| 1. |
- Gelius, Ulrik, et al.
(author)
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ESCA studies of molecular core and valence levels in the gas phase
- 1972
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In: Faraday Discussions of the Chemical Society. - : Royal Society of Chemistry (RSC). - 0301-7249. ; 54, s. 257-268
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Journal article (peer-reviewed)abstract
- The study of molecules in the gas phase by ESCA offers several advantages. Particularly, the opportunity to make direct comparisons between theoretical and experimental results is of importance. From such comparisons a more complete understanding of several fundamental phenomena in ESCA has been gained. The present paper reviews some recent work in Uppsala along this line. The effect of electron reorganization on core binding energies in atoms and molecules is analyzed. Chemical shifts in ESCA and n.m.r. are discussed. The existence of a general relation involving these chemical shifts and nuclear spin-rotation constants is pointed out. A model for analyzing ESCA intensities of the valence electrons in molecules is presented. It is shown that the analysis may be useful in identifying the molecular orbitals.For most applications of ESCA it is highly desirable to improve the resolution and the intensity. An instrument, particularly designed to achieve this for gases, is discussed. It can also handle solid samples. It makes use of a high-emission, fine-focus electron gun, a rotating anode and a double focusing quartz crystal. The first electron spectrum recorded with this new instrument is presented.
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| 2. |
- Lundkvist, Peder, et al.
(author)
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Experimental Study of Oscillation Mark Depth in Continuous Casting of Steel
- 2014
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In: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 41:4, s. 304-309
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Journal article (peer-reviewed)abstract
- Mould oscillation is needed to reduce friction and thus prevent sticking and breakout of the liquid metal during casting. However, this oscillation is known to cause surface defects in the solidified steel slabs, so called oscillation marks. In this paper, the depth and the depth variation of these oscillation marks were studied using a two-level full factorial experiment (24) with four additional centre point runs. Four factors were studied: stroke length of the mould, oscillation frequency, motion pattern (strip factor) and casting speed. The stroke length affected the depth of the marks the most, where larger strokes created deeper marks. The interaction between the oscillation frequency and the strip factor of the mould also affected the oscillation mark depth. The oscillation mark depth variation was also increased by increased stroke lengths and at higher oscillation frequencies. The largest effect on the oscillation depth variation was found for the interaction between the stroke length and the oscillation frequency.
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| 3. |
- Triguero, Luciano, et al.
(author)
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Metal oxides : O2- chemistry and dynamical effects on oxide reactivity
- 1999
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In: FARADAY DISCUSS. - : Royal Society of Chemistry (RSC). - 0301-7249. ; 114, s. 351-362
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Journal article (peer-reviewed)abstract
- Doping of CeO2 with calcium introduces defects and oxygen vacancies and leads to a strong increase of the catalytic activity. Desulfurization of SO2 with CO involves oxygen abstraction from the lattice and charge-transfer (CT) excitation; this reaction runs at a 70 degrees C lower temperature on the doped substrate. The doping reduces the CT energy cost and the oxygen binding energy, but oxygen abstraction by CO is still not favorable for the lattice at 0 K. The charge state of the ion depends on the Madelung potential, which depends on the lattice structure. Introducing changes in temperature is found to generate vibrations of sufficiently large amplitudes that oxygen anions and cerium cations sometimes can be found at positions where they are sufficiently destabilized so as to be reactive. As the CT energies and oxygen binding energies depend on the instantaneous positions of the ions, active sites appear and disappear at the surface dynamically. The activity of the catalyst substrate is a dynamical quantity that depends on the amplitudes of thermal motion of the surface ions.
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