Scanning atomic microscopy modification

Nanostructured materials have also been formed by scanning tunneling microscopy (STM) [24], scanning electrochemical microscopy (SECM) [25], and atomic force microscopy (AFM) [26], Recent reports on the modification of atomic sites at bare surfaces by STM [27] and the formation of nanometer-scale defects by STM [28] and AFM [29] illustrate the power of these techniques. 

In research on the mechanisms gouverning the modification reactions, the thin silica layers allow the application of various surface analytical techniques, which are of no use for analysis inside porous systems. Reaction mechanisms are simplified by the elimination of porosity and may be studied by direct surface techniques such as ellipsometry, as well as microscopic techniques such as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).59... 

Topics 1-3 can be addressed by the combined use of electron microscopy [HRTEM and scanning electron microscopy (SEM)] (47) and methods that probe the surfaces at the atomic level (e.g., by analyzing the modifications induced in the vibrational spectra of simple probe molecules adsorbed on the different coordinatively unsaturated sites (22, 23). 

J. R. Krogmeier and R. C. Dunn, Focused ion beam modification of atomic force microscopy tips for near-field scanning optical microscopy, Appl. Phys. Lett., 79 (2001) 4494-4496. 

The microscopic methods can be divided into several categories optical or light microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and several modifications... 

Singha et al. reported DA cross-linked products [158] using furan-modified polymethacrylate (PFMA) as the polymeric precursor, which was prepared through atom transfer radical polymerization (ATRP) and free-radical polymerization (FRP). Furthermore, the self-healing behavior of a triblock copolymer (PFMA-co-MMA) prepared by ATRP was demonstrated by means of scanning electron microscopy (SEM). With the modification, an almost fully recovered surface from knife-cut samples has been observed [159]. Chen et al. also reported the DA polymer product of PFMA-BM possessing thermal reversibility, whereas the homopolymer was prepared from anionic polymerization [160]. 

In order to understand the behavior of surfaces after surface modification, it is essential to examine their surface composition and structure in detail. A large number of techniques are available, and it is often desirable to combine several of these methods. The techniques used to monitor surface properties include scanning electron microscopy (SEM), optical profilometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, imaging ellipsometry, and water contact angle measurements. 

A whole host of characterization techniques have been employed to assess the occurrence and the extent of the modification. These tools include FTIR and XPS spectroscopy, elemental analysis, contact angle measurements, inverse gas chromatography (IGC) and scanning electron microscopy (SEM). New emerging techniques, such as the take-off angle photoelectron spectroscopy, secondary ion mass spectrometry (SIMS), solid state NMR, confo-cal fluorescence microscopy and atomic force microscopy (AFM) have recently started to he used in this field. 

On the basis of these estimates, one can imagine the possibility of developing a scanning electron microscopy technique with picosecond time resolution using low-energy electrons and laser focusing. This modification of laser-controlled electron microscopy would be of interest because low-energy electrons are sensitive to the atomic and molecular structure of the surface of the specimen. 

Modified electrodes can be characterized by electrochemical methods, spectroscopic methods (such as X-ray photoelectron spectroscopy), and microscopy methods (such as atomic force microscopy and scanning electron microscopy). These techniques when combined give a good idea of the effectiveness of the modification, the properties of the layer and the integrity of the surface coverage. A description of a selection of characterization techniques follows. 

Fig. 12 (a-c) Molecular models of 2D sheets formed by self-assembly of amphiphilic oligopeptoids. (d) Scanning electron microscopy images and (d) atomic force microscopy height scans of sheets formed from two different peptoids (a) on substrate. Reproduced, with modification, from [109] and [111], with permission from Macmillan Publishers Ltd. and Wiley Periodicals Inc... 

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