Experimental techniques probe microscopy

Experimental techniques based on the application of mechanical forces to single molecules in small assemblies have been applied to study the binding properties of biomolecules and their response to external mechanical manipulations. Among such techniques are atomic force microscopy (AFM), optical tweezers, biomembrane force probe, and surface force apparatus experiments (Binning et al., 1986 Block and Svoboda, 1994 Evans et ah, 1995 Israelachvili, 1992). These techniques have inspired us and others (see also the chapters by Eichinger et al. and by Hermans et al. in this volume) to adopt a similar approach for the study of biomolecules by means of computer simulations. 

After an overview over the experimental techniques and results from the literature (Sect. 7.2) and some words about technical aspects and our experience concerning problems with some materials (Sect. 7.3), the experiments of the authors can be outlined as follows first, measurements of ohmic and capacitive currents in the contact mode are described (Sect. 7.4), followed by a description of some surface charge measurements in the non-contact mode (Sect. 7.5). The chapter closes with some experiments to probe electro-mechanical properties by the use of piezo response microscopy (Sect. 7.6) with its own brief literature overview. All three experimental parts are opened by a short introduction to the SFM techniques implemented in our lab. 

Experimental approaches to bioelectrochemical systems include other techniques which introduce new environments for interfacial bioelectrochemical function. Introduction of single-crystal, atomically planar electrode surfaces has opened a basis for the use of the scanning probe microscopies, STM and AFM, also for biological macromolecules. Importantly this extends to the electrochemical STM mode where electrochemical surfaces, adsorbate molecules, and now also biological macromolecules can be mapped directly in their natural aqueous environment, with full electrochemical potential control in situ STM and... 

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. 

The structure of PEMs, in particular their phase-separated morphology at nm-scale, has been studied with a number of experimental techniques, including small- and wide-angle X-ray and neutron scattering, infrared and Raman spectra, time-dependent FTIR, NMR, electron microscopy, positron annihilation spectroscopy, scanning probe microscopy, and scanning electrochemical microscopy (SECM) (for a review of this literature see [31]). Structural studies of PEMs have mainly focused on Nafion. A thorough recent review on this particular membrane is provided in [32]. 

Different forms of carbons have different physical and chemical properties, but these different carbon forms are of interest in electrochemical studies and for many applications. Sufficient electrochemical research has already been done on carbon materials to demonstrate their importance in electrochemical energy storage, which is of societal importance. Various experimental techniques have been employed in conjunction with electrochemical methods to characterize carbon-based materials, such as Raman spectroscopy, scaiming probe microscopy, electron microscopy, photoelectron spectroscopy, and others. Various manufacturing techniques have also been developed, for commercializing electrochemical carbon-based materials, especially in batteries for energy storage. 

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