FOURIER-TRANSFORM EMISSION-SPECTROSCOPY OF HFH AND HFD

The electronic emission spectra of HfH and HfD were investigated in the 476 nm to 1 mu m spectral region using a Fourier transform spectrometer. The bands were excited in a hafnium hollow cathode lamp in the presence of a mixture of neon and H-2 or D-2. For HfH, two Delta Omega=0 electronic transitions with a common Omega''=3/2 lower state, most probably the X (2) Delta(3/2) ground state, were identified at 14 495 and 19 147 cm(-1). These bands have been assigned as the [14.5]3/2-X (2) Delta(3/2) and the [19.1]3/2-X (2) Delta(3/2) transitions. The rotational analysis of the 0-0 and 1-1 bands of the [14.5](3/2)-X (2) Delta(3/2) system and the 0-0 band of the [19.1]3/2-X (2) Delta(3/2) system provides the following equilibrium constants for the ground state of HfH: B''(e) = 5.019 11(8) cm(-1), alpha''(e) = 0.120 26(11) cm(-1) , and r''(e) = 1.830 691(15) Angstrom. For HfD, only the 0-0 band of the [19.1]3/2-X (2) Delta(3/2) transition at 19 134 cm(-1) was identified. This work represents the first observation of the HfH and the HfD molecules.