Lateral force microscopy LFM

Lateral force microscopy (LFM) has provided a new tool for the investigation of tribological (friction and wear) phenomena on a nanometre scale [110]. Alternatively known as friction force microscopy (FFM), this variant of AFM focuses on the lateral forces experienced by the tip as it traverses the sample surface, which... 

In 1987 Mate et al. [468] used, for the first time, an atomic force microscope (AFM) to measure friction forces on the nanometer scale (review Ref. [469]). This technique became known as friction force microscopy (FFM) or lateral force microscopy (LFM). To measure friction forces with the AFM, the fast scan direction of the sample is chosen perpendicular to the direction of the cantilever. Friction between the tip and the sample causes the flexible cantilever to twist (Fig. 11.7). This torsion of the cantilever is measured by using a reflected beam of light and a position-sensitive detector in the form of a quadrant arrangement of photodiodes. This new method made it possible for the first time to study friction and lubrication on the nanometer scale. 

For example, chemical contrast images were obtained by lateral force microscopy (LFM) from a topologically flat surface of a self assembled monolayer consisting of chemically different domains. In order to make the chemical adhesion the dominant contribution to the friction signal, the tip was modified by a monolayer with appropriate terminal groups [149-155]. However, since LFM operates in contact mode, the surface deformation is inevitable. 

Abstract. Quantitative measurements of lateral force required for displacement of SWNTs bundle on the surface of highly oriented pyrolytic graphite with the help of atomic force microscope (AFM) were performed in real time . New method of quantitative calibration of lateral forces was used for interpretation results of lateral force microscopy (LFM). It allows us to receive numerical values of adhesion force of bundle to substrate easy and without specific equipment. 

Atomic force microscopy [6, 7] is one of the most suitable methods for research carbon nanotubes. AFM allows to receive not only a relief of the studied sample, but also distribution of mechanical characteristics, electric, magnetic and other properties on its surface. With the help of AFM, controllable manipulation of individual CNTs and CNTs bundles became possible. In this paper we report our approach to manipulating SWCNTs bundles with lateral force microscopy. LFM gives possibility to study lateral forces that probe acts upon bundles. In spite of good visualization of LFM, its lack is absence of reliable techniques of quantitative interpretation of results. The new way of calibration developed ourselves has allowed to pass from qualitative estimations to quantitative investigations [8], The given calibration technique is much more exact, than others known till now [9, 10], and does not assume simplification. With the help of new technique we may study adhesion of bundles to substrate and adhesion of CNTs in bundle qualitatively in real time more easy way. This result will provide new possibilities for nanotube application. 

Lateral force microscopy (LFM), where the longitudinal vibrations of the cantilever are monitored. 

The core concept that the water meniscus at the tip-substrate contact can indeed be controlled and can be used as the molecular transport medium came from basic investigations of water meniscus on lateral force microscopy (LFM) [83]. It was... 

Lateral force microscopy (LFM) is performed simultaneously with topographical imaging in contact mode using V-shaped Si3N4 cantilevers with a nominal spring constant of 0.06 N/m. All lateral force data are acquired under Milli-Q water. We use the open cell configuration (see Sect. 3.3 in Chap. 3). To ensure meaningful comparisons of friction data acquired on different films, the same tip must be used for all the films tested. 

Constant Height Mode AFM Constant Force Mode AFM Constant Error Mode AFM Lateral Force Microscopy (LFM) Spreading Resistance Imaging... 

In actual operation in the contact mode, the tip touches the surface like the stylus of a record player. In the non-contact mode, the cantilever is oscillated at a frequency close to the resonance frequency with a large amplitude. In this mode, vertical long-range forces are probed, whereas lateral forces (friction-like forces in the plane of the sample surface) are almost non-effective. These forces have been employed in lateral force microscopy (LFM). 

