Importance of adsorption in ion beam induced deposition of carbon

Ion beam induced deposition of carbon films has been studied as a function of temperature and pressure for both 2-bromo vinyl benzene and 2-bromo ethyl benzene. In contrast to recently published results involving vinyl and ethyl benzene, deposition is possible for both materials at and below room temperature for a wide range of pressures. Further, deposition yield for each material scales directly with its vapor pressure at the deposition temperature. This behavior shows that physical adsorption plays the dominant role in determining deposition properties. In addition, the yield of 2-bromo vinyl benzene is consistently higher than 2-bromo ethyl benzene at a given normalized pressure. The importance of the double bond on the vinyl substituent observed in previous work is simply a manifestation of enhanced physical adsorption due to the presence of this double bond.