Nitrogen Broadening of Acetylene Lines in the ν5Band at Low Temperature

Abstract

N2-broadening coefficients have been measured for 22 lines of C2H2 at 173.4 K in the P and R branches of the nu5 band, using a tunable diode-laser spectrometer. The lines with J values ranging from 1 to 29 are located in the spectral range of 661-762 cm-1. The collisional widths obtained by Rautian profiles fitting closely the measured spectral shape of the lines are slightly larger than those derived from Voigt profiles. Semiclassical calculations of these broadenings have been performed by considering, in addition to electrostatic interactions, successively the atom-atom model and the Tipping-Herman intermolecular potential. The results obtained, which for some of them are in good agreement with the experimental data, depend significantly on the isotropic potential used to describe the trajectory model. By comparing broadening coefficients at room and low temperature, their temperature dependencies have been determined both experimentally and theoretically Copyright 1998 Academic Press.

Line-Mixing Effects in He- and N2-Broadened Q Branches of C2H2 at Low Temperatures

“…In Fig. 3 we compare the broadening coefficients calculated at room and low temperatures to those obtained experimentally in the ν 5 band for C 2 H 2 -N 2 (6,15,16). For C 2 H 2 -He, however, no data on broadenings at low temperature are available to our knowledge.…”

H2-Broadening Coefficients in the ν4 Band of NH3

“…The theoretical broadening coefficients may depend significantly on the isotropic potential used (26). Therefore, we have determined LJ parameters for NH 3 by fitting as in Ref.…”

Linewidths of C2H2 perturbed by H2: experiments and calculations from an ab initio potential

“…Much less attention has been paid to the molecular-broadening of acetylene lines. Experimentally, N 2 -, O 2 -, H 2 -pressure broadening [6,[15][16][17][18][19][20][21][22] and self broadening pressure coefficients [6,15,23] have been measured at various temperatures between 147 and 300 K.…”

“…Before this work, the theoretical studies of molecular partners [18][19][20][21][22][23] were typically per-2 formed on the basis of the Robert-Bonamy semi-classical formalism [24] using semi-empirical potential energy surfaces (PES). Only two of these works dealt with hydrogen.…”