Scanning probe microscopy response

Fast scan measurements, i.e. for investigations of the dynamics of surface diffusion or reconstruction are done preferably in constant height instead of constant current mode because no electronic feedback circuit, limiting response time and scan speed, is involved in this mode. Obviously this works only with very smooth electrode surfaces. An electronic setup (bipotentiostat) that allows fast transient methods combined with scanning probe microscopies has been reported [21]. 

Lau, K., Liu, Y, Chen, H., Withers, RL., 2013. Effect of armeaUng temperature on the morphology and piezo response characterisation of poly(vinylidene fluoride-trifluoroethylene) films via scanning probe microscopy. Adv. Cond. Matter Ph. 2013,1-5. 

Scanning electrochemical cell microscopy (SECCM) is a recent innovation [161, 167] in electrochemical scanning probe microscopy [168] that has been proven particularly powerful for visualizing electroactivity. In the case of HOPG, the SECCM response also informs on the location of the measurement, that is, basal... 

Tip Characterization. The tip is the central parameter of any scanning probe microscope, and an accurate knowledge of the size and of the shape of the tip should normally be a necessary requirement to get a quantitative measurement. The nanometer size, or atomic size, of the tip makes scanning probe microscopy attractive, but results in the relevant part of the tip responsible for the interaction to be unknown. Therefore, reproducible experimental data accompanied with a theoretical description will be required to have a robust interpretation of the experimental data. Nevertheless, numerous attempts have been made to estimate the shape and size of the tip, here we... 

Perhaps the most significant complication in the interpretation of nanoscale adhesion and mechanical properties measurements is the fact that the contact sizes are below the optical limit ( 1 t,im). Macroscopic adhesion studies and mechanical property measurements often rely on optical observations of the contact, and many of the contact mechanics models are formulated around direct measurement of the contact area or radius as a function of experimentally controlled parameters, such as load or displacement. In studies of colloids, scanning electron microscopy (SEM) has been used to view particle/surface contact sizes from the side to measure contact radius [3]. However, such a configuration is not easily employed in AFM and nanoindentation studies, and undesirable surface interactions from charging or contamination may arise. For adhesion studies (e.g. Johnson-Kendall-Roberts (JKR) [4] and probe-tack tests [5,6]), the probe/sample contact area is monitored as a function of load or displacement. This allows evaluation of load/area or even stress/strain response [7] as well as comparison to and development of contact mechanics theories. Area measurements are also important in traditional indentation experiments, where hardness is determined by measuring the residual contact area of the deformation optically [8J. For micro- and nanoscale studies, the dimensions of both the contact and residual deformation (if any) are below the optical limit. 

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