LOW TEMPERATURE PRESSURE BROADENING RESULTS AND AN IMPROVED POTENTIAL SURFACE FOR H(D)CL-HE
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Date
1992
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Ohio State University
Abstract
We have used low temperature pressure broadening data from a collisional cooling experiment to make improvements on an existing HCl-He potential $surface.^{1}$ As evidenced in earlier work on the CO-He $system^{2}$, theoretically calculated pressure broadening cross sections at 77 K and above are quite insensitive to details of the intermolecular potential surface. However, at very low temperature ($<10$ K) where resonance phenomena dominate, small changes in the potential surface can have dramatic effects on predicted cross sections. These cross sections are especially sensitive to changes in the short range, attractive part of the potential. Using pressure broadening data on the $J=0-1$ transition of DCl taken at temperatures between 1.8 and 4.2 K and at 300 K, incremental modifications were made to an existing potential surface to more faithfully reproduce both the low temperature and room temperature data. The resulting $potential^{3}$ surface predicts both low temperature and 300 K cross sections to within $\sim$10\% and is in good agreement with other determinations of the isotropic part of the HCl - He potential.
Description
1. L.A. Collins and N.F. Lane, Phys. Rev. A 12, 811 (1975). 2. S. Green and L.D. Thomas, J. Chem. Phys. 83, 5391 (1980). 3. D.R. Willey, V. Choong, and F.C. De Lucia, J. Chem. Phys. 96, 898 (1992).
Author Institution: Physics Department, Allegheny College; Physics Department, Allegheny College; Department of Physics, The Ohio State University
Author Institution: Physics Department, Allegheny College; Physics Department, Allegheny College; Department of Physics, The Ohio State University