Proton sputtering from polycrystalline Al surface interacting with highly charged ions at grazing incidence angle

Sputtering processes of protons from a polycrystalline Al surface interacting with Arq+ (q = 3–14) ions at a grazing incidence angle (∼0.5°) were investigated. The intensity of protons (IH) detected in coincidence with scattered Ar atoms was measured as a function of q. IH saturated at q ⩾ 10, although it increased rapidly with q at 3 ⩽ q ⩽ 8. The angular distribution of protons with low kinetic energy (⩽2 eV) began to deviate from the cosine distribution and assumed a rather flat equidistribution as q increased. To analyze the sputtering processes of protons at the grazing incidence angle, a modified model of the “above-surface potential sputtering model” was proposed by considering image acceleration of projectile ions.