Showing papers by "Guy Millot published in 1988"
TL;DR: In this paper, an infrared double resonance laser spectroscopic technique is used to study state-resolved rotational and vibrational energy transfer in the isotopically substituted methane molecule, 13CD4.
Abstract: An infrared double resonance laser spectroscopic technique is used to study state‐resolved rotational and vibrational energy transfer in the isotopically substituted methane molecule,13CD4 . Molecules are prepared in a selected rovibrational state by CO2 laser pumping, with the quantum numbers v, J, and Cn completely specified. Measurements of both the total rate of depopulation by collisions, and the rates of transfer into specific final rovibrational states (v’, J’, Cn’ ) are carried out using time‐resolved tunable diode laser absorption spectroscopy. The depopulation rates due to collisions between methane and the rare gases are on the order of the Lennard‐Jones collision frequencies. Self‐relaxation is slightly more efficient than the Lennard‐Jones estimate. The rather small relaxation rates are characteristic of a short‐range potential, or ‘‘strong‐collision’’ regime, expected for a molecule without a dipole moment. The state‐to‐state energy transfer measurements reveal a dramatic selectivity of rota...
52 citations
TL;DR: In this article, the authors presented the first Raman spectrum of 13CD4 recorded at room temperature in the pentad region by inverse Raman spectroscopy, thus including the ν1, 2ν2 (A1), 2ν4 (A 1), and ν2 + ν4(F1 + F2) Q branches.
33 citations
TL;DR: In this article, the authors describe the mechanical, optical and electronic improvements of the wavemeters which has been presented previously (J. Optics, vol.15, no.1, p.31-41, 1984).
Abstract: Describes the mechanical, optical and electronic improvements of the wavemeters which has been presented previously (J. Optics, vol.15 , no.1, p.31-41, 1984). These improvements have made the apparatus (Michelson interferometer) more reliable. Measurement accuracy has been improved. The wavemeter has been tested with two reference lasers (Ar+ at 514 nm and He-Ne at 633 nm), stabilized on hyperfine components of 127I2 The measurement uncertainties have been evaluated (systematic and statistical dispersion). The experimental results exhibit an accuracy of the interferometer equal to 3,5 10-9. They describe two examples of high resolution stimulated Raman spectra calibration.
29 citations
TL;DR: In this paper, a pulsed CO2 laser is used to pump dyad←ground state transitions, and triad → ground state transitions are probed with a tunable diode laser.
Abstract: Time‐resolved infrared double resonance experiments have been carried out on silane. A pulsed CO2 laser is used to pump dyad←ground state transitions, and triad←dyad transitions are probed with a tunable diode laser. Two‐photon (triad←ground state) signals are observed with the CO2 10P(20), 10P(22), and 10P(28) pump lines. Rotational relaxation rates have been measured for E, F2, and A2 symmetry components of the v4=1, J=13 level of silane in collisions with silane, argon, and methane. The relaxation efficiencies follow the order σrot (F2)>σrot (A2)>σrot (E), which parallels the behavior of pressure‐broadening coefficients for infrared absorption lines of methane.
20 citations
TL;DR: In this article, spectroscopic constants of the ground state of 14N2 were deduced from CARS spectra recorded in a 4 Torr d.c. N2 glow discharge.
Abstract: Spectroscopic constants of the X1Σg+ ground state of 14N2 are deduced from CARS spectra recorded in a 4 Torr d.c. N2 glow discharge. Vibrational states up to ν = 14 have been observed but only the 11 lower levels which have a good signal-to-noise ratio have been processed. The Dunham constants that were deduced yield vibrational band centre positions in good agreement with those of Lofthus and Krupenie.
10 citations
TL;DR: In this article, the Fourier transform absorption spectrum of 13CD4 methane has been recorded from 924 to 1190 cm−1 and the accuracy of the line frequency is better than 10−4
Abstract: The Fourier transform absorption spectrum of 13CD4 methane has been recorded from 924 to 1190 cm−1. The full width half maximum (3 × 10−3 cm−1) of the lines in the experimental spectrum is close to the Doppler–Fizeau width (2.7 × 10−3 cm−1) and the accuracy of the line frequency is better than 10−4 cm−1. The reduced effective Hamiltonian is formulated in terms of irreducible tensorial operators set in the Td group. With 1147 isolated infrared lines, we have determined 10 Hamiltonian parameters for the ground state up to sixth order and 30 parameters of the 0100 and 0001 vibrational states up to the fifth order of approximation. The standard deviation obtained is 10−4 cm−1.
9 citations