Abstract
The peculiarity of atom-atom collision sequences spreading in crystallographic directions where their advancement is considerably influenced upon by ‘lenses’ formed from surrounding atoms has been identified with the help of a computer-simulation method (the dynamic model). An α-Fe b.c.c. crystal was investigated. For the 〈100〉 direction it is found that the transmission of the kinetic energy by the collision sequences (the most general case of dynamic crowdions spreading is examined) goes through two stages. At first the main portion of the energy is transmitted by an atom chain but part of the energy is used to move the lenses apart. After some time the lenses relax and the atoms of the chain arc speeded up once more. A secondary transmission of energy passes through the atom chain. The effect is less noticeable in the 〈111〉 close-packed direction. The secondary transmission of the energy in collision sequences is used to explain the occurrence of additional peaks (in a low-energy region) which have recently been discovered in the 〈100〉 direction by Thompson, Reid and Farmery (1978) while sputtering a {100} gold crystal surface.