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We study dependence of dipole-dipole interaction in dense Rb vapour on optical excitation. We measure the dipole-dipole contribution to the selective reflection spectrum of D2 line. Optical excitation is created by intense laser beam, which depletes the 5S1/2 population and decreases the dipole-dipole interaction, narrowing the observed spectrum. The limit of the dipole-dipole interaction change is determined by the optical saturation of the D2 transition and corresponds to the 5S1/2 population approximately equal to 1/3.

See the retraction notice E3S Web of Conferences 549, 00001 (2024), https://doi.org/10.1051/e3sconf/202454900001

Charged particle detection systems are widely used in modern atomic physics experiments. In this paper we describe an experimental setup for ultracold plasma (UCP) diagnostics based on the basis of a microchannel plate-based detector (MCP). Two different readout techniques for the MCP output are described in detail. Expansion of the low-density UCP and the frequency-dependent response of the UCP to an external electric field are measured. Preliminary results are obtained.

In this article, effects of the strong long-range interaction of Rydberg atoms on the Autler–Townes splitting spectrum are investigated. Preliminary results are obtained for various excitation times and Rydberg atom densities. The 2 S 1 / 2 and 2 P 1 / 2 levels of lithium-7 are coupled with strong laser field and probed by another laser via excitation into a 70 S Rydberg level. Interactions between Rydberg atoms excited by the probe beam lead to the broadening of the Autler–Townes spectra. At high concentrations of Rydberg atoms, a suppression of the excitation of the Autler–Townes peak at red detuning is observed. [ABSTRACT FROM AUTHOR]

We report a measurement of the photoionization cross-section of the lithium 2P3/2 state in a magneto-optical trap (MOT) by means of a single-frequency cw laser. Intensity of the photoionizing radiation seen by atoms is determined by means of averaging the intensity distribution of the photoionizing beam over the spatial distribution of trapped atoms. We use the photoionizing laser beam with large waist to reduce a possible misalignment between the photoionizing beam and the MOT density distribution. The excited state fraction is also accurately measured under our MOT conditions. The near-threshold photoionization cross-section of lithium-7 2P3/2 state at λPI = 349.846(1) nm is found to be equal to σ = 13.7(1.4) Mb, with better accuracy in comparison with the previous measurements. We study the variation of the photoionization cross section on the polarization of the ionizing beam. Further experiments are suggested. [ABSTRACT FROM AUTHOR]

We report the accurate quantitative measurements of the photoionization (PI) cross section of lithium-7 confined in a magneto-optical trap (MOT). The losses from the MOT induced by radiation of the low-power light-emitting diodes (LEDs) are measured as a function of the photoionizing radiation intensity. On the basis of these measurements, the PI cross section from the 2 P 3/2 excited state of lithium is evaluated for three different LEDs. The PI cross sections of lithium from the 2 P 3/2 state at 259, 280, 307 nm are determined to be (5.4 ± 0.4), (8.1 ± 0.8) and (9.5 ± 1.1) Mb respectively. Accuracy of our measurements is better than that of previous reported results. The semiclassical calculations taking into account the fine structure of the first excited state of lithium are performed. Our values are in good agreement with experimental results earlier reported and are consistent with the theoretical data. [Display omitted] • Photoionization cross section of the 2 P 3/2 excited state of lithium in the UV-C range is measured. • High sensitivity for low-power photoionizing radiation is reached. • Semiclassical calculations taking into account the fine structure of the first excited state are performed [ABSTRACT FROM AUTHOR]