559 research outputs found
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 ) are
investigated experimentally and theoretically. The study is performed on the
line ( of and concentrates on the two
situations and , the most contrasted ones with
respect to the length dependence of the coherent Dicke narrowing. For , the Dicke-narrowed absorption profile simply broadens and
saturates in amplitude when increasing the light intensity, while for , sub-Doppler dips of reduced absorption at line-center appear on the
broad absorption profile. For a fluorescence detection at ,
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
A whiter shade of pale, a blacker shade of dark: Parameters of spatially induced blackness
The surface-mode property of “blackness” is induced by simultaneous contrast with an adjacent, more luminant surround. As numerous studies have shown, the degree of blackness induced within an achromatic test field is a
function of the relative luminance of the adjacent chromatic inducing field, but not of its hue. But in the converse case of chromatic test fields, susceptibility to blackening has been reported to vary with wavelength. The present study investigates this possibility, that some wavelengths are more susceptible. We also questioned whether “white” and “black” sensory components function as opposites in blackness appearance. We recorded the appearance of a
central monochromatic test field of constant luminance (10 cd/m2), with wavelength ranging across the visible spectrum, while a broadband white annulus was set to six luminance levels ranging across three log steps. Three color-normal observers followed a color-naming technique. All six opponent-hue names and their combinations were response options; blackness and whiteness in the test field could therefore be reported independently. Of primary
interest were the achromatic responses. When represented within a multidimensional space, these revealed the “white-to-black” dimension but in addition a quality ~dimension! of “desaturation.” Compared against chromatic
properties of the test field, the results provide evidence that blackness is a function of inducing field brightness (not luminance). This result is in accord with observations made by Shinomori et al. (1997) using a different procedure. We conclude that blackness induction occurs at a stage of visual processing subsequent to the origin of the brightness signal from a combination of opponent-process channels
Types of loan words applied to french anglicisms
В статье выявлены основные типы заимствований в языках на основании анализа различных классификаций известных лингвистов. Анализ проведен на примере английских заимствований во французском языке.The article identifies the main types of loan words of languages basing on an analysis of various classifications of famous linguists. The analysis is performed on the example of English loan words in the French language
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