Channeling and blocking along polar lattice directions

Abstract

Calculations show that the critical angle for channeling is unaffected in the two opposite directions of polar strings -AB-AB-, where A and B are different atoms. However, there is a significant difference in critical angles for blocking. The region where ions are no longer well channeled, but are not necessarily immediately lost from the channel shows an unusual distribution of reflected ions. A distinguishable difference in the rate of dechanneling in the two directions is anticipated. The calculations show that the location of substitutional foreign ions may be identified uniquely using the blocking pattern given by these ions.