Crossedhyphen;Molecularhyphen;Beam Measurements of the Total Cross Sections of Arsngbnd;N2, Arsngbnd;Ne, Arsngbnd;He, and Arsngbnd;H2at Thermal Energies

摘要

Total cross sections have been measured for the scattering of Ar beams from perpendicular intersecting beams of N2, Ne, He, and H2. The beams were at 300deg;K and contained Maxwellian velocity distributions. The slit system approximated ideal slits, and the scatteringhyphen;center density was calculated from ratehyphen;ofhyphen;flow measurements and a modification of the usual beamhyphen;intensity equations. In addition, beams of He and H2were scattered from an intersecting beam of Ar. Beam reversal reduced the angularhyphen;resolution correction to less than 1. The background scattering of the primary beam could be estimated without recourse to pressurehyphen;gauge readings. Comparison of the experimental results was made with the Schiffmdash;Landaumdash;Lifshitz formula and calculations with the partialhyphen;wave WKB approximation with an assumed Lennardhyphen;Jones (12, 6) potential. The Lhyphen;J total cross sections do not agree with the experimental results for Arsngbnd;He and Arsngbnd;H2systems. The Lhyphen;J angularhyphen;resolution corrections do not bring the beamhyphen;reversal measurements in line with the measurements with Ar as the scattering gas.