Intramolecular Diffusive Motion in Alkane Monolayers Studied by High-Resolution Quasielastic Neutron Scattering and Molecular Dynamics Simulations

Molecular dynamics simulations of a tetracosane ([Formula presented]) monolayer adsorbed on a graphite basal-plane surface show that there are diffusive motions associated with the creation and annihilation of gauche defects occurring on a time scale of [Formula presented]. We present evidence that these relatively slow motions are observable by high-energy-resolution quasielastic neutron scattering (QNS) thus demonstrating QNS as a technique, complementary to nuclear magnetic resonance, for studying conformational dynamics on a nanosecond time scale in molecular monolayers.