The spin probe technique in the EPR-imaging of structurally heterogeneous media

Abstract

The application of the spin-probe technique for the study of spatial distributions by means of EPR-imaging is of great interest for structurally heterogeneous systems with a different mobility of probes, or for systems with a high concentration gradient. Diferent molecular mobilities of spin probes in the sample provoke the existence of a set of probe lineshapes complicating essentially the task of reconstructing the spatial distribution of centers. The methods and approaches enabling the spatial probe distributions to be obtained without additional measurements are worked out and tested with a set of lines of different shapes being present in the sample. As an application, processes of polypropylene destruction under loading and wheat grain swelling in water have been investigated using TEMPO as the nitroxide spin probe.