THE DNF (A)OVER-TILDE(2)A'-(X)OVER-TILDE(2)A''-BAND SYSTEM - ROTATIONAL ANALYSIS OF THE ORIGIN BAND AND PARTIAL ANALYSIS OF SEVERAL HIGHER BANDS

The laser fluorescence excitation spectrum of the 000 band of the DNF ã2A′-X̃2A″ system was obtained and rotationally analyzed. The K″a = 0-4 subbands were recorded at 0.06 cm-1 resolution, while higher subbands (K″a ≤ 7) were obtained at lower resolution (0.2 cm-1). The assigned lines in this hand were fitted to obtain rotational, centrifugal distortion, and spin-rotation parameters for the zero-point levels of the ã2A′ and X̃2A″ electronic states. Combining these rotational constants with those previously derived by Woodman [J. Mol. Spectrosc.33, 311-344 (1970)] from analysis of the analogous HNF band allowed estimation of the mean geometries in both electronic states independent of any assumptions about bond lengths. Fluorescence excitation scans were also taken over the 240, 230310 and 260 bands. The K structure in these bands is simpler because fluorescence can be detected only for excitation of the K′ = 0 and 1 stacks. Fits of measured line positions in the K′a = 0-K″a = 1 subband allowed estimation of (B′ + C′)/2 for the upper vibrational levels of these bands. © 1993 Academic Press, Inc.