Optical spectroscopy is a sensitive probe of charge, spin, and lattice degrees of freedom. In
this talk, I will detail our magneto-optical work on alpha'-NaV2O5, a prototypical ladder
material, as well as the new Na2V3O7 nanotubes. Using changes in electronic structure with
temperature and applied magnetic field, we have mapped out the H-T phase diagram of
alpha'-NaV2O5. We find a temperature independent phase boundary at 27 T which persists
above Tc (34 K), a kink in Tc(H) near 27 T, and H$\wedge $2 behavior of Tc(H) in the high field
phase with an unusually small coupling constant. The energy scale of Tc and the newly
discovered phase boundary at Hc (27 T) are identical. Confinement effects are investigated in
the related nanotubes. Results include a larger gap than in analogous bulk materials as well
as a low-energy rattling mode, which corresponds to the motion of Na+ ions inside the
nanotube.
Structural resolution of inorganic nanotubes with complex stoichiometry
