Role of Tip Chemical Reactivity on Atom Manipulation Process in Dynamic Force Microscopy

Abstract

The effect of tip chemical reactivity on the lateral manipulation of intrinsic Si adatoms toward a vacancy site on a Si(111)-(7 × 7) surface has been investigated by noncontact atomic force microscopy at room temperature. Here we measure the atom-hopping probabilities associated with different manipulation processes as a function of the tip-surface distance by means of constant height scans with chemically different types of tips. The interactions between different tips and Si atoms are evaluated by force spectroscopic measurements. Our results demonstrate that the ability to manipulate Si adatoms depends extremely on the chemical nature of the tip apex and is correlated with the maximal attractive force measured over Si adatoms. We rationalize the observed dependence of the atom manipulation process on tip-apex chemical reactivity by means of density functional theory calculations. The results of these calculations suggest that the ability to reduce the energy barrier associated with the Si adatom movement depends profoundly on tip chemical reactivity and that the level of energy barrier reduction is higher with tips that exhibit high chemical reactivity with Si adatoms. The results of this study provide a better way to control the efficiency of the atomic manipulation process for chemisorption systems.

Unique Determination of “Subatomic” Contrast by Imaging Covalent Backbonding

“…approximately 2 nN). 3,4,22 We assign this very small force as being the result of a passivated tip, similar to those described previously. 3,29,30 This very small attractive force helps explain the contrast inversion observed in constant ∆ f feedback by taking into account the total ∆ f values measured.…”

Atomic Force Microscopy for Imaging, Identification and Manipulation of Single Atoms

“…Recently, we also found the correlation between the capability of this manipulation and magnitude of the interaction force measured by AFM [24]. All tips used in this study produce clear atomic resolution.…”

Force-induced tautomerization in a single molecule

“…A most interesting question is how the chemical reactivity of the tip apex affects a tip-induced reaction. For instance, a critical role of tip reactivity has been predicted by DFT calculations for AFMinduced Si atom hopping on Si(111) 35 . To examine the effects of tip reactivity, we functionalized the tip apex by adsorbing a single Xe atom using vertical manipulation 36 (Fig.…”