STRUCTURE AND KINETICS OF THE SLIDING Q1 CDW IN NBSE3

Using crystallographically perfect single crystal whiskers of NbSe3 and the synchrotron x-ray scattering facilities at CHESS, we have performed detailed high resolution measurements of the structure of a sliding CDW. We observe the longitudinal strain of the CDW associated with the phase slip necessary to convert between normal and collective current at the electrical contacts. Using a stroboscopic x-ray scattering technique, we have extended these measurements into the time domain and studied the evolution of the structure of the sliding CDW as it responds to a reversal of the direction of an applied d.c. electric field. The time constant characterizing this structural evolution is on the order of milliseconds for fields well above threshold. Near threshold the CDW splits into two components; one component is pinned and the other is sliding. As the electric field strength is increased, the fraction of the CDW which remains pinned decreases monotonically.