Application of concentrated TiO2 sols for γ-ray radiation dosimetry

Upon exposure to gamma -radiation, a concentrated TiO2 sol changes from colorless to deep blue with an absorption maximum at 540 nm. The absorption has been assigned to trapped electrons or Ti3+ states in the solid matrix based on its spectroscopic similarity to the samples irradiated with UV light. Unlike the conduction-band electrons generated from direct excitation by UV radiation, the origin of the trapped electrons during gamma -ray irradiation may be traced to a series of reducing species produced by the high energy electrons, which in turn, are the direct result of gamma -irradiation. As the absorption intensity is linearly related to the duration of exposure to gamma -radiation, it may have an application in gamma -ray dosimetry. The sensitivity of its dosage response has been found to be influenced by the semiconductor particle concentration and the dispersing solvent. (C) 2001 Elsevier Science Ltd. All rights reserved.