A. Baldacci

High-resolution infrared study of the 2ν50 band of CF3Cl

Abstract The vibration-rotation spectrum of the 2 ν 5 0 band of CF 3 Cl, with natural isotopic abundance, has been investigated using a tunable diode laser spectrometer. The measurements have been performed at low temperature (∼200 K) in order to minimize the congestion of the “hot” bands. The K structure was resolved and identified; the assignment of rotational transitions has been extended in the R branch up to J = 49 and 48 for CF 3 35 Cl and CF 3 37 Cl, respectively. The low- K values of the main isotopic species were found to be rotationally perturbed and the interaction mechanisms have been interpreted on the basis of l (2, 2) and l (2, −1) resonances between 2 ν 5 0 and 2 ν 5 ±2 . Excited state parameters up to quartic terms have been determined for both isotopic varieties.

Diode laser spectrum of CF3Cl in the region of 1120 cm−1

Abstract The gas-phase infrared spectrum of CF3Cl, with natural isotopic abundance, has been investigated in the ν1 region near 1120 cm−1 using a tunable diode laser spectrometer. The measurements have been carried out by keeping the sample at low temperature (∼200 K) to minimize the strong interference arising from “hot” band transitions. The K structure of many R(J,K) clusters belonging to the ν1 fundamental of CF335Cl (J = 41–65) and CF337Cl (J = 45–67) has been resolved and unambiguously identified. About 500 and 150 lines for CF335Cl and CF337Cl, respectively, have been analyzed by a least-squares procedure and spectroscopic parameters up to the sextic terms have been determined for both isotopomers. Additionally, for the CF335Cl species a weak Δl = Δk = ±2 type interaction of ν1 with 2ν5±2, no line of which has been observed, occurs locally for K = 18–21 rotational levels.

Analysis of the ν1 band of trifluorobromomethane by diode laser spectroscopy

Abstract The vibration-rotation spectrum of the ν 1 band of CF 3 Br, with natural isotopic abundance, has been investigated by means of a tunable diode laser spectrometer. The measurements have been performed by keeping the sample at low temperature (∼200 K) in order to minimize the strong interferences due to “hot” band absorptions. The fine structure of many P ( J ) and R ( J ) clusters has been resolved and analyzed. The assignment of rotational transitions has been extended up to K = 24 and J = 51 and 50 for CF 3 79 Br and CF 3 81 Br, respectively. A total of 344 (CF 3 79 Br) and 433 (CF 3 81 Br) unblended lines were used in a least-squares fit to the energy expression up to the quartic coefficients, σ ( J , K ) ≅ 8 × 10 −4 cm −1 , and molecular parameters for the ν 1 fundamental of both isotopomers were determined.

Infrared study of the 2ν50 band of CF3Br by diode laser spectroscopy

Abstract The gas phase infrared spectrum of natural CF3Br has been studied in the 2ν50 region near 1100 cm−1 employing a tunable diode laser spectrometer. Interfering contributions caused by “hot” band transitions have been drastically reduced by performing the measurements at low temperature (⋍200 K). The K structure of many R(J) manifolds has been resolved and identified; the maximum J value reached in the analysis was 52 and 53 (K ≤ 36) for CF379Br and CF381Br, respectively. Transitions with low K values were found to be rotationally perturbed by 2ν5±2. Effective molecular constants up to fourth order for the 2ν50 band of both isotopomers have been determined.

Diode laser measurements of CF3Cl near 1258 cm−1: Rovibrational analysis of ν2 + ν3 combination and its hot bands

Abstract The gas-phase infrared spectrum of natural CF 3 Cl has been investigated in the range 1244–1275 cm −1 with a resolution of about 0.002 cm −1 using a tunable diode laser spectrometer. The K structure of many P ( J ) and R ( J ) clusters of the ν 2 + ν 3 band has been resolved and analyzed: the maximum J values reached for individual transitions were 66 and 62 for CF 3 35 Cl and CF 3 37 Cl, respectively. Small irregularities found in the K = 15, 18 lines of most manifolds of the main species have been attributed to perturbations with the ν 5 + 2 ν 6 vibration, and different interaction mechanisms have been considered. From a least-squares fit of the assigned transitions, accurate parameters up to the quartic terms have been determined for the ν 2 + ν 3 combination of both the isotopomers. Residual features due to the hot bands ν 2 + 2 ν 3 − ν 3 and ν 2 + ν 3 + ν 6 − ν 6 of CF 3 35 Cl have also been identified and spectroscopic constants have been derived by polynomial and manifold contour simulation methods.