Observation and Rovibrational Analysis of the Intermolecular HCl Libration Band in OC−HCl. Modeling of the Intermolecular Potential Energy Surface

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 108; no. 9; pp. 1524 - 1530
• Main Authors: Larsen, R. Wugt, Hegelund, F, Nelander, B
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04-03-2004
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp036935u

The high-resolution far-infrared spectrum of the intermolecular HCl libration band of the OC−H35Cl heterodimer is recorded in the gas phase by means of Fourier transform IR spectroscopy in a static multipass absorption cell at 137 K using a synchrotron radiation source. This is the first direct observation of an intermolecular vibration band of the OC−HCl dimer in the gas phase. The rotational structure of the band has the typical appearance of a perpendicular band of a linear polyatomic molecule. The structure is analyzed to yield the band origin ν0 = 201.20464(27) cm-1 together with values for the upper state rotational constant, the upper state quartic and sextic centrifugal distortion constants, and the l-type doubling constant. The determined values for the rotational constant and the centrifugal distortion constants are used to obtain a Morse potential for the stretching of the intermolecular distance. The results are compared to the results from quantum-chemical calculations.