1,721,172 research outputs found
Synchrotron radiation based characterization of structural evolution of alkali halide clusters
Get PDFAbstractIn this work, evolution of structural properties of anhydrous and hydrated alkali halide clusters are studied using synchrotron radiation based photoelectron spectroscopy. Alkali metal core level spectra of small anhydrous RbCl, RbBr, CsCl and CsBr clusters indicate a NaCl structure. For larger CsBr clusters a structural phase transition to CsCl structure is likely the case. Alkali halide core level spectra of mixed RbBr-water clusters indicate that at dilute concentration the salt is dissolved by the water cluster but ion pairing increases with concentration. Modeling of gas phase cluster formation and electronic structure calculations of core level chemical shifts are used to interpret the experimental spectra.Original papersOriginal papers are not included in the electronic version of the dissertation.Hautala, L., Jänkälä, K., Mikkelä, M.-H., Tchaplyguine, M., & Huttula, M. (2015). Surface site coordination dependent responses resolved in free clusters: applications for neutral sub-nanometer cluster studies. Physical Chemistry Chemical Physics, 17(10), 7012–7022. https://doi.org/10.1039/c4cp05422aHautala, L., Jänkälä, K., Löytynoja, T., Mikkelä, M.-H., Prisle, N., Tchaplyguine, M., & Huttula, M. (2017). Experimental observation of structural phase transition in CsBr clusters. Physical Review B, 95(4). https://doi.org/10.1103/physrevb.95.045402Self-archived versionHautala, L., Jänkälä, K., Mikkelä, M.-H., Turunen, P., Prisle, N. L., Patanen, M., … Huttula, M. (2017). Probing RbBr solvation in freestanding sub-2 nm water clusters. Physical Chemistry Chemical Physics, 19(36), 25158–25167. https://doi.org/10.1039/c7cp04398hSelf-archived versionOsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Hautala, L., Jänkälä, K., Mikkelä, M.-H., Tchaplyguine, M., & Huttula, M. (2015). Surface site coordination dependent responses resolved in free clusters: applications for neutral sub-nanometer cluster studies. Physical Chemistry Chemical Physics, 17(10), 7012–7022. https://doi.org/10.1039/c4cp05422aHautala, L., Jänkälä, K., Löytynoja, T., Mikkelä, M.-H., Prisle, N., Tchaplyguine, M., & Huttula, M. (2017). Experimental observation of structural phase transition in CsBr clusters. Physical Review B, 95(4). https://doi.org/10.1103/physrevb.95.045402Rinnakkaistallennettu versioHautala, L., Jänkälä, K., Mikkelä, M.-H., Turunen, P., Prisle, N. L., Patanen, M., … Huttula, M. (2017). Probing RbBr solvation in freestanding sub-2 nm water clusters. Physical Chemistry Chemical Physics, 19(36), 25158–25167. https://doi.org/10.1039/c7cp04398hRinnakkaistallennettu versioAcademic Dissertation to be presented with the assent of the Faculty of Science, University of Oulu, for public discussion in the Auditorium YB210, on December 1st, 2017, at 12 o’clock noon.Abstract
In this work, evolution of structural properties of anhydrous and hydrated alkali halide clusters are studied using synchrotron radiation based photoelectron spectroscopy. Alkali metal core level spectra of small anhydrous RbCl, RbBr, CsCl and CsBr clusters indicate a NaCl structure. For larger CsBr clusters a structural phase transition to CsCl structure is likely the case. Alkali halide core level spectra of mixed RbBr-water clusters indicate that at dilute concentration the salt is dissolved by the water cluster but ion pairing increases with concentration. Modeling of gas phase cluster formation and electronic structure calculations of core level chemical shifts are used to interpret the experimental spectra
Electric arc characterisation and furnace process monitoring with optical emission spectroscopy and image analysis
No full textAbstractElectric arc furnaces (EAFs) and ladle furnaces (LFs) are the main recycling units for scrap metal. With lower CO₂ emissions than traditional ore-based steelmaking, the importance of EAFs can be expected to increase in the future. Increasing steel production rates and demand for high-quality and special steels require innovative process control systems to be developed for the steel industry. However, the harsh conditions inside the furnaces set strict requirements for durability and viable data acquisition methods for online measurement systems.In this thesis, the applicability of optical emission spectroscopy (OES) as an online measurement system for industrial EAFs and LFs is discussed, based on the results from pilot-scale and industrial EAFs, and an industrial LF.The electric arc has been characterised with OES, plasma diagnostics, and image analysis in the pilot-scale EAF measurements. These studies highlighted the influence of slag composition on the overall properties of the electric arc, the electrical parameters of the furnace, and the arc length{voltage relation. The majority of the atomic emission lines in the electric arc OES spectra were observed to originate from the slag components.In the industrial EAF campaign, high alloyed steel grade was observed to have high-quality arc spectra within 30 mins before tapping and higher radiative heat transfer compared with the carbon steel grade. The spectra from the carbon steel grade, on the other hand, were used to observe how spectra evolve during slag foaming. Additionally, the molten bath surface temperature was estimated from the OES spectra. The slag composition was evaluated with OES in the industrial LF campaign, indicating that the CaF₂, MgO, and MnO content of the slag could be evaluated from the spectra.Original papersOriginal papers are not included in the electronic version of the dissertation.Pauna, H., Willms, T., Aula, M., Echterhof, T., Huttula, M., & Fabritius, T. (2019). Pilot-scale AC electric arc furnace plasma characterization. Plasma Research Express, 1(3), 035007. https://doi.org/10.1088/2516-1067/ab30ddSelf-archived versionPauna, H., Willms, T., Aula, M., Echterhof, T., Huttula, M., & Fabritius, T. (2020). Electric Arc Length-Voltage and Conductivity Characteristics in a Pilot-Scale AC Electric Arc Furnace. Metallurgical and Materials Transactions B, 51(4), 1646–1655. https://doi.org/10.1007/s11663-020-01859-zSelf-archived versionPauna, H., Aula, M., Seehausen, J., Klung, J.-S., Huttula, M., & Fabritius, T. (2020). Optical Emission Spectroscopy as an Online Analysis Method in Industrial Electric Arc Furnaces. Steel Research International, 2000051. https://doi.org/10.1002/srin.202000051Self-archived versionPauna, H., Aula, M., Seehausen, J., Klung, J.-S., Huttula, M., & Fabritius, T. (2020). Industrial Ladle Furnace Slag Composition Analysis with Optical Emissions from the Arc. ISIJ International, 60(9), 1985–1992. https://doi.org/10.2355/isijinternational.isijint-2019-676Self-archived versionOsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Pauna, H., Willms, T., Aula, M., Echterhof, T., Huttula, M., & Fabritius, T. (2019). Pilot-scale AC electric arc furnace plasma characterization. Plasma Research Express, 1(3), 035007. https://doi.org/10.1088/2516-1067/ab30ddRinnakkaistallennettu versioPauna, H., Willms, T., Aula, M., Echterhof, T., Huttula, M., & Fabritius, T. (2020). Electric Arc Length-Voltage and Conductivity Characteristics in a Pilot-Scale AC Electric Arc Furnace. Metallurgical and Materials Transactions B, 51(4), 1646–1655. https://doi.org/10.1007/s11663-020-01859-zRinnakkaistallennettu versioPauna, H., Aula, M., Seehausen, J., Klung, J.-S., Huttula, M., & Fabritius, T. (2020). Optical Emission Spectroscopy as an Online Analysis Method in Industrial Electric Arc Furnaces. Steel Research International, 2000051