About a type of ion-electron emission of alkaline-hloid crystals

A phenomenological model of ion-electron emission of alkaline-haloid crystals with preliminary excitation by elastic collision with bombarding ions is proposed. The calculations are made for a NaCl crystal bombarded by Ar ions. The shift of Cl- in dependence on the amount of transmitted energy has been calculated in the approximation of two coordination spheres on the basis of the concept of pair potentials of atomic interaction. The ''pressure'' of surrounding atoms on a haloid in the course of its shifting has been estimated as well as the ''pressure'' of a bombarding ion on the haloid. The results obtained are in a good agreement with experimental data and show that the changes in the interatomic distance in the crystal under all-round compression to pressures of several hundred kilobars are close to those in the local region of the haloid shifted as a result of a collision with a bombarding ion at an energy of several electron-volts. Calculations show that the cross section of transmission of the energy to Cl- has a maximum value at an Ar+ ion energy of approximately 15 eV