Study of carbonaceous mesophase through the e.s.r. spectra of vanadyl chelates

The behaviour of vanadyl chelate complexes in Iranian heavy oil and ethylene tar pitch during the carbonization process has been investigated by the e.s.r. technique to obtain information on the mesophase transformation. Activation energies for rotation of chelates incorporated with aromatic lamellae, and ordering parameters, are estimated from correlation times and intensities of e.s.r. spectra. The molecular plane of the chelates incorporated into the mesophase was found to be oriented parallel to the applied field. The value of activation energy is higher for a mesophase of small size than for a larger one.