Spacecraft molecular contamination can be increased under vacuum ultraviolet irradiation because of contaminant sticking induced by photochemical reactions. Tridecan-2-one was experimentally studied as model contaminant. Thin films were irradiated by a deuterium lamp in order to investigate the quantitative formation of different volatility molecules. In this article, on the basis of a parametric irradiation study the authors highlight the formation of three populations of irradiation products. More volatile species come from photolysis that is showed to be strongly temperature dependent and fitted by an Arrhenius law (27 kJ/mol). Less volatile species are initially formed and eliminated afterward when photolysis stops. Nonvolatile species are continuously formed until saturation amount. With tridecan-2-one saturation occurred when 80% of the initial deposit was removed by photolysis and 20% stuck. Complementary gas chromatography coupled mass spectrometry results interpretation lead to a mechanism corresponding to primary molecular dissociation into free radicals followed by addition of radicals forming molecules of various volatility. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3271134]