AFM Measurements

Measurements were performed with a Solver-Pro instrument by NT-MDT. 

We wish to thank the DFG foeus program Organie Field-Effect Transistors (grant TE 247/4-3) and the DFG Graduate Sehool 611 Functional Materials for financial support. We thank Carsten Brandt and Lisa Roeder for support with the experimental work. 

Ziemann, M. Buttner, 23. A. Romanyuk, and P. Oelhafen, Surf. 

Terfort, Appl. Phys. Lett. 91,052110 (2007). 

Moores, F. Goettmann, C. Sanchez, and P. Le Floch, Chem. Commun. 

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A unique but widely studied polymeric LB system are the polyglutamates or hairy rod polymers. These polymers have a hydrophilic rod of helical polyglutamate with hydrophobic alkyl side chains. Their rigidity and amphiphilic-ity imparts order (lyotropic and thermotropic) in LB films and they take on a F-type stmcture such as that illustrated in Fig. XV-16 [182]. These LB films are useful for waveguides, photoresists, and chemical sensors. LB films of these polymers are very thermally stable, as was indicated by the lack of interdiffusion up to 414 K shown by neutron reflectivity of alternating hydrogenated and deuterated layers [183]. AFM measurements have shown that these films take on different stmctures if directly deposited onto silicon or onto LB films of cadmium arachidate [184]. 

AFM measures the spatial distribution of the forces between an ultrafme tip and the sample. This distribution of these forces is also highly correlated with the atomic structure. STM is able to image many semiconductor and metal surfaces with atomic resolution. AFM is necessary for insulating materials, however, as electron conduction is required for STM in order to achieve tiumelling. Note that there are many modes of operation for these instruments, and many variations in use. In addition, there are other types of scaiming probe microscopies under development. 

Fig. 5.6. Cross-sectional view of a liquid cell for in-situ AFM measurements of surface processes.

Langry KC, Ratio TV, Rudd RE, McElfresh MW. 2005. The AFM measured force required to rupture the dithiolate linkage of thioctic acid to gold is less than the rupture force of a simple gold-alkyl thiolate bond. Langmuir 21 12064-12067. 

High-quality resolved images and atomic details of surface features on Ce02(l 11) in various oxidation states have also been obtained recently by dynamic AFM measurements by Gritschneder et al. [162],... 

Figure 8.7 Simultaneously recorded 80A x 150A STM and NC-AFM images of Ti02(l 1 0). (a) A current map represents the STM image. Because the tip is oscillating during NC-AFM measurements, the time-averaged current is recorded. The current map is color contoured so that OHb appear as broad, red spots and Ob-vacs appear as...

To prepare an antibody protein array, a monolayer of protein A, which was compressed at a surface pressure of 11 mN m l was transferred to a compartment containing anti-ferritin antibody in 10 mM pH 7.0 phosphate buffer. The antibody molecules were self assembled onto the protein A layer. The protein A/antibody molecular membrane was transfered to a compartment containing ultrapure water for rinsing, and was then transfered onto the surface of an HOPG plate by the horizontal method. AFM measurements were made in a pH 7.0 of 10 mM phosphate buffer solution. 

The antibody array that was self-assembled on the protein A array was also visualized in molecular alignment by AFM. The antibody array was in contact with a pH 7.0, 10 mM phosphate buffer. The AFM measurement was conducted at a controlled force of molecular size of the antibody was estimated as 7 nm in diameter. 

Recent studies on PEO-PPO, PEO-PBO di- and triblock copolymers include the works of Bahadur et al. [121], who examined the role of various additives on the micellization behavior, of Guo et al. [122], who used FT-Raman spectroscopy to study the hydration and conformation as a function of temperature, of Booth and coworkers [ 123], who were mainly interested in PEO-PBO block copolymers with long PEO sequences, and of Hamley et al., who used in situ AFM measurements in water to characterize the morphology of PEO-PPO micelles [56,57]. 

PAMAM dendrimers No. of molecules MW (AFM) measured MW theoretical Relative error (%) Polydispersity... 

Core-shell tecto-dendrimers Theoretical calculations AFM measurement ... 

In comparing the diffusion behavior of these two membranes at low MeOH concentrations, MeOH in BPSH 40 membranes exhibits significantly higher diffusion coefficients than those in Nafion 117. This may be the result of differences in morphology. Tapping mode AFM measurements found that, for dry membranes, the domains for BPSH 40 appeared to be 10-25 nm in diameter for Nafion 117, the domains were smaller, approximately 4-10 nm. Although one would expect restricted diffusion in both cases, it is possible that the smaller domains limit diffusion to a greater extent. 

Figure 44. Qualitative description of LajZrjOy (LZ) formation at the LSM/YSZ single-crystal interface based on HRTEM and AFM measurements, as explained in the text. Shaded region corresponds to LZ. (Adapted with permission from ref 215. Copyright 1998 Elsevier.)...

Acknowledgements The authors would like to acknowledge the financial support of the National Science Foundation (DMR-0729977, DMR-0423786). We also acknowledge Professor Stephen Z. D. Cheng (The University of Akron) for AFM measurements and Dr. Wayne Jennings (Case Western Reserve University MATNET Center) for help with XPS. 

In the classical contact mode (Fig. 6a) AFM measures the hard-sphere repulsion forces between the tip and the sample. As a raster-scan drags the tip over the sample surface, the detector measures the vertical deflection of the cantilever, which indicates the local sample height. A feedback loop adjusts the position of the cantilever above the surface as it is scanned and monitors the changes in the surface height, generating a 3D image—a decisive advantage of AFM over TEM [3]. 

Tapping Mode AFM measures contours by tapping the surface with an oscillating probe tip thereby minimizing shear forces that may damage soft surfaces. This allows increased surface resolution. This is currently the most widely employed AFM mode. 

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