Measurement of the Lifetime and the Electron-Impact Excitation Cross Section and Polarization of the2P3Term of Singly Ionized Lithium

Abstract

The lifetime of the $2 {}_{}{}^3{}_{}{}^{}P_j^{}{}_{}{}^{}$ states in singly ionized lithium has been measured using an rf magnetic-resonance technique; the value is $\tau =45\mathrm{}\pm 5$ nsec. Neutral lithium was ionized and excited by a unidirectional beam of electrons which produced an alignment in the excited state. The cross section for the electron-impact excitation $1s^{2}2s{}_{}{}^2{}_{}{}^{}S\to 1s2p{}_{}{}^3{}_{}{}^{}P$ near threshold was measured to be ${10}^{-22\mathrm{}\pm 1}$ ${\mathrm{cm}}^2$. Implications for the feasibility of rf resonance spectroscopy on the fine and hyperfine structure of the $2 {}_{}{}^3{}_{}{}^{}P$ term will be discussed.