Background Accurate mechanical characterization by the atomic force microscope at highest spatial resolution requires that topography is deconvoluted from indentation. The measured height of nanoscale features in (AFM) almost always smaller than true value, which often explained away as sample deformation, formation salt deposits and/or dehydration. We show real nano-objects cannot be obtained directly: a result arising consequence local probe-sample geometry. Methods and Findings have...

We provide a method to characterize the tip radius of an atomic force microscopy in situ by monitoring dynamics cantilever ambient conditions. The key concept is that value free amplitude for which transitions from attractive repulsive regimes are observed, strongly depends on curvature tip. In practice, smaller required observe transition, sharper This general behavior remarkably independent properties sample and characteristics shows strong dependence radius. main advantage this rapid...

Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic hydrophobic patches can mitigate such biofouling effectively an environmentally friendly manner. The are synthesized by copolymerizing (Hydroxyethyl)methacrylate perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of was estimated be ∼1.4–1.75 nm fitting...

Abstract While it is commonly accepted that Learning Analytics (LA) tools can support teachers' awareness and classroom orchestration, not all forms of pedagogy are congruent to the types data generated by digital technologies or algorithms used analyse them. One such has been so far underserved LA exploratory learning, exemplified as simulators, virtual labs, microworlds some interactive educational games. This paper argues combination intelligent analysis interaction from an Exploratory...

Measuring the level of hydrophilicity heterogeneous surfaces and true height water layers that form on them in hydrated conditions has a myriad applications wide range scientific technological fields. Here, we describe non-contact mode operation atomic force microscopy ambient method to establish source apparent height. A dependency measured operational parameters is identified with perturbations due uncontrolled modes imaging where intermittent contact layer, or even surface, might occur....

Standard models accounting for capillary interactions typically involve expressions that display a significant decay in force with separation. These forces are commonly investigated the nanoscale atomic microscope. Here we show experimental observations not predicted by these common dynamic interactions. Since microscopy methods cantilever is vibrated over surface, nanoscopic tip submitted to nonlinear sample periodic fashion. That is, dependencies involved can be probed. We describe two...

Here we explore the raw parameter space in air bimodal atomic force microscopy (AFM) order to enhance resolution, provide multiparameter maps, and produce suitable transformations that lead physically intuitive maps general enough be recognized by broader community, i.e., stiffness, Hamaker constant, adhesion force. We further consider model free transforms form of alternative more intelligible contrast maps. employ highly oriented pyrolytic graphite, calcite, polypropylene, dsDNA on mica...

Vertical stacking of monolayers via van der Waals (vdW) assembly is an emerging field that opens promising routes toward engineering physical properties two-dimensional materials. Industrial exploitation these heterostructures as robust functional materials still requires bounding their measured so to enhance theoretical tractability and assist in experimental designs. Specifically, the short-range attractive vdW forces are responsible for adhesion chemically inert components recognized play...

Since the inception of atomic force microscope (AFM) in 1986, influential papers have been presented by community and tremendous advances reported. Being able to routinely image conductive non-conductive surfaces air, liquid vacuum environments with nanoscale, sometimes atomic, resolution, AFM has long perceived many as instrument unlock nanoscale. From exploiting a basic form Hooke's law interpret data interpreting seeming zoo maps more advanced multifrequency methods however, an inflection...

Results of classical force field geometry optimizations for twisted graphene nanoribbons with a number twists N(t) varying from 0 to 7 (the case N(t)=1 corresponds half-twist Möbius nanoribbon) are presented in this work. Their structural stability was investigated using the Brenner reactive field. The best molecular geometries were used as input semiempirical calculations, which electronic properties (energy levels, HOMO, LUMO orbitals) computed each structure. CI wavefunctions also...

The dynamics of the oscillating microcantilever for amplitude modulation atomic force microscopy (AM AFM) operating in air is well understood theoretically but experimental outcomes are still emerging. We use double-stranded DNA on mica as a model biomolecular system investigating connection between theory and experiment. A demonstration that switching two cantilever oscillation states stochastic nature achieved, it can be induced by means topographical anomalies surface. Whether one or...

A way to operate fundamental mode amplitude modulation atomic force microscopy is introduced which optimizes stability and resolution for a given tip size shows negligible wear over extended time periods (∼24 h). In small set-point (SASS) imaging, the cantilever oscillates with sub-nanometer amplitudes in proximity of sample, without requirement using large drive forces, as dynamics smoothly lead surface through water layer. SASS demonstrated on single molecules double-stranded DNA ambient...

