Binding and Coulomb-deflection effects in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>L</mml:mi></mml:math>-shell Coulomb ionization by heavy charged particles. Low particle velocities

Abstract

Experimental cross sections for $L$ -shell ionization by heavy charged particles, of atomic number small compared to the target atomic number and with velocities low compared to the $L$ -shell orbital velocities, can be smaller by more than an order of magnitude than the quantum-mechanical predictions in the plane-wave Born approximation (PWBA). The contribution of two effects, not contained in the PWBA, is derived. These effects are the binding of the $L$ -shell electrons to the moving particle during collision and the Coulomb deflection of the particle in the field of the target nucleus. As developed here for $L$ shells and previously for $K$ shells, the theory treats the excitation of inner shells from perturbed stationary states (PSS) and incorporates the effect of the Coulomb-distorted wave of the heavy charged projectile semiclassically. It agrees well with experimental $L$ -shell cross sections of 16 different target atoms for protons, and accounts for the isotope effect observed on various targets with protons and deuterosn of equal velocities.