Janice L. Musfeldt, University of Tennessee, DMR 0600089

1. Chemical Structure / Physical Property Relationships in Layered Organic Solids as Investigated by Infrared Spectroscopy • Quantum spin ladders have attracted considerable interest as intermediaries between one-dimensional chains and two-dimensional square lattices. Whereas most ladder systems of current interest are structural ladders, several other ladder-like compounds such as (DTTTF)2Cu(mnt)2 are formed from molecular building blocks. • In order to assess the charge ordering pattern of (DTTTF)2Cu(mnt)2 within the context of recent theoretical predictions, we measured the variable temperature infrared response of small single crystals. • The low temperature distortion along the chain direction is consistent with expectations based on structural studies for a doubling along b. • There is, however, a massive transverse distortion through the 235 K metal-insulator transition. • This result has important implications for the charge ordering pattern in (DTTTF)2Cu(mnt)2. It rules out the rectangular ladder model and supports the zig zag scenario. • The zigzag model has the bond-charge density wave ground state shown in panel (e), a consequence of cooperative charge and bond ordering. • A mode analysis provides a microscopic basis for this distortion and an estimate of the degree of charge ordering. Janice L. Musfeldt, University of Tennessee, DMR 0600089

2. Education and Human DevelopmentJanice L. Musfeldt, University of Tennessee, DMR 0600089 • Broad, interdisciplinary training of students in materials spectroscopy • Close interaction and collaboration with materials design and theory groups. Active collaborations at Argonne National Laboratory and the National High Magnetic Field Laboratory. • 14 undergraduates and 3 high school students over a 10 year period. • ~40% female participation, with both African American and Hispanic American female students. • Projects in the area of organic superconductivity, vibrational dynamics, and negative thermal expansion provide group members with important opportunities at every level of seniority and interest. High school, undergraduate, and graduate students as well as postdoctoral researchers have been involved in these projects.