The structure of water films in contact with surfaces has direct implications many important interfacial processes, from biology to climatology, as well ice nucleation. Here we report on the detection individual ice-like layers adsorbed ambient conditions. Reconstructed force profiles obtained amplitude modulation atomic microscopy (AM-AFM) top (111) BaF2 surfaces, a lattice constant close distance facing molecules hexagonal (Ih), showed characteristic oscillations attractive regime...

We describe fundamental energy dissipation in dynamic nanoscale processes terms of the localization interactions. In this respect, areal density dissipated per cycle and effective area interaction which each process occurs are calculated for four elementary dissipative processes. It is ratio between these two, we term M, that provides information about how localized interactions are. While our results general, use concepts from atomic force microscopy to physical phenomenon. show neither...

The size of an atomic force microscope tip can vary rapidly during interaction with a surface but this is typically overlooked. Here, we treat the radius as dynamic variable. Comparison nanoscission DNA molecules shows that pressure in nanoscale contact cannot increase without bound, rather gradually blunts energy cantilever increased. We develop method to stabilize and then reliably calculate effective area dissipation eV/atom situ. Tip stabilizes around 20–30 nm keeps maximum below ∼1 GPa.

We present experimental and computational investigations of tetramodal pentamodal atomic force microscopy (AFM), respectively, whereby the first four or five flexural eigenmodes cantilever are simultaneously excited externally. This leads to six eight additional observables in form amplitude phase signals, with respect monomodal modulation method. convert these into three dissipation virial expressions, show that quantities can provide enhanced contrast would otherwise remain hidden original...

Wetting at the nanoscale is investigated and discussed in relation to samples presenting amphiphilic domains by employing dynamic atomic force microscopy (AFM) operating amplitude modulation (AM) mode. First, capability of monitoring growth subsequent reduction water films on flat homogeneous surfaces, i.e., graphite with an AFM demonstrated. The AM data provide spectroscopy-like footprints presence amount surface terms variations profiles, conservative dissipative interactions. These...

In amplitude modulation atomic force microscopy the attractive and repulsive regimes induce phase shifts above below 90°, respectively. more recent multifrequency approach, however, multiple operation have been reported theory should be revisited. Here, a of contrast in is developed discussed terms energy transfer between modes, dissipation kinetic associated with externally driven harmonics. The single frequency virial that controls shift might undergo transitions sign while average (modal...

The irreversible loss of energy that occurs when a nanoscale tip vibrates over surface can be monitored and quantified in amplitude modulation atomic force microscopy (AM AFM). Furthermore, two distinct dissipative processes identified related to viscous hysteretic forces respectively. Here, experimental evidence transition from prevalent dissipation during mechanical contact is provided as the size increases few nm 10 or more. Long range dissipation, defined distances for which does not...

We present a theory that exploits four observables in bimodal atomic force microscopy to produce maps of the Hamaker constant H. The quantitative H may be employed by broader community directly interpret high resolution standard AFM images as chemical while simultaneously quantifying chemistry non-contact regime. further provide simple methodology optimize range operational parameters for which is closest agreement with Lifshitz order (1) simplify data acquisition and (2) generalize any set...

Adsorption of ascorbic acid (AsA) on C60 is investigated using classical molecular mechanics and density functional theory (DFT). Classical annealing was performed to explore the space configurations adsorbed C60, searching for optimal geometries. From structure with smallest total energy, 10 initial were prepared by applying rotations 90° about three orthogonal axes. Each one these optimized DFT (for both LDA GGA exchange−correlation functionals), an estimate their adsorption energies...

Imaging with nanoscale resolution has become routine practice the use of scanning probe techniques. Nevertheless, quantification material properties and processes been hampered by complexity tip-surface interaction dependency dynamics on operational parameters. Here, we propose a framework for coefficients viscoelasticity, surface energy, energy hysteresis elastic modulus. Quantification these parameters at will provide firm ground to understanding modelling tribology sciences true resolution.

We present some computational simulations of graphene-based nanoribbons with a number half-twists varying from 0 to 4 and two types defects obtained by removing single carbon atom different sites. Optimized geometries are found using mix classical quantum semiempirical computations. According the results, local curvature increases at defect sites, especially for higher half-twists. The HOMO-LUMO energy gap nanostructures has significant variation when defective nanoribbons. At level, first...

During their synthesis, multi-walled carbon nanotubes can be aligned and impregnated in a polymer matrix to form an electrically conductive flexible nanocomposite with high backing density. The material exhibits the highest reported electrical conductivity of CNT-epoxy composites (350 S/m). Here, we show how atomic force microscopy used study transport mechanism order explain enhanced properties composite. spatial resolution versatility technique allows us further decouple two main...