The use of in situ ion detection in alkali vapors coupled with multiphoton ionization provides a technique of highest sensitivity for the investigation of the spectroscopy of excimer states involving alkali atoms. This technique has been applied in this work to the molecular components of the spectrum of the $6S\ensuremath{-}7P$ absorption doublet of cesium. The dispersion curve was obtained with a tunable dye laser for the two-photon ionization of cesium over the 4500-4600-\AA{} wavelength range as a function of vapor pressure and source intensity. Strongly developed satellite bands were observed to be associated with the atomic lines $6^{2}S_{\frac{1}{2}}\ensuremath{\rightarrow}7^{2}P_{\frac{1}{2}}$ and $6^{2}S_{\frac{1}{2}}\ensuremath{\rightarrow}7^{2}P_{\frac{3}{2}}$, and were found to have well-defined band heads at 29.4 and 31.4 ${\mathrm{cm}}^{\ensuremath{-}1}$ to longer wavelengths, respectively. Sensitivity was observed to be an order of magnitude in excess of that obtained from classical absorption techniques, and the observation of a quadratic dependence of the molecular components confirmed the multiphoton nature of the detection sequence.The use of in situ ion detection in alkali vapors coupled with multiphoton ionization provides a technique of highest sensitivity for the investigation of the spectroscopy of excimer states involving alkali atoms. This technique has been applied in this work to the molecular components of the spectrum of the $6S\ensuremath{-}7P$ absorption doublet of cesium. The dispersion curve was obtained with a tunable dye laser for the two-photon ionization of cesium over the 4500-4600-\AA{} wavelength range as a function of vapor pressure and source intensity. Strongly developed satellite bands were observed to be associated with the atomic lines $6^{2}S_{\frac{1}{2}}\ensuremath{\rightarrow}7^{2}P_{\frac{1}{2}}$ and $6^{2}S_{\frac{1}{2}}\ensuremath{\rightarrow}7^{2}P_{\frac{3}{2}}$, and were found to have well-defined band heads at 29.4 and 31.4 ${\mathrm{cm}}^{\ensuremath{-}1}$ to longer wavelengths, respectively. Sensitivity was observed to be an order of magnitude in excess of that obtained from classical absorption techniques, and the observation of a quadratic dependence of the molecular components confirmed the multiphoton nature of the detection sequence.

Physical Review AOct 1, 19774 citations

Probabilities of the energy-level transitions between the cesium atom excited states

Лебедев, V. E. Cherkovets, S.V. Yusim

Jan 1, 19730 citations

Charge-induced optical bistability in thermal Rydberg vapor

Daniel Weller, Alban Urvoy, Andy Rico +2 more

We investigate the phenomenon of optical bistability in a driven ensemble of Rydberg atoms. By performing two experiments with thermal vapors of rubidium and cesium, we are able to shed light on the underlying interaction mechanisms causing such a nonlinear behavior. Due to the different properties of these two atomic species, we conclude that the large polarizability of Rydberg states in combination with electric fields of spontaneously ionized Rydberg atoms is the relevant interaction mechanism. In the case of rubidium, we directly measure the electric field in a bistable situation via two-species spectroscopy. In cesium, we make use of the different sign of the polarizability for different $l$ states and the possibility of applying electric fields. Both these experiments allow us to rule out dipole-dipole interactions and support our hypothesis of a charge-induced bistability.We investigate the phenomenon of optical bistability in a driven ensemble of Rydberg atoms. By performing two experiments with thermal vapors of rubidium and cesium, we are able to shed light on the underlying interaction mechanisms causing such a nonlinear behavior. Due to the different properties of these two atomic species, we conclude that the large polarizability of Rydberg states in combination with electric fields of spontaneously ionized Rydberg atoms is the relevant interaction mechanism. In the case of rubidium, we directly measure the electric field in a bistable situation via two-species spectroscopy. In cesium, we make use of the different sign of the polarizability for different $l$ states and the possibility of applying electric fields. Both these experiments allow us to rule out dipole-dipole interactions and support our hypothesis of a charge-induced bistability.

