Electrolytic coloration of O22−-doped NaCl crystals

Electrolytic coloration and spectral properties of OH−- and Cu+-codoped NaCl crystals

“…Some F color centers come from the photoconversion of the V-type (V K , V 2 , etc.) color centers under illumination like the case of our previous electrolytic colorations [5,10]. The other F color centers come from other reactions as discussed next.…”

“…1. A strong absorption band peaked at 195 nm associates with U (substitutional H À ion, whiles named H a À ion) and U A color centers [9,10]. Herein the U A color centers are formed from the U color centers perturbed with the doped Cu + ions.…”

“…After the electrolytic coloration, the colored crystals still contain more Cu + ions although some Cu + ions have been converted to other products such as Cu 0 , Cu À and OH À -perturbed Cu + color centers. The absorption band peaked at 274 nm associates with the O 2À -V a + color centers [10]. The V a + denotes an anionic vacancy.…”