Direct observation of fullerene-adsorbed tips by scanning tunneling microscopy

Abstract

High-temperature scanning tunneling microscopy study of the Li/Si(111) surface J.We have succeeded in imaging individual C 60 molecules that have been adsorbed onto the tunneling region of a scanning tunneling microscopy tip. The individual tip-adsorbed molecules are imaged by scanning the fullerene-adsorbed tip over a defect covered graphite surface. The defects are generated by low energy argon ion bombardment and protrude from the graphite surface. These nanometer-size defects serve as a surface tip array which inverse images the molecules adsorbed to the tip when the surface is scanned.

On the topography multiplicity of non-planar titanyl (IV) phthalocyanine molecules and the STM imaging mechanism

“…Kelly et al have reported that the nanometer-size defects protruding from the graphite surface could serve as a surface tip array which inversely imaged the C 60 molecules adsorbed to the tip when the HOPG surface was scanned [17]. Herein, the atomically sharp titanyl groups protruding from the adsorbed TiOPc molecules could serve as ''probes" for detecting the tip electronic states.…”

“…Kelly et al have reported the in situ characterization of C 60 adsorbed onto the active region of tunneling tips by ''inverse imaging" with graphite defects [17]. To achieve atomic scale resolution of a STM nano-tip in situ, the tunneling sites on the surface must be sharper than a normal STM tip.…”

Probing relaxations of atomic-scale junctions in the Pauli repulsion range

“…Termination of the tip apex with a single C 60 molecule was routinely achieved by applying previously reported procedures [30,44]. The orientation of the tip apex molecule was determined by imaging atomic protrusions on the surface [30,45,46]. Cu(111) and Pb(111) surfaces were prepared by Ar + bombardment and annealing.…”

A robust molecular probe for Ångstrom-scale analytics in liquids

“…C 60 geometry permits easier lateral manipulation and transfer to the tip from the surface at ambient conditions than, for example, CO, and the protocol for C 60 transfer is well established 19 22 24 32 . Single C 60 -terminated STM tips are routinely used to probe organic materials and C 60 clusters anchored on metal STM tips have also been demonstrated previously, to investigate low-dimensional surface defects 33 . Such molecular cluster-based tips are relatively robust (loss of a single molecule at the apex can be compensated by its nearest neighbour) but interpretation of the observed chemical contrast improvements is not trivial.…”