High-resolution vib-rotational analysis of the nu3 and nu4

Abstract

High-resolution Fourier-transform spectra of isotopically natural pure chlorine nitrate, ClONO2, were recorded with a resolution of 0.00094 cm-1 at temperatures of 190 and 297 K. An extensive vib-rotational analysis of the n4 and n3 fundamental bands as well as the hot band, nu4 + nu9 - nu9, of the most abundant 35Cl isotopomer was performed for the 190 K spectrum. In addition, the cold bands of the lesser abundant 37Cl isotopomer were partially assigned. Accurate upper state rotational Hamiltonian constants were derived. In particular, the following band centers were determined: nu0(nu4) = 780.2161(8) cm-1, nu0(nu3) = 809.7513(8) cm-1, nu0(nu4 + nu9 – nu9) = 778.7235(8) cm-1 for 35ClONO2 and nu0(nu4) = 778.8695(8) cm-1 for 37ClONO2. These constants were used to generate spectral parameters that permit a precise modeling of experimental cross sections of the nu4 fundamental Q-branch of 35ClONO2 over the temperature range of 190–297 K and atmospheric pressures up to 150 mbar. This Q-branch is used for atmospheric retrievals.