Structural characterization of the sliding charge-density-wave conductor, Rb0.30MoO3, by nuclear magnetic resonance

Nuclear magnetic resonance is used to determine the electric field gradients and magnetic chemical shifts at the Rb87 sites in single crystals of Rb0.30MoO3 at several temperatures in the high-temperature phase and in the charge-density-wave (CDW) state, below 180 K. The chemical-shift anisotropy is small; spectral shift and shape are dominated by electric field gradients. An analysis of spectral shape, as a function of crystal orientation, that draws upon analogy with image reconstruction from projections, gives a picture of spatial orientation and probability distribution of field gradients caused by the CDW that agree with x-ray results except for a suggestion that a small component of CDW may be present along the crystal a axis. A simple electrostatic model of the CDW implies that a charge equivalent to 2 electrons per unit cell is responsible for the observed spectral broadening.