Deposition behavior of thin films of contaminants (less than 10 A) has been studied under vacuum conditions. Dependence of deposition behavior on the composition of the contaminant and of the condensing surface was considered. Quartz crystal microbalances (QCMs) were used to measure the mass accumulation rates of contaminants. Experimental results indicate that rough surfaces have higher mass accumulation than smooth surfaces and that polar attraction between the contaminant and the condensing surface affect deposition behavior.