Diode laser spectrum and rovibrational analysis of the ν2 + ν5 band of CF 3Cl

Abstract

The vibration-rotation spectrum of the ν 2 + ν 5 band of CF 3Cl, with natural isotopic abundance, has been investigated in the range 1332–1360 cm −1 with a resolution of about 0.002 cm −1 using a tunable diode laser spectrometer. The measurements have been performed by keeping the sample at low temperature (⋍240 K) to reduce the interferences arising from hot bands. Both J and K structures have been resolved and analyzed in the P, R ( P, Q, R) subbranches, and many individual transitions covering the ranges −28 ≤ KΔ K ≤ 24 up to J = 68, and −18 ≤ KΔ K ≤ 24 up to J = 58, have been identified for CF 3 35Cl and CF 3 37Cl, respectively. The perturbation effect due to the Δ1 = Δ k = ±2 resonance has been found significant even in other transitions with low K values and not only for the kl = 1 level. Excited state parameters up to the quartic terms have been determined for the ν 2 + ν 5 band of both isotopic varieties from a fit of 1140 ( 35Cl) and 187 ( 37Cl) lines with standard deviations of 5.8 and 6.7 × 10 −4 cm −1, respectively.