Energy and angular distribution of low energy H+ and D+ backscattered from polycrystalline carbon

The energy distributions of H+ and D+ backscattered from a polycrystalline graphite sample were recorded as a function of total scattering angle, angle of incidence, and for incident beam energies 200 < E/sub i/ < 3000 eV. The general shapes of the distributions are discussed qualitatively, and their variation with incident energy and total scattering angle are explained and compared with theoretical and other experimental results. The average energies E-+, of the distributions are found to increase relative to the single scattering energy, E/sub k/, with decreasing incident energy, E-+/E/sub k/ also increases with increasing exit angle from the solid in a way which is slightly dependent upon the angle of incidence. The integrated intensities of the distributions are found to depend strongly upon the angle of incidence, with a normally incident beam producing a nearly cosine distribution of backscattered ions and grazing angles of incidence producing an intensity which peaks at an angle forward of the specular direction. Using charge fractions obtained previously for surface scattering from graphite and transmission through thin carbon foil, values of the particle reflection coefficient R/sub N/ are obtained as a function of energy