THE (1)(3)PHI-]A(3)DELTA AND (2)(3)DELTA-]A(3)DELTA (0-0)-TRANSITIONS OF SCANDIUM MONOCHLORIDE

The results of a study of the (1)(3) Phi --> alpha a(3) Delta and (2)(3) Delta --> alpha(3) Delta near-infrared systems of scandium monochloride are presented. The principal subbands of the (0-0) transitions have been observed in the molecular emission spectrum at 1500 K. The analysis of the dense rotational structures has been facilitated by the information obtained in laser-induced fluorescence experiments. Indeed, a number of fluorescent lines have been observed, corresponding to Delta Sigma = 0 transitions from (2)(3) Delta(3,2,1)(upsilon = 0) to alpha(3) Delta(3,2,1)(upsilon = 0) levels, induced after excitation by near-infrared lines of a titanium sapphire laser. The spectra have all been recorded with a Fourier transform spectrometer. Each substate has been treated as a separate singlet state. The origins of the subbands and rotational constants of the substates are determined, except for (2)(3) Delta(1)(upsilon = 0), in which perturbational effects are recognized. All three states are regular and an estimation of the spin-orbit constant in the alpha(3) Delta state is made. The wavenumbers of the 900 observed lines are listed in an Appendix. (C) 1995 Academic Press, Inc.