Effect of multiplicity of collisions of atomic particles with a solid on the measurement of electronic stopping powers

It has been shown that the difference of the electron energy losses in collisions of atomic particles (ions or atoms) with a solid target measured by the backscattering technique from those measured by the method of beam transmission through a thin film is due to the effect of the multiplicity of collisions on the length of the trajectory of particles in the solid target. The length of the trajectory of an incident particle at low energies (0.7 keV) can exceed the thickness of the film by a factor of more than 2.5; consequently, the traditional definition of the stopping power as the energy loss per unit length of the projective path is inapplicable.