81 research outputs found
Moroccorp: tien miljoen woorden uit twee Marokkaans- Nederlandse chatkanalen
In dit artikel stellen we een nieuw corpus voor van computer-gemedieerde communicatie in het Nederlands door Marokkaans-Nederlandse taalgebruikers, dat bestaat uit tien miljoen woorden chat-materiaal. We behandelen de achtergrond, de compilatiemethode en de interne structuur van het corpus, en we leggen het verband tussen ons eigen werk en eerdere pogingen om een corpus van Nederlandse chattaal te bouwen. We hebben ook een Stable Lexical Marker analyse uitgevoerd en een gevalstudie over een welbekende morfosyntactische eigenschap van het Marokkaans Nederlands om op die manier de representativiteit van het corpus te beoordelen.Trefwoorden: Nederlands, marokkaans nederlands, corpus, chat, stable lexical marker analysis, etnisch nederlands, representativitei
Evidence for two-electron processes in the mutual neutralization of O- with O+ and N+ at Subthermal Collision Energies
We have measured total absolute cross sections for the Mutual Neutralization
(MN) of O- with O+/N+. A fine resolution (of about 50 meV) in the kinetic
energy spectra of the product neutral atoms allows unique identification of the
atomic states participating in the mutual neutralization process. Cross
sections and branching ratios have also been calculated down to 1 meV
center-of-mass collision energy for these two systems with a multi-channel
Landau-Zener model and an asymptotic method for the ionic-covalent coupling
matrix elements. The importance of two-electron processes in one-electron
transfer is demonstrated by the dominant contribution of a core-excited
configuration of the nitrogen atom in N+ + O- collisions. This effect is
partially accounted for by introducing configuration mixing in the evaluation
of coupling matrix elements.Comment: 5 pages, 4 figure
Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks
We demonstrate the use of high power diode laser stacks to photodetach fast
hydrogen and carbon anions and produce ground term neutral atomic beams. We
achieve photodetachment efficiencies of 7.4\% for H at a beam energy
of 10\,keV and 3.7\% for C at 28\,keV. The diode laser systems used
here operate at 975\,nm and 808\,nm, respectively, and provide high continuous
power levels of up to 2\,kW, without the need of additional enhancements like
optical cavities. The alignment of the beams is straightforward and operation
at constant power levels is very stable, while maintenance is minimal. We
present a dedicated photodetachment setup that is suitable to efficiently
neutralize the majority of stable negative ions in the periodic table
Failure of hydrogenation in protecting polycyclic aromatic hydrocarbons from fragmentation
A recent study of soft X-ray absorption in native and hydrogenated coronene
cations, CH , led to the conclusion that additional
hydrogen atoms protect (interstellar) Polycyclic Aromatic Hydrocarbon (PAH)
molecules from fragmentation [Reitsma et al., Phys. Rev. Lett. 113, 053002
(2014)]. The present experiment with collisions between fast (30-200 eV) He
atoms and pyrene (CH, , 6, and 16) and simulations
without reference to the excitation method suggests the opposite. We find that
the absolute carbon-backbone fragmentation cross section does not decrease but
increases with the degree of hydrogenation for pyrene molecules.Comment: 10 pages, 5 figure
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