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P Pianetta

Publications and source records attributed to P Pianetta.

At least 19 recordsLinked to original sources
PubMed2000

Direct measurement of valence-charge asymmetry by x-ray standing waves.

By monitoring valence-photoelectron emission under condition of strong x-ray Bragg reflection, we have determined that a majority of GaAs valence charge resides on the anion sites of this heteropolar crystal, in quantitative agreement with the GaAs bond polarity as calculated from the Hartree-Fock term values. In contrast, the valence-charge distribution in Ge is found to be symmetric. In both cases, the valence emission is found to be closely coupled to the atomic cores.

Journal Article↗
PubMed1997

Early work with synchrotron radiation at stanford.

The use of synchrotron radiation in the soft and hard X-ray spectral region received major impetus with the start of parasitic operation of the Stanford Synchrotron Radiation Project (SSRP) in 1974. This was the first time that synchrotron radiation from a multi-GeV electron storage ring was made available in a user facility for studying the structure of matter. Here we review the early work at SSRP as well as the activities that preceded it, highlighting the scientific accomplishments (soft X-ray photoemission, EXAFS, protein crystallography), beamline instrumentation developments and source improvements. The early work using bending-magnet radiation led to the funding of several dedicated facilities in the US and elsewhere in the world - the so-called second-generation light sources. Early work with wiggler and undulator insertion devices led to funding of third-generation sources better optimized for insertion device sources, particularly undulators.

Journal Article↗
PubMed1996

Evidence for

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