title: A theoretical and experimental study of pressure broadening of the oxygen A-band by helium.
abstract: The rotationally resolved magnetic dipole absorption spectrum of the oxygen A-band b(1)Σ(g)(+)(v=0) <- X(3)Σ(g)(-)(v=0) perturbed by collisions with helium was studied theoretically using the impact approximation. To calculate the relaxation matrix, scattering calculations were performed on a newly computed helium-oxygen (b(1)Σ(g)(+)) interaction potential as well as on a helium-oxygen (X(3)Σ(g)(-)) interaction potential from the literature. The calculated integrated line cross sections and broadening coefficients are in good agreement with experimental results from the literature. Additionally, cavity ring-down experiments were performed in the wings of the spectral lines for a quantitative study of line-mixing, i.e., the redistribution of rotational line intensities by helium-oxygen collisions. It is shown that inclusion of line-mixing in the theory is required to reproduce the experimentally determined absolute absorption strengths as a function of the density of the helium gas.
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Dennis L A G
authors.initials: DL
authors.lastname: Grimminck
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Frans R
authors.initials: FR
authors.lastname: Spiering
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Liesbeth M C
authors.initials: LM
authors.lastname: Janssen
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Ad
authors.initials: A
authors.lastname: van der Avoird
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Wim J
authors.initials: WJ
authors.lastname: van der Zande
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Gerrit C
authors.initials: GC
authors.lastname: Groenenboom