One-dimensional surface damage at grazing projectile incidence: linear vacancy chains on channeled planes

The onset of erosion pattern formation through exposure of the pristine {211} and {321} tungsten surface with 5 keV He atoms at grazing incidence has been investigated at 21 K by field ion microscopy. We demonstrate that the <111> linear chains of surface vacancies related to irradiation are created in addition to expected individual vacancies and two-dimensional vacancy clusters. The vacancy chains were ideally straight and did not displayed atomic-scale kinks. The asymmetry of the radiation adatom production on the two lateral sides of the <111> vacancy chains was revealed on the W {321} plane. Possible origins for the asymmetry of damage production with respect to the vacancy chains were analyzed in terms of the details of the energy landscape of interatomic interactions on this surface.