Characterization of multifunctional β-NaEuF4/NaGdF4 core–shell nanoparticles with narrow size distribution

We characterized NaEuF4/NaGdF4 core–shell nanoparticles

Atomically-precise texturing of hexagonal boron nitride nanostripes

Monolayer hexagonal boron nitride (hBN) is attracting considerable attention because of its potential applications in areas such as nano- and opto-electronics, quantum optics and nanomagnetism. However, the implementation of such functional hBN demands precise lateral nanostructuration and integration with other two-dimensional materials, and hence, novel routes of synthesis beyond exfoliation. Here, a disruptive approach is demonstrated, namely, imprinting the lateral pattern of an atomically stepped one-dimensional template into a hBN monolayer. Specifically, hBN is epitaxially grown on vicinal Rhodium (Rh) surfaces using a Rh curved crystal for a systematic exploration, which produces a periodically textured, nanostriped hBN carpet that coats Rh(111)-oriented terraces and lattice-matched Rh(337) facets with tunable width. The electronic structure reveals a nanoscale periodic modulation of the hBN atomic potential that leads to an effective lateral semiconductor multi-stripe. The potential of such atomically thin hBN heterostructure for future applications is discussed.The authors acknowledge financial support from the Spanish Ministry of Science and Innovation (Grants MAT-2017-88374-P, PID2019-107338RB-C63, MAT2017-88492-R, and Severo Ochoa CEX2019-000910-S), the CSIC (Grant 2020AEP178), the Basque Government (Grant IT-1255-19), the Marie Sklodowska-Curie European Union's Horizon 2020 program (grant MagicFACE 797109), the European Research Council (Advanced Grant 789104-eNANO), and Elettra Sincrotrone Trieste for providing access to its synchrotron radiation facilities. I.P. and F.B. acknowledge funding from EUROFEL, and D.U. from the Ministry of Science and Higher Education of the Russian Federation [Grant No. 075-15-2020-797 (13.1902.21.0024)]. A.A.M. acknowledges the German Ministry for Education and Research (Grant 05K19KER).Peer reviewe

The study of gas molecule interaction with supported noncontinuous bimetallic films

We deposited several submonolayer films of rhodium and vanadium onto polycrystalline -Al2O3 substrate. Prepared samples were different in ratio of deposited amount of rhodium and vanadium. XPS spectra of surface were measured after every particular step of metal deposition, sample annealing and CO, oxygen adsorption. Adsorption and temperature stimulated desorption of gas molecules were performed using Molecular Beam and Thermo Programmed Desorption methods. Furthermore, we studied a bimetallic system prepared by deposition of vanadium onto polycrytalline Rh foil and growth of vanadium on -Al2O3

Electronic structure of bimetallic systems - study of gas molecule interaction

Bimetallic Rh-V system was studied by means of surface science experimental methods. Properties of ultra-thin Rh-V layers supported by γ-Al2O3 were compared with model systems prepared by vacuum V deposition on Rh(111), Rh(110) and polycrystalline rhodium. Formation of ordered V- Rh(111)-(2×2), V-Rh(110)-(2×1) and V-Rh(110)-(1×2) subsurface alloys and their electronic and atomic structure were investigated and models of the surface reconstructions were proposed. Influence of the subsurface alloy formation on interaction with CO and O2 molecules as well as the influence of the molecule adsorption on this alloy was investigated. The bond between CO molecules and Rh-V alloy surface was weakened due to pronounced changes in surface valence band structure. Oxygen which adsorbed on the alloy surface reacted with the subsurface vanadium at elevated temperature and blocked the interaction of the metal substrate with CO molecules

Studium nesených nespojitých bimetalických vrstev a jejich interakce s molekulami plynů

V předložené práci jsme deponovali vrstvy vanadu a rhodia o tloušťce zlomku monovrstvy až několika monovrstev na polykrystalickou podložku -Al2O3. Připravené vzorky se lišily v poměru zastoupení obou kovů a v pořadí jejich depozice. Po depozici byly vzorky ohřívány a byla studována jejich interakce s molekulami CO a O2. Po každém experimentálním kroku (depozice, ohřev, adsorpce či desorpce plynů) byly vzorky proměřeny metodou XPS. Ke studiu interakce plynů s povrchem (adsorpce a desorpce ) byly použity metody Molekulárních svazků (MB) a Teplotně stimulované desorpce (TDS). Podobně byl studován i bimetalický systém vanadu deponovaného na polykristalickou fólii Rh a růst vanadu na polykrystalické podložce -Al2O3.We deposited several submonolayer films of rhodium and vanadium onto polycrystalline -Al2O3 substrate. Prepared samples were different in ratio of deposited amount of rhodium and vanadium. XPS spectra of surface were measured after every particular step of metal deposition, sample annealing and CO, oxygen adsorption. Adsorption and temperature stimulated desorption of gas molecules were performed using Molecular Beam and Thermo Programmed Desorption methods. Furthermore, we studied a bimetallic system prepared by deposition of vanadium onto polycrytalline Rh foil and growth of vanadium on -Al2O3.Department of Surface and Plasma ScienceKatedra fyziky povrchů a plazmatuMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Změny elektronické struktury bimetalických systémů při interakci s molekulami plynu

