In a research that we are conducting on synthetic quartz, we have subjected several quartz crystals to anisotropic stress conditions, from 100 to 350 Mpa. We measure the density of dislocations on quartz powders by TEM. We need to determine a correlation (if any) of dislocation density with the number of active sites that develop on the surface of the quartz under stress. Currently, the active sites are measured using a colorimetric method, based on the immersion of the sample in solutions of DPPH (2,2-diphenyl-1-picrylhydrazyl), a molecule known for its radical scavenger properties. But, unfortunately, it is well known that the number of active sites are variable with time, from a large number immediately after the stress, to a poor number after some hours. For these reasons it is impossible to reach a good correlation.

Can someone give us a suggestion?