PubMed Health⌕ Search

Biomedical subjects

V Formoso

Publications and source records attributed to V Formoso.

5 recordsLinked to original sources

Multiple scattering approach to DAFS.

In this article we outline a general approach to the anomalous correction to the atomic scattering factor "ab-initio" calculation based on the multiple scattering theory. This approach can be used for structural determination in any system and in particular in the surfaces where symmetry conditions make usual analysis impossible. We show as an application of the formalism calculations related to experimental data of bulk Ge.

Journal Article↗

Following local adsorption sites through a surface chemical reaction: CH3SH on Cu(111)

Studying the interaction of CH3SH, methanethiol, with Cu(111) as a model system, we demonstrate the ability of chemical-shift normal incidence x-ray standing wave field measurements to identify the local adsorption geometries of coadsorbed reaction products at different temperatures, a technical problem of broad chemical significance. In the present case the local geometries of four distinct S-containing adsorbate species (intact CH3SH, two thiolate (CH3S-) reaction intermediates and atomic S) are determined.

Journal Article↗

Trace element analysis on Si wafer surfaces by TXRF at the ID32 ESRF undulator beamline.

Synchrotron radiation total-reflection X-ray fluorescence (SR-TXRF) has been applied to the impurity analysis of Si wafers using a third-generation synchrotron radiation undulator source. A lower limit of detectability (LLD) for Ni atoms of 17 fg (1.7 x 10(8) atoms cm(-2)) has been achieved with an optical set-up based on an Si(111) double-crystal monochromator and a horizontal sample geometry. These first results are very promising for synchrotron radiation trace element analysis since we estimate that it is possible to lower the LLD by a factor of about 25 by employing appropriate optics and detectors. The use of a crystal monochromator opens new possibilities to perform absorption and scattering experiments (NEXAFS and X-ray standing-wave methods) for chemical and structural analysis of ultratrace elements.

Journal Article↗