Mean life of the4sS122resonance level in Ali

Abstract

The mean life of the $4s{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ 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 Å and observing its decay by means of the transition at 3961.52 Å, increase with increasing vapor density. This vapor-density dependence was interpreted as being due to the imprisonment of the 3962-Å radiation. Imprisonment theory at low densities was applied to the experimental data to yield the following results: ${\tau }_0=6.78\mathrm{}\pm 0.06$ ns, $f_{3944}=0.115\mathrm{}\pm 0.001$, and $f_{3962}=0.116\mathrm{}\pm 0.001$. Experimental and theoretical results of other workers are presented for comparison with the results of the present work.