Validating Isomorph theory

The goal of the experiment is to continue our work on the first experimental test of the predictions from isomorph theory, that the structure of a liquid, in reduced units, is invariant along certain lines, isomorphs, in the (P, T)-phase diagram. Isomorph theory predicts that the relaxation time of the liquid is invariant along isomorphs. Experimentally we therefore identify candidates for isomorphs as lines along which the relaxation time is the same (isochrones). We wish to examine the temperature and pressure dependent changes to the structure, by measuring on both deuterated and hydrogen-containing cumene (isopropylbenzene, C9H12). Using isotopic substitution and EPSR to analyze the results. The unique construction of SANDALS (and NIMROD) makes it possible to measure neutron diffraction on both hydrogen-containing as well as deuterated samples.