X-ray microscopes

Fig. 11-2. The General Electric X-ray Microscope. The equipment uses x-ray shadow projection to magnify and reveal detailed internal structure of specimens opaque to electrons or light. (Courtesy of General Electric Company.)...

The fine-focus electron optical system of the General Electric X-ray Microscope has been used as the basis for an x-ray emission electron-microprobe.9 10... 

Flea, x-ray microscope picture, 296 Fluidization, study by x-ray absorptiometry, 84... 

X-ray intensity, see Intensity X-ray irradiance, definition, 6 X-ray methods of analysis, comparative, statistics, 254-256, 280 use of Coolidge tubes in, 6 X-ray Microscope, General Electric, 291-296... 

Other instruments which have been devised for microstructure examination include the X-ray microscope, with greater resolving power than the EM (Ref 41), and the electron microprobe, capable of indicating subtle changes in composition over small specimen areas (Refs 57 62)... 

X-rays are primarily used for diagnostic radiography in medicine, and in crystallography. Other notable uses are x-ray microscopic analysis, x-ray fluorescence as an analytical method, and industrial radiography for inspection of industrial parts, such as tires and welds. 

If X-rays could be focused easily, could one build an X-ray microscope that would permit the immediate viewing of molecular structures X-ray holograms at the molecular level have been obtained.387 388 However, currently the only practical X-ray microscope for protein structures involves the measurement of diffraction patterns created by the scattering of X-rays (or of neutrons) from the crystalline lattice. The details of this procedure can be found in other SOurces.372-375/378 389-390 It is sufficient to point out here that a pattern of many... 

In the fifth step of an X-ray structure determination the electron density map is calculated using the intensities and phase information. This map can be thought of as a true three-dimensional image of the molecule revealed by the X-ray microscope. It is usually displayed as a stereoscopic view on a computer graphics system (Fig. 3-22). It is also often prepared in the form of a series of transparencies mounted on plastic sheets. Each sheet represents a layer, perhaps 0.1 ran thick, with contour lines representing different levels of electron density. 

MICROSCOPY tChemical). Use of a microscope primarily for study of physical struclure and identification of materials. This is especially useful in forensic chemistry and police laboratories. Many types of microscopes are used in industry most important arc the optical, ultra-, polarizing, stereoscopic, electron, and X-ray microscopes, Organic- dyes of various types are used to stain samples for precise identification. 

Figure 17.4. Schematic of a scanning transmission X-ray microscope. This setup uses soft X rays (250-800 eV) from an undulator on beamline XIA of the National Synchrotron Light Source in Brookhaven National Laboratory, Upton, NY.

Feser, M., Carlucci-Dayton, M., Jacobsen, C., Kirz, J., Neuhausler, U., Smith, G., and Yu, B. (1998). Applications and instrumentation advances with the Stony Brook scanning transmission x-ray microscope. In X-Ray Microfocusing Applications and Techniques, McNulty, I., ed., Proceedings of Society of Photo-optical Instrumentation Engineers, San Diego, CA, Vol. 3449, pp. 19-29. 

Wiesemann, U., Thieme, J., Guttmann, P, Fruke, R., Rehbein, S., Niemann, B., Rudolph, D., and Schmahl, G. (2003). First results of the new scanning transmission X-ray microscope at BESSY-II. /. Phys. FV104, 95-98. 

Enhanced X-ray optical systems are needed to permit imaging at higher resolution. In particular, zone plate optics, which are currently the limiting factor for scanning transmission X-ray microscopes (STXM) and full-field X-ray microscopes (TXM), need to be improved. 

The preliminary results of the X-ray, microscopic, and microspectroscopic analyses are summarized in Tables II and III. 

The typical biological macromolecule of structural interest, be it protein, DNA or RNA, is on the order of 10 to 100 A in its dimensions. Despite these relatively large sizes, much of what makes these molecular structures biologically interesting is at the atomic scale 1 to 2A. To date, as there are no X-ray microscopes that function at this resolution, only 2 practical ways remain for obtaining 3-dimensional atomic models (or equivalently, electron density distributions) of biological macromolecules. 

Schmal G, Rudolph D, Guttsmann P, Schneider G, Thieme J, Niemann B. Phase-contrast studies of biological specimens with the x-ray microscope at BESSY. Rev Sci Instrum 1995 66 1282-1286. 

The performance of our PTFE lenses was checked with a beam of hard x-rays ( =10 keV, A / 2.4xl0-4) from Hyogo beam-line (BL24XU) at SPring-8 [86]. The beam size was varied with two slits in the vertical and with the other two in the horizontal. The focal spot was observed with an x-ray microscope (Hamamatsu-C5333, resolution of 0.5 fini). Two-dimensional intensity mapping is displayed in Fig. 45 for beams focused by the ID and... 

Fig. 44 SEM picture of one parabolic curvature of the 2D lens formed on PTFE by using SR etching. The insert shows an x-ray microscopic observation of the 10-keV beam focused by the 2D lens made of PTFE...

---