Four emission bands, all belonging to the main thallium centres, have been detected in CsI:Tl, and their spectral, polarization and kinetic characteristics have been studied at 0.35-320 K. A new model is proposed for the excited states responsible for the luminescence of thallium-doped caesium iodide. In this model, the main thallium centre is considered as a cluster consisting of a Tl+ ion and at least 12 I- and 11 Cs+ ions. Two weak ultraviolet emission bands of CsI:Tl (3.31 and 3.09 eV) are ascribed to electronic transitions from trigonal and tetragonal Jahn-Teller minima of the triplet relaxed excited state, whose structure is similar to that of Tl+ centres in FCC alkali halides. Two intense visible bands (2.55 and 2.25 eV) are assumed to arise from two different ("weak" and "strong") off-centre configurations of a selftrapped exciton perturbed by the TI+ ion. The minima responsible for all the emission bands are located on the same adiabatic potential energy surface. The excitonic-like nature of visible emission could explain the high scintillation efficiency of CsI:Tl.
Delay-time investigation of electromagnetic waves through homogeneous medium and photonic crystal left-handed materials Appl. Phys. Lett. 85, 1125 (2004); 10.1063/1.1781742 Delay-time and aging effects on contrast and sensitivity of hydrogen silsesquioxane
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.