J-DEPENDENT LIFETIMES OF NO($B^{2}\Pi$)v=$7^{*}$

$^{*}$Research supported by NSF $^{1}$G. E. Gadd and T. G. Slanger, J. Chem. Phys. 92, 2194 (1990).""Author Institution: CSIRO Div. of Appl. Phys.; Molecular Physics Laboratory, SRI InternationlHomogeneous interaction between the Rydberg $C^{2}\Pi$ and valence $B^{2}\Pi$ states of NO leads to both interesting spectroscopy and difficult interpretation of radiative properties, made more complicated by predissociation. We have performed rotationally resolved LIF studies of the radiative properties of the v=7 vibrational level of the $B^{2}\Pi$ state of NO from J=0.5 to J=17.5. Three types of data were obtained: (1) fluorescence-excitation spectra to investigate the rotational dependence of bands in the B-X 7-v"" progression, (2) dispersed fluorescence spectra from excitation of specific J levels, and (3) radiative lifetimes as functions of J. The $\Omega$=1/2 sublevels of the B(7) state lie 30 $cm^{-1}$ or more below C(0,J). They have lifetimes in the range 200 to 700 ns,with a modest decrease as the dissociation limit is crossed at J=7.5. The J-dependence of the lifetimes and of the excitation and fluorescence spectra illustrate the influence of distant interaction with the C-state (see our previous $study^{1}$ of the lower $v=0-6$ levels). The $\Omega=3/2$ sublevels of B(7), which intersect the two $\Omega$ components of C(0) near J=2.5-4.5, have much shorter decay lifetimes for low J values, about 40 ns, due to strong localized interaction with C(0). The decay rate decreases rapidly as J increases, merging with the values obtained for $\Omega$=1/2 by J=10.