title: Submolecular Resolution Imaging of Molecules by Atomic Force Microscopy: The Influence of the Electrostatic Force.
abstract: The forces governing the contrast in submolecular resolution imaging of molecules with atomic force microscopy (AFM) have recently become a topic of intense debate. Here, we show that the electrostatic force is essential to understand the contrast in atomically resolved AFM images of polar molecules. Specifically, we image strongly polarized molecules with negatively and positively charged tips. A contrast inversion is observed above the polar groups. By taking into account the electrostatic forces between tip and molecule, the observed contrast differences can be reproduced using a molecular mechanics model. In addition, we analyze the height dependence of the various force components contributing to the high-resolution AFM contrast.
authors.affiliation: Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: van der Lit
authors.affiliation: Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands.
authors.forename: Francesca
authors.initials: F
authors.lastname: Di Cicco
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic Cukrovarnicka 10, 1862 53 Prague, Czech Republic.
authors.forename: Prokop
authors.initials: P
authors.lastname: Hapala
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic Cukrovarnicka 10, 1862 53 Prague, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jelinek
authors.affiliation: Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands.
authors.forename: Ingmar
authors.initials: I
authors.lastname: Swart