PubMed · 4599319
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A V Crewe. 1974. Scanning transmission electron microscopy.. https://doi.org/10.1111/j.1365-2818.1974.tb03937.x
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The realization of spin-based devices requires high density, ordered arrays of magnetic materials with a high degree of spin polarization at surfaces. We have synthesized, for the first time, highly spin polarized complex magnetic oxide nanostructures embedded in a paramagnetic matrix by electron beam lithography and ion implantation. Imaging the magnetic domains with X-ray photoemission electron microscopy and magnetic force microscopy reveals a delicate balance between magnetocrystalline, magnetoelastic, and magnetostatic energies that can be tuned by the choice of SrTiO3 substrate orientation, film thickness, island size, and island shape.
Simple methods for determining the enantiomeric purity of mevalonolactone and linalool by NMR using the chiral shift reagent Eu(hfc)3 are reported. These methods are more reliable than polarimetry and require only a few milligrams of sample to detect as little as 2% of the minor enantiomer. The accuracy of these methods is limited primarily by spectral resolution for samples of high enantiomeric excess and by errors inherent in measuring peak intensities for samples of low enantiomeric excess. The Cornforth synthesis (Cornforth, R. M., J. W. Cornforth, and G. Popják. 1962. Tetrahedron. 18: 1351-1354) of (S)-mevalonolactone from (R)-linalool has been improved and shown to proceed with negligible racemization.
From measurements of screen-film sensitometry, Wiener spectra, and x-ray spectra, the speed, mottle, and quantum efficiency of several rare earth screen-film systems have been characterized. These systems offer exposure reductions of from two- to tenfold over conventional calcium tungstate systems. At the slower end, the noise (mottle) and resolution are comparable to what is available with conventional systems. Moreover, films designed to be used in such systems can be made with significantly lower silver content. As the speed advantage is increased from two- to genfold, however, the mottle also increases.