First analysis of the ν5 band of DNO 3 (deuterated nitric acid) in the 11 μm region

Abstract

The infrared spectrum of DNO 3 (deuterated nitric acid) was recorded at high resolution (0.0027 cm −1) in the 700–1400 cm −1 region on a Bruker IFS 120 HR Fourier transform spectrometer. The analysis of the ν 5 band of DNO 3 centred at 887.657 cm –1 which is mostly an A-type band, was performed making use of the ground state parameters achieved by Drouin et al. [Drouin BJ, Miller CE, Fry JL, Petkie DT, Helminger P, Medvedev IR. J Mol Spectrosc 2006;236:29–34]. The ν 5 fundamental band is strongly perturbed because of the existence of the ν 7+ ν 9 dark combination band at 882.21 cm –1. The 5 1 and 7 19 1 energy levels of DNO 3 are coupled through A and B type Coriolis resonances, and as a consequence, numerous lines from the ν 7+ ν 9 dark combination band could be identified also. In this way about 1070 and 75 energy levels of the 5 1 and 7 19 1 vibrational states, respectively, were satisfactorily reproduced by the energy levels calculation which account for the observed resonances. A reasonable estimation of the absolute line intensities for the ν 5 band of DNO 3 was performed using the ν 5 transition operator from H 14NO 3. The spectrum also features the ν 5+ ν 6− ν 6, ν 5+ ν 7− ν 7 and ν 5+ ν 9−ν 9 hot bands located at 881.03, 882.61 and 884.45 cm −1, respectively.