The research under the direction of Dr. Coppens will make extensive use of the synchrotron radiation facilities at the National Synchrotron Light Source and at the Cornell High Energy Synchrotron Source. A major effort will focus on the structural analysis of modulated solids, in which the three-dimensional symmetry is modified by superposition of incommensurate modulation waves. Such modulations can strongly affect physical properties such as electrical conductivity. In addition Dr. Coppens will develop further the experimental capability of his laboratory at SUNY-Buffalo to carry out low temperature measurements. This capability will complement the work at the synchrotron facilities by permitting preliminary measurements to be carried out in a more systematic manner. This research activity on electron densities and phase transitions in molecular crystals is expected to provide new fundamental insights in several areas. In particular, the understanding of electrical conductivity and superconductivity is still not complete. These studies could impact the search for new materials for electronic devices or for high temperature superconductors.