The rovibrational analysis of the high-resolution IR spectrum of CD2HF below 1200 cm: an interacting tetrad of vibrational levels

The spectrum of CD₂HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm^?1 fwhm) between 800 and 1200 cm^?1 covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν₉: 912.2028 cm^?1, ν₆:964.4994 cm^?1, ν₅: 1050.5104 cm^?1, ν₄: 1093.8632 cm^?1) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν₉ and ν₆ (ξ_a= 1.069 cm^?1, ξ_c= ?0.3535 cm^?1) and between ν₅ and ν₄ (ξ_b= ?0.80606 cm^?1). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level.