Radiation effect on cathodoluminescence and thermoluminescence emission of Ca-rich oxalates from the human body.

ABSTRACT

The radiation effect of luminescence emission of Ca-rich oxalate biogenic materials (gallbladder and renal calculi) and a commercial standard sample (CaC2 O4 ·H2 O) is reported. The samples were characterized by environmental scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric and differential thermal analyses, display complex cathodoluminescence (CL) and thermoluminescence (TL) glow emissions. CL spectra (in the UV-infrared range) displayed non-well defined peaks, and exhibited emission at (i) higher energies (300-490 nm) mainly associated with non-bridging oxygen hole centers, oxygen-deficient centers and peroxy intrinsic defects, regardless of the sample; and (ii) higher, narrow and sharp wavebands, in the red region, probably induced by the presence of traces of Sm3+ (4 G5/2 →6 H9/2 transition) and/or Tb3+ (5 D4 →7 F3 transition) only for mineral-like materials in the human body. The UV-blue TL emission showed low-intensity maxima in which it was possible to distinguish at least four groups of components in each sample.