ELECTRONIC SPECTROSCOPY OF JET-COOLED RHODIUM MONONITRIDE AND RHODIUM MONOCARBIDE IN THE VISIBLE REGION

Abstract

We report the gas phase spectroscopic studies of the rhodium mononitride (RhN) and rhodium monocarbide (RhC) radicals. RhN/RhC molecules were produced in a laser vaporization apparatus utilizing rhodium metal and ammonia/methane. Laser induced fluorescence spectra were recorded in the $390-750 nm$ region. It is believed that this is the first observation of the RhN radical in the laboratory. Transitions with $\Lambda = 0$ and 1 have been noted. Rotational and vibrational analyses have been performed and assignments made based on these and on ${^{14}}N/^{15}N$ isotopic shifts, excited state lifetimes and dispersed fluorescence (DF) spectra. The $Rh^{14}N DF$ spectra reveal the presence of several low-lying electronic states and long progressions have provided information on the vibrational spacing. A $\ldots \delta^{4}\sigma^{2}$ electronic configuration is proposed for the ground state of RhN which agrees with the observation that all the jet-cooled spectra have ${^{1}}\Sigma$ as their lower state. Possible electronic configurations for other low-lying electronic states as well as excited states will be discussed. The RhC bands observed by Lagerqvist and $Scullman^{a}$ have been re-examined. Many bands not reported by them have also been observed. The new results suggest that the B-X spectra need to be reinterpreted. The DF spectra from both B and C states show long ground state progressions$(v=0 to v=10)$. Emission to the $A^{2}\Pi$ state has also been observed.