Neutron diffraction study of the S2 monolayer phase of ethane physisorbed on graphite

Abstract

Motivated by low-energy electron diffraction (LEED) experiments, we have re-examined the structure of the S2 monolayer phase of ethane (C 2D 6) adsorbed on the graphite (0001) surface. Profile analysis of the neutron diffraction pattern of the S2 phase yields a structural model similar to that inferred by LEED: an incommensurate rectangular unit cell, 7.52 A ̊ × 5.24 A ̊ , containing two molecules arranged in a herringbone pattern. The orientation of the molecules found experimentally is consistent with potential energy calculations on a monolayer cluster but differs somewhat from results of molecular dynamics simulations.