Abstract 9322504 Fayer This research examines fast dynamics and the relationship of dynamics to local structure in a variety of condensed matter systems using multiple time scale non-linear experiments. The materials to be examined include low temperature glasses, high temperature glasses near the glass transition, glass forming liquids and the glass transition, and liquids with local structure such as liquid crystals and polymer melts. The proposal is divided into three subsections for organizational purposes: (A) Psec Vibrational Photon Echoes in Condensed Matter Systems; (B) Optical Coherence Studies of Low Temperature Glasses and Glasses and Liquids Near the Glass Transition; and (C) Dynamics of Complex Liquids: Glass Forming Liquids, Polymer Melts, and Liquid Crystals Probed with Fsec Transient Grating Experiments. The information in (A) will provide: 1) a direct method for examining the interactions of a molecule's vibrational degrees of freedom with its dynamic environment, and 2) detailed insights into dynamics in glasses and liquids and dynamical intermolecular interactions. In (B), fluctuation rate distributions are mapped out for liquids and glasses. The experiments examine homogeneous dephasing and spectral diffusion over a wide range of temperatures and time scales. The subsection (C) includes examination of the role of local structure on the dynamics of complex liquids. The experiments span time scales of tens of fsec to hundreds of nsec and longer. %%% Using laser-based techniques, this proposal addresses a number of basic questions concerning the interplay of dynamics and structure at the microscopic level. The materials to be examined include low temperature glasses, high temperature glasses near the glass transition, glass forming liquids and the glass transition, and liquids with local structure such as liquid crystals and polymer melts. The questions to be answered are as follows. On what time scales do dynamics in molecular condensed matter systems occur? How do dynamics of a medium influence the mechanical and electronic degrees of freedom of an embedded molecule? How does local structure determine the nature of dynamics occurring on a molecular level? What are the time scales and pathways for the flow of energy into and out of molecules? How do differences in the nature of glasses, liquids, and crystals influence dynamical processes? How do dynamics in structured liquids, e. g., liquid crystals, in polymer melts, and in glass forming liquids differ from dynamics in simple liquids?
