Ch. Lambeau

The absorption of ethylene in the 10- mu m region

The nu /sub 7/, nu /sub 10/, and nu /sub 4/ interacting band system has been studied from three complementary sources: classical, diode laser, and waveguide laser spectra. In addition to the two first-order Coriolis interaction terms associated with zeta /sub 7,10//sup a/ and zeta /sub 4,10//sup b /, we were obliged to introduce the corresponding second-order terms to obtain a statistical agreement between calculated and experimental data. High-quality vibrational and rotational data are presented for the two infrared active fundamentals, nu /sub 7/ and nu /sub 10/, and the rotational constants for the inactive nu /sub 4/ fundamental are determined for the first time. The authors present the list of all the infrared transitions starting from the vibrational ground state of ethylene and being in quasi coincidence with CO/sub 2/ or N/sub 2/O laser lines.

Laser spectroscopy of ethylene with waveguide CO2 and N2O lasers

Abstract Fifty Doppler-broadened absorption lines of ethylene have been measured within large profiles CO2 or N2O lase lines. These laser lines are produced by a high pressure waveguide laser and have a full width between 200 and 900 MHz. Eleven absorption lines, the more intense ones, have been assigned to the ν7 band of C2H4. The other absorption lines must belong to hot bands or to the ν7 band of H2 12C13CH2.

Saturated Absorption of C2h4 With a Co2 Waveguide Laser

Abstract Saturated spectroscopy of C 2 H 4 was performed with a CO 2 waveguide laser. Seventeen lines were measured with a precision of the order of 200 kHz. On the basis of these data and of a new highly accurate determination of the ground-state rotational constants a better analysis of the ν 4 , ν 7 , and ν 10 levels was achieved.

Spin-flip laser spectra of ethylene in the 2000 cm/sup -1/ region

With the use of a /b Q/-switched spin-flip Raman laser rovibrational lines of ethylene in the 2000 cm/sup -1/ region have been measured with an accuracy of the order of 0.005 cm/sup -1/. On the basis of these data and previous conventional high resolution spectra an analysis of nu /sub 7/+ nu /sub 8/, nu /sub 4 /+ nu /sub 8/ and nu /sub 10/+ nu /sub 8/ has been performed. The results permit calculation of the harmonic and anharmonic contributions to the rotational constants of nu /sub 7/ and nu /sub 7/+ nu /sub 8/, and allow the nu /sub 8/ rotational constants to be estimated.

High-resolution infrared study of /sup 12/C/sup 13/CH/sub 4/ ethylene in the 10- mu m region

High-resolution infrared spectra of H/sub 2//sup 12/C /sup 13/CH/sub 2/ were recorded between 835 and 855 cm/sup -1 / and between 908 and 992 cm/sup -1/. For the first time, the nu /sub 7/, nu /sub 8/, nu /sub 4/, nu /sub 6/, and nu /sub 10/ interacting band system was studied. The rovibrational parameters of these bands were accurately determined in a five-level analysis, with a standard deviation of 0.0027 cm/sup -1/. The transitions which are in quasi-coincidence with the N/sub 2/, CO/sub 2/ and isotopic CO/sub 2/ laser lines were determined.

Intracavity CO2 laser Stark spectrometer with almost-free propagation.

A high performance Stark cell has been made of which the essential features are stainless steel plates, 2-mm spacing, electric fields up to 100 kV/cm, field uniformity better than 5 x 10(-5). This Stark cell has been placed at a waist created inside a CO2 laser cavity, so that the beam propagates almost freely inside the cell. Thus we get the high sensitivity of intracavity spectroscopy but we preserve the quality and the stability of extracavity spectroscopy.

Simultaneous Analysis of Laser Stark and High-resolution Infrared-spectra - the Nu-5 Band of Methylacetylene

The υ5 band of methylacetylene has been studied simultaneously by means of CO2 Laser Stark spectroscopy and high resolution infrared absorption spectroscopy (0.012 cm−1). The primary aim of this work was to assign all the Stark coïncidences. Effective vibration-rotation parameters and the dipole moment of the v5=1 state have been determined.

Absorption spectroscopy of ethylene H212C13CH2 in the 4500-cm−1 region

Abstract The ν 5 + ν 12 b -type band of H 2 12 C 13 CH 2 was recorded between 4380 and 4643 cm −1 and completely analyzed. For the first time, we determined the rotational parameters for the ground state of this ethylene isotopic species from a set of more than 1000 ground-state combination differences. The ν 1 + ν 12 a -type band was also extensively observed and the ξ 1,5 c Coriolis interaction constant accurately determined. We have identified six other levels which cause some local perturbations in ν 5 + ν 12 . The least-squares analysis was simultaneously applied on ν 5 + ν 12 , ν 1 + ν 12 , ν 6 + 2 ν 8 + ν 12 , and ν 4 + ν 6 + ν 10 + ν 12 levels. The upper-state energy levels were fitted with a standard deviation of 0.009 cm −1 .