Radiative lifetimes of excited electronic states in molecular ions

Abstract

Radiative lifetimes of excited electronic states of several molecular ions have been measured using a technique which permits the mass selective storage of ions for periods of many ms. This technique is used to record radiative lifetimes ranging from 60 ns to approx. 10 ..mu..s. The use of a radiofrequency quadrupole ion trap to confne the ions reduces the problem of space charge induced spatial dissipation of ions and permits the selective excitation of electronic states. Using this technique, careful measurements of the B/sup 2/..sigma../sup +//sub u/ state of N/sup +//sub 2/ and the A/sup 2/Pi states of N/sup +//sub 2/ and CO/sup +/ have been made. The results obtained are in good agreement with previous studies. The analysis of the radiative lifetime for the CH/sup +/ and CD/sup +/ A/sup 1/Pi(..nu..' = 0) state results in a value significantly larger than earlier determinations. The new results are used to make revised estimates of interstellar abundances of CH/sup +/.