Browsing by Subject "Lateral stiffness"

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    Artifacts related to tip asymmetry in high-resolution atomic force microscopy and scanning tunneling microscopy measurements of graphitic surfaces
    (American Institute of Physics Inc., 2015) Uluutku, B.; Baykara, M. Z.
    The effect of tip asymmetry on atomic-resolution scanning tunneling microscopy and atomic force microscopy measurements of graphitic surfaces has been investigated via numerical simulations. Employing a three-dimensional, crystalline, metallic tip apex and a two-layer thick graphene sample as a model system, basic calculations of the tip-sample interaction have revealed a significant effect of tip asymmetry on obtained results, including artificial modulation of site-specific chemical interaction forces and spatial distortion of observed features. Related artifacts are shown to be enhanced for tips with low lateral stiffness values. Our results emphasize that potentially erroneous interpretations of atomic-scale surface properties via imaging and spectroscopy measurements can be caused or enhanced by tip asymmetry.
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    Noncontact lateral-force gradient measurement on Si(111)-7×7 surface with small-amplitude off-resonance atomic force microscopy
    (2009) Atabak, M.; Ünverdi O.; Özer H.O.; Oral, A.
    In this work, the authors report on a quantitative investigation of lateral-force gradient and lateral force between a tungsten tip and Si (111) - (7×7) surface using combined noncontact lateral-force microscopy and scanning tunneling microscopy. Simultaneous lateral-force gradient and scanning tunneling microscopy images of single and multiatomic step are obtained. In our measurement, tunnel current is used as feedback. The lateral-stiffness contrast has been observed to be 2.5 Nm at a single atomic step, in contrast to 13 Nm at a multiatomic step on Si (111) surface. They also carried out a series of lateral stiffness-distance spectroscopy, which show a sharp increase in tip-surface interaction stiffness as the sample is approached toward the surface. © 2009 American Vacuum Society.