Effect of magnetic particles on NMR spectra of Murchison meteorite organic matter and a polymer-based model system

Organic matter from the Murchison meteorite shows pronounced spinning sidebands of the H-1 MAS NMR spectrum and exhibits a large bulk magnetization of 0.75 emu/g extrapolated to 94 kOe at 300K. By comparison with data of diamagnetic polystyrene and laponite clay mixed with ferrimagnetic gamma-Fe2O3 nano-particles, we show that the spinning sidebands arise from a combination of dipolar couplings of a given H-1 to magnetic particles, seen in a backscattered-electron image, and to other protons. Signal loss and significant broadening of protonated-carbon peaks in C-13 MAS NMR spectra of polystyrene with Fe2O3 nano-particles is demonstrated, and implications for C-13 NMR spectroscopy of Murchison meteorite are discussed. (C) 2007 Elsevier Inc. All rights reserved.