Kinetics and Energetics of Oligomer Desorption from Surfaces

Andrew J. Gellman, Carnegie Mellon University
Kris R. Paserba, Carnegie Mellon University

Abstract or Description

The dynamics of oligomer desorption from surfaces has been studied by measuring the desorption kinetics of a set of straight chain alkanes [ H(CH2)nH, with n = 5 to 60] from the surface of single crystalline graphite. Desorption is observed to be a first-order process and the preexponent of the desorption rate constant has a value ν = 1019.6±0.5 sec-1 and is independent of the oligomer chain length. More interestingly, we find that the barrier to desorption has a nonlinear dependence on chain length and takes the form ΔEdes‡ = A+Bnα, with the exponent α = 0.50±0.01.