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Точкові радіаційні дефекти у монокристалах Li₆YB₃O₉:Eu³⁺
No full textThe point radiation defects in Li₆YB₃O₉:Eu³⁺ single crystals have been studied. The irradiation of Li₆YB₃O₉:Eu³⁺ single crystals with beta particles has been found to cause a valence state change (Eu³⁺ -> Eu²⁺) in some fraction of europium ions being detected by decrease of Eu³⁺ photoluminescence integral intensity, as well as formation of O⁻ hole centers resulting in appearance of a radiation induced broad absorption band in the λ = 320-500 nm range. Two models of hole centers in Li₆YB₃O₉:Eu³⁺ crystals (O⁻ isolated ion or BO₃²⁻ complex ion) have been proposed.Розглянуто точкові радіаційні дефекти у монокристалах Li₆YB₃O₉:Eu³⁺. Встановлено, що опромінення монокристалів Li₆YB₃O₉:Eu³⁺ бета-частинками спричиняє зміну валентного стану частини іонів європію Eu³⁺ -> Eu²⁺, що проявляється у зниженні інтегральної інтенсивності фотолюмінесценції іонів Eu³⁺, а також утворення діркових O⁻ центрів, що викликає появу широкої полоси індукованого оптичного поглинання в області довжин хвиль λ = 320-500 нм. Запропоновано дві моделі діркового центру у кристалах Li₆YB₃O₉:Eu³⁺: ізольований іон O⁻ або комплексний BO₃²⁻ іон.Изучены точечные радиационные дефекты в монокристаллах Li₆YB₃O₉:Eu³⁺. 'Установлено, что облучение монокристаллов Li₆YB₃O₉:Eu³⁺ бета-частицами приводит к изменению зарядового состояния части ионов европия Eu³⁺ -> Eu²⁺, фиксируемого по снижению интегральной интенсивности фотолюминесценции ионов Eu³⁺, а также к формированию дырочных O⁻ центров, что вызывает появление широкой полосы наведенного оптического поглощения в области длин волн λ = 320-500 нм. Предложены две модели дырочного центра в кристаллах Li₆YB₃O₉:Eu³⁺: изолированный ион O⁻ или комплексный BO₃²⁻ ион
Точкові радіаційні дефекти у монокристалах Li₆YB₃O₉:Eu³⁺
No full textThe point radiation defects in Li₆YB₃O₉:Eu³⁺ single crystals have been studied. The irradiation of Li₆YB₃O₉:Eu³⁺ single crystals with beta particles has been found to cause a valence state change (Eu³⁺ -> Eu²⁺) in some fraction of europium ions being detected by decrease of Eu³⁺ photoluminescence integral intensity, as well as formation of O⁻ hole centers resulting in appearance of a radiation induced broad absorption band in the λ = 320-500 nm range. Two models of hole centers in Li₆YB₃O₉:Eu³⁺ crystals (O⁻ isolated ion or BO₃²⁻ complex ion) have been proposed.Розглянуто точкові радіаційні дефекти у монокристалах Li₆YB₃O₉:Eu³⁺. Встановлено, що опромінення монокристалів Li₆YB₃O₉:Eu³⁺ бета-частинками спричиняє зміну валентного стану частини іонів європію Eu³⁺ -> Eu²⁺, що проявляється у зниженні інтегральної інтенсивності фотолюмінесценції іонів Eu³⁺, а також утворення діркових O⁻ центрів, що викликає появу широкої полоси індукованого оптичного поглинання в області довжин хвиль λ = 320-500 нм. Запропоновано дві моделі діркового центру у кристалах Li₆YB₃O₉:Eu³⁺: ізольований іон O⁻ або комплексний BO₃²⁻ іон.Изучены точечные радиационные дефекты в монокристаллах Li₆YB₃O₉:Eu³⁺. 'Установлено, что облучение монокристаллов Li₆YB₃O₉:Eu³⁺ бета-частицами приводит к изменению зарядового состояния части ионов европия Eu³⁺ -> Eu²⁺, фиксируемого по снижению интегральной интенсивности фотолюминесценции ионов Eu³⁺, а также к формированию дырочных O⁻ центров, что вызывает появление широкой полосы наведенного оптического поглощения в области длин волн λ = 320-500 нм. Предложены две модели дырочного центра в кристаллах Li₆YB₃O₉:Eu³⁺: изолированный ион O⁻ или комплексный BO₃²⁻ ион
Magnetically Tunable Feshbach Resonances in Ultracold Li-Yb Mixtures
Full text linkWe investigate the possibility of forming Li+Yb ultracold molecules by magnetoassociation in mixtures of ultracold atoms. We find that magnetically tunable Feshbach resonances exist, but are extremely narrow for even-mass ytterbium isotopes, which all have zero spin. For odd-mass Yb isotopes, however, there is a new mechanism due to hyperfine coupling between the electron spin and the Yb nuclear magnetic moment. This mechanism produces Feshbach resonances for fermionic Yb isotopes that can be more than 2 orders of magnitude larger than for the bosonic counterparts
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Cold Li–Yb<sup>+</sup> mixtures in a hybrid trap setup
Full text linkIn this PhD thesis, we describe the design and construction of an experimental apparatus capable of trapping, cooling and spatially overlapping neutral 6Li atoms and Yb+ ions. Our main goal is to reach the quantum regime in atom-ion mixtures and to investigate fundamental atom-ion scattering physics. In particular, we answer two important questions: 1) How does the atom-ion quantum simulator behave when we include micromotion in its theoretical description? To answer this question, we analyze in theory the quantum dynamics of an atom-ion quantum simulator unit cell in which a single atom interacts with a single trapped ion. 2) Is the combination Yb+/Li suitable for the experimental applications intended? To find this out we experimentally establish if the chemical reaction rate in colliding Li–Yb+ systems is low enough to allow for quantum applications and sympathetic cooling
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