Abstract: A method for mask-free molecular or atomic patterning of surfaces of reactive solids is disclosed. A molecular-scale pattern of adsorbate molecules is used in place of the conventional macroscopic "mask". Molecules adsorb at surfaces in patterns, governed by the structure of the surface, the chemical nature of the adsorbate, and the adsorbate coverage at the surface. The surface is patterned and then marked or imprinted with the pattern by inducing localized chemical reaction between adsorbate molecules and the surface of the solid, resulting in an imprint being formed in the vicinity of the adsorbate molecules. In one aspect of the invention, photoinduced reaction of the patterned adsorbate leads to patterned photoreaction with the surface.