THE B-1-PI -] X-1-SIGMA(+) SYSTEM OF SCANDIUM MONOIODIDE

Rotational analyses have been carried out on eight thermically excited emission bands of the infrared B-1 Pi --> X-1 Sigma(+) system of scan dium monoiodide between 4000 to 5000 cm(-1), recorded by Fourier trans form spectrometry. Rotational constants and energies are obtained for X-1 Sigma(+) (v = 0, 1, 2) and B (1) Pi (v = 0-4) levels from which eq uilibrium constants of the states are derived. Perturbational effects are observed in the bands with v '' = 1 that are interpreted as conseq uences of the avoided crossing of X-1 Sigma(+) (v = 1) and a(3) Delta( 1) (v = 0) at J = 70, A treatment of the perturbation is made using an effective 2 x 2 matrix representation of the rotational energies of t he two levels. (C) 1998 Academic Press.