Fourier transform emission spectroscopy of the g(4)Delta-a(4)Delta system of FeF

The emission spectrum of FeF has been observed in the near infrared region from 9000 to 12 000 cm(-1). The bands were excited in a high temperature carbon tube furnace and recorded with a Fourier transform spectrometer at a resolution of 0.02 cm(-1). The observed bands have been assigned as the 0-1, 0-0, 1-0, and 2-0 bands of the g(4) Delta(i)-a(4) Delta(i) transition analogous to the F-4 Delta i(-)X(4)Delta>(i) transition of FeH at 1 mu m. Each vibrational band consists of four sub-bands assigned as (4) Delta(1/2)-(4) Delta(1/2), (4) Delta(3/2)-(4) Delta(3/2), (4) Delta(5/2)-(4) Delta(5/2), and (4) Delta(7/2)-(4) Delta(7/2). The rotational analysis of these bands has been performed and molecular constants have been determined. This work represents the first observation of the g(4) Delta-a(4) Delta transition of FeF. We discuss the correspondence between the low-lying electronic states of FeF, FeH, and Fe+. (C) 1996 Academic Press, Inc.