n{\phantom{\rule{0.28em}{0ex}}}^{1}{F}_{3}$ Rydberg states with $n\ensuremath{\simeq}300$ is $\ensuremath{\approx}8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}$. Scaling rules derived in this paper predict that for cold collisions $\ensuremath{\sigma}$ may increase by a further factor of 4.

Physical Review AAug 4, 20202 citations

Collisions of high Rydberg atoms with neutral atoms or molecules

E. de Prunelé, J. Pascale

Physics of Electronic and Atomic Collisions: ICPEAC XIJan 1, 19790 citations

Lifetime measurement of ultracold caesium Rydberg states

Zhigang Feng, Linjie Zhang, Jianming Zhao +2 more

We measure the nS and nD (n = 30–40) state lifetimes of caesium Rydberg atoms in a conventional magneto-optical trap using the field ionization technique, which is consistent with the existing theoretical model through suppressing collisions and super-radiance effects. We also investigate variation of the lifetimes with densities of Rydberg atoms by changing the pulse energy of the dye laser. The results indicate that collisions and super-radiance effects have a large influence on the accuracy of lifetime measurement at high densities of Rydberg atoms.We measure the nS and nD (n = 30–40) state lifetimes of caesium Rydberg atoms in a conventional magneto-optical trap using the field ionization technique, which is consistent with the existing theoretical model through suppressing collisions and super-radiance effects. We also investigate variation of the lifetimes with densities of Rydberg atoms by changing the pulse energy of the dye laser. The results indicate that collisions and super-radiance effects have a large influence on the accuracy of lifetime measurement at high densities of Rydberg atoms.

Journal of Physics B Atomic Molecular and Optical PhysicsJun 17, 200927 citations

State changing in thermal-energy collisions between strontium atoms in very-high-

n

, $n\ensuremath{\approx}300$,

n{\phantom{\rule{0.16em}{0ex}}}^{1}{F}_{3}

Rydberg states is studied. In collisions between Rydberg atoms, the dipole-dipole interaction generates an effective electric field at each atom, which triggers Stark precession and the evolution of their angular momenta,

L

. Such

L

-changing collisions are examined using both quantum and classical theory. The theoretical predictions are experimentally verified by monitoring the damping of quantum beats induced by the sudden application of a DC ``pump'' field. The present work shows that, due to the long-range nature of the interactions, the cross sections, $\ensuremath{\sigma}$, for

L

changing are considerably larger than the geometric collision cross section. For thermal collisions the cross section $\ensuremath{\sigma}$ for

n{\phantom{\rule{0.28em}{0ex}}}^{1}{F}_{3}

Rydberg states with $n\ensuremath{\simeq}300$ is $\ensuremath{\approx}8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}$. Scaling rules derived in this paper predict that for cold collisions $\ensuremath{\sigma}$ may increase by a further factor of 4.