Specific Ionization Measurements and Energy Requirements for F-Center Formation

Abstract

Measurements were made of the energy required to produce F centers in pure and sensitized alkali halide crystals by bombardment with electrons and deuterons accelerated in a Van de Graaff generator. In KBr+KH exposed to 1.2‐Mev electrons, 35 ev were required per F center. This value is in agreement with other published data. A value of approximately 100 ev was required with deuterons and KBr+KH. Slightly lower yields were found for several other salts. The specific ionizations of electrons, deuterons, and gamma rays were investigated and used to determine the accelerator beam size and penetration. The ranges of electrons in KBr, KCl, and NaCl were measured as a function of accelerator voltage and found to agree well with ranges predicted by the Feather rule. Energy transport and features of the specific ionization pattern are discussed in terms of the Seitz synthesis of crystal imperfections.