FTIR and solid-state 13C CP/MAS NMR spectroscopy of charred and non-charred solid organic residues preserved in roman iron age vessels from the Netherlands

In this study, solid-state C-13 magnetic resonance spectroscopy using cross-polarization combined with high-powered proton decoupling and magic-angle sample spinning and Fourier transform infrared spectroscopy using a diamond anvil cell, are employed to give information about the organic functional groups present in charred and non-charred solid organic residues and to give an insight into the degree of condensation of the chars. Residues were preserved in ceramic vessels recovered from the indigenous settlement of Uitgeest-Groot Dorregeest, dating back to the Roman period. In addition, the application of these solid-state techniques is used for verification of earlier results obtained in analytical pyrolysis studies and to clarify the relationship between the already thermally degraded charred residues and the controlled heating fragmentation taking place during analytical pyrolysis and direct temperature-resolved mass spectrometry.