Optical detection of paramagnetic centres: From crystals to glass-ceramics

Abstract

An unambiguous attribution of the absorption spectra to definite paramagnetic centres identified by the EPR techniques in the most cases is problematic. This problem may be solved by applying of a direct measurement techniques—the EPR detected via the magnetic circular dichroism, or briefly MCD–EPR. The present survey reports on the advantages and disadvantages applying the MCD–EPR techniques to simple and complex paramagnetic centres in crystals as well as glasses and glass-ceramics.

EPR characterization of erbium in glasses and glass ceramics

“…A direct correlation of optical properties to particular defect or impurity centres can be achieved via optically detected magnetic resonance (ODMR) measurement techniques. One of the variations of ODMR is EPR detected via magnetic circular dichroism (MCD-EPR) [52]. MCD and MCD-EPR spectra for erbium doped CF glass ceramics are shown in Fig.…”

EPR in glass ceramics

“…In this particular study, the EPR signal was detected optically on a magnetic circular dichroism (MCD) band. Optical detection of paramagnetic activators is especially advantageous for a direct and unambiguous attribution of optical properties to paramagnetic center local structure [90]. The MCD-EPR technique has been applied previously to detect cubic CaF 2 :Gd 3 + centers as well [72].…”

Optical Detection of Paramagnetic Centres in Activated Oxyfluoride Glass-Ceramics

“…Investigations of the paramagnetic centres by the conventional EPR techniques usually do not allow to directly attribute these centres to particular optical bands of the given sample. For this purpose the most convenient is the EPR optically detected via the magnetic circular dichroism (MCD and MCD-EPR) [5][6][7]. Usually the correlation between the optical and paramagnetic properties of point defects has been studied in crystalline materials, where the angular dependences of the magnetic resonances are well pronounced [5].…”

“…Usually the correlation between the optical and paramagnetic properties of point defects has been studied in crystalline materials, where the angular dependences of the magnetic resonances are well pronounced [5]. Nevertheless, the correlation of optical and paramagnetic properties of activator centres is an actual task also in glass-ceramics and ceramic samples [7].…”