Energy transfer in rare gas collisions with hydroxyl- and methyl-terminated self-assembled monolayers

Gas–surface scattering experiments are used to probe the dynamics of energy transfer and thermalization in collisions of 80 kJ/mol Ar with self-assembled monolayers composed of SH–(CH2)11–CH3 and SH–(CH2)11–OH alkanethiols on gold. We find that the extent of thermalization and the fractional energy transferred to the surface during the collision are significantly greater for the CH3-terminated surface than for the OH-terminated surface. Since the two monolayers are similar in structure, packing density, and mass, the differences in scattering dynamics are likely due to a combination of factors that may include differences in the available energy modes between the two terminal groups and the hydrogen-bonding nature of the OH-terminated alkanethiol self-assembled monolayer.