Potential of NMR method for the study of asphaltenes structural and dynamic organization in the condensed state

The asphaltenes extracted from three different oils were studied by nuclear magnetic resonance (NMR) method. It was found that the transverse relaxation parameters for asphaltenes depend on the structural-group composition of the original oil. The part $P_s$ of the solid component characterized by a short transverse relaxation time $T_{2s}$ ($\sim10^{-5}$ s) is the main characteristic of the nuclear magnetic relaxation for asphaltenes in the condensed state.
For studying structural and dynamic properties of asphaltenes the Solid-Echo pulse sequence ($90^\circ_{0^\circ}$ – $\tau$ – $90^\circ_{90^\circ}$ – $\tau$ – solid-echo signal) was mainly used. Basing on the comparative analysis of pulsed and continuous-wave NMR data it is concluded that the most correct information on the part $P_s$ could be obtained by the extrapolation to the time $\tau=0$ of exponential decomposition parameters for solid-echo signal at different values of time $\tau$.