THE LOCKING PHENOMENON IN SCATTERING OF P-STATE ATOMS .1. QUASI-CLASSICAL THEORY OF INTERFERENCE EFFECTS FOR WAVES SCATTERED BY 2 DIFFERENTPOTENTIALS

A quasiclassical theory is presented for scattering of atoms in a spin less P state by a spherical target. The scattering amplitudes can be e xpressed analytically as a function of a few parameters which are not only the phaseshifts for elastic scattering along the Sigma and Pi mol ecular potentials, but also the locking angles and the slipping probab ilities. Interference effects, for one scattering angle, occur between contributions of classical trajectories corresponding to different po tentials. The locking angle appears explicitly in the amplitude of the high-frequency oscillations. It turns out that this type of interfere nce survives the statistical averaging over initial substates, resulti ng in an oscillating pattern of the differential cross section for sca ttering of unpolarized atoms. It is shown that the existence of the lo cking phenomenon is a necessary condition to the observation of such a n effect.