Effects of the Superlattices on STM Imaging of Self-organized Substituted Alkyl Chain Monolayers on a Graphite Surface

Abstract

We characterized the physisorption of p-iodo-phenyl octadecyl ether molecules (I-POE) onto superlattice regions of graphite surfaces using scanning tunneling microscopy (STM). The formation of self-organized I-POE monolayers does not affect the overall structures of moiré patterns and their modulation periods. However, the packing density of the I-POE monolayer and the orientations of lamella structures were sensitive to the underlying superlattice structure. Depending on the bias voltage, the STM images selectively showed moiré pattern, I-POE layer, or both. Reflecting the local density of states at a certain energy level, the STM images thereby revealed the relative energy level scale of the superlattice with respect to the molecular orbitals of I-POE.

Nanoscale stripe arrays templated on Moiré patterns in graphite

“…Superlattices in HOPG can be seen of a long range, well ordered 'defect' state, which modifies the local density of states and reactivities of the surface. It has been shown that superlattices can modify the density, packing and alignment of SAMs [12].…”