The ν1 band system of HCN

Abstract

The emission spectrum of HCN has been recorded at 1463 K using hot gas molecular emission (HOTGAME) spectroscopy in the wavenumber region of 2900–3500 cm −1 with a resolution of 0.01 cm −1. The dense emission spectrum was analyzed with the spectrum analysis software SyMath™ implemented in the Mathematica™ computer algebra system. This work reports the analysis of the 1 v 2 l 0 → 0 v 2 l 0 band series up to v 2 = 8 and of the 1 v 2 l 1 → 0 v 2 l 1 band series up to v 2 = 6.36 rovibronic ( v 1, v 2, l, e/ f, v 3) substates of HCN including all l = 0, 2, 4, 6, 8 sublevels of the v 1 v 2 l v 3 = 18 l 0 highly excited bending combination mode have been characterized for the first time and for the 22 known vibrational sublevels it was possible to improve the existing spectroscopic constants substantially. 18 ( v 1, v 2, l, v 3) vibrational sublevels are located for the first time relative to the 00 00 state. The analysis reported here includes rovibrational states up to very large rotational excitations of J = 60–80. For the 1 v 2 l 0 combination states the rotational states have been determined up to J = 86 which corresponds to 7000 cm −1 rotational excitation energy, this state is only 2000 cm −1 below the isomerization barrier. It was possible to determine for the first time the L v high order rotational constant for many states reported in this work.