9503009 Gruner This project investigates the surface electrodynamic response of metallic systems referred to as charged quantum liquids. The experiments are unique in that they probe a broad frequency range, at low temperatures, where deviations from conventional Fermi liquid behavior can be pronounced. The experiments will provide important tests of theories of non-Fermi liquids. The project involves low temperatures, to 0.35 Kelvin, and high magnetic fields, to 9 Tesla. The materials to be investigated include UPt3, a conventional Fermi liquid, and suspected non-Fermi liquid alloys, cerium-copper-gold and uranium-yttrium-palladium, as well as two-dimensional organic metals. The work is of fundamental interest, but the results may also bear on other important non-Fermi liquid materials such as the high temperature superconductors. %%% This project looks at the response of unusual metallic systems, including so-called organic metals, to a broad range of electromagnetic radiation (light). The response to the radiation is measured at very low temperatures and at very high magnetic fields. The motivation of the work is to understand differences in the response of these materials as compared to ordinary metals, whose electrical properties are much better understood. The experiments are technically complex and can only be carried out in a few laboratories in the world. The materials to be investigated include UPt3, a conventional metallic material, the suspected non-conventional metal alloys: cerium-copper-gold and uranium-yttrium-palladium, as well as two-dimensional "organic" metals. The work is of fundamental interest, but the results may also bear on other important non-Fermi liquid materials such as the high temperature superconductors. ***