LASER AND FOURIER-TRANSFORM SPECTROSCOPY OF THE [23.8]1-X-0(+) SYSTEMOF REN

The emission spectrum of ReN has been observed in the 400-476 nm spect ral region using a Fourier transform spectrometer. The bands were exci ted in a rhenium hollow cathode lamp in the presence of a trace of N-2 . The observed bands, with the 0-0 band at 23 746.42 cm(-1), have been assigned as the [23.8] 1-X0(+) electronic transition. A rotational an alysis of the 0-1, 0-0, and 1-0 bands for both (ReN)-Re-187 and (ReN)- Re-185 isotopomers has been performed. The principal ground state equi librium molecular constants for (ReN)-Re-187 obtained from this analys is are B-e('') = 0.482414(11) cm(-1), r(e)('') = 1.63780(2) Angstrom, while the corresponding excited state values are B-e(') = 0.441093(13) cm(-1), r(e)(') = 1.71280(3) Angstrom. The 0-0 band was also observed by pulsed dye laser excitation spectroscopy using a free jet expansio n source. In this experiment, the ReN was made by laser vaporization o f a rhenium rod followed by reaction with NH3. The excited [23.8] 1 st ate has a fluorescence lifetime of 201 +/- 1 nsec. There are no previo usly reported observations of the ReN molecule. (C) 1994 Academic Pres s, Inc.