New Molecular Collisional Interaction Effect in Low-Energy Sputtering

Abstract

An unexpected pronounced enhancement is observed in sputtering yields per atom for ${\mathrm{N}}_{2}^{+}$ compared to ${\mathrm{N}}^{+}$ from a polycrystalline gold target. This effect is seen when the kinetic energy per projectile atom is below 500 eV and increases as projectile energy decreases to near-threshold energies. Enhancements for ${\mathrm{O}}_{2}^{+}$ over ${\mathrm{O}}^{+}$ begin at even lower kinetic energies below 100 eV per atom. This new molecular interaction effect may be explained qualitatively by invoking a simple energy transfer model which involves the vibrational frequency of the molecule and the collisional interaction time.