The TiO c(1)Phi-a(1)Delta (0-0) band at sub-Doppler spectral resolution: Spin-orbit interactions in the c state

The c(1) Phi-a(1) Delta (0-0) band of titanium monoxide has been studied at sub-Doppler resolution by crossing a beam of TiO molecules with a cw tunable laser beam and collecting the laser-induced fluorescence. The rotational structures of the P, Q, and R branches have been observed up to rotational quantum numbers equal to 52, 94, and 96, respectively. The spectroscopic data have been reduced to a set of 11 effective molecular constants with a root mean squared values of the residuals equal to 7 x 10(-4) cm(-1). However, the necessity of including seventh order terms in the rotational development of the energy put into evidence a very strong spin-orbit interaction between the c(1) Phi (v> = 0) and C-3 Delta(3) (v = 2 and v = 3) levels. The derived spin-orbit parameter allows for the reproduction of the measured wavenumbers without the introduction of higher order rotational terms into the energy development. The value of the spin-orbit parameter indicates the necessity of revisiting the configuration scheme of the involved electronic states. (C) 1996 Academic Press, Inc.