Accurate lifetime measurements of excited states in argon II using the photon-photon delayed coincidence technique

Abstract

The photon-photon delayed coincidence technique has been used to measure the lifetimes of four excited states in argon II. Pressure-dependent effects have been avoided by using very low target gas pressures. A method of data analysis has been employed in which the instrumental response function is obtained directly and each time spectrum is analysed by a least-squares fit to the exponential decay convoluted with this known instrumental response function. The four levels, together with their measured lifetimes are as follows: 4p⁴P₅2/⁰(7.78+or-0.12)ns, 4p⁴P₃2/⁰(7.02+or-0.03)ns, 4p²D₅2/⁰(9.11+or-0.23)ns, 4p²D₃2/⁰(8.94+or-0.41)ns.