The formation of carbonaceous compounds (“coke”) from propene and isobutene on a 5A zeolite and their effects on the capacity for nitrogen adsorption were investigated in a microbalance system. The ...operating conditions of coking were as follows: 100−420 °C, pressure of alkene of 0.97 bar, 0.085 g of the 5A zeolite, and operating time from 5 min to 100 h. At low temperatures (100−150 °C), coke constituted mainly of oligomers formed on the acid sites of the zeolite. These oligomers located in the α cages can be removed by thermal treatment in vacuum at high temperatures. The effect on the adsorption capacity was more pronounced for coke formed from isobutene due to the preferential location of oligomers in α cages near the outer surface of the crystallites. At high temperatures (350−420 °C), aromatics and polyaromatics were formed which cannot be removed by a simple thermal treatment. The effect of coke on the adsorption capacity showed that whatever their origin, these coke molecules (most likely the polyaromatic ones) blocked the access of adsorbates to the zeolite pores.
This paper presents a new technique using energy filtered TEM (EFTEM) for inelastic electron scattering contrast imaging of Germanium distribution in Si–SiGe nanostructures. Comparing electron energy ...loss spectra (EELS) obtained in both SiGe and Si single crystals, we found a spectrum area strongly sensitive to the presence of Ge in the range 50–100eV. In this energy loss window, EELS spectrum shows a smooth steeply shaped background strongly depending on Ge concentration. Germanium mapping inside SiGe can thus be performed through imaging of the EELS background slope variation, obtained by processing the ratio of two energy filtered TEM images, respectively, acquired at 90 and 60eV. This technique gives contrasted images strongly similar to those obtained using STEM Z-contrast, but presenting some advantages: elastic interaction (diffraction) is eliminated, and contrast is insensitive to polycrystalline grains orientation or specimen thickness. Moreover, since the extracted signal is a spectral signature (inelastic energy loss) we demonstrate that it can be used for observation and quantification of Ge concentration depth profile of SiGe buried layers.
Possible background reductions in double beta decay experiments Arnold, R.; Augier, C.; Baker, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2003, Letnik:
503, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The background induced by radioactive impurities of
208
Tl
and
214
Bi
in the source of the double beta experiment NEMO-3 has been investigated. New methods of data analysis which decrease the ...background from the above-mentioned contamination are identified. The techniques can also be applied to other double beta decay experiments capable of measuring independently the energies of the two electrons.
Magneto-photoluminescence (MPL) of self-organised MOCVD epitaxially grown InAs dots embedded in GaAs has been investigated in order to identify the nature of the corresponding optical transitions and ...to determine the effective mass of confined electrons and holes. MPL was studied in the range of 0–28 T in Faraday and Voigt configurations. At zero field we have observed up to three PL peaks corresponding to a ground state transition (∼1 eV) and two excited state transitions (∼1.1 and ∼1.2 eV). The ground state transition showed a small diamagnetic shift, the first excited transition was split into two components and three split components were observed for the second excited transition as a function of magnetic field in the Faraday configuration. A simple one-particle Fock–Darwin model of two-dimensional electrons confined in a parabolic well seems to describe the PL behaviour in magnetic field.
In this communication, we used a modern analytical TEM–STEM fully equipped to carry out a complete physical and chemical study of Al/Ti/W/TiN interconnection evolution after 450
°C annealing. Using ...energy filtered TEM, compositional mapping, scanning TEM (STEM) Z contrast imaging, EDX and EELS spectrum imaging and micro-diffraction, we evidence at the Al/W top contacts interface a reaction between Al and W leading to the growth of Al
x
W inclusions inside the Al grains.
The NEMO-3 tracking detector is located in the Frejus Underground Laboratory. It was designed to study double beta decay in a number of different isotopes. Presented here are the experimental ...half-life limits on the double beta decay process for the isotopes 100Mo and 82Se for different Majoron emission modes and limits on the effective neutrino-Majoron coupling constants. In particular, new limits on "ordinary" Majoron (spectral index 1) decay of 100Mo T1/2 > 2.7cdot10 22 and 82Se T1/2 1.5cdot10 22) have been obtained. Corresponding bounds on the Majoron-neutrino coupling constant are g ee0.4-1.9 \cdot 10^{-4} and (0.66-1.7) \cdot 10 -4.
Here, using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay (2νββ) half-life of 82Se as T2ν1/2=9.39±0.17( stat )±0.58( syst )×1019 y under the single-state ...dominance hypothesis for this nuclear transition.
Technical design and performance of the NEMO 3 detector Arnold, R.; Augier, C.; Bakalyarov, A.M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2005, 2005-1-00, Letnik:
536, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The development of the Neutrino Ettore Majorana Observatory (NEMO
∼
3
) detector, which is now running in the Fréjus Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun more ...than ten years ago. The NEMO 3 detector uses a tracking-calorimeter technique in order to investigate double beta decay processes for several isotopes. The technical description of the detector is followed by the presentation of its performance.
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