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Highly excited rovibrational states of HNC

Georg Ch. Mellau
Organization: Justus-Liebig-Universität Giessen
Department: Physikalisch-Chemisches-Institut
Journal / Anthology

Journal of Molecular Spectroscopy
Year: 2011
Volume: 269
Issue: 1
Page range: 77-85

The [H, C,N] molecular system is a very important model system to many fields of chemical physics. The experimental characterization of highly excited vibrational states of this molecular system with a stable HCN and a metastable HNC isomer is of special interest. This work substantially extends the spectroscopic characterization of the rovibrational states of the [H, C,N] molecular system around the HNC minimum of the potential surface. The emission spectrum of the HNC isomer has been recorded at 1463 K using hot gas molecular emission (HOTGAME) spectroscopy from the far infrared up to the near infrared wavenumber region. The dense emission spectrum was analyzed using the spectrum analysis software SyMath™ implemented in the Mathematica™ computer algebra system. This work reports the analysis of highly excited rovibrational states. The rotational structure for 27 vibrational states (0vl 21 states from v2 = 4 to v2 = 7, the 0vl 22 from v2 = 1 to v2 = 4 and 2vl 20 states from v2 = 3 to v2 = 4) have been characterized for the first time and for five known vibrational levels it was possible to improve the existing spectroscopic constants substantially. Together with the author’s three recent papers accurate spectroscopic constants for 94 HNC rovibrational states have been determined. New expansion coefficients for the vibrational dependence of the spectroscopic constants are reported from the analysis of all these states.