Abstract
To control the time-response performance of widely used cerium-activated scintillators in cutting-edge medical-imaging devices, such as time-of-flight positron-emission tomography, a comprehensive understanding of the role of Ce valence states, especially stable , in the scintillation mechanism is essential. However, despite some progress made recently, an understanding of the physical processes involving is still lacking. The aim of this work is to clarify the role of in scintillators by studying codoped . By using a combination of optical absorption spectra and x-ray absorption near-edge spectroscopies, the correlation between codoping content and the fraction is seen. The energy-level diagrams of and in the host are established by using theoretical and experimental methods, which indicate a higher position of the state of in the forbidden gap in comparison to that of . Underlying reasons for the decay-time acceleration resulting from codoping are revealed, and the physical processes of the -emission model are proposed and further demonstrated by temperature-dependent radioluminescence spectra under x-ray excitation.
1 More- Received 24 June 2014
DOI:https://doi.org/10.1103/PhysRevApplied.2.044009
© 2014 American Physical Society