High Resolution Replication of Metallic Microcrystals
Bradley's well known direct carbon replication technique with Pt-C shadowing offers the best resolution of any method currently in use. In the present study variations of this technique were applied to a system of gold microcrystals in an effort to obtain replicas of the highest possible resolution. Crystals with diameter on the order of 1000Å and thickness ∼100 Å have been examined for surface defects which might effect the growth process. This requires replication with higher resolution than is normally obtained.The basic technique consists of evaporating a suspension of the particles onto a clean glass slide, depositing 100-200 angstroms of carbon by vacuum evaporation, floating the carbon film on a solvent to remove the particles, and mounting the replica on support grids for shadowing. The factors limiting the resolution of the replica are:The accuracy in the reproduction of the surface topography by the carbon film.“Pile-up” effects due to the physical thickness of the carbon and Pt-C in the shadowing direction.Contamination of the specimen and replica surfaces by a layer of hydrocarbons.Granularity of the shadowing material.