Fourier transform infrared emission spectroscopy and ab initio calculations on RuN

Abstract

The emission spectrum of RuN has been observed in the near infrared using a Fourier transform spectrometer. RuN molecules were excited in a hollow cathode lamp operated with neon gas and a trace of nitrogen. Two bands with 0–0 Q heads near 7354 and 8079 cm−1 and a common lower state have been assigned as 2Π1/2–2Σ+ and 2Π3/2–2Σ+ subbands, respectively, of a C 2Π–X 2Σ+ transition. A rotational analysis of these bands has been performed and molecular constants have been extracted. The principal molecular constants for the ground X 2Σ+ state of the most abundant 102RuN isotopomer are: B0=0.552 782 9(70) cm−1, D0=5.515(13)×10−7 cm−1, γ0 =−0.044 432(22) cm−1 and r0=1.573 869(10) Å. The excited C 2Π state has the following molecular constants: T00=7714.342 60(53) cm−1, A0=725.8064(11) cm−1, B0=0.516 843 4(80) cm−1, D0=5.685(16)×10−7 cm−1, p0=5.467(36)×10−3 cm−1 and r0=1.627 670(13) Å. Ab initio calculations have been carried out on RuN to ascertain the nature of the experimentally observed states and to predict the spectroscopic properties of the low-lying electronic states. Our electronic assignment is supported by these calculations and is also consistent with the observations for the isoelectronic RhC molecule [Kaving and Scullman, J. Mol. Spectrosc. 32, 475–500 (1969)]. The valence electron configuration 1σ22σ21π41δ43σ1 is proposed for the X 2Σ+ ground state of RuN and the configurations for the excited states have been discussed. There is no previous experimental or theoretical work on RuN.