Unraveling thermoluminescence

The book is essentially about the theoretical aspects of thermoluminescence (TL). It is structured and written in a manner which will specially be of interest to the fresh undergraduate students and young researchers planning to take up work in the field of thermoluminescence. It is arranged into seven chapters, starting with the historical growth of the subject of TL and an overview of the luminescence phenomena. A Physical model involving thermally disconnected deep traps is specially described. Using this model expressions are derived for the TL intensity growth curve, the supralinearity f

Effect of temperature on X-ray excited luminescence of nutural CaF<SUB>2</SUB> and its implication in thermoluminescence

A number of glow peaks have been observed in the thermoluminescence (TL) of natural and doped CaF2 crystals from room temperature to 650&#176;C. The object of the present work is to find out the effect of temperature on the luminescence efficiency at the various glow peaks. X-ray excited luminescence (XEL) intensity is recorded at various elevated temperatures for this purpose. The experimental results lead to the following conclusions. (1) A continuous fall in the intensity of XEL occurs in the temperature range 320&#176;C to 500&#176;C. (2) The effect of temperature on emissions from different impurity ions is not the same. Main emissions observed in the TL and XEL spectra are from four lanthanide impurities, namely Ce, Gd, Tb and Dy in the wavelength range 200–500 nm. Gd emission decreases sharply with temperature right from room temperature. Dy emission increases till about 200&#176;C and then decreases. The emission from Ce and Tb impurities shows a decrease from room temperature to 100&#176;C, an increase from 100&#176;C to 320&#176;C and a continuous decrease thereafter. These observations are contrary to the general behaviour known as thermal quenching in the luminescence phenomena. The changes are explained qualitatively on the basis of the population of the emitting centres, their conversion to non-emitting species by the irradiation and restoration by the heat

A geochemical basis for endomyocardial fibrosis

Analysis of hearts of patients dying from endomyocardial fibrosis showed a significantly greater concentration of cerium, a lanthanide present in leafy vegetables and root tubers, than in control hearts. This may be important in the pathogenesis of the disease and provides a geographical basis for the prevalence of the disease in the tropics