MEAN-LIFE OF THE 4S2S1/2 RESONANCE LEVEL IN ALI

The mean life of the 4sS122 resonance level in Al i has been measured at seven different vapor densities using a tunable dye laser for excitation and a method of delayed coincidence for detection. The lifetime values, obtained by exciting the level with radiation at the resonance wavelength of 3944.01 and observing its decay by means of the transition at 3961.52, increase with increasing vapor density. This vapor-density dependence was interpreted as being due to the imprisonment of the 3962- radiation. Imprisonment theory at low densities was applied to the experimental data to yield the following results: 0=6.78+0.06 ns, f3944=0.115+0.001, and f3962=0.116+0.001. Experimental and theoretical results of other workers are presented for comparison with the results of the present work. © 1979 The American Physical Society.