In this section, glass transition behavior at the surface in the PS films is discussed. Our experimental technique to probe this was lateral force microscopy (LFM) in addition to SVM. The details of why LFM can reveal such behavior are described elsewhere [24, 25]. In short, the central part of the idea is that lateral force, namely frictional force, is essentially related to energy dissipation. That is, lateral force is somehow proportional to loss modulus at the surface. 

Figure 10.14 Lateral force microscopy (LFM) image of PPY nanopattern written at 0.8gm s . (Reprinted with permission from Advanced Materials, Electrostatically Driven Dip-Pen Nanolithography of Conducting Polymers by J.-H. Lim and C. A. Mirkin, 14, 20, 1474-1477. Copyright (2002) Wiley-VCH)...

The variations in friction between the tip and sample causes a stick and slip movement of the lever s tip. If the fast scan direction (jc) is perpendicular to the lever axis this results in lever torsion. Deflection of the light beam by a twisted lever on the position sensitive detector is perpendicular to the usual deviation stemming from normal (z) forces. Thereby, discrimination of Fx and F is possible. Lateral force microscopy (LFM) measures the forces parallel to the surface plane. The feedback loop must be slowed down, as always when a force channel is measured. 

Lateral force microscopy (LFM) measures the lateral deflections in the cantilever that are present from forces on the cantilever parallel to the plane of the sample surface. Lateral deflections of the cantilever are normally attributable to changes in surface friction or changes in slope. The LFM has been used to image variation in surface friction which can arise from inhomogeneity in the surface material. 

Lateral force microscopy (LFM) This mode measures the frictional forces on a surface. By measuring the twist of the cantilever, rather than merely its deflection, one can qualitatively determine areas of higher and lower friction. 

The present study aims to understand the influence of solvent quality on the molecular-level friction mechanism of tethered, brushlike polymers. It involves complementary adsorption studies of PLL-,g-PEG by means of optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microbalance with dissipation (QCM-D) as well as friction studies performed on the nanoscale using colloidal-probe lateral force microscopy (LFM). The adsorbed mass measured by QGM-D includes a contribution from solvent molecules absorbed within the surface-bound polymer fllm. This is in contrast to optical techniques, such as OWLS, which are sensitive only to the dry mass of a polymer adsorbed onto the surface of the waveguide.By subtracting the dry mass , derived from OWLS measurements, from the wet mass , derived from QCM-D measurements, it is therefore possible to determine the mass of the solvent per unit substrate area absorbed in the brushlike structure of PLL- -PEG, expressed as areal solvation, P. Areal solvation was varied by choosing solvents (aqueous buffer solution, methanol, ethanol, and 2-propanol) of different quality with respect to the PEG brush. The solvents were characterized in terms of the three-component Hansen solubility parameters, and these values were compared with measured areal solvation of the PEG brush. 

In this article, we aim to introduce our recent investigation relating to the surface molecular aggregation structure and surface molecular motion of the flu-oro(co)polymers with Rf side group. GI-WAXD measurement and X-ray photoelectron spectroscopy (XPS) using Cgo ion beam were applied to the surface molecular aggregation structure analysis and the depth analysis of the fluoropolymer films, respectively. Temperature dependence of the dynamic contact angle, XPS measurement in pseudo-hydrated state, and lateral force microscopy (LFM) measurement... 

Lateral Force Microscopy (LFM) measures the lateral deflections in the cantilever that are present from forces... 

NTS/FOETS) mixed monolayer showed phase-separated structure like sea-island, whose domain and matrix phases were composed of crystalline NTS and amorphous FOETS molecules, respectively. The (NTSQQQ /FOETS) mixed monolayer with the hydrophilic domain and the hydrophobic matrix was obtained by selective oxidization of the NTS phase in the (NTS/FOETS) mixed monolayer. Furthermore, the local height control on the NTScqoh phase of the (NTS ooh/P S) mixed monolayer was performed by chemisorption of NTS from the solution. The height increase in the NTScqoh phase was confirmed by AFM and lateral force microscopy (LFM). 

---