Latent-image generation by deposition of monodisperse silver clusters

Abstract

Silver cluster ions (${\mathrm{Ag}}_1$ ${\mathrm{}}^{+}$, ${\mathrm{Ag}}_3$ ${\mathrm{}}^{+}$, ${\mathrm{Ag}}_4$ ${\mathrm{}}^{+}$, ${\mathrm{Ag}}_5$ ${\mathrm{}}^{+}$, ${\mathrm{Ag}}_7$ ${\mathrm{}}^{+}$, and ${\mathrm{Ag}}_9$ ${\mathrm{}}^{+}$) generated in a sputtering arrangement were filtered in energy selected by size, and deposited onto specimens containing binder-free AgBr microcrystals prepared from a photographic emulsion. Development was observed after exposure to beams containing ${\mathrm{Ag}}_4$ ${\mathrm{}}^{+}$ or larger aggregates. No development occurred after exposure to beams of smaller cluster sizes. These experiments prove directly the existence of a ‘‘critical’’ size required for catalyzing development. This size may depend on the development conditions (e.g., the redox potential), as suggested by theories.