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Biomedical subjects

M S Altman

Publications and source records attributed to M S Altman.

8 recordsLinked to original sources
PubMed2005

Ultrathin chromium oxide films on the W(100) surface.

Ultrathin chromium oxide films were prepared on a W(100) surface under ultrahigh-vacuum conditions and investigated in situ by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. The results show that, at Cr coverage of less than 1 monolayer, CrO2 is formed by oxidizing pre-deposited Cr at 300-320 K in approximately 10(-7) mbar oxygen. However, an increase of temperature causes formation of Cr2O3. At Cr coverage above 1 monolayer, only Cr2O3 is detected.

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PubMed2005

Spin-dependent Fabry-Pérot interference from a Cu thin film grown on fcc Co(001).

Spin-dependent electron reflection from a Cu thin film grown on Co/Cu(001) was investigated using spin-polarized low-energy electron microscopy (SPLEEM). Fabry-Pe rot type interference was observed and is explained using the phase accumulation model. SPLEEM images of the Cu overlayer reveal magnetic domains in the Co underlayer, with the domain contrast oscillating with electron energy and Cu film thickness. This behavior is attributed to the spin-dependent electron reflectivity at the Cu/Co interface which leads to spin-dependent Fabry-Pe rot electron interference in the Cu film.

Journal Article↗
PubMed2004

Kinetic limitations in electronic growth of Ag films on Fe(100).

Quantum well (QW) resonances are identified in Ag films on an Fe(100) surface and are used in low energy electron microscopy to monitor film morphology during annealing and growth. We find that Ag films thermally decompose to thicknesses that are stabilized by QW states at the Gamma point. Novel growth morphologies are also observed that highlight the competition between kinetic limitations and the QW state energetics that promote electronic growth. These combined observations help to explain the unusual bifurcation mode of thermal decomposition that was reported previously for this system.

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PubMed2003

Layer spacings in coherently strained epitaxial metal films.

Laterally resolved measurements of the quantum size effect (QSE) in electron reflectivity are made with low energy electron microscopy on coherently strained Ag films on a W(110) surface. The evolution of the total film thickness with increasing number of atomic layers is determined accurately by dynamical theory analysis of the QSE features. Combined with a model of layer spacings obtained from first-principles calculations, this provides for a novel approach to determine the buried interface layer spacing, which is inaccessible to other methods.

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PubMed2002

Surface diffusion anomaly near a substrate phase transition: H on W(100).

Using a linear optical diffraction method, we have experimentally studied the long predicted diffusion anomalous behavior for H/W(100) near the reconstructive phase transition of the W(100) substrate. This anomaly manifests itself in the form of a strong dip in the diffusion coefficient D at the transition temperature T(C). We interpret the strong reduction of D as a result of the diverging friction damping near the transition. The finite dip in D instead of a vanishing D at T(C) also demonstrates the importance of the non-Markovian (memory) deviation from the simple instantaneous damping picture.

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