Role of N2(Arsquo;thinsp;5Sgr;+g) in the enhancement of N2Bthinsp;3Pgr;g(V=10) populations in the afterglow

摘要

Timehyphen;resolved spectroscopic observations of the N21PG afterglow,Bthinsp;3Pgr;grarr;Athinsp;3Sgr;+u, following a pulsed discharge show both an enhancement in the overall intensity and significant changes the shape of bands which arise from thev=10 level of theBthinsp;3Pgr;g. Model results indicate that these changes in shape are produced by an enhancement of the population of the lowJlevels of the OHgr;=2 component of thev=10 level. In addition, we also observe bands of the Herman Infrared system of N2(HIR),Clsquo;thinsp;5Pgr;urarr;Arsquo;thinsp;5Sgr;+g, specifically the (3,1) and (2,0) bands. During the afterglow, both the 1PG and HIR are being produced by energy pooling processes. The timehyphen;dependent increase of the 1PGvrsquo;=10 band intensities show a strong correlation with the variation in the HIR band intensities which predominately populate the lower levels of theArsquo;thinsp;5Sgr;+g. Recent work has shown theArsquo;thinsp;5Sgr;+gto have a significantly deeper potential well than previously thought so that it is now thought to cross theBthinsp;3Pgr;gvery close tov=10 rather thanv=12. Consequently, we consider theArsquo;thinsp;5Sgr;+gto be the most likely candidate as the source of the observed intensity enhancements in thev=10 level of theBthinsp;3Pgr;g. Based on our measurements and a simple model of the afterglow we have estimated the apparent rate coefficient for collisional transfer betweenArsquo;thinsp;5Sgr;+gand the highvlevels of theBthinsp;3Pgr;gdue to collisions with the N2ground state. The value for collisional transfer fromArsquo;toBis approximately 1.0times;10minus;11cc/moleculethinsp;s. Our observations indicate theArsquo;thinsp;5Sgr;+gmay have an even deeper potential and we estimate an upper bound forv=0 to be sim;3590plusmn;32 cmminus;1below the dissociation limit which is sim;500plusmn;32 cmminus;1deeper than the recent theoretical estimate.