9631298 Sievers Technical Abstract The proposal experimental study focuses on identifying the static and dynamic properties of multiple elastic configurations in crystals and glasses. The method is to examine the energy transport between the low lying equilibrium and non-equilibrium states and configurations of solids with a variety of linear and nonlinear spectroscopic tools, including persistent IR spectral hole burning, IR pump-probe transient hole burning, Raman scattering and fourier transform IR spectroscopy. Interest has grown in the possibility that intrinsic localized modes, made possible by the lattice anharmonicity, may exist in bulk crystals, at their surfaces or at their edges. The progress in localized vibrational mode studies is leading to the exploration of intrinsic localized excitations in other nonlinear dynamical systems. Antiferromagnetic crystals provide new experimental opportunities to search for intrinsic localized excitations. %%% Non-Technical Abstract An outstanding problem in condensed matter physics is identifying the source of the static and dynamic behavior of near-equilibrium vibrational states in crystals and glasses. The proposed method is to examine the energy transport between the low lying equilibrium and non- equilibrium configurations of solids with a variety of spectroscopic tools. Recently, interest has grown in the likelihood of a new type of localized vibrational excitation made possible by the lattice nonlinearity that may exist in bulk crystals, at their surfaces or at their edges. Progress here is leading to the exploration of intrinsic localized excitations in nonlinear magnetic systems. The proposed measurements should impact on topics as diverse as the role of structural defects in optical materials used for information storage, amplification and optical transmission, and on the science and technology of fast-ion conductors and that of magnetic structures. ***
