Search results for "force microscopy"

Towards an atomistic understanding of solid friction by computer simulations

2002

Friction between two solid bodies in sliding motion takes place on a large spectrum of length and time scales: From the nanometer/second scale in an atomic force microscope up to the extremely macroscopic scales of tectonic motion. Despite our familiarity with friction, fundamental questions about its atomistic origins remain unanswered. Phenomenological laws that describe the friction in many systems were published more than 300 years ago by Amontons: The frictional force is proportional to the applied load and independent of the apparent area of contact. The atomistic origins of this simple law is still controversial. Many explanations, which seemed to be well-established until recently, …

Applications of near-field optics to the characterization of optoelectronics components

1997

In the race towards purely optical communications, the necessity of producing integrated components is linked to the requirement for the precise characteriza-tion of optoelectronic components. Near-field detection techniques meet this requirement, AFM (Atomic Force Microscopy), for instance, can provide the topography of a given sample. In conjunction with these new tools, several different kinds of near-field optical microscopes (NFOM) have appeared. They enable the characteriza-tion of the components with a resolution better than that imposed by the Rayleigh criterion. This is primarily due to the fact that they are sensitive to the evanescent waves. This document presents several areas r…

Nuclear magnetic resonance at millitesla fields using a zero-field spectrometer

2016

We describe new analytical capabilities for nuclear magnetic resonance (NMR) experiments in which signal detection is performed with chemical resolution (via spin-spin J couplings) in the zero to ultra-low magnetic field region, below 1μT. Using magnetic fields in the 100μT to 1mT range, we demonstrate the implementation of conventional NMR pulse sequences with spin-species selectivity.

Physics of Near-Field Optical Images

2005

Discriminating short-range from van der Waals forces using total force data in noncontact atomic force microscopy

2014

Noncontact atomic force microscopy (NC-AFM) features the measurement of forces with highest spatial resolution and sensitivity, resolving forces of the order of pico-Newtons with submolecular resolution. However, the measured total force is a mixture composed of various interactions. While some interactions such as electrostatic or magnetic forces can be excluded by a careful design of the experiment, the subtraction of van der Waals forces, which mainly originate from London dispersion interactions between the macroscopic tip shank and the bulk sample, remains a challenge. We present the determination of the inherently present van der Waals forces in total interaction force data from fitti…

Atomic-resolution imaging of the polar (0001¯) surface of LiNbO3in aqueous solution by frequency modulation atomic force microscopy

2012

S. Rode,1 R. Holscher,2 S. Sanna,2 S. Klassen,1 K. Kobayashi,3 H. Yamada,3 W. G. Schmidt,2 and A. Kuhnle1,* 1Institut fur Physikalische Chemie, Fachbereich Chemie, Johannes Gutenberg-Universitat Mainz, Jakob-Welder-Weg 11, 55099 Mainz, Germany 2Lehrstuhl fur Theoretische Physik, Universitat Paderborn, 33095 Paderborn, Germany 3Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan (Received 31 March 2012; revised manuscript received 12 June 2012; published 29 August 2012)

Atomistic Simulations of Solid Friction

2002

Friction between two solid bodies in relative sliding motion takes place on a large spectrum of length and time scales: From the nanometer/second scale in an atomic force microscope up to the extremely macroscopic scales of tectonic motion. Despite our familiarity with the effects of friction, fundamental questions remain unanswered. The atomistic origins of well-established phenomenological friction laws are controversial. Many explanations, seemingly well-established, have recently been called into question by new experimental results. Computer simulations have also revealed flaws in previous theoretical approaches and led to new insights into the atomistic processes responsible for frict…

Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

2013

The microscopic structure of the polar (000$\overline{1}$) and (0001) surfaces of lithium niobate is investigated by atomic-resolution frequency modulation atomic force microscopy and first-principles calculations. It is found that the surface reconstructs at annealing temperatures sufficiently high to drive off external adsorbates. In particular a ($\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7}$)$R$19.1${}^{\ensuremath{\circ}}$ reconstruction is found for the (000$\overline{1}$) surface. Density-functional theory calculations show that---apart from the $(\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7})$---a series of adatom-induced surface reconstructions exist that lower the surfa…

Status of the EPIC thin and medium filters on-board XMM-Newton after more than 10 years of operation I: laboratory measurements on back-up filters

2013

After more than ten years of operation of the EPIC camera on board the X-ray observatory XMM-Newton, we have reviewed the status of its Thin and Medium filters by performing both laboratory measurements on back-up filters, and analysis of data collected in-flight. We have selected a set of Thin and Medium back-up filters among those still available in the EPIC consortium, and have started a program to investigate their status by different laboratory measurements including: UV/VIS transmission, X-ray transmission, RAMAN IR spectroscopy, X-Ray Photoelectron Spectroscopy, and Atomic Force Microscopy. We report the results of the measurements conducted up to now, and point out some lessons lear…

Solution processed pentacene thin films: new routes for building-up plastic field effect transistors

2008