Structural studies of marine exoskeletons: redox mechanisms observed in the Cu-supported CaCO3 surfaces studied by EPR

摘要

Electron Paramagnetic Resonance (EPR), optical and infrared (IR) spectral studies have been performed on the pure and Cu-adsorbed exoskeletons of marine environment. The EPR spectrum of exoskeletons at room temperature exhibits a sharp signal at g approximate to 1.9970. The possible redox mechanisms have been noticed on heating these exoskeletons in which the low spin Mn3+ reduces to Mn2+. The optical absorption spectra also give the evidence of the presence of Mn3+ ions. The effects of thermal sintering on the EPR spectra have been studied and discussed in detail. The Cu-adsorbed samples clearly showed the adsorption of the Cu2+ ions over CaCO3 and the redox mechanism in these samples have been monitored by EPR. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 36]