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Laser–solid interactions are highly suited as a potential source of high energy X-rays for nondestructive imaging. A bright, energetic X-ray pulse can be driven from a small source, making it ideal for high resolution X-ray radiography. By limiting the lateral dimensions of the target we are able to confine the region over which X-rays are produced, enabling imaging with enhanced resolution and contrast. Using constrained targets we demonstrate experimentally a $(20\pm 3)~\unicode[STIX]{x03BC}\text{m}$ X-ray source, improving the image quality compared to unconstrained foil targets. Modelling demonstrates that a larger sheath field envelope around the perimeter of the constrained targets increases the proportion of electron current that recirculates through the target, driving a brighter source of X-rays.

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SYNOPSISRaman spectroscopy and atomic force microscopy have been used to investigate the composition and surface structure of polyacrylic acid modified zinc phosphate crystal conversion coatings on steel. Zinc phosphate coatings are used extensively to provide corrosion protection and to improve adherence of topcoatings to steel. Within the last few years it has been demonstrated that addition of high molecular weight polyacrylic acid (PAA) to the phosphating bath can significantly improve both resistance to corrosion and topcoat adherence. It has been reported that the addition of PAA reduces the size of crystallites, which leads to greater film ductility, and therefore to fewer sites for corrosive attack, and that organic molecular segments from the PAA are incorporated into the surface structure and provide additional adhesive bonding with polymeric topcoats. In this work Raman spectra show the compositions of both unmodified and PAA modified films to be zinc phosphate dihydrate, Zn3 ( PO,), -2H20. Atomic force microscopy ( AFM ) was used to measure the morphologies of single crystallite surfaces. Morphologies of the unmodified and modified films obtained by AFM are in general quite similar, but subtle differences are apparent.

Tunable diode laser spectroscopy offers unique advantages for high resolution infrared reflection absorption spectroscopy (IRRAS) studies of monolayers on single crystal surfes. Its greatest potentials lie in anal'ses of lineshapes less than 1 cm (FWHM), for resolving narrow features on absorption peaks, and for in situ solid-liquid interfacial studies, where high intensity is often required. Other IRRAS techniques introduce instrumental broadening sufficient to create considerable uncertainty in the intrinsic linewidth of very narrow peaks, and can mask sharp features. Using isolated or 0-81 94-0782-8192/$4.0O

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