Relaxation of atomic state multipoles by radiation re-absorption: Neon [formula omitted] atoms in a discharge plasma

Abstract

In a positive column of a glow discharge in the magnetic field of 36.4 G, a linearly polarized laser pulse or a circularly polarized laser pulse has produced polarized neon atoms (alignment or orientation) in the 2 p 2 (Paschen notation) level from the 1 s 3 level. The subsequent fluorescence to the 1 s 2 level was observed with its polarized components resolved. Depopulation, disorientation and disalignment rates of the 2 p 2 atom were measured and their discharge current dependences were examined for a discharge current from 0.4 to 2.0 mA. The degrees of radiation re-absorption, or the optical thickness, of the transition lines from the 2 p 2 level to the 1 s 2 - 1 s 5 levels were measured as functions of the discharge current. A Monte Carlo simulation was performed by which the depopulation, disorientation and disalignment rates by the radiation re-absorption for these transitions were determined. The calculated rates were compared with the observed ones and found to reproduce the their discharge current dependences. D’Yankonov and Perel's analytical expression for these rates was quantified from comparison with the Monte Carlo results.