Theory of the off-centre instability is developed for the impurity ions (Li', CuC, and Ag') in alkali halides on the basis of the charge transfer excitation model which is different in the involved electronic processes from the earlier theory based on the polarizable-point charge ion model. The lowest potential minima for the impurity ion along < 11 1 ), ( 110 ), and < 100 ) crystal axes are ca...

Crystal Calorimetry in future high-energy physics experiments faces a new challenge to maintain its precision in a hostile radiation environment. This paper discusses the effects of radiation damage in scintillating crystals, and concludes that the predominant radiation damage effect in crystal scintillators is the radiation-induced absorption, or color center formation, not the loss of scintil...

The direct replacement of aromatic fluorine in hexafluorobenzene has hitherto been possible only by the use of nucleophilic reagents. In this investigation, the replacement of nuclear fluorine by nonnucleophilic, or weakly nucleophilic, reagents was achieved by reaction at relatively high temperatures, 300 to 850 °C. For example, the reaction of hexafluorobenzene with such reagents as bromine, ...

The optical constants of thin films of CsI, KI, and KBr in the spectral range of 53.6-174.4 nm were obtained from the measurements of reflectivity as a function of the incidence angle. The effect of film heating to 420 K and exposure to UV radiation on the optical constants of the three materials was also investigated. The quantum efficiencies (QEs) of the planar photocathodes made with the thr...