Spectroscopy of 142NdO: New results

Abstract 142 NdO molecules have been produced by heating 142 Nd 2 O 3 to about 2100 K in a vacuum furnace in the presence of argon gas. A ring dye laser operating with DCM dye has been used to excite 142 NdO transitions in the 636–666 nm spectral region, and induced fluorescence has been spectroscopically analysed at high resolution with a Fourier transform spectrometer. Contributions from thermal emission have been simultaneously observed. Two new low-lying electronic states have been detected, at energies of about 2708 and 4139 cm −1 , designated as [2.7], most probably observed at ν  = 1, and [4.1], likely to be (2)6 (observed at ν  = 0). The ν  = 1 level of the (1)6 state, already known at ν  = 0, has been observed for the first time. Most levels pumped by the laser, between 14 000 and 17 400 cm −1 , could be identified from earlier work. In addition, by studying in more detail recently obtained fluorescence spectra [J. Mol. Spectrosc. 225 (2004) 132] spectroscopic constants have been improved for a number of states. Finally, from thermal emission spectra, rotational analyses of the 0–0 bands of two new systems, [16.4] − (2)5 and [14.1] −  X 4, and reanalyses at higher resolution of the 0–0 bands of the systems V, VII, VIII, and X have been carried out. A consistent set of spectroscopic constants of the levels of 142 NdO characterized as yet is presented.