This research, part of the Experimental Physical Chemistry Program, utilizes electron diffraction techniques to measure the structure and dynamics of liquid droplets and new low temperature crystal phases. These experiments coupled with model calculations will elucidate the nature of condensed phases consisting of highly supercooled microdrops and new low temperature crystal phases. The data obtained in these unique experiments will be used by modellers to both verify their theoretical constructs and to suggest new models for liquids and solids consisting of small numbers of molecular units. The electron diffraction patterns of supercooled liquid microdrops and new low temperature crystal phases, formed by homogeneous nucleation from the vapor phase in supersonic flows, will be observed. The data obtained will enhance knowledge of nucleation and growth of molecular clusters and will supply stringent new tests of current theories of molecular liquids. By coupling the experimental results with Monte Carlo simulations, more realistic representations of the interactions between polyatomic molecules will be made. In view of the fact that liquids are the least understood common form of matter, this fresh approach can be expected to yield new significant insights. The other phenomenon be addressed is nucleation. The ability to control the form of clusters nucleated and to study their structure within microseconds of formation will be provide useful data for the basic understanding of the energetics and dynamics of nucleation.
