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We study the time-resolved Rydberg excitation dynamics for Lithium atoms confined in a magneto-optical trap. Loss of neutral atoms due to Rydberg excitation is measured by means of analyzing the absorption of a weak probe beam. Our experiment demonstrates the existence of both density-dependent excitation blockade and excitation facilitation effects. Moreover, we measure the frequency shift of the Rydberg transition at various durations of excitation pulses. This frequency shift can be attributed to the formation of ultracold ions from the high-density ensemble of Rydberg atoms. [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 discuss the experimental research of an optical resonant saturation of a dipole–dipole-broadened atomic transition in the high-density rubidium vapor. The dipole–dipole width of the selected transition 5S1/2−5P3/2 is estimated as 2π・8.8 GHz; it is approximately ten times more than the contribution of the Doppler broadening. In the experiment, we record the selective reflection resonances at various laser beam intensities. The spectral width of the resonance is reduced when the optical intensity is increased. Reduction of the dipole-dipole width is the dominant process to compare with the variation of the Rabi broadening. This behavior confirms that the dipole–dipole interactions can be explained by a quasistatic model. [ABSTRACT FROM AUTHOR]

In this work, we discuss a far-off resonance optical dipole trap for cold lithium-7 atoms. A single optical trapping beam was produced by a continuous-wave fiber laser. Using our experimental data, we obtained important parameters of the trap, such as size of the cold atomic cloud, and evaluate the dipole potential and the rate of the trap losses. Information on temperature is acquired from observation of parametric resonances. We investigate the parametric resonances obtained with strong modulation of the trap potential and record superharmonics. We plan to prepare ultra-cold gas of highly-excited lithium atoms and study interactions between Rydberg atoms. [ABSTRACT FROM AUTHOR]

We study Doppler-free saturation resonances in the absorption band $$ {{\mathrm{B}}^1}{\Pi_{\mathrm{u}}}-{{\mathrm{X}}^1}\Sigma_{{^{\mathrm{g}}}}^{+} $$ of rubidium diatomic molecules in the frequency range near the D 2 line of lithium atoms (671 nm). We observe contrast saturation resonances and record a variation in the laser light transmission of 4% due to optical saturation. The large optical nonlinearities in the molecular diatomic gas can be used for investigating the four-wave mixing and other nonlinear effects. [ABSTRACT FROM AUTHOR]

We study the selective reflection of the laser beam from rubidium atomic vapor at the D2 line (wavelength λ = 780 nm) at different atomic densities. We use a tunable free-running diode laser. We observed a measurable signal at a low atomic density N when the mean distance between resonance atoms reached two wavelengths. In our experiment, the dimensionless parameter N1 /3 λ varied from 0.5 to 2.8. The reflectivity increased with density monotonically. It is interesting to perform experiments when the parameter N1 /3 λ ≪ 1. [ABSTRACT FROM AUTHOR]