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281.
The effect of hole self-trapping in Ba3(PO4)2 at low temperatures has been studied. The TSL peak at 135 K is due to hole delocalization and diffusion by thermally activated hopping between perfect lattice sites, resulting in a composite uv band, corresponding to the tunneling recombination of holes with localized electrons. 相似文献
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Absorption spectra of tetracene and pentacene layers prepared by vapor deposition onto cooled substrates were measured as a function of sample formation temperature Tf, evaporation rate and recording temperature. Profile-analysis indicates that the main absorption peak is of gaussian shape. The width varies between 300 cm?1 and 650 cm?1, higher values referring to lower formation temperatures and/or higher evaporation rates and reflecting larger fluctuation of the site-energies. Appearance of a second electronic band equivalent to the upper Davydov component in the crystal spectrum indicates presence of short-range order. The low-energy behavior is dominated by a structural defect. No Urbacht-tail is observed. It is concluded that tetracene and pentacene layers represent examples for intermediate structural disorder. 相似文献
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Paramee Kumkrong Benjaporn Thiensong Phuong Mai Le Garnet McRae Anthony Windust Suladda Deawtong Juris Meija Paulette Maxwell Lu Yang Zoltán Mester 《Analytica chimica acta》2016
Methods based on species specific isotope dilution were developed for the accurate and SI traceable determination of arsenobetaine (AsBet) and methylmercury (MeHg) in prawn and cuttlefish tissues by LC-MS/MS and SPME GC-ICPMS. Quantitation of AsBet and MeHg were achieved by using a 13C-enriched AsBet spike (NRC CRM CBET-1) and an enriched spike of Me198Hg (NRC CRM EMMS-1), respectively, wherein analyte mass fractions in enriched spikes were determined by reverse isotope dilution using natural abundance AsBet and MeHg primary standards. Purity of these primary standards were characterized by quantitative 1H-NMR with the use of NIST SRM 350b benzoic acid as a primary calibrator, ensuring the final measurement results traceable to SI. Validation of employed methods of ID LC-MS/MS and ID SPME GC-ICPMS was demonstrated by analysis of several biological CRMs (DORM-4, TORT-3, DOLT-5, BCR-627 and BCR-463) with satisfying results. 相似文献
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288.
Temperature‐dependent EXAFS study of the local structure and lattice dynamics in cubic Y2O3
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Inga Jonane Karlis Lazdins Janis Timoshenko Alexei Kuzmin Juris Purans Pavel Vladimirov Tim Gräning Jan Hoffmann 《Journal of synchrotron radiation》2016,23(2):510-518
The local structure and lattice dynamics in cubic Y2O3 were studied at the Y K‐edge by X‐ray absorption spectroscopy in the temperature range from 300 to 1273 K. The temperature dependence of the extended X‐ray absorption fine structure was successfully interpreted using classical molecular dynamics and a novel reverse Monte Carlo method, coupled with the evolutionary algorithm. The obtained results allowed the temperature dependence of the yttria atomic structure to be followed up to ~6 Å and to validate two force‐field models. 相似文献
289.
Juris Steprāns 《Israel Journal of Mathematics》1993,83(3):257-274
It is shown to be consistent with Martin’s Axiom and
>ℵ1 that every twoP
c-points inβℕ\ℕ have the same topological type.
This research was partially supported by NSERC. The author would also like to thank Saharon Shelah for making some enlightening
remarks, on an earlier version of this paper, which resulted in Definition 2.3. 相似文献
290.
Density fingering of the chlorite-tetrathionate reaction has been studied experimentally in a Hele-Shaw cell. The initially emerging cellular structure transforms into a single cell with constant--asymmetric and symmetric--shape in narrow reaction vessels. The interactions of fingers in wider Hele-Shaw cells lead to the coarsening of the patterns, however, splitting of fingers is observed as well. The long time evolution has been quantitatively described by the change in the mixing length, i.e., the amplitude of the patterns, and by the power-averaged cell number of the structures. 相似文献