Magnetic deflection analysis of supersonic metastable atom beams

Abstract

Deflection of 3S1 and 3P2 metastable rare-gas atoms in an electron-impact-excited thermal supersonic expansion by an inhomogeneous magnetic field produces well-defined daughter beams for each M state. The deflection patterns are spatially resolved with a translatable detector and used to derive fine-structure populations in the 3P0 and 3P2 states, and to measure absolute efficiency of state selection by optical depletion. The fine-structure population ratio 3P2/3P0 is measured for electron excitation energies from 100–400 eV, showing a 20%–40% decline with increasing energy for all the rare gases. Radiative decay due to perturbation by the magnetic field appears to be negligible, but the M-state-resolved populations are unequal and asymmetric, perhaps due to Majorana transitions at the entrance to the field. The method may also be useful in polarized angular momentum studies of metastable atom–molecule collisions.