Surface self-diffusion of tungsten and molybdenum activated by low-energy bombardment by helium atoms

Using low-temperature field ion microscope techniques and mathematical modelling the interaction between helium atom and ions with atomically smooth tungsten and molybdenum surface was studied. The elementaryevents of radiation-induced surface diffusion were studied. It was demonstrated that the low-energy He atomic bombardment was able to induce a substantial surface mobility of adatoms preferentially along the beam direction. The long impact induced jumps of adatoms, spanning more than a nearest-neighbor distance, were revealed. Performed molecular dynamics simulations reproduce the general experimental trends and conclusions.