High-resolution study of the mid-infrared region of FNO2

Of the gas-phase IR spectrum of nitrylfluoride, FNO2, between 1200 and 1900 cm(-1), the bands nu(4), 2 nu(6), nu(2) + nu(3), and nu(1) have been studi ed at a resolution of ca. 0.003 cm(-1). Improved ground state rotational an d centrifugal distortion constants have been obtained from a simultaneous a nalysis of the data from F. Hegelund, H. Burger, and G. Pawelke [J. Mol. Sp ectrosc. 184, 350-361 (1997)] and the present data from nu(4) and nu(1). Th e nu(4) and 2 nu(6) bands are free from local perturbations, and upper stat e spectroscopic constants have been obtained from the conventional Watson H amiltonian. The bands nu(1) and nu(2) + nu(3) are strongly perturbed by Cor iolis interactions with the nearby dark levels nu(5) + nu(6), nu(3) + nu(6) , and nu(2) + nu(5). Upper state constants for nu(1) and nu(2) + nu(3) are obtained from triad and tetrad models, respectively, including Coriolis res onances within this system. In addition Coriolis interaction parameters and the vibrational energies for the three dark states together with some of t heir rotational constants are determined from the observed perturbation eff ects on nu(1) and nu(2) + nu(3). (C) 2000 Academic Press.