Metastable atoms in gasdynamic and atomic beams: Velocity distribution and state density by laser diagnostics

摘要

The velocity distributions and state densities of metastable Ca(4s4p 3P2) atoms emerging from discharge beam sources were measured by probing the Doppler shift in laser induced fluorescence. In order to cover the widely spread distribution of the longitudinal velocity component a single‐mode dye laser was used in mode hopping technique. In this way up to 4 Å can be covered in steps of 182 MHz distance. The longitudinal and transverse components are sampled simultaneously. For the gasdynamic jet the transfer velocities were measured from some 10 m/s up to supersonic values. Using the transverse laser beam the absorption caused by Ca in the 3P2 state was tested. Absorptions up to 0.995 could be achieved in the free jet. A 3P density of 7×1011 cm-3 is calculated. Similarly for the atomic beam 2×1010 cm-3 is found, the flux being 4.7×1015 metastable atoms/s sr. Details of the atomic beam source for metastable atoms are given.