Zone plates

The development of mote intense sources (eg, plasma sources, soft x-ray lasers, and synchrotron sources) has made possible highly effective instmments both for x-ray microscopy and x-ray diffraction on a few cubic nanometer sample. The optical problem of focusing x-rays is accompHshed by the use of zone plates or by improved grazing incidence or multilayer reflectors. 

Soft x-rays with wavelengths of 1—10 nm ate used for scanning x-ray microscopy. A zone plate is used to focus the x-ray beam to a diameter of a few tens of nanometers. This parameter fixes and limits the resolution. Holographic x-ray microscopy also utilizes soft x-rays with photoresist as detector. With a strong source of x-rays, eg, synchrotron, resolution is in the 5—20-nm range. Shadow projection x-ray microscopy is a commercially estabflshed method. The sample, a thin film or thin section, is placed very close to a point source of x-rays. The "shadow" is projected onto a detector, usually photographic film. The spot size is usually about 1 ]lni in diameter, hence the resolution cannot be better than that. 

Fresnel zone plate producing a virtual image (any cross section of the hyperboloids) [29]... 

The most advanced STXMs presently use laser interferometers to reduce the effect of imperfections in sample positioning during NEXAFS scans (Kilcoyne et al., 2003). High-precision mirrors attached to the sample and the zone plate... 

There are many ways of achieving monochromatization (reflection and transmission gratings, Bragg reflection on crystals or multilayers, zone plates), and many different designs have been worked out (see references in [Sch92a]). 

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. 

Settling zone plates (or tubes) on which the solids settle,... 

Neither Mars nor Venus has well-defined smoothly moving plates, thousands of kilometres long from ridge to subduction zone. Plate tectonics needs water to help cool the new plate. 

Kemner KM, Yun W, Cai Z, Lai B, Lee H-R, Maser J, Legnini DG, Rodriques W, Jastrow JD, Miller RM, Pratt ST, Schneegurt MA, Kulpa CF Jr (1999) Using zone plates for X-ray microimaging and microspectroscopy in environmental samples. J Synchrotron Rad 6 639-641 Kendelewicz T, Doyle CS, Carrier X, Brown GE Jr (1999) Reaction of water with clean surfaces of MnO(lOO). Surf Rev Lett 6 1255-1263... 

To produce micrometer sized focused beams, one employs highly demagnifying optics to image the source onto the sample. Such optics can include Kirkpatrick-Baez mirrors, Fresnel zone plates, tapered capillaries, and compound refractive lenses, all of which have been used to produce submicron focal spots at third generation storage rings. 

APS 2-ID Argonne National Laboratory High resolution imaging Undulator (7 GeV) Zone plate 0.1 1 108... 

These instruments are complementary in terms of spatial resolution, sensitivity, flexibility and availability. The APS undulator source, in combination with KB mirrors, is an excellent X-ray microprobe source, delivering 1 pm X-ray beams with fluxes that are factors of 103 greater than those on other sources. The APS zone plate microprobe achieves smaller spot sizes at the expense of sensitivity and chromaticity. The choice of the optimum instrument for a particular experiment depends on the specific requirements. On the other hand, because of the unique characteristics of the APS insertion device, the APS microprobes must share time with other techniques, the resource is limited and only those experiments that require the undulator typically receive beam time. In addition, these microprobes are historically oversubscribed. The NSLS and ALS microprobes have the advantage of residing on dedicated beam lines so that more beam time is typically available for particular experiments. These microprobes have poorer sensitivity and spatial resolution than the APS instruments but are very well suited for many experiments. 

Diffraction-based focusing devices include Fresnel zone plate (FZP) multilayer structures. Zone plates operating in the hard X-ray regime have achieved sub-micrometer beams (Yun et al. 1999 Kagoshima et al. 2001 Suzuki et al. 2001) at the expense of... 

Jenkins R (1999) X-ray Fluorescence Spectrometry, Second Edition. John Wiley and Sons, New York, NY Jones KW, Berry WJ, Borsay DJ, Cline HT, Conner WC, Fullmer CS (1997) Applications of synchrotron radiation-induced X-ray emission (SRIXE). X-ray Spectrometry 26 (6) 350-358 Kagoshima Y, Takai K, Ibuki T, Yokoyama Y, Hashida T, Yokoyama K, Takeda S, Urakawa M, Miyamoto N, Tsusake Y, Matsui J, Aino M (2001) Scanning hard X-ray microscope with tantalum phase zone plate at the Hyogo-Bl (BL24XU) of SPring-8. Nucl Instrum Methods Phys Res A 467-468 872-876... 

Sutton SR, Rivers ML (1999) Hard X-ray synchrotron microprobe techniques and applications. In Synchrotron Methods in Clay Science. CMS Workshop Lectures Vol. 9. Schulze DG, Stucki JW, Bertsch PM. (eds). The Clay Mineral Society, Boulder CO, p 146-163 Sutton SR, Flynn G, Rivers M, Newville M, Eng P (2000) X-ray fluorescence microtomography of individual interplanetary dust particles. Lunar Planet Sci XXXI 1857 Sutton SR, Rivers ML, Bajt S, Jones KW, Smith JV (1994) Synchrotron X-ray-fluorescence microprobe-a microanalytical instrument for trace element studies in geochemistry, cosmochemistry, and the soil and environmental sciences. Nucl Instrum Methods Phys Res A 347 412-416 Suzuki Y, Awaji M, Kohmura Y, Takeuchi A, Takano H, Kamijo N, Tamura S, Yasumoto M, Handa (2001) X-ray microbeam with sputtered-shced Fresnel zone plate at SPring-8 undulator beamline. Nucl Instrum Methods Phys Res A 467-468 951-953... 

Yun W, Lai B, Cai Z, Maser J, Legnini D, Gluskin E, Chen Z, Krasnoperova AA, Vladimirsky Y, Cerrina F, Di Fabrizio E, Gentili M (1999) Nanometer focusing of hard x rays by phase zone plates. Rev Sci Instrum 70 2238-2241... 

For imaging with X-rays, the X-ray beam can be focused on a small spot using zone plates, Kirkpatrick-Baez mirrors, or tapered capillaries (Attwood 2000 Bertsch and Hunter... 

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