Dynamical force microscopy, quantitative

Dynamic force spectroscopy (DFS) was introduced [1] allowing us to understand quantitatively dissipative and non-dissipative processes in dynamic force microscopy [2]. Using a combined experimental and computer simulation technique it is possible to reconstruct force/distance ciuves without using any model potentials and parameters. This method opens the perspective to extract material parameters such as atomic densities of the surface investigated as well as local elastic properties... 

PMMA) was employed. In addition, atomic force microscopy is used for a more quantitative read-out of the PMMA. Since it is a two-step process - an image formation step on the photoresist followed by a magnification of the miniature contact print formed on the resist - it is difficult to use in the study of dynamic processes. The use of flash sources such as X-ray lasers or laser-produced plasmas in addition to the use of synchrotron radiation sources increased the activity of X-ray contact imaging, allowing the capture of the image on a nanosecond time scale. 

We present a quantitative study of frictional properties of pure self-assembled monolayers (SAMs) of alkanethiols as a function of chain length and mixed SAMs of dodecanethiol and 11-mercapto-l-undecanol as a function of surface composition on Au (111) using atomic force/friction force microscopy (AFM/FFM). The lateral and normal forces were calibrated in situ using a combined two-slope and added-mass method. Molecular dynamics simulations were also carried out to interpret the chain length dependence of frictional properties of alkanethiols. We then extended the in situ force calibration method to the mixed SAMs and investigated the effects of chemical nature and relative humidity on the frictional properties. Friction coefficients were plotted as a function of surface composition with different relative humidity. Such a plot could serve as a reference in determining surface composition in a nanoscale domain by measuring its friction coefficient. 

B. W. Hoogenboom, H. J. Hug, Y. Pellmont, S. Martin, P. L. T. M. Frederix, D. Fotiadis, and A. Engel, Quantitative dynamic-mode scanning force microscopy in liquid, Appl. Phys. Lett 88,193109 (2006). 

The ramifications of nanotechnology in the food arena have yet to be fully realized. This requires further research into biopolymer assembly behavior and applications of nanomaterials in the food industry. Researchers should keep abreast of the development of research tools and what is being done to push resolution limits for techniques such as atomic force spectroscopy or the synchrotron coupled to various spectroscopic techniques and higher resolution microscopy. New techniques should be exploited and the knowledge gained used to understand the dynamics and interactions of food materials at the single-molecule level and to describe assembly behavior in quantitative thermodynamic terms. There are questions about the interactions of nanoparticles with the food matrix and within the human body. These questions need to be addressed by future research (Simon and Joner, 2008 Sletmoen et ah, 2008). 

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