We have constructed a beam-laser lifetime-measuring apparatus and tested it by measuring the well known lifetime of the v=0 level of the ${}_{}{}^2{}_{}{}^{}\mathrm{\Sigma }_{\mathrm{u}}^{+}{}_{}{}^{}$ state of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}_2^{+}{}_{}{}^{}$. Our result of 61.8(5) ns is in excellent agreement with previous high-precision measurements. Employing this technique we performed measurements of the lifetimes of the four lowest vibrational levels of the B ${}_{}{}^2{}_{}{}^{}\mathrm{\Sigma }_{}^{+}{}_{}{}^{}$ state of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}_{}^{16}{}_{}{}^{}$${\mathrm{O}}^{+}$. The results are (in ns) 69.5(6), 72.4(5), 75.2(5), and 78.0(8) for v=0, 1, 2, and 2, respectively.

• Received 20 June 1994

DOI:https://doi.org/10.1103/PhysRevA.51.2014