Resonant electron capture to high Rydberg states and field effects

Serge Martin, Jérôme Bernard, L. Chen +2 more

Double Rydberg states were populated by triple electron capture in collisions of highly charged ions with atoms. The highest stabilization of states produced by triple capture at $v\ensuremath{\cong}0.2\mathrm{a}.\mathrm{u}.$ was found for binding energies of the projectile electrons near the limits of the $({2,n,n}^{\ensuremath{'}})$ and $({3,n,n}^{\ensuremath{'}})$ series. Population of triply excited double Rydberg states was confirmed by the emission of Rydberg transitions. Results are interpreted by two successive autotransfer into Rydberg states for $({3,n,n}^{\ensuremath{'}})$ states and of one-step two-electron autotransfer for $({2,n,n}^{\ensuremath{'}})$ states.

James Carl Day

Michio Matsuzawa

Fenghao Sun, Chenxu Lu, Yongzhe Ma +8 more

Rather than being freed to the continuum, the strong-field tunneled electrons can make a trajectory driven by the remaining laser fields and have certain probability to be captured by the high lying Rydberg states of the parent atoms or molecules. To explore the effect of molecular orbital on Rydberg state excitation, the ellipticity dependence of Rydberg state yields of N2 and O2 molecules are experimentally investigated using cold target recoil ion momentum spectroscopy and are compared with their counterpart atoms Ar and Xe with comparable ionization potentials. We found the generation probability of the neutral Rydberg fragment O2* was orders of magnitude higher than that of Xe* due to the butterfly-shaped highest occupied molecular orbital of O2. Meanwhile, our experimental and simulation results reveal that it is the initial momentum distribution (determined by the detailed characteristics of orbitals) that finally leads to the tendency that the Rydberg state yield of O2 (Ar) decreased slower than that obtained for Xe (N2) when the ellipticity of the excitation laser field is increased.

Shilin Hu, xiaopeng Yi, Li Shuai Guo +2 more

We investigated the Rydberg-state excitation process of a hydrogen atom subjected to spatially homogeneous and inhomogeneous laser fields by means of ab initio calculations. It is found that, comparing with atoms exposed to spatially homogeneous laser fields, the excitation probability decreases and the electron tends to occupy the states with lower principal quantum numbers and angular quantum numbers for atoms in spatially inhomogeneous laser pulses. Furthermore, calculations of a quantum model without taking into account ionization of the electron after it is coherently captured by the Rydberg state are inconsistent with the above-stated findings by ab initio calculations. Analysis indicates that the aforementioned intriguing features can be attributed to the enhanced ionization of the Rydberg states by inhomogeneous laser fields since the distributions of Rydberg states of high principal quantum numbers and angular quantum numbers locate far away from the core where the inhomogeneous electric fields become significant.

Eric Paradis, Stefan Zigo, Georg A. Raithel