Janine Dupre-Maquaire

Emission spectrum of CO2 in the 9.6 μm region

Abstract The emission spectrum of 12C16O2 in the 9.6 μm region has been observed with a high resolution spectrometer. The 000-0200 transition appears with a high intensity. Some additional transitions have also been observed and effective rotational constants for the corresponding bands have been calculated. Because of the overlapping of some “hot” lines with the principal ones, care has to be taken in using the 0001–0200 transition as reference for calibration of high resolution spectra.

A new approach for vibronic ground-state analysis of C3v molecules: Application to 12CD3H

Abstract The ground-state analysis of trideuteromethane 12CD3H is performed on the basis of all the experimental data recently assigned in the range 872–1400 cm−1, for the three bands ν3, ν5, and ν6 (with line precision of 0.002 cm−1). These data include for ν3 and ν6 about fifty “forbidden” (perturbation allowed) transitions with Δ∥K − l6∥ = ±3, allowing us to determine the pure K-dependent constants C0 and D0K, besides B0, D0J, D0JK, H0J, H0JJK, and H0JKK. The computational procedure is based on a ground-state energy calculation including all the matrix contributions within the fourth order of approximation. Thus, the two nondiagonal elements 〈J, K∥H+∥J, K ± 3〉 and 〈J, K∥H+∥J, K ± 6〉, coming from second- and fourth-order terms, respectively, are taken into account. The energies are derived by diagonalizing the energy matrix written in the basis of symmetrized functions, i.e., factorized in blocks A1, A2, E, and E. The fit of 1174 combination differences, including J″ values up to 23 and involving 69 “allowed-forbidden” or “forbidden-forbidden” relations, leads to significant values for the eight constants mentioned above with an overall standard deviation equal to 0.003 cm−1. The nondiagonal contributions appear to be nonsignificant in the present case, but their tentative adjustment points out that the H constants contribute specifically beyond the effect of nondiagonal contributions.

Molecular constants of some levels of the ν2 mode of carbonyl sulfide

Abstract Spectra of OCS have been measured at 4.8 and 9.6 μm, using two high-resolution spectrometers. Some transitions involving 0 v 2 l 0 levels have been observed. Effective constants have been determined from a simultaneous least-squares fit of the data.

Absorption spectrum of trideuteromethane between 7 and 11 μm. Analysis of the ν5 band

Abstract The absorption spectrum of trideuteromethane was recorded in the range 900–1400 cm−1 with a resolution of 0.020–0.025 cm−1. The ν5 band centered at 1292.499 cm−1 is analyzed here. A fit based on 869 observed transitions including J′ values up to 22, leads to a set of spectroscopic constants suitable for energy calculations in the upper-state v5 = 1. These constants reproduce the experimental wavenumbers with a standard deviation equal to 0.008 cm−1. The tabulated line strengths are calculated on the basis of the value S = 27.1 cm−2 atm−1 at 300 K, measured by Hiller and Straley, for the band strength of ν5. A useful comparison is made between the values now derived for some constants and the corresponding ones predicted by Gray and Robiette in their recent force field calculations of methane and isotopic species.

Absorption spectrum of trideuteromethane between 8 and 11.5 μm: Analysis of the ν3 and ν6 bands

Abstract The analysis of the absorption spectrum of 12 CD 3 H, previously reported for the region 1200–1400 cm −1 concerned with the ν 5 band, is now extended to cover the region 872–1213 cm −1 including the two bands ν 3 and ν 6 . These are centered at 1004.553 and 1035.917 cm −1 , respectively, and strongly coupled by a Coriolis interaction. A formulation taking this interaction into account rigorously was used; as a result, the energies for the upper states v 3 = 1 and v 6 = 1 are derived as eigenvalues of an effective Hamiltonian ( J. Mol. Spectrosc. 79, 31–46 (1980)). The fit of the upper-state constants based on 1434 observed transitions including J ′ and K ′ values up to 22 leads to a set of 22 significant values which reproduce the observed wavenumbers with a standard deviation of 0.007 cm −1 close to the experimental uncertainties.

Vibrational luminescence of N2O excited by dc discharge: Rotation-vibration constants

Abstract High resolution measurements have been performed on 19 emission and absorption bands of the nitrous oxide molecule at 4.7 μm and 2.9 μm. Accurate values of the vibrational and rotational constants of 23 vibration levels were obtained.

Emission spectrum of N2O in the 8 μm range

Abstract A spectrum of N 2 O excited by a dc discharge has made possible the observation of 15 bands (type Δ v 1 = 1) in the 8 μm range. Effective constants of the involved levels were determined from a simultaneous least-squares fit of the data.

Complement to the analysis of the ν5 band of 12CD3H

Abstract A new analysis of the ν 5 band of 12 CD 3 H is presented using the ground state constants that were determined from the three fundamentals ν 3 , ν 5 , and ν 6 . New lines are assigned and the fit based on 1169 observed transitions including J ′ and K ′ values up to 23 leads to a set of 16 spectroscopic constants for v 5 = 1, allowing the reproduction of experimental wavenumbers with a standard deviation of 0.0047 cm −1 .

High-resolution analysis of the ν3 and ν6 bands of CD3Cl

Abstract This paper describes the analysis of the ν 3 and ν 6 fundamental bands of methyl chloride d 3 using a high-resolution spectrum (resolving power of the apparatus: 0.0015 cm −1 ). These bands are coupled by a weak Coriolis interaction and are then treated simultaneously. Spectroscopic constants are derived for the two isotopic species CD 3 35 Cl and CD 3 37 Cl.

Approaches to dissociation processes of SF6 by one or two T.E.A. CO2 lasers

Abstract We present experimental results on the variation of the SF6 dissociation rate as a function of the frequency and energy of the CO2 T.E.A. laser. We give a possible explanation of dissociation by classical absorption mechanisms involving ΔJ = ±2 transitions, and we present a process that we call “probabilities-crossing mechanism”.