Radiative lifetimes of trapped molecular ions: HCl+and HBr+

摘要

Excitation spectra in theAthinsp;2Sgr;+minus;Xthinsp;2Pgr; system of HCl+(0,0) and HBr+(1,0) as well as radiative lifetimes of selectively excited rotational levels in theAthinsp;2Sgr;+electronic states have been measured in a RF ion trap using laser induced fluorescence and timehyphen;resolved singlehyphen;photon counting techniques. Coherent ultraviolet radiation was generated by frequency mixing of a Nd:YAG/dye laser system. For HBr+the lifetimes of four rotational levels adjacent to thevprime;=1 predissociation limit atJprime;=25/2 were measured. No statistically significant variation withJwas found. The average of these four values (3.89plusmn;0.15 mgr;s) is therefore reported as the effective lifetime of thevprime;=1 level ofAthinsp;2Sgr;+HBr+. For HCl+the lifetime measurements likewise indicate no strong variation withJ. The average lifetime of thevprime;=0 level of theAthinsp;2Sgr;+state of HCl+is 3.4plusmn;0.4 mgr;s. Measurements of radiative lifetimes of molecular ions by the RF ion trap technique eliminates the determinate error that results from drift of ions out of the detection volume in conventional experiments.