Electrons are scattered or up-sucked easily by air molecules, therefore copies must be respected in a vacuum. This requires removing or repairing each possible water in a sample, since the water in the vacuum can evaporate. This is fine for inorganic samples, but biological copies generally contain water and are not conductive. These requirements for the example preparation means the SEM actual therefore accordingly for the analysis of not best biological rehearsing in their native condition. Even despite that relatively new developments, to such expenditures, including the development of the coolingproducing electron microscopy (CryoEM) or the climatic scanning electron microscopy (ESEM), these to overcome restrictions finally resulted in the necessity at an alternative method of the example analysis. To a category of instruments, those belongs to 3.2 the scanning test prod microscope revolution the nuclear power microscope (flight manual) is scanning test prod microscopes (SPM) to be familiar, that catches up information using a sharp test prod or tilts directly to `feel the surface of a given sample. Although the eighties-years take the credit note for developing the highly soluble scanning test prod microscopes, which we see today, basic rules behind their development go to that extent the twenties-years and in particular regarding the recording head interpretative program back (develops 1929 from Schmalz). 3.2.1
the recording head interpretative program this instrument used an optical lever arm, which was attached at the end of a Kragbalkens, in order to supervise the movement of a sharp test prod over the surface of the sample. By noting the movement of the recording head, it was possible to produce pictures with to 1000mal linear rendition. The main impairment of this method was possible bending of examines you, when it found large surface properties. 1971 showed Russell boy a form of the non-contact recording head forming, by using the fact, which is the electron Feldemissionstrom between a sharp metal test prod and electrically leading sample dependent on the distance, which separates them. For its interpretative program which it called more topographiner, became the test prod directly at a piezoelectric ceramic raster Scan the surface used in the XY surface attached. In order to overcome the obstacle of the surface properties to adjust an electronic feedback loop assigned around the vertical position of the test prod. By the monitoring of the test prod in the Zrichtung, while, scannend over the surface in the XY surface, a detailed three-dimensional picture could be designed. 3.2.2 the scanning tunnel construction microscope 1981 would use Binnig and Rohrer the basic rules, which were used in more topographiner, in order the first SPM, the scanning tunnel construction microscope (STM) to develop. By the monitoring of the quantum tunnel construction of the electrons from the example surface to the test prod, in detail information about the sample could be seized in a similar way too more topographiner. However actual the quantum tunnel construction far more sensitively than electron.
|
