The Role of Metal Ions in the Study of Ancient Paper by Electron Paramagnetic Resonance

Samples from covers and endleaves of sixteenth to eighteenth century books in good conservation state from the Biblioteca Nazionale Marciana in Venice have been investigated by means of electron paramagnetic resonance (EPR) spectroscopy and optical microscopy to characterize the embedded paramagnetic species and to test differences and similarities of the materials in the two types of book components. We detected the Mn(II), Fe(III), and Cu(II) paramagnetic ions, and analyzed their EPR signals by comparing them with previous results in literature of EPR studies on paper. Interestingly, the Mn(II) EPR spectrum profile appears as a fingerprint for samples coming from the same book, either from cover or endleaf, and it looks different for samples extracted from different books. We discuss the role of EPR as a spectroscopic tool for characterizing the interaction of the ions with the paper components and as possible agents of degradation.