CHARACTERIZATION OF THE C(3)SIGMA(+) STATE OF SCF - THE C3-SIGMA+-X1-SIGMA+ SYSTEM

Thermal emission of scandium monofluoride has been spectroscopically investigated at high resolution in the region 7000-12 000 cm-1 with a Fourier transform spectrometer. The predicted low-energy c3SIGMA+ state is observed in a transition to the ground state; six bands of the c3SIGMA+-X1sigma+ system, 0-0, 0- 1, 0-2, 1-0, 1-3, 2-0, are rotationally analyzed. Molecular constants are obtained for c3SIGMA+ (upsilon = 0, 1, 2). The rotational dependence of the spin-splitting parameters epsilon and gamma is evaluated. Principal constants (in cm-1) for c3SIGMA+(upsilon = 0) are T = 9384.59, B = 0.34432, D = 0.450 x 10(-6), epsilon = -16.00, and gamma = 0.1132. In addition to the appearance of the forbidden transition c3SIGMA+-X1SIGMA+, some other consequences of the interaction c3SIGMA+ is similar to B1PI are recognized: (i) the large values of epsilon and gamma in c3SIGMA+ decrease markedly on going from upsilon = 0 eq upsilon = 1, and at the same time, in B1PI the large A-doubling in upsilon = 0 decreases rapidly in magnitude with increasing v, and (ii) a broadening of the Q lines in B1PI(upsilon = 0)-X1SIGMA+ bands correlated with a narrowing of (P)Q and (R)Q lines in C3SIGMA+(upsilon = 0)-X1SIGMA+ bands, both effects being attenuated in upsilon' = 1 bands and becoming unobservable in upsilon' = 2 bands which show sharp Q in the singlet-singlet system and intrinsically broadened (P)Q and (R)Q lines in the triplet-singlet system. (C) 1994 Academic Press, Inc.