Scanning probe microscopes

Three scanning probe techniques are described in more detail below the scanning tunneling microscope, the atomic force microscope, and the friction force microscope. 

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Two working modes are used for the STM first, the constant height-mode, in which the recorded signal is the tunneling current versus the position of the tip over the sample, and the initial height of the STM tip with respect to the sample surface is kept constant (Fig. 22(a)). In the constant currentmode, a controller keeps the measured tunneling current constant. In order to do that, the distance between tip and sample must be adjusted to the surface structure and to the local electron density of the probed sample via a feedback loop (Fig. 22(b)). 

STM can be operated in a wide range of environments a stable tunnel current can be maintained in almost any nonconducting medium, including air, liquid, or vacuum. It is also relatively forgiving for an STM operation to prepare a sample the main requirement is that the sample conduct 

Binnig et al. [48] invented the atomic force microscope in 1985. Their original model of the AFM consisted of a diamond shard attached to a strip of gold foil. The diamond tip contacted the surface directly, with the inter-atomic van der Waals forces providing the interaction mechanism. Detection of the cantilever s vertical movement was done with a second tip—an STM placed above the cantilever. Today, most AFMs use a laser beam deflection system, introduced by Meyer and Amer [49], where a laser is reflected from the back of the reflective AFM lever and onto a position-sensitive detector. 

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Light microscope Scanning electron microscope Transmission electron microscope Scanning probe microscope... 

STM and SFM belong to an expanding family of instruments commonly termed Scanning Probe Microscopes (SPMs). Other common members include the magnetic force microscope, the scanning capacitance microscope, and the scanning acoustic microscope. ... 

The three-dimensional, digital nature of SFM and STM data makes the instruments excellent high-resolution profilometers. Like traditional stylus or optical profilometers, scanning probe microscopes provide reliable height information. However, traditional profilometers scan in one dimension only and cannot match SPM s height and lateral resolution. 

A scanning-probe microscope consists of a sharply pointed object, preferably so sharp that its tip is a sin-... 

FIGURE 9.14 Typical approach force curve (solid line) for a sample which is penetrated by the scanning probe microscope (SPM) tip. Also shown is the force curve (dashed line) when the tip encounters a hard surface (glass) and schematic drawings of the relative positions of the SPM tip and the sample surface as related to the force curves. (From Huson, M.G. and Maxwell, J.M., Polym. Test., 25, 2, 2006.)... 

FIGURE 9.16 Resilience values for chlorobutyl rubber (CIIR), butadiene rubber (BR), unfilled natural rubber (NR), filled natural rubber (SRB), and polyurethane (PU) samples tested using a Shore rebound resibometer, an Instron compression tester and a scanning probe microscope (SPM). (From Huson, M.G. and Maxweb, J.M.,... 

Huson, M.G. and Maxwell, J.M., The measurement of resilience with a scanning probe microscope, Polym. Test., 25(1), 2-11, 2006. 

It is worth to note that the authors experience has been accumulated working with scanning probe microscopes MultiMode and DimensionSOOO (both products of Digital Instruments/Veeco Instruments) but most of the results and conclusions are also relevant for practical work with scanning probe microscopes of other manufacturers. 

Jersch, J., Demming, F., Hildenhagen, L. J. and Dickmann, K. (1998) Field enhancement of optical radiation in the nearfield of scanning probe microscope tips. Appl. Rhys. A, 66, 29-34. 

Hiroshi Fukumura received his M.Sc and Ph.D. degrees from Tohoku University, Japan. He studied biocompatibility of polymers in the Government Industrial Research Institute of Osaka from 1983 to 1988. He became an assistant professor at Kyoto Institute of Technology in 1988, and then moved to the Department of Applied Physics, Osaka University in 1991, where he worked on the mechanism of laser ablation and laser molecular implantation. Since 1998, he is a professor in the Department of Chemistry at Tohoku University. He received the Award of the Japanese Photochemistry Association in 2000, and the Award for Creative Work from The Chemical Society Japan in 2005. His main research interest is the physical chemistry of organic molecules including polymeric materials studied with various kinds of time-resolved techniques and scanning probe microscopes. 

Mayer D, Ataka K, Heberle J, Offenhaeusser A. 2005. Scanning probe microscopic studies of the oriented attachment and membrane reconstitution of cytochrome c oxidase to a gold electrode. Langmuir 21 8580-8583. 

The success of STM has resulted in the development of a whole variety of related scanning probe microscopes, the most important of which is atomic force microscopy, AFM, also known as scanning force microscopy. AFM was first reported in 1986 by Binnig, Quate and Gerber. 

The area of complex condensed matter depends crucially on the availability of appropriate tools for both fabrication and characterization. These tools are of intermediate size they are neither a test tube nor a synchrotron. Typical tools— scanning probe microscopes, x-ray photoelectron spectrometers, electron microscopes, clean rooms—cost from 0.1 million to 5 million. They are shared-use facilities, but they must be local to the user group—travel to distance facilities for routine measurements is not practical. 

Schmid, G. and Peschel, S., Preparation and scanning probe microscopic characterization of mono-layers of ligand-stabilized transition metal clusters and colloids, New J. Chem., 22, 669, 1998. 

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