Radiative and Collision-Induced Relaxation of Atomic States in the2p53pConfiguration of Neon

Abstract

Application of techniques previously developed by the authors for the precise measurement of excited-state lifetimes has been made to radiative and collision-induced relaxation in the ten fine-structure levels of the $2p^{5}3p$ configuration of atomic neon. Lifetimes are determined as a function of pressure by studying the transient decay of isolated optical transitions from levels excited by short bursts of threshold-energy electrons. Measurements of the total radiative lifetimes have been made for these ten states within errors ranging from about 1 to 3%. The present work represents an improvement in the accuracy with which these lifetimes have been determined of at least an order of magnitude over previous experimental determinations. Discrepancies (which in some cases amount to an order of magnitude in the mean values) with previous lifetime studies are shown to be easily attributable to radiative cascade effects arising from nonthreshold excitation. The radiative lifetimes for these levels (Paschen notation) are, in nsec: $2p_1(14.4\mathrm{}\pm 0.3)$; $2p_2(18.8\mathrm{}\pm 0.3)$; $2p_3(17.6\mathrm{}\pm 0.2)$; $2p_4(19.1\mathrm{}\pm 0.3)$; $2p_5(19.9\mathrm{}\pm 0.4)$; $2p_6(19.7\mathrm{}\pm 0.2)$; $2p_7(19.9\mathrm{}\pm 0.4)$; $2p_8(19.8\mathrm{}\pm 0.2)$; $2p_9(19.4\mathrm{}\pm 0.6)$; and $2p_{10}(24.8\mathrm{}\pm 0.4)$. Variations ≈ 5% in the radial part of the transition probability were encountered for different $3p\to 3s$ transitions; these variations may be attributed to configuration interaction. Calculations of ${\sigma }^2$ from the Coulomb approximation agreed with the experimentally determined values within this spread. Cross sections for inelastic excitation transfer were encountered for the more closely spaced states which were comparable to gas kinetic cross sections, but which could not be determined in the present work to within much less than 50% error in most cases. The relationship of the present work to problems in the gas laser field is discussed.