Ray optics

The introductory treatment of x-ray spectra, characteristic (1.8) and continuous (1.5), needs expansion to make it a more useful basis for discussing x-ray optics. This expansion brings with it other benefits such as the deeper insight into the excitation of x-rays by electrons (1.4) that results from a better understanding of the intensity-wavelength relationship in the continuous spectrum. 

The basis of Method II may be deduced from Figure 6-3. To do this, let us consider the ideal case, in which the x-rays involved are monochromatic, all influences of composition are absent, the simplest x-ray optics obtain, and excitation of a characteristic line in the film by a characteristic line of the substrate does not occur. Suppose now that a beam of intensity Iq falls upon a metal film d cm thick to excite a characteristic line of intensity Id- The contribution to Id of a volume element of constant area and of thickness dx, located at depth x, is... 

Fig. 8-10. Contour maps showing spectrograph sensitivities for the iron Ka line for various positions of the sample, (a) At surface of sample holder, (b) 0.16 inch below surface of sample holder, (c) 0.32 inch below surface of sample holder. The sensitivity changes with the x-ray optical system, with the goniometer setting, and with the distance of the sample below the surface of the sample holder. The contour interval is 20 counts per second. (Authors unpublished results.)...

Angstrom unit (A), definition, 307 Antimony, determination by x-ray emission spectrography, 328 in silicate, determination by absorption-edge method, 140 in solution, determination by absorption-edge method, 140 Aperture, relative, of x-ray optical system, 113... 

Transmission, by collimator in x-ray optical system, 113 of x-rays by windows, 45 Transmittance of x-rays, as function of absorber thickness, 11 Transmitted beam, components, 18 Tubes, x-ray, see X-ray tubes Tungstate solutions, absorption effects in, 168-170... 

The diffractometer has gradually evolved in terms of maximum power of sealed X-ray tubes, rotating anodes, new X-ray optics, better detector efficiency, position-sensitive detection and, lately, real-time multiple-strip (RTMS) fast X-ray detection, which replaces a single detector by an integrated array of parallel detectors to provide an up to 100-fold increase in efficiency compared with traditional detectors without compromise on resolution. Time-resolved powder diffraction is... 

When one has a planar surface, one can take advantage of X-ray optics to enhance surface sensitivity.61,62 The most important is specular or mirror reflection, and this is due to the fact that at X-ray energies the index of refraction of matter is slightly less than one and is given by ... 

The unique field penetration into the liquid of a nonevanescent resonant mode like Tlij(7)0 is very promising for the sensing applications. To understand the origin of this behavior and further optimize the devices, a ray optical picture71 is presented. This type of resonant modes exist as if rays are bounced at the liquid/silica interface and confined in the liquid region as plotted in Fig. 8.32. From the viewpoint of ray optics, light is partially reflected (termed ray 1) and partially transmitted when it is... 

Mark s contributions while at the I. G. were not limited to the emerging field of polymer science. In those five years, he also took part in studies of X-ray optics and continued his study of the X-ray structure of metals and metal salts. Other seemingly unrelated paper were published on the width of X-ray emission lines (12), Schlenk isomerism (13), the structure of aromatic compounds (14), and a special "hobby" the optical Stark Effect (15, 16). Regarding this latter work, Mark relates that his supervisors tolerated the research commenting that "as long as they are doing something decent and important" it was okay "as sport doesn t cost much money". 

Certainly biomolecular NMR is not the single method which is important for hit identification in pharmaceutical research. It is always a combination of techniques and a team effort that leads to a successful drug. This can involve biologists (basic understanding, assay development, bio-informatics), chemists (both bench chemists and modelers), screening specialists (HTS/natural products) and spectroscopists (X-ray, optical methods, surface plasmon resonance, NMR). 

Ashkin, A., Forces of a single-beam gradient laser trap on a dielectric sphere in the ray optics regime, Biophys.., 61, 1992, 569-582. 

Fong, C.Y. and Poon, A.W., 2004, Planar comer-cut square microcavities ray optics and FDTD analysis. Opt Express 12(20) 4864-4874. 

Figure 1. Ray optical description of lens aberrations, (a) Perfect lens imaging a point P in the object plane onto a sharp point in the image plane, (b) Lens affected by spherical aberration, (c) Lens underfocused by a distance Z. (d) Lens overfocused by a distance Z. Spherical aberration and defocusing cause a blurring of the point P in the image plane.

We first define the geometry and instrumental parameters common to high resolntion diffractometry. As a reference, we then develop the dnMond diagram for visualisation of X-ray optics and use it to discuss practical beam conditioners. Next we treat the principal aberrations of high resolution diffractometry tilt, curvature and dispersion. We discuss the requirements on X-ray detectors, and finally show how to set up a high resolution measurement in practice. 

It is qualitatively very helpful if instead of having to solve the equations or simulate the solutions every time, we can get some physical understanding which reduces the task. Ray optics is one such method we look at the geometrical optics before the physical optics. Rays are reasonable concepts if diffraction broadening is not too great, that is, for a ray path, where A is the width of... 

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