arXiv:1609.02330Physical Review ADec 8, 201647 citations

Energy pooling in cesium vapor

Cedomil Vadla, Kay Niemax, J. Brust

Zeitschrift für Physik D Atoms Molecules and ClustersSep 1, 199616 citations

Formation of antihydrogen molecular ions by associative ionization

Josiah Taylor, Brandon Vargo, Daniel Hoffman +2 more

Recent calculations have suggested that it may be feasible to produce antihydrogen molecular ions in the near future [Zammit et al., Phys. Rev. A 100, 042709 (2019)]. The proposed scheme would laser excite cold antihydrogen $\overline{\text{H}}(1s)$ atoms held in a magnetic-field minimum trap and the resulting metastable $\overline{\text{H}}(2s)$ atoms would interact to form the antihydrogen molecular ion, ${\overline{\text{H}}}_{2}{}^{\ensuremath{-}}$, by associative ionization. Estimates for the efficiencies of the proposed formation and depletion processes relied on low-energy extrapolations of rate coefficients that were computed at thermal energies. In the present work, we provide quantum calculations of the rate coefficients for associative ionization and for the competing Penning ionization process, which would deplete the population of trapped $\overline{\text{H}}$ . In contrast to the low-energy extrapolations, it is found that Penning ionization is the dominant ionization process at all temperatures and the relative efficiency of associative ionization is within a factor of 3 at the low temperatures required by the experimental scheme. Rate constants for single and double excitation transfer are computed as possible loss mechanisms and all rates are found to be small compared to spin-flip decay rates from Stark-induced mixing with $\overline{\text{H}}(2p$ ) states.Recent calculations have suggested that it may be feasible to produce antihydrogen molecular ions in the near future [Zammit et al., Phys. Rev. A 100, 042709 (2019)]. The proposed scheme would laser excite cold antihydrogen $\overline{\text{H}}(1s)$ atoms held in a magnetic-field minimum trap and the resulting metastable $\overline{\text{H}}(2s)$ atoms would interact to form the antihydrogen molecular ion, ${\overline{\text{H}}}_{2}{}^{\ensuremath{-}}$, by associative ionization. Estimates for the efficiencies of the proposed formation and depletion processes relied on low-energy extrapolations of rate coefficients that were computed at thermal energies. In the present work, we provide quantum calculations of the rate coefficients for associative ionization and for the competing Penning ionization process, which would deplete the population of trapped $\overline{\text{H}}$. In contrast to the low-energy extrapolations, it is found that Penning ionization is the dominant ionization process at all temperatures and the relative efficiency of associative ionization is within a factor of 3 at the low temperatures required by the experimental scheme. Rate constants for single and double excitation transfer are computed as possible loss mechanisms and all rates are found to be small compared to spin-flip decay rates from Stark-induced mixing with $\overline{\text{H}}(2p$) states.

Physical Review AMay 15, 20242 citations

l

states and the possibility of applying electric fields. Both these experiments allow us to rule out dipole-dipole interactions and support our hypothesis of a charge-induced bistability.

\overline{\text{H}}(1s)

atoms held in a magnetic-field minimum trap and the resulting metastable

\overline{\text{H}}(2s)

atoms would interact to form the antihydrogen molecular ion, ${\overline{\text{H}}}_{2}{}^{\ensuremath{-}}$, by associative ionization. Estimates for the efficiencies of the proposed formation and depletion processes relied on low-energy extrapolations of rate coefficients that were computed at thermal energies. In the present work, we provide quantum calculations of the rate coefficients for associative ionization and for the competing Penning ionization process, which would deplete the population of trapped

\overline{\text{H}}

. In contrast to the low-energy extrapolations, it is found that Penning ionization is the dominant ionization process at all temperatures and the relative efficiency of associative ionization is within a factor of 3 at the low temperatures required by the experimental scheme. Rate constants for single and double excitation transfer are computed as possible loss mechanisms and all rates are found to be small compared to spin-flip decay rates from Stark-induced mixing with

\overline{\text{H}}(2p

) states.