In situ imaging of samples

Recently a whole new family of microscopic techniques has been invented which enable the in situ imaging of solid surfaces using local probes. By local we mean that resolution can approach atomic dimensions, implying that probe size and accuracy of controlling its movement over the surface limit the resolution. The probe is usually located at atomic distances from the sample and is not influenced by the medium. 

For in situ investigations of electrode surfaces, that is, for the study of electrodes in an electrochemical environment and under potential control, the metal tip inevitably also becomes immersed into the electrolyte, commonly an aqueous solution. As a consequence, electrochemical processes will occur at the tip/solution interface as well, giving rise to an electric current at the tip that is superimposed on the tunnel current and hence will cause the feedback circuit and therefore the imaging process to malfunction. The STM tip nolens volens becomes a fourth electrode in our system that needs to be potential controlled like our sample by a bipotentiostat. A schematic diagram of such an electric circuit, employed to combine electrochemical studies with electron tunneling between tip and sample, is provided in Figure 5.4. To reduce the electrochemical current at the tip/solution... 

Techniques of microscopic XRF ( j,-XRF) developed in the last 20 years provide 2D images and elemental maps of each element present in the target material. Portable/in situ p-XRF, j,-XRF spectrometers synchrotron-based ( -SRXRF) and micro-x-ray absorption spectroscopy/micro-x-ray absorption near-edge structure spectroscopy (XAS/ J,-XANES) have improved the mineralogical characterization, as well as the elemental and chemical imaging of samples at the submicrometer scale [61]. 

A scanning force microscope equipped with a temperature cell enabled in-situ monitoring of the motion of the single molecules and small molecular clusters at elevated temperature.190 The diagram on the left side of Figure 30 depicts the traces of the molecules that were recorded by imaging the sample within intervals of 4 h 20 min over a period of 12 h at 35... 

The imaging of biologically relevant polymers must be performed in most cases under liquids in order to reduce the forces between the scanned probe tip and the sample surface or, more importantly, to ensure that the polymers of interest retain their integrity, shape, and biological function when studied by AFM approaches. This Chapter will provide an introduction to AFM operation under liquid and will elucidate the peculiarities of force microscopy operation in conjunction with a liquid cell. Finally, ex situ and in situ studies of biopolymeric specimens will be highlighted. 

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