Direct determination of excited-state lifetimes by electron impact excitation and single-photon counting techniques

Abstract

Excited atomic states are produced by electron impact with a pulsed beam of electrons of fixed energy and sharp cut-off. The spontaneous decay of these states is obtained as a function of time by a single-photon counting technique. Experimental values for the lifetimes of the 4 3S, 5 3S, 4 1S, 5 1S, 3 3P, 4 3P, 3 1P, 4 1D and 5 1D states of neutral helium are given.