Bimetallic Rh-V system was studied by means of surface science experimental methods. Properties of ultra-thin Rh-V layers supported by γ-Al2O3 were compared with model systems prepared by vacuum V deposition on Rh(111), Rh(110) and polycrystalline rhodium. Formation of ordered V- Rh(111)-(2×2), V-Rh(110)-(2×1) and V-Rh(110)-(1×2) subsurface alloys and their electronic and atomic structure were investigated and models of the surface reconstructions were proposed. Influence of the subsurface alloy formation on interaction with CO and O2 molecules as well as the influence of the molecule adsorption on this alloy was investigated. The bond between CO molecules and Rh-V alloy surface was weakened due to pronounced changes in surface valence band structure. Oxygen which adsorbed on the alloy surface reacted with the subsurface vanadium at elevated temperature and blocked the interaction of the metal substrate with CO molecules.Práce je věnována studiu bimetalického Rh-V systému pomocí metod fyziky povrchů. Vlastnosti ultra-tenkých Rh-V vrstev nesených na γ-Al2O3 byly porovnány s modelovými systémy připravenými vakuovou depozicí V na Rh(111), Rh(110) a polykrystalické rhodium. Bylo zkoumáno vytváření V-Rh(111)-(2×2), V-Rh(110)-(2×1) a V-Rh(110)-(1×2) podpovrchových slitin a jejich elektronická a atomární struktura. Byly navrženy modely povrchových rekonstrukcí těchto slitin. Dále byl zkoumán vliv vzniku podpovrchové slitiny na interakci s molekulami CO a O2 a vliv adsorpce molekul na tuto slitinu. Vazba mezi CO molekulami a povrchem slitiny byla oslabena v důsledku markantních změn ve struktuře valenčního pásu kovového povrchu. Kyslík adsorbovaný na povrchu slitiny reagoval při zvýšené teplotě s podpovrchovým vanadem, což zabraňovalo interakci kovového substrátu s molekulami CO.Katedra fyziky povrchů a plazmatuDepartment of Surface and Plasma ScienceFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Vznik orientovaného vrstveného MoS2 z amorfního tenkého filmu odhalený polarizovanou rentgenovou absorpční spektroskopií

MoS2 is a prototypical two-dimensional van der Waals (vdW) solid, where covalently bonded S–Mo–S triplets are held together by weaker vdW forces. In this work, we have studied structural transformation from a three-dimensional amorphous phase of MoS2 into a layered vdW crystal using S L2;3 edge x-ray absorption near-edge structure (XANES) spectroscopy with in-plane and out-of-plane polarized x-ray beam. The crystallization process, which starts from an isotropic amorphous phase, is accompanied by the establishment of vdW interaction between covalently bonded layers, resulting in the anisotropic nature of the crystalline phase. We have disclosed that the preferential growth of MoS2 layers along the (200) Bragg reflection commences immediately from the amorphous phase with no intermediate crystal orientations. We have additionally identified a unique signature in the S L2;3 edge spectrum that is associated with vdW bonds and can be possibly used to determine sulfur-based single-layered and multi-layered transition metal dichalcogenides.MoS2 je typická dvourozměrná pevná látka s van der Waalsovou (vdW) vazbou, kde kovalentně vázané triplety S–Mo–S drží pohromadě slabší vdW síly. V této práci jsme studovali strukturní transformaci z trojrozměrné amorfní fáze MoS2 na vrstvený vdW krystal pomocí spektroskopie rentgenové absorpční struktury blízké hrany (XANES) při absorpční hraně S L2,3 s polarizovaným rentgenovým paprskem v rovině a mimo rovinu. Proces krystalizace, který začíná z izotropní amorfní fáze, je doprovázen ustavením interakce vdW mezi kovalentně vázanými vrstvami, což má za následek anizotropní povahu krystalické fáze. Zjistili jsme, že preferenční růst vrstev MoS2 podél (200) Braggova odrazu začíná okamžitě od amorfní fáze bez dalších krystalových orientací. Dále jsme identifikovali jedinečný podpis ve spektru absorpční hrany S L2;3, který je spojen s vdW vazbami a může být potenciálně použit ke stanovení jednovrstvých a vícevrstvých dichalkogenidů přechodných kovů na bázi síry

Passenger Route Choice and Assignment Model for Combined Fixed and Flexible Public Transport Systems

The recent technological innovations have given rise to innovative mobility solutions. Public transport systems combining such services need novel models for the design of services. We develop a multimodal route choice and assignment model for combined use of line/schedule based public transport systems (fixed public transport) and demand responsive services (flexible public transport). The model takes into account the dynamic demand-supply interaction using an iterative learning model framework. Flexible public transport can be used to perform any part of the trip, ranging from a first/last mile service to an exclusive direct door-to-door connection. The developed model is implemented in an agent based simulation framework. The model is applied to the test network of Sioux Falls. Results, in terms of modal split, fleet utilization, and passenger waiting times are analysed for scenarios in which fixed and flexible public transport are offered as competing modes as well as potential complementing modes.Transport and PlanningTransport and Plannin