""Spectra of secondary electrons (SE) emitted from a polycrystalline Al surface have been measured in coincidence with 500 eV-electrons for energy losses between 10 and 155 eV. The spectra for a given energy loss are qualitatively similar, consisting of surface and volume plasmon decay and a contribution attributable to direct electron-electron scattering. The similarity of the contribution of surface and volume plasmon decay in the SE spectra proves directly that electron multiple scattering is governed by a Markov-type process. The average value of the surface plasmon decay contribution to the SE spectrum amounts to similar to 25%. (C) 2011 American Institute of Physics. [doi:10.1063\\\/1.3658455]"

The double-differential spectrum of coincidences between backscattered electrons and secondary electrons (SEs) emitted from a polycrystalline Al surface bombarded with 100-eV electrons was measured. For energy losses of the scattered electron in between the work function of Al and the bulk plasmon energy, a sharp peak is observed in the SE spectra, corresponding to ejection of a single electron near the Fermi edge receiving the full energy loss and momentum of the primary electron. This process predominantly takes place when the primary electron suffers a surface energy loss in vacuum, and leads to SE ejection from the very surface. At energy losses just above the bulk plasmon energy, a sharp transition is observed, corresponding to a sudden increase in the depth of ejection. The latter is a direct consequence of the complementarity of surface and bulk plasmons, the so-called Begrenzungs effect.When an energetic electron strikes a solid surface it may transfer part of its energy to the solid-state electrons. If the energy transfer exceeds the work function of the solid, an electron near the Fermi edge may escape over the surface barrier as a secondary electron (SE) or may in turn suffer energy losses, giving rise to the formation of a cascade of slow electrons. 1-4 The above phenomenon of electroninduced SE emission is highly relevant in a broad variety of applications but, due to a lack of spectral features in the cascade, SE emission is still far from being quantitatively understood. 5 While the different excitation channels can be easily discriminated with electron-energy-loss spectroscopy, the mechanism by which the deposited energy is dissipated away over the degrees of freedom of the solid is not easily resolvable by experiment. It is obvious that this requires the detection of correlated electron pairs, where one electron carries the signature of the involved excitation, while the other provides information on its decay. [6][7][8][9][10][11][12][13][14] This Rapid Communication presents the double-differential secondary-electron electron-energy-loss coincidence spectrum (SE2ELCS) of Al bombarded with 100-eV primary electrons. In the coincidence data, events can be distinguished in which the primary electron experiences a surface energy loss in vacuum, leading to ejection of a solid-state electron from the very surface (less than half an angstrom below the surface) that reaches the detector without traversing the solid at all. The choice of Al as the material for these investigations is motivated by the fact that the electron-solid interaction is Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.characterized by a sharp surface and bulk plasmon, making it possible to distinguish the single-and multiple-scattering regime in experimental data with the bare eye, considerably simplifying the identification of relevant ...

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AIM Neurodevelopment is a key outcome for many childhood trials and observational studies. Clinically important decisions may rest on finding relatively small differences in neurodevelopment between groups receiving complex and costly interventions. Our purpose was to determine whether studies which measure neurodevelopment report the numbers, training, and auditing of assessors and, for multiple assessor studies, whether the results were adjusted and if so by which method?METHOD Electronic searches were conducted using Medline, Embase, Cinahl, PsycINFO, and the Cochrane Library. A study was eligible if it reported neurodevelopmental outcome in children resident in the UK, less than or equal to 18 years and was published between 2000 and 2015. Trials and observational studies were included.RESULTS Three hundred and seven full papers were reviewed: 52% of papers did not report the number of assessors used; 21% used a single assessor; and 27% used multiple assessors. Thirty-five per cent mentioned that assessors were trained in the use of the neurodevelopmental tool; 13% of assessors were audited; and only 1% of studies adjusted statistically for the number of assessors.

Results are presented that have been obtained while operating the graphite hollow cathode duoplasmatron ion source in dual mode under constant discharge current. This dual mode operation enabled us to obtain the mass and emission spectra simultaneously. In mass spectra C3 is the main feature but C4 and C5 are also prominent, whereas in emission spectra C2 is also there and its presence shows that it is in an excited state rather than in an ionic state. These facts provide evidence that C3 is produced due to the regeneration of a soot forming sequence and leave it in ionic state. C3 is a stable molecule and the only dominant species among the carbon clusters that survives in a regenerative sooting environment at high-pressure discharges.