15min:

V. SIRONNEAU, J.-M. FLAUD, I. KLEINER, P. CHELIN, Laboratoire Interuniversitaire des Systèmes Atmosphériques, CNRS et Universités Paris 7 et Paris 12, 61 av. Général de Gaulle, 94010, Créteil, France; J. ORPHAL, Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.

Nitrous acid is an important species in the atmosphere of the Earth since it is a significant daytime source of OH radicals, known to play an important role in tropospheric ozone formation. It is also a molecule of interest for molecular dynamics and ab-initio calculations. In this work, relative line intensities of trans- and cis- HONO and –DONO have been measured using absorption spectra in the far-infrared previously recorded by high-resolution Fourier-transform spectroscopy . These relative line intensities measurements were fitted in a least-squared procedure leading to the determination of the b-component of the permanent dipole moments for those species and their rotational corrections. Scaling those values to the absolute values derived from Stark effect measurements allowed us to re-determine the energy difference between the two isomers ( E_HONO) to be 107\pm26 cm^-1. This value is in good agreement with previous experimental studies calculations and with recent high-level ab-initio calculations.