X-ray monochromators

Laue Method for Macromolecule X-Ray Diffraction. As indicated above it is possible to determine the stmctures of macromolecules from x-ray diffraction however, it normally takes a relatively long period of data collection time (even at synchrotrons) to collect all of the data. A new technique, the Laue method, can be used to collect all of the data in a fraction of a second. Instead of using monochromated x-rays, a wide spectmm of incident x-rays is used. In this case, all of the reflections that ate diffracted on to an area detector are recorded at just one setting of the detector and the crystal. By collecting many complete data sets over a short period of time, the Laue method can be used to foUow the reaction of an enzyme with its substrate. This technique caimot be used with conventional x-ray sources. 

The interaction of adsorbed thiol molecules with gold nanoparticles as a function of the mean particle size has also been studied [180]. Monochromated X-ray Photoelectron Spectroscopy (MXPS) measurements showed the attachment of the thiol sulfur headgroup onto the cluster surface leading to a positive BE shift in the Au 4f corelevel. No line width broadening could be observed indicating that the thiol-gold interaction affects the whole... 

The application of X-ray photoelectron spectroscopy (XPS) [1, 20-22], has considerably extended the possibilities. The main advantage of XPS is that, in contrast to the spectroscopic techniques mentioned above, it can in principle provide information on all valence levels. A drawback is that the energy resolution of spectra of solid samples is low, especially when a non-monochromated X-ray source (A1 Ka radiation with a natural width of 1 eV) is used. 

Birknes, B., and Hansen, L. K. A method for collection of step-scan data on a CAD 4 diffractometer homogeneity of the monochromated X-ray beam. J. Appl. Cryst. 16, 11-13 (1983). 

Powder X-ray dififiaction patterns were recorded using Cu Ka (1.5418 A) radiation on a Philips 1050/81 vertical goniometer, fitted with a diffracted beam graphite monochromator. X-ray photoelectron experiments were carried out in a Escalab 200R (Fisons Instrumrats) using monochromatic A1 Ka radiation and operating at 10" Torr base pressure. Transmission electron microscopy analysis was performed in a JEOL lOOCX either by direct observation or after extractive replication of samples (support dissolution). 

Sensitive materials, such as metal salts or organometallic compounds, may decompose during XPS analysis, particularly when a standard x-ray source is used. Apart from the x-rays themselves, heat and electrons from the source may cause damage to the samples. In such cases, a monochromated x-ray source can offer a... 

A more complete approach to reducing the analysis spot size is to use the above transfer demagnification lens along with a focused x-ray soiu ce (13). Figure 5 shows this method schematically. By using a standard bent quartz crystal aluminum K-o monochromator, x-rays produc-... 

Ammonium molybdate (VI) monochromator, x-ray diffraction analysis Graphite... 

As discussed in Section in.B, AEx is at best 0.3 eV in XPS, when using a monochromated X-ray source, and 10 meV in UPS. To minimize the influence of the analyzer, AEa should by no means exceed these values. In both cases, this corresponds to a relative resolution of at least 1 1000. 

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