The optical characteristic of electron irradiated beryl by UV-Visible and mid-IR spectroscopic analyses

Abstract

ptical properties of crystal are the most important aspects in evaluating the beauty and the value of heliodor. The color of some yellow heliodor can be improved by irradiation. In this work, electron irradiation was performed on heliodors to characterize of changed in their optical properties. The specimens were irradiated with 20 MeV electrons to fluences in range of 4.46×1015-2.65×1016 cm−2. Their characteristic spectra were investigated by UV-Vis,
FTIR and EDXRF spectroscopy for comparison to pristine samples. The absorption bands in the 500-800 nm region of natural heliodor crystals caused by electron irradiation belong to a complex center, which consists of Fe3+ ions and radiation defect. The behaviors of water in the specimens were detected in the region of 4,000 – 4,800 cm-1. The releases of water from channels in specimen crystals were appeared after electron irradiation.