Spatial Distribution of CO2 and H2O Molecules on Reflection and Sublimation from a Cold Surface

An effusive molecular beam, a copper target, and several quartz crystal microbalances were used to measure the spatial distributions of reflected and sublimated CO2 and H2O molecules. These spatial distributions were found to be identical for surface temperatures ranging from 55 to 210 K for CO2 and from 55 to 160 K for H2O, and for gas temperatures below 300 K. Experimental results agreed with the diffuse cosine law spatial distribution within the accuracy of the measurement.