M. De Vleeschouwer

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.

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 .