STRUCTURE AND KINETICS OF THE SLIDING Q1 CDW IN NBSE3

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