The self-absorption effect on the X-ray excited luminescence and cathodoluminescence spectra of YAG: Yb crystals

Y3Al5O12:Yb (YAG:Yb) crystal has been applied as not only the laser crystal with infrared (IR) luminescence but also the fast scintillation crystal with the fast ultraviolet (UV) scintillation light. In the investigation, both the X-ray excited luminescence (XEL) and cathodoluminescence (CL) spectra of YAG:Yb crystals with various Yb concentrations were measured and compared. Generally, the CL spectrum is considered to be equivalent to the XEL spectrum in characterizing the luminescence of scintillation crystals. However, the inconsistent correlations between Yb concentrations and the spectrally integrated XEL, CL intensities were observed for the UV luminescence. Meanwhile the consistent correlations between Yb concentrations and the spectrally integrated XEL, CL intensities were observed for the IR luminescence. The phenomenon was attributed to the stronger self-absorption effect in the XEL spectra measurements, compared to the CL spectra measurement. It indicates the correction on the luminescence intensity is needed in comparing the integrated XEL intensity of scintillation crystal with self-absorption effect.