Matrix effects on radiative and radiationless rates of NBrbthinsp;1Sgr;+andathinsp;1Dgr; trapped in solid argon

摘要

NBr in solid argon has been excited to thebthinsp;1Sgr;+state with a pulsed tunable dye laser. In addition to the wellhyphen;known fluorescence spectrum of thebstate, infrared emission from the vibrationally relaxedathinsp;1Dgr; state was detected at 1086 nm. Three major trapping sites were resolved in absorption and fluorescence excitation spectra of thebndash;Xsystem. Additional sites could be identified in the excitation spectrum of theastate, which is populated via thebstate by internal conversion. There is a weak site effect on the lifetime of the vibrationally relaxedbstate, which varies between 40 and 30 mgr;s. Vibrational relaxation rates in thebstate show a stronger site dependence. Internal conversion frombthinsp;1Sgr;+toathinsp;1Dgr; accounts for 0.1percnt; to at least 17percnt; of the decay rate of NBrbthinsp;1Sgr;+,v=0. Orbitally forbidden transitions to theX10+component of the ground state were identified 23.0 to 25.5 cmminus;1on the highhyphen;energy side of the more intenseathinsp;1Dgr;rarr;X21plusmn;transition of several sites. The lifetime of theastate varies between 152plusmn;12 ms in the least perturbed site and 121plusmn;15 ms in the site with the strongestathinsp;1Dgr;rarr;X10+forbidden component. NBr trapped in double vacancies of pure fcc argon, of single stacking faults, and of multiple stacking faults (hcp pockets) in argon, can account for the sites.