F centre production in CsI and CsI–Tl crystals under Kr ion irradiation at 15 K

Abstract

We present results of simultaneous in situ luminescence and optical absorption studies in scintillator CsI and CsI±Tl crystals, exposed to very dense electronic excitations induced by 86 Kr ions (8.63 MeV/amu). Irradiation at 15 K leads to the formation of the prominent F absorption band. In addition, several other features of the broad absorption between exciton and F bands were ascribed to an anion vacancy, a centre (240 nm), self-trapped hole, V k centre (410 nm) and interstitials, H centres (560 nm). We have found that low doping of thallium ($10 17 cm À3 ) causes the F centre formation to proceed more rapidly than in pure crystal. On the other hand, we were not able to create any amount of F centres in heavily doped CsI±Tl. We have shown that point defects created by heavy ions manifested themselves in luminescence ageing. Ó

Influence of complex impurity centres on radiation damage in wide-gap metal oxides

“…Similar situation can probably be realized in Lu3Al5O12:Nd 3 scintillators a well. The important example of luminescent protection against SHI-induced radiation damage was reported earlier for a CsI:Tl classical scintillator with bcc lattice [47].…”

Radiation damage mechanisms in CsI(Tl) studied by ion beam induced luminescence

“…2.5 Â 10 7 eV/center versus 6-15 Â 10 2 eV/center [14]. Moreover, Amolo et al [15] after irradiation with 1 MeV protons up to 6 Â 10 16 ions/cm 2 detected the presence only of simple compound defects like F 2 centers in addition to the standard point defects.…”

“…In fact, a study performed at 15 K evidenced that the amount of energy which is necessary to create an F center in CsI is about five orders of magnitude higher than in other alkali halides [14].…”

Low-temperature creation of Frenkel defects via hot electron-hole recombination in highly pure NaCl single crystals

“…The analysis of the creation spectrum of F centres by synchrotron radiation measured at 12 K using a highly sensitive luminescent method allowed to conclude that, similar to a number of metal oxides, [8][9][10][11] the recombination of hot (nonrelaxed) conduction electrons and holes causes the creation of pairs of stable anion FDs (F-H pairs) in a NaCl crystal with an inequality E FD > E g at cryotem-peratures. At low temperatures, neither the decay of anion (7.8-8.4 eV) or cation excitons ($33.4 eV) nor the recombination of relaxed (cold) electrons and holes lead to the creation of stable Frenkel pairs, the accumulation and aggregation of which determines the radiation resistance of wide-gap materials against prolonged irradiation.…”