Measurement of Metastable Population in Gadolinium Atomic Beam by Resonance Photoionization

Abstract

Population of metastable levels in a gadolinium atomic beam produced by electron beam heating were measured using the resonance photoionization technique. The population followed the Boltzmann distribution and the atomic excitation temperature was determined. The atomic excitation temperature is far lower than the temperature of the evaporation surface and nearly equal to the temperature which characterizes the distribution in the velocity component parallel to the gadolinium atomic beam axis. This suggests that the atomic excitation energy and the translational energy exchange each other at high reaction rate in the atomic vapor expanding from the evaporation surface into vacuum.