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Sub-Doppler cooling has been achieved for the two closed hyperfine transitions: F = 4 → F' = 5 and F = 3 → F' = 2, of the cesium D2 line. One-dimension optical molasses is experimentally investigated and compared for both j → j + 1 and j → j - 1 transitions, on different laser polarization configurations, in the presence, and absence of a static magnetic field. One remarkable point is that cooling is obtained with blue laser detuning for the j → j - 1 transition. An applied static magnetic field can also shift the sub-Doppler-cooled molasses peaks to nonzero velocities without any extra heating, for the polarization gradient configurations.

We characterize, for the first time to our knowledge, the laser-induced backward fluorescence (retrofluorescence) spectra that result from energy-pooling collisions between Cs atoms near a dissipative thin Cs layer on a glass substrate. We resolve, experimentally and theoretically, the laser spectroscopic problem of energypooling processes related to the nature of the glass-metallic vapor interface. Our study focused on the integrated laser-induced retrofluorescence spectra for the 455.5-nm (7 2 P 3/2-6 2 S 1/2) and 852.2-nm (6 2 P 3/2-6 2 S 1/2) lines as a function of laser scanning through pumping resonance at the 852.2-nm line. We experimentally investigate the retrofluorescence from 420 to 930 nm, induced by a diode laser tuned either in the wings or in the center of the pumping resonance line. We present a detailed theoretical model of the retrofluorescence signal based on the radiative transfer equation, taking into account the evanescent wave of the excited atomic dipole strongly coupled with a dissipative surface. Based on theoretical and experimental results, we evaluate the effective nonradiative transfer rate Ā 6 2 P 3/2 →6 2 S 1/2s f for atoms in the excited 6 2 P 3/2 level located in the near-field region of the surface of the cell. Values extracted from the energy-pooling process analysis are equivalent to those found directly from the 852.2-nm resonance retrofluorescence line. We show that the effective energy-pooling coefficients k 7 2 P 3/2 and k 7 2 P 1/2 are approximately equal. The agreement between theory and experiment is remarkably good, considering the simplicity of the model.

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