The charge-density-wave (CDW) phase transition has been studied for a range of depth of 20–10000 Å below the (201¯) surface of ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_3$ by use of grazing-incidence x-ray diffraction. It is found that the CDW wave vector is the same as in the bulk. The transition temperature as well as the temperature dependence of the order parameter (down to 125 K) appear to be independent of the depth probed by the x-ray beam. The fact that the surface does not appear to modify the characteristics of the CDW in this particular case is probably related to the weak coupling between the slabs of ${\mathrm{MoO}}_6$ octahedra, perpendicular to the (201¯) surface.

• Received 6 August 1990

DOI:https://doi.org/10.1103/PhysRevB.42.8791