Multilayer gas cells for sub-Doppler spectroscopy

We have carried out theoretical research on ultra-high resolution spectroscopy of atoms (or molecules) in the suggested cell with a series of plane-parallel thin gas layers between spatially separated gas regions of this cell for optical pumping and probing. It is shown the effective velocity selection of optically pumped atoms because of their specific transit time and collisional relaxation in such a cell, which lead to narrow sub-Doppler resonances in absorption of the probe monochromatic light beam. Resolution of this spectroscopic method is analyzed in cases of stationary and definite nonstationary optical pumping of atoms by the broadband radiation versus geometrical parameters of given cells and pumping intensity. The suggested multilayer gas cell is the compact analog of many parallel atomic (molecular) beams and may be used also as the basis of new compact optical frequency standards of high accuracy.Comment: 12 pages, 4 figure

Saturation effects in the sub-Doppler spectroscopy of Cesium vapor confined in an Extremely Thin Cell

Saturation effects affecting absorption and fluorescence spectra of an atomic vapor confined in an Extremely Thin Cell (cell thickness $L < 1 \mu m$) are investigated experimentally and theoretically. The study is performed on the $D_{2}$ line ($\lambda ~= ~852 nm)$ of $Cs$ and concentrates on the two situations $L = \lambda /2$ and $L =\lambda$, the most contrasted ones with respect to the length dependence of the coherent Dicke narrowing. For $L = \lambda /2$, the Dicke-narrowed absorption profile simply broadens and saturates in amplitude when increasing the light intensity, while for $L =\lambda$, sub-Doppler dips of reduced absorption at line-center appear on the broad absorption profile. For a fluorescence detection at $L =\lambda$, saturation induces narrow dips, but only for hyperfine components undergoing a population loss through optical pumping. These experimental results are interpreted with the help of the various existing models, and are compared with numerical calculations based upon a two-level modelling that considers both a closed and an open system.Comment: 11 pages, 12 figure

Testing the limits of the Maxwell distribution of velocities for atoms flying nearly parallel to the walls of a thin cell

This is the initial submission (but for 3 lines suppressed as bearing a small error) of manuscript now accepted for publication in Journal of Chemical Physics. An update with the revised published version will appear when the requested embargo will have expired. The differences between the two versions are mostly in a shortened introduction, having implied a renumbering of the referencesNow published as J Chem Phys 147, 194202 (2017)International audienceFor a gas at thermal equilibrium, it is usually assumed that the velocity distribution follows an isotropic 3-dimensional Maxwell-Boltzmann (M-B) law. This assumption classically implies the assumption of a "cos theta" law for the flux of atoms leaving the surface, although such a law has no grounds in surface physics. In a variety of recently developed sub-Doppler laser spectroscopy techniques for gases one-dimensionally confined in a thin cell, the specific contribution of atoms moving nearly parallel to the boundary of the vapor container becomes essential. We report here on the implementation of an experiment to probe effectively the distribution of atomic velocities parallel to the windows for a thin (60 microns) Cs vapor cell. The principle of the set-up relies on a spatially separated pump-probe experiment, where the variations of the signal amplitude with the pump-probe separation provide the information on the velocity distribution. The experiment is performed in a sapphire cell on the Cs resonance line, which benefits of a long-lived hyperfine optical pumping. Presently, we can analyze specifically the density of atoms with slow normal velocities ~ 5-20 m/s, already corresponding to unusual grazing flight theta at ~85{\deg}-88.5{\deg} from the normal to the surface and no deviation from the M-B law is found within the limits of our elementary set-up. Finally we suggest tracks to explore more parallel velocities, when surface details -roughness or structure- and the atom-surface interaction should play a key role to restrict the applicability of a M-B-type distribution

Configurational Mechanism of X-Shaped Figures Recognition

The geometrical model of linear picture recognition made with the use of the multidimensional scaling technique for estimations of the perceptive differences between the selected X-shaped figures is described in the article. We analyzed the constructed space of the configurations by means of the terms of Sokolov and Izmailov’s spherical model of differentiating stimuli. In our research we showed that the process of the X-shaped figures discrimination was realized by the three-channel neuron network detecting two sensory features of the stimuli. Comparing the results of this work with the results of the researches of the different diagrammatic representations discrimination (lines, angles, three-linear figures) demonstrated that the X-shaped figures, recognized by the angular value and orientation, were the basic elements for human visual perception