FTIR spectra of CH2F2 in the 1000-1300 cm(-1) region: Rovibrational analysis and modeling of the Coriolis and anharmonic resonances in the nu 3, nu 5, nu 7, nu 9 and 2 nu(4) polyad

The FTIR spectra of CH2F2 have been investigated in a region of atmospheric interest (1000-1300 cm(-1)) where four fundamentals nu(3), nu(5), nu(7) and nu(9) occur. These vibrations perturb each other by different Coriolis interactions and the forbidden nu(5) borrows intensity from the neighboring levels. Furthermore, the nu(4)=2 state has been found to interact with the nu(3)=1 and nu(5)=1 states by anharmonic and c-type Coriolis resonances, respectively. The spectral analysis resulted in the assignment of about 7500 rovibrational transitions which have been simultaneously fitted, together with microwave data available in literature (Hirota E. J Mol Spectrosc 1978; 69: 409-420) [15] using the Watson's A-reduction Hamiltonian in the I-r representation and the relevant perturbation operators. The model employed includes eight types of resonances within the pentad nu(3)/nu(5)/nu(7)/nu(9)/2 nu(4). A set of spectroscopic constants for the four fundamentals as well as parameters for the nu(4)=2 state and eighteen coupling terms have been determined. The simulations performed in different spectral regions well reproduce the experimental data. (C) 2016 Elsevier Ltd. All rights reserved.