# PRESSURE-INDUCED WIDTHS AND SHIFTS OF METHANE TRANSITIONS

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 Title: PRESSURE-INDUCED WIDTHS AND SHIFTS OF METHANE TRANSITIONS Creators: Neshyba, S. P.; Lynch, R.; Gamache, Robert R. Issue Date: 1993 Publisher: Ohio State University Abstract: A new implementation of linewidth $theory,^{1-3}$ which yields line-widths and shifts together, is applied to air-broadened spectroscopic lines of methane. We include long-range (electrostatic) interactions, as well as short-range ones given by atom-atom Lennard-Jones terms. The latter are derived in a spherical tensor expansion to sixth order in the intermolecular separation, using a generalised computer-assisted analytic procedure. Complex-valued integrals describing the intermolecular dynamics ("resonance functions") are evaluated analytically in the parabolic $approximation,^{3}$ and compared to results got by exact numerical solution to Hamilton's equations. Results are compared to experimental measurements, with particular attention to observed large changes in angular momentum resulting from a single $collision.^{4}$ Description: Author Institution: Center for Atmospheric Research, U. Mass Lowell. Lowell MA 01854. $^{1.}$ PW Anderson, Phys. Rev. 76, 647 (1949). 2. CJ Tsao and B Curnutte, J. Quant. Spect. Rad. Trans. 2, 41 (1962). 3. D Robert and J Bonamy. J. Phys. (Paris) 40, 923 (1979). 4. B Foy, J Hetzler, G Millot, and Jl Steinfeld, JCP 88, 6838 (1988). URI: http://hdl.handle.net/1811/18436 Other Identifiers: 1993-FD-6