Gas–surface energy exchange and thermal accommodation of CO2 and Ar in collisions with methyl, hydroxyl, and perfluorinated self-assembled monolayers

摘要: Molecular beams of CO2 and Ar were scattered from long-chain methyl (CH3–), hydroxyl (OH–), perfluoro ((CF2)7CF3–) functionalized alkanethiol self-assembled monolayers (SAMs) on gold to study the dynamics energy exchange thermal accommodation model organic surfaces. collisions, for incident energies ranging 25 150 kJ mol−1, exhibit final distributions that depend significantly terminal functional group SAM. The CH3-terminated serve as an excellent sink dissipating translational energy. For example, at greater than 90% collision is transferred CH3–SAM surface specularly-scattered atoms (θi = θf 30° normal). However, OH–SAM a more rigid partner due formation intra-monolayer hydrogen bonding network (CF2)7CF3–SAM (F–SAM) provides high degree rigidity massive CF3 groups. triatomic, CO2, scattering three surfaces are remarkably similar results scattering. only significant difference in transfer these two gases appears collisions with OH–SAM. Strong gas–surface attractive forces between appear counter hydrogen-bonding help bring majority molecules equilibrium all up resulting increased comparison Ar. similarities CH3– F–SAMs suggest internal degrees freedom triatomic play small role determining outcome under conditions employed this work.