Search results for "iTED"
showing 10 items of 2408 documents
Bright Visible Luminescence in Silica Nanoparticles
2011
International audience; We demonstrate that a porous film of silica nanoparticles emits a bright visible luminescence associated with defects stabilized by oxygen chemisorption at oxygen deficient center sites. Time-resolved spectra excited by a tunable laser allow us to distinguish the luminescence at 1.99 eV, characteristic of the nonbridging oxygen hole center (NBOHC) (Si-O)3 Si-O*, and a fast and a slow emission: the first (lifetime τ ≈ 25 ns) is peaked at 2.27 eV with an excitation spectrum centered at 5.5 eV; the second (τ ≈ 7.5 μs) is peaked at 2.41 eV and is excited around 3.2 and 5.2 eV. Reaction in an air atmosphere leads to the disappearance of the NBOHC luminescence and of the …
Nationalism and Internationalism Reconciled : British Concepts for a New World Order during and after the World Wars
2018
The carnage of World War I gave rise to liberal visions for a new world order with democratized foreign policy and informed international public opinion. Conservatives emphasized continuity in national sovereignty, while socialists focused on the interests of the working class. While British diplomacy in the construction of the League of Nations has been widely discussed, we focus on contemporary uses of nationalism and internationalism in parliamentary and press debates that are more ideological. We also examine how failed internationalist visions influenced uses of these concepts during World War II, supporting alternative organizational solutions, caution with the rhetoric of democracy a…
Search for the double-beta decay of 82Se to the excited states of 82Kr with NEMO-3
2020
The double-beta decay of 82Se to the 0+1 excited state of 82Kr has been studied with the NEMO-3 detector using 0.93 kg of enriched 82Se measured for 4.75 y, corresponding to an exposure of 4.42 kg y. A dedicated analysis to reconstruct the gamma-rays has been performed to search for events in the 2e2g channel. No evidence of a 2nbb decay to the 0+1 state has been observed and a limit of T2n 1/2(82Se; 0+gs -> 0+1) > 1.3 1021 y at 90% CL has been set. Concerning the 0nbb decay to the 0+1 state, a limit for this decay has been obtained with T0n 1/2(82Se; 0+g s -> 0+1) > 2.3 1022 y at 90% CL, independently from the 2nbb decay process. These results are obtained for the first time with a tracko-…
High-sensitivity study of levels in 30Al following β decay of 30Mg
2016
γ -ray and fast-timing spectroscopy were used to study levels in 30Al populated following the β− decay of 30Mg. Five new transitions and three new levels were located in 30Al. A search was made to identify the third 1+ state expected at an excitation energy of ∼2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) βγγ (t) method we have measured the lifetime of the 243.8-keV state to be T1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2+ → 3+) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-k…
Quantum Motion of Chemisorbed Hydrogen on Ni Surfaces
1983
Quantum mechanical energy levels and wave functions have been calculated for the motion of chemisorbed hydrogen atoms on Ni surfaces. The results show considerable quantum effects for the adatom in both the ground and the excited states. The description of the adparticles as being delocalized along the surface offers a novel interpretation of several phenomena, in particular the vibrational excitations. Peer reviewed
Shape staggering of midshell mercury isotopes from in-source laser spectroscopy compared with density-functional-theory and Monte Carlo shell-model c…
2019
Neutron-deficient Hg177-185 isotopes were studied using in-source laser resonance-ionization spectroscopy at the CERN-ISOLDE radioactive ion-beam facility in an experiment combining different detection methods tailored to the studied isotopes. These include either α-decay tagging or multireflection time-of-flight gating for isotope identification. The endpoint of the odd-even nuclear shape staggering in mercury was observed directly by measuring for the first time the isotope shifts and hyperfine structures of Hg177-180. Changes in the mean-square charge radii for all mentioned isotopes, magnetic dipole, and electric quadrupole moments of the odd-A isotopes and arguments in favor of I=7/2 s…
Prezidenta Džo Baidena inugurācijas dienas tiešsaistes ziņu multimodālā analīze
2022
Amerikas Savienoto Valstu prezidenta inaugurācija ir viens no visvairāk dokumentētajiem notikumiem pasaulē, kuru plaši apraksta tiešsaistes mediju avoti. Ņemot vērā notikuma nozīmi un tiešsaistes ziņu lomu informācijas nodošanā mūsdienās, šī pētījuma mērķis bija parādīt lingvistisko un vizuālo līdzekļu integratīvo lomu nozīmes veidošanā, attēlojot Amerikas Savienoto Valstu prezidenta Džo Baidena inaugurāciju kā svarīgu notikumu tiešsaistes ziņās. Lai sasniegtu izvirzīto mērķi, tika apkopots un analizēts ziņu rakstu korpuss, kas publicēts dažādās starptautiskās ziņu vietnēs, izmantojot lingvistisko un vizuālo līdzekļu modeli un multimodālo diskursa analīzi. Rezultāti atklāja, ka izmantotie v…
Joke’s on You : So-called undocumented students in the US
2018
This chapter focuses on the experience of undocumented college students in the USA. While K‐12 education has been opened to undocumented students, at least on paper, since the landmark case Plyler vs. Doe, college education remains a highly precarious terrain for undocumented students, which offers little to no legal protection. Within the United States, the situation of undocumented college students differs greatly among individual states. This chapter provides an overview of national‐level policies or nationally relevant work in the area, as well as insights into some successful local initiatives. peerReviewed
Technology-enhanced or Technology-exhausted Learning in Adult Migrant Literacy Education in Finland : Exploring Teachers’ Experiences and Views in Pr…
2023
This exploratory mixed data study investigated the role of technology in adult migrant language and late literacy education in Finland. In addition to an online pre-pandemic survey targeted at Finnish language and literacy teachers, four in-service teachers were interviewed during the COVID-19 pandemic in late 2020. With means of qualitative content analysis an account of teachers’ individual experiences and views of technology-equipped language and literacy learning was generated. Problematic issues were the use of devices for educational purposes, lacking user experience, inadequate provision of suitable devices, IT courses, and insufficient support for learners and teachers, causing ineq…
Photoluminescence time decay of surface oxygen deficient centers in un‐doped and Ge‐doped silica
2005
We report a study of the emission decay from the singlet excited state of two fold coordinated Si and Ge centers stabilized on the surface of silica and Ge-doped silica. The PL lifetimes are of the order of nanoseconds and increase on decreasing the temperature. The results suggest that, for the surface centers, the phonon assisted intersystem-crossing process linking the excited states affects the decay rates, is effective down to low temperatures and is distributed because of the inhomogeneity of the defects. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)