Generation and conversion of electronic defects in calcium carbonates by UV/Vis light
Radical species like CO2-, CO3-, SO2-, and SO3- can be created by exposing natural and synthetic calcium carbonates to sunlight or to the light of a Hg(Xe) lamp. This poses as a risk for ESR dating of these materials, because the radicals formed by light exposure cannot be distinguished from those generated by radioactivity. Furthermore, paramagnetic centers like SO2- electrons trapped near Zn2+ or Cd2+ ions, surface defects, and radicals with g' = 2.0040, can be bleached in gamma-irradiated samples by light and show conversion effects.
Bartoll
J
Federal Institute for Materials Research and Testing (BAM), Berlin, Germany.
Stosser
R
Nofz
M