light input required to form a film having a desired thickness will depend to some extent on the density of the psi containing units coated on the substrate prior to light induced metal precipitation although thick films may be produced according to these methods thin films having nanometer range thicknesses e g 1 to 10 nm are preferably synthesized to take advantage of the precise deposition control offered by this invention none of the traditional film forming technology such as cvd pvd sputtering or epitaxial growth can provide a comparable level of control moreover the films of this invention can be advantageously provided as patterned metal layers using conventional photolithographic techniques in another embodiment of the invention a method is provided for the production of metallic nanoparticles in this approach desired psi metal complexes are formed as described in the above embodiments however the psi metal complexes are not applied to a substrate to effect film formation rather after the light induced reductive precipitation reactions the psi metal complexes are treated in a manner which allows for the separation of metallic particles from the psi containing units this can be accomplished by any of a number of approaches for example the psi metal complexes could be treated with various surfactants e g sodium dodecyl sulfate sds or could be subjected to sufficient agitation ultrasonication etc in order to disrupt the association between the metal particles and the psi units alternatively the biological components present in the psi metal complexes could be solubilized with an organic solvent or degraded using enzymatic reactions e g using nucleases proteases etc to remove the metal particles provided the treatment does not unacceptably compromise the integrity.