NOVELTY - Production of gold-based heterogeneous catalyst system includes depositing fine nanoscale gold onto a nanoparticulate support medium by physical vapor deposition in oxidizing atmosphere.    USE - The process is used for producing gold-based heterogeneous catalyst system for use in respiratory protection article and in catalysis processes (claimed). The gold-based catalyst system is useful for cost effective carbon monoxide abatement (e.g. through use in personal respirators and in vehicle and building protection), purification of exhaust gases from internal combustion engines, removal of carbon monoxide from fuel cell feedstocks, and catalysis of other oxidation reactions such as oxidation of carbonaceous soot in diesel exhaust streams and selective oxidation of organic compounds (e.g. unsaturated and saturated hydrocarbons).    ADVANTAGE - The process produces gold-based catalyst system having enhanced catalytic activity at lower cost than current processes. The process eliminates the need for heat treatment to activate the catalyst as is the case with some other methodologies, making the process well-suited for use with oxidatively-sensitive supports (e.g. carbon). The resulting catalyst system is effective in humid environments and can work over a wide temperature range including room temperature (22-27 degrees C) and cooler temperature (less than 5 degrees C). Unlike solution state processes, the physical vapor deposition process is very clean and introduces no impurities into the catalyst system. There is no need for washing steps to remove chloride or other undesirable ions, molecules, or reaction by-products. Other metals can be deposited simultaneously or sequentially to enable catalysis of more than one reaction.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a catalyst system comprising fine nanoscale gold (greater than 1 wt.%) on nanoparticulate titania exhibiting a color that is described by a set of CIE color coordinates in which Lasterisk color coordinate is greater than 64, aasterisk color coordinate is less than 0, and basterisk color coordinate is less than 0, as determined by total reflectance measurements using d/8 degrees geometry.    DESCRIPTION OF DRAWING(S) - The drawing is a perspective view of a deposition apparatus.    Housing (12)    Vacuum chamber (14)    Particle agitator (16)    Base (18)    Port (20)    Rubber plate (28)    Opening (34)    Shaft (40)    Blades (42)    Holes (44)