Creation and Destruction of X Centres in Alkali Halides by X‐Radiation

Abstract

The production (qand destruction efficiencies cf X, centres in NaCI, KCl, KBr, and KI by X-radiation versus the irradiation temperature (in the range of 80 to 320 K) are investigated by optical absorption and thermoluminescence methods. Both, the increase (80 to 150 K) and decrease (200 to 250 K) of qs3 in KBr and KI a t the adsorbed dose of lOlS to loz1 eV cm-3 are shown to be in correlation with the F-centre creation efficiency ( 7~) .I n chlorides q p does not decrease with qx7 and these crystals are characterized by 8 high defect creation efficiency at approximately room temperatures. It is supposed that the creation of large halogen aggregates is much more efficient in chlorides than in bromides and iodides.y 3)

Peculiarities of the diffusion-controlled radiation defect accumulation kinetics under high fluencies

“…The accumulation of various color centers was most comprehensively studied in the alkali halides and some simple oxides. In particular, clear effects of temperature, crystal structure, impurities and the type of radiation [34,35,36,37,38,39,40,41] were reported. Moreover, it has been more than once demonstrated that the saturation effects are most easily observed in case of ion irradiation.…”

Photo‐ and Thermochemical Reactions with Participation of Br− Centres in X‐Rayed KBr

“…Jn conclusion, on the ground of previous [a, 8, 10, 17, 181 and present studies, we consider the growth scheme of halogen associates in KBr typical of the X-irradiation a t temperatures above 200K (Fig. 9).…”

“…9). At these temperatures the elementary Br; centres (V, and V, centres) in pure KBr are unstable under irradiation [17] and only larger associates such as Br;, Bry, A,, A,, etc. survive.…”