Sub-Doppler Spectroscopy in Thin Gas Cells upon Excitation of Atoms by Broadband Pulsed Radiation

A method of sub-Doppler spectroscopy is proposed, based on the peculiarities of narrowing over time of the velocity distribution of optically excited atoms (molecules) of a rarefied gas medium in a thin cell after exposure to a sufficiently short pulse of broadband radiation. Recording of narrow sub-Doppler resonances at the central frequencies of quantum transitions from the atomic state excited by such a pump pulse is carried out by subsequent probe monochromatic light pulses. The optimal conditions for the implementation of this spectroscopy method occur when the radiation decay time of an optically excited atomic level exceeds the characteristic time of flight of atoms between the walls of the thin cell under consideration, the inner thickness of which is many times smaller than its transverse dimensions.