Mean lives of four electronically excited atomic levels in Ar I have been determined using a method of delayed coincidence. The measured values of the mean lives of the 2p1 through 2p4 (Paschen notation) levels in neutral argon determined from transitions with associated wavelengths extending from 6677 to 7147 Å are as follows: 2p1, 21±2 nsec; 2p2, 25±1 nsec; 2P3, 26±1 nsec, and 2p4, 31±2 nsec. The lifetimes were estimated to contain systematic errors varying from 5% to 15% and are presented in comparison With results of other workers.
JULES Z. KLOSE, "Lifetimes of Some 4p Levels in Argon I," J. Opt. Soc. Am. 57, 1242-1244 (1967)