  Widths of shocks are compared, under liquid and solid conditions, for a
two-dimensional layer of charged microspheres levitated in a plasma. In this
strongly coupled dusty plasma, a shock was launched as a blast wave by moving
an exciter wire at a supersonic speed and then bringing it to a halt. Runs were
repeated with the layer of microspheres prepared two ways: a crystalline-like
solid, and a liquid. The liquid was sustained using laser heating, with
conditions that were otherwise the same as in the solid. The shock width was
found to be less in a liquid than in a solid, where it was 4 to 6 lattice
constants. These measurements were based on the high-gradient region of density
profiles. The profiles were obtained from particle coordinates, measured by
high-speed video imaging. The spatial resolution was improved by combining
particle coordinates, in the shock's frame of reference, from a sequence of
images.
