Development of a stable radiophotoluminescent thermoluminescent phosphor with linear response for radiation dosimetry in high dose region

Abstract

Light is a form of energy. To create light, another form of energy must be newlinesupplied. There are two common ways for this to occur, luminescence and newlineincandescence. The word luminescence is represented as cold light the newlinephenomenon of luminescence occurs when a substance is excited by some kind of newlineexternal energy and the excited electron returns to ground state to give light. The newlineterm luminescence implies luminous emission which is not purely thermal in origin newlinei.e. luminescence is cold light , light from other sources of energy, which takes newlineplace at normal and lower temperature. In luminescence, some energy sources newlinekicks an electron of an atom from its ground state (lowest energy) into an exited newlinestate (highest energy) by supplying extra energy, then as this excited state is not newlinestable electron jumps back to its ground state by giving out this energy in the form newlineof light. We can observe the luminescence phenomenon in nature like during newlinelightening, in glow worms, fireflies, certain sea bacteria and deep-sea animals. newlineLuminescence can be divided into fluorescence or phosphorescence. In both newlinecases, outermost electrons of an atom or ions are excited from ground state to newlineexcited states and light is emitted on their return to ground state. Fluorescence newlineoccurs within a very short time (usually lt 10-8s) following photo-excitation since newlinethe electronic transitions in this case are allowed transitions as per Laporte selection newlineRule. The emission time is usually temperature independent. Phosphorescence newlinerefers to delayed emission. The time delay between photo-excitation and emission newlinecan be of the order of and#956;s, ms, sec, min, hours or even more. newline