Physical interpretation of glory undulations in scattering cross sections

The physical interpretation of the spacing of glory undulations as a function of energy is approached through the interpretation of the coefficients in a semiclassical expansion in the relative kinetic energy of the form (a1 − A1 K−1+ A2K−2+ ··· ). The coefficient a1 measures the area of the intermolecular potential well along the glory trajectory, whereas A1 and A2 give measures of the square and cube of the well, respectively. Examples are given for square-well and Lennard-Jones (n, 6) potentials. Measured values of the spacings of the glory oscillations for a system do not give as specific information on the potential as has sometimes been conjectured, but the information obtainable is quite definite and can be used to put constraints on the form of the potential for that system.