11 research outputs found
Recent studies of cements and concretes by synchrotron radiation crystallographic and cognate methods
The portfolio of available synchrotron radiation techniques is increasing notably for cements
and pastes. Furthermore, sometimes the terminology is confusing and an overall picture highlighting
similarities and differences of related techniques was lacking. Therefore, the main
objective of this work is to review recent advances in synchrotron techniques providing a
comprehensive overview. This work is not intended to gather all publications in cement chemistry
but to give a unified picture through selected examples. Crystallographic techniques are
used for structure determination, quantitative phase analyses and microstructure characterization.
These studies are not only carried out in standard conditions but synchrotron techniques
are especially suited to non-ambient conditions: high temperatures and pressures, hydration,
etc., and combinations. Related crystallographic techniques, like Pair Distribution Function,
are being used for the analysis of ill-crystalline phase(s). Furthermore, crystallographic tools
are also employed in imaging techniques including scanning diffraction microscopy and
tomography and coherent diffraction imaging. Other synchrotron techniques are also reviewed
including X-rays absorption spectroscopy for local structure and speciation characterizations;
small angle X-ray scattering for microstructure analysis and several imaging techniques for
microstructure quantification: full-field soft and hard X-ray nano-tomographies; scanning
infrared spectro-microscopy; scanning transmission and fluorescence X-ray tomographies.
Finally, a personal outlook is provided.I am grateful to all my coauthors, collaborators, colleagues and PhD students, for all our work together
during more than two decades. I thank the University of Malaga and ALBA Synchrotron Light Source
for the support and the stirring environments. I acknowledge the Spanish science funding agencies (they
change the name quite often) for funding my studentship, to do the PhD and the three summer research
stays at Oxford University, to the last ongoing research project. To all synchrotrons I have been allowed to
enjoy carrying out experiments: SRS, ESRF, Max-Lab, DLS, APS, SLS and ALBA. Finally, this work has
been supported by the Spanish MINECO through the BIA2014-57658-C2-1-R research grant
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Cross sections for photoionization of fullerene molecular ions Cn+ with n = 40, 50, 70, 76, 78, and 84
© 2017 American Physical Society. Absolute cross-section measurements are reported for single photoionization of Cn+ fullerene molecular ions (n=40, 50, 70, 76, 78, and 84) in the photon-energy range 18-70 eV. The experiments were performed by merging a mass and charge selected beam of Cn+ molecular ions with a beam of monochromatized synchrotron radiation and measuring the yield of Cn2+ product ions as a function of the photon energy. Oscillator strengths determined by integrating the measured cross sections over this energy range exhibit a linear dependence on n. The cross sections are parametrized by fits to three Lorentzian functions to represent plasmon excitations and a linear function for direct ionization. The highest-energy resonance in the data near 46 eV is similar to that previously observed in single photoionization of C60 and may be attributable to a harmonic of the dominant surface-plasmon resonance near 23 eV
Recommended from our members
Cross sections for photoionization of fullerene molecular ions Cn+ with n = 40, 50, 70, 76, 78, and 84
© 2017 American Physical Society. Absolute cross-section measurements are reported for single photoionization of Cn+ fullerene molecular ions (n=40, 50, 70, 76, 78, and 84) in the photon-energy range 18-70 eV. The experiments were performed by merging a mass and charge selected beam of Cn+ molecular ions with a beam of monochromatized synchrotron radiation and measuring the yield of Cn2+ product ions as a function of the photon energy. Oscillator strengths determined by integrating the measured cross sections over this energy range exhibit a linear dependence on n. The cross sections are parametrized by fits to three Lorentzian functions to represent plasmon excitations and a linear function for direct ionization. The highest-energy resonance in the data near 46 eV is similar to that previously observed in single photoionization of C60 and may be attributable to a harmonic of the dominant surface-plasmon resonance near 23 eV