Vibrational relaxation in ground statephyphen;difluorobenzene: Single level preparation by stimulated emission pumping

摘要

We have measured the cross section for vibrational relaxation from the 52302level (egr;vib= 2036 cmminus;1) ofS0phyphen;difluorobenzene (pDFB) due topDFBhyphen;pDFB collisions. Stimulated emission pumping has been used to selectively populate the 52302level. Single vibronic level fluorescence from theS1level 302, generated by exciting the 5023022transition at a variable delay time after 52302has been populated, has been used to monitor the population dynamics of 52302. We obtain a value of 4plusmn;1times;107sminus;1Torrminus;1for the vibrational relaxation rate coefficient, a value which is 2ndash;3 times the hard sphere value. This large cross section is consistent with the cross sections observed inS1benzene but is an order of magnitude larger than the cross sections observed previously for a variety of molecules in the ground electronic state. (AIP)