15min:

J.-M. FLAUD, J. ORPHAL, Laboratoire de Photophysique Moléculaire, C.N.R.S., Bât. 350, Université Paris-Sud, 91405 Orsay Cedex, France; W. J. LAFFERTY, Optical Technology Division, NIST, Gaithersburg, MD 20899, U.S.A; M. BIRK AND G. WAGNER, Institute for Opto-electronics, DLR, 82234 Oberpfaffenhofen, Germany.

A ro-vibrational analysis of the C-type ₈ fundamental band of ³⁵ClONO₂ as well as the hot band, ₈ + ₉ - ₉, has been carried out using a Fourier-transform infrared spectrum of natural chlorine nitrate. This spectrum was recorded with a resolution of 0.00094~cm^-1 at a temperature of 190~K. Accurate upper state constants have been determined for both bands including the following band centers: ₀ ( ₈) = 711.20763(9) and ₀ ( ₈+ ₉ - ₉) = 714.9050(12)~cm^-1. These constants have been used, together with a transition moment operator which takes into account the observed Herman-Wallis effect, to successfully model the experimental spectrum. Moreover the constants of the 8¹9¹ state have been used to model the ₈ + ₉ band, allowing us to assign nearly 100 Q-branch transitions and, therefore, to determine the band center of the ₈ + ₉ band , ₀ ( ₈ + ₉ )= 838.6269(15)~cm^-1. Consequently we are able for the first time to obtain a precise band center of ₉ : ₀ ( ₉) = 123.7219(20)~cm^-1. Finally this establishes unambiguously that the band at 714.9~cm^-1 previously attributed to ₅ + ₇ - ₉ is actually the ₈ + ₉ - ₉ hot band.