Diode laser spectra of the ν1 band of CF335Cl

Abstract The vibration-rotation spectrum of the ν 1 fundamental of CF 3 Cl, with natural isotopic abundance, has been recorded in the 1099 to 1116 cm −1 region using a tunable diode laser spectrometer. A majority of the measurements has been made by keeping the sample at low temperature (≈200°K) in order to avoid the strong interference arising from “hot” band absorptions. The K structure of many P ( J ) and R ( J ) multiplets as well as the individual lines of the Q branch of CF 3 35 Cl isotopic species have been positively identified; the assignment of rotational transitions has been extended up to J = 40. A weak perturbation affecting the rotational levels with K = 18 and J ′ ≥ 28 has also been observed. More than 1000 P , Q , and R transitions have been used for the least-squares fit to the energy expression including the quartic centrifugal distance coefficients. Molecular constants have been evaluated for the ν 1 band of CF 3 35 Cl.