Rovibrational spectra of DCF_3 in the 1900 cm~(-1) region: High-resolution study of the v_3 = v_4 = 1/v_3 = 2, v_6 = 1 Fermi-interacting levels

摘要

The degenerate combination levels of E symmetry v_3 = v_4 = 1 (1900.21 cm~(-1)) and v_3 = 2, v_6 = 1 (1889.30 cm~(-1)) were investigated for the first time with high-resolution, using a Fourier-transform infrared spectrum recorded in the 1600-2000 cm~(-1) region, at a resolution of 0.0024 cm~(-1). These combination levels strongly interact through a Fermi-type anharmonic coupling, which plays an essential role in the studied system. Besides the Fermi-interaction, the other important Coriolis (Δk = ±1, Δl = ±2) and higherorder (Δk = Δl = ±2) inter-vibrational interactions were also considered, in a similar manner as in the lower v_3 + v_6/v_4 dyad [P. Pracna et al., J. Mol. Spectrosc. 259 (2010) 1-10]. The fitted wavenumbers of the rovibrational transitions of the v_3 + v_4 and 2v_3 + v_6 bands provide a set of molecular parameters which ensure an accurate reproduction of the spectrum. Moreover, these molecular parameters show good agreement with those of the lower system v_3 + v_6/v_4.