title: Identifying tips for intramolecular NC-AFM imaging via in situ fingerprinting.
abstract: A practical experimental strategy is proposed that could potentially enable greater control of the tip apex in non-contact atomic force microscopy experiments. It is based on a preparation of a structure of interest alongside a reference surface reconstruction on the same sample. Our proposed strategy is as follows. Spectroscopy measurements are first performed on the reference surface to identify the tip apex structure using a previously collected database of responses of different tips to this surface. Next, immediately following the tip identification protocol, the surface of interest is studied (imaging, manipulation and/or spectroscopy). The prototype system we choose is the mixed Si(111)-7×7 and Ag:Si(111)-(√3 × √3) R30° surface which can be prepared on the same sample with a controlled ratio of reactive and passivated regions. Using an "in silico" approach based on ab initio density functional calculations and a set of tips with varying chemical reactivities, we show how one can perform tip fingerprinting using the Si(111)-7×7 reference surface. Then it is found by examining the imaging of a naphthalene tetracarboxylic diimide (NTCDI) molecule adsorbed on Ag:Si(111)-(√3 × √3) R30° surface that negatively charged tips produce the best intramolecular contrast attributed to the enhancement of repulsive interactions.
authors.affiliation: 1] School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China [2] Department of Physics, King's College London, The Strand, London, WC2R 2LS, U.K.
authors.forename: Hongqian
authors.initials: H
authors.lastname: Sang
authors.affiliation: The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K.
authors.forename: Samuel P
authors.initials: SP
authors.lastname: Jarvis
authors.affiliation: School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K.
authors.forename: Peter
authors.initials: P
authors.lastname: Sharp
authors.affiliation: The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K.
authors.forename: Philip
authors.initials: P
authors.lastname: Moriarty
authors.affiliation: School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Physics, King's College London, The Strand, London, WC2R 2LS, U.K.
authors.forename: Lev
authors.initials: L
authors.lastname: Kantorovich