Mean life of the 27 887-cm−1level inUi

Abstract

Measurements of the mean life of the 27 887-${\mathrm{cm}}^{-1\mathrm{}}$ level in ${\mathrm{U}}_{\mathrm{i}}$ have been made at a single vapor density using electronic excitation and a method of delayed coincidence. The lifetime values were obtained by optically detecting the decay of the 3584.9-Å resonance transition. Using branching ratios obtained from known relative $f$ values, the average of the measured lifetimes was corrected for imprisonment of the resonance radiation, and absolute $f$ values were derived from the corrected lifetime giving the following results: ${\tau }_0=7.3\mathrm{}\pm 1.1$ nsec, $f_{3585}=0.18\mathrm{}\pm 0.03$, and $f_{4620}=0.20\mathrm{}\pm 0.03$. The error given with each quantity is the standard deviation as determined from the dispersion of the individual measurements. A systematic error of 1% due to possible nonlinearities in the time scale of the system is also assigned to the results. Unaccounted for systematic errors affect only the correction in the measured lifetime, which is small compared to the statistical error. The lifetime and $f$ values are presented in comparison with the experimental results of another group of workers.