Scintillation mechanisms in cerium fluoride

• Published in: Journal of luminescence 1994-02, Vol.59 (1), p.89-100
• Main Authors: Moses, W.W., Derenzo, S.E., Weber, M.J., Ray-Chaudhuri, A.K., Cerrina, F.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other solid inorganic materials; Photoluminescence; Physics
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/0022-2313(94)90026-4

Ultraviolet photoelectron spectroscopy, optical transmission, fluorescence excitation spectroscopy and time-resolved fluorescence spectroscopy are used to investigate the scintillation mechanisms of cerium fluoride (CeF 3) and of lanthanum fluoride doped with cerium in concentrations between 0.01 and 50 mol% cerium. In LaF 3:Ce, the absorption of either optical or ionizing radiation directly or indirectly results in excitation of the Ce 3+ 4f electron to the lowest 5d level followed by 5d→4f fluorescence at 284–300 nm. Whereas for optical excitation the fluorescence has a 20 ns decay time, for ionizing radiation there is an additional faster (2–10 ns) initial decay component. As the cerium concentration increases, another band appears that partially absorbs the 284–300 nm emission and re-radiates it in a broad band peaking at 340 nm and having a longer (∼30 ns) decay time. In the limit of 100% CeF 3, radiation trapping is very pronounced. The additional absorption and emission bands present at large Ce concentrations are attributed to Ce 3+ ions in perturbed sites. The relative efficiency for excitation of unperturbed and perturbed cerium sites via the Ce 3+ 5d and 6s bands, the F - 2p valence band, and the Ce 3+ or La 3+ 5p core levels are determined from fluorescence excitation spectra.