Thermoluminescent properties of crystalline halogen substituted uracils

The thermoluminescent properties of crystalline uracil (U), and its halogen-substituted derivatives, 5 bromo-uracil (5BrU), 5 fluorouracil (5FU) and 5 iodo-uracil (5IU), have been investigated. The X-ray-induced thermoluminescent output increases in the order U less than 5 FU less than 5BrU less than 5IU. However, a reversed relationship is found for the U.V.-stimulated thermoluminescence. The thermoluminescence-emission spectra suggest that the same de-excitation process operates in all the halogen-substituted uracils, but the glow curves show that the charge-trapping characteristics are different for each material.