Fourier Transform Emission Spectroscopy of ScH and ScD: The New Singlet Electronic States A 1 Delta, D 1 Pi, E 1 Delta, and F 1 Sigma-

The emission spectra of ScH and ScD have been investigated in the near infrared and visible using a Fourier transform spectrometer. The molecules were excited in a scandium hollow cathode lamp operated with neon gas and a trace of hydrogen or deuterium. Apart from the X 1 Sigma+ , B 1 Pi, C 1 Sigma+ , and G 1 Pi states reported previously [R. S. Ram and P. F. Bernath, J. Chem. Phys. 105, 2668-2674 (1996)], four additional new singlet electronic states A 1 Delta, D 1 Pi, E 1 Delta, and F 1 Sigma- have been identified below 21 000 cm-1 . The rotational analysis of several vibrational bands of the D 1 Pi-X 1 Sigma+ , D 1 Pi-A 1 Delta, E 1 Delta-B 1 Pi, E 1 Delta-A 1 Delta, and F 1 Sigma- -B 1 Pi transitions has been carried out and spectroscopic constants have been determined. The E 1 Delta state of ScH was not located because of the very weak intensity of the E 1 Delta-B 1 Pi and E 1 Delta-A 1 Delta transitions.