Argon Repulsive Potential from Collision Cross-Section Measurements

The total collision cross section has been measured for argon atoms, with energies between 300 and 1100 electron volts, scattered in room temperature argon. In the region between 700 and 1000 volts, the cross section shows a maximum indicative of inelastic scattering, probably due to ionization by the high energy atoms. The repulsive potential between two argon atoms has been evaluated from elastic collision cross sections (deduced from observed values of the total collision cross section) using a method which takes account of the greater probability of small angle scattering by averaging the cross section over the length of the scattering path. The results may be expressed by V(r)=4.61×10−11/r4.33 ergsor V(r)=3.66×10−8 exp(−6.88r12) ergsfor values of r between 1.37 and 1.84A.