A significant decrease in the magnitude of the Casimir force (from 21% to
35%) was observed after an indium tin oxide (ITO) sample interacting with an Au
sphere was subjected to the UV treatment. Measurements were performed by using
an atomic force microscope (AFM) in high vacuum. The experimental results are
compared with theory, and a hypothetical explanation for the observed
phenomenon is proposed.Comment: 9 pages, 3 figures, to appear in Phys. Rev. Let