ELECTRONIC SINGLET-STATES OF SCANDIUM MONOCHLORIDE

We present the results of a study of singlet transitions of scandium m onochloride, corresponding to (i) the developed red C(2)(1) Sigma(+) - -> X(1) Sigma(+) and infrared B(1)(1) Pi --> X(1) Sigma(+) systems obs erved in thermal emission, (ii) fluorescence from (3)(1) Pi to B(1)(1) Pi and from(3)(1) Sigma(+) to B(1)(1) Pi, following excitation by Ar laser lines 476.5 or 457.9 nm. Transitions belonging to both isotopic molecules (ScCl)-Sc-45-Cl-35 and (ScCl)-Sc-45-Cl-37 have been observe d, and spectra have been recorded with a Fourier transform spectromete r. We give values of the effective molecular constants for a number of vibrational levels in five electronic states as they result from an o verall fit of the experimental data for each isotopomer (some 5400 lin e wavenumbers are reproduced with a standard deviation of 0.006 cm(-1) ). The (3)(1) Sigma(+) state is characterized for the first time, in t he upsilon = 0 level. Local rotational perturbations are observed in t he first five vibrational levels of B(1)(1) Pi. (C) 1996 Academic Pres s, Inc.