15min:

A. PERRIN, Laboratoire Inter Universitaire des Systemes Atmosphériques, CNRS, Université Paris 12, 61 Av du Général de Gaulle, 94010 Créteil Cedex France; R. MBIAKE, Centre de Physique Atomique et Moléculaire et Optique Quantique (CEPAMOQ), Université de Douala, B.P. 8580, Cameroun.

We present the first high resolution Fourier transform analysis of the 11~µm bands for H¹⁵NO₃ which is the second most abundant isotopomer of nitric acid (a=0.00365). In this way the analysis of the ₅ and 2 ₉ cold bands centered at 871.095 and 893.452 cm^-1 was performed. As for H¹⁴NO₃, these bands are significantly perturbed since rather strong resonances couple the 5¹ and 9² rotational levels. The theoretical model that we used to compute the line positions and line intensities is directly issued from the one which we used recently for H¹⁴NO₃ . Actually for the H¹⁵NO₃ line positions, the Hamiltonian matrix accounts for the rather strong Fermi and the weaker Coriolis interactions linking the v=5¹ and v=9² rotational energy levels. Using this model which describes correctly the strong mixing of the 5¹ and 9² upper state energy levels, the ₅ and 2 ₉ line intensities for H¹⁵NO₃ were satisfactorily computed using the ₅ and 2 ₉ transition moment operators achieved previously for the ¹⁴N (main) isotopic species. In this way, the transfer of intensities from the ₅ fundamental (and presumably strong) band to the 2 ₉ overtone (and presumably weak) band could be explained for H¹⁵NO₃ as it was done previously for the ¹⁴N (main) isotopic species.