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3244. Looking for a topological insulator in the tetradymite familyZipporah Rini Benher, Sandra Gardonio, Mattia Fanetti, Polina M. Sheverdyaeva, Paolo Moras, Matjaž Valant, 2019, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Materials that are topological insulators (TI) manifest a novel state for their electrons. They possess topological surface states that are not destroyed by the presence of non-magnetic impurities on their surfaces. This unique property lies in the bulk band structure and it is typically found in narrow gap semiconductor with strong spin-orbit coupling.
Bi2Se3 and Bi2Te3 belong to the class of compounds called tetradymites and are considered as the 3D-prototypical TI materials. However, these compounds are not usually insulators but have metallic bulk conductivity as a consequence of intrinsic defect doping: vacancies and anti-site defects. For these reasons, it is difficult to electrically gate these materials for the manipulation and control of charge carriers for realizing devices. This led to the search for other topological materials, which might have better insulating behavior in their bulk.
Theoretical studies have pointed out that ternary variants of the Bi2Se3 and Bi2Te3, such as Bi2Te2Se, Bi2Te2S, Bi2Se2S Sb2Te2Se and Sb2Te2S, should be stable TIs and potentially offer a chemical way to control TI behavior, in particular by lowering native doping. Among the cited ternary compounds, Bi2Se2S should manifest a genuine topological spin-transport regime hosting an isolated Dirac cone with the Dirac point in the gap as well. However, it has been poorly studied from the TI experimental perspective.
Therefore, to uncover the full potential of the predicted topological electronic properties of the Bi-Se-S system, in this presentation we will revisit the crystallographic and electronic structure of Bi2Se3-Bi2S3 solid solutions. The combined use of bulk and surface sensitive techniques such as X-ray diffraction (XRD), low energy electron diffraction (LEED), scanning electron microscopy (SEM) with Energy Dispersive X-ray spectroscopy (EDX) and X-ray photoemission spectroscopy (XPS) was applied to analyze single crystal samples grown by us. The quality of the single crystals was suitable for rigorous measurement of the electronic properties by means of Angle Resolved Photoemission Spectroscopy. We unambiguously showed that within a certain solid solution range, the single crystals of Bi-Se-S have a rombohedral structure with the topological surface states as theoretically predicted.
Ključne besede: topological insulators, ternary tetradymite, electronic properties.
Objavljeno v RUNG: 19.12.2019; Ogledov: 3892; Prenosov: 0
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3247. Determination of Iron in Environmental Water Samples by FIA-TLSMiha Tomšič, Leja Goljat, Hanna Budasheva, Dorota Korte, Arne Bratkič, Mladen Franko, 2019, izvirni znanstveni članek Opis: The determination of low concentration of iron in natural waters can be difficult due to the complexity of natural water, but primarily because it requires preconcentration of the sample with solvent extraction. In this work we report on results of thermal lens spectrometry (TLS) coupled to flow injection analysis (FIA) as a highly sensitive FIA-TLS method of iron detection. The concentration of iron redox species was determined using 1,10-phenanthroline (PHN), that forms stable complexes with Fe(II) ions which are characterized by an absorption maximum at 508 nm. The TLS system using a 633 nm probe laser and 530 nm pump laser beam was exploited for on-line detection in flow injection analysis, where a PHN solution was used as the carrier solution for FIA. The concentration of the complexing agent affects the quality of the TLS signal, and the optimal concentration was found at 1 mM PHN. The achieved limits of detection (LODs) for Fe(II) and total iron were 33 nM for Fe(II) and 21 nM for total iron concentration. The method was further validated by determining the linear concentration range, specificity in terms of analytical yield and by determining concentration of iron in a water sample from a local water stream.
Ključne besede: Flow injection analysis, iron concentration, thermal lens spectroscopy
Objavljeno v RUNG: 18.12.2019; Ogledov: 3262; Prenosov: 105
 Celotno besedilo (690,39 KB) |
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3250. Comparative literature and digital humanitiesAleš Vaupotič, 2019, objavljeni povzetek znanstvenega prispevka na konferenci Opis: The "Comparative literature and digital humanities" paper was part of the panel "Postdigital Comparatism: New methods, new frameworks, new questions?", organized by Amelia Sanz (Complutense University of Madrid), Aleš Vaupotič (University of Nova Gorica), and Silvia Ulrich (Universita di Torino). This panel tries to describe and to evaluate the headway the Comparatism made at a time when cultures, literatures and criticism can be considered inevitably post-digital: after the digital revolution dealing with cultural habitus in the 21st century. Looking forward, what difference does it make? The point is the following: are digital archives, electronic devices, and tools modifying our disciplinary field just with regard to new available sources and dissemination strategies? Or are they creating any specific epistemological modeling? Is there any comparatist condition to be satisfied by digital methodologies? Are the digital humanities and the digital literary studies (still) distinguishable from general literary studies? Can electronic technologies and digital methodologies become hegemonic, even hypercolonial, over any epistemological sovereignty? How are the comparatists coping with the interdisciplinary constellations involved in using computer technologies in research? What is the difference between digitized literatures, and digital arts and literatures from a comparatist point of view? We should reflect on the use of the communication models from new-media art as a source for the emerging digital humanities genres. Why do comparatists seem so suspicious and skeptical towards digitization process and digital arts, whereas they are used to cross over cultures, oceans and media?
Ključne besede: digital humanities, comparative literature, methodology
Objavljeno v RUNG: 13.12.2019; Ogledov: 3091; Prenosov: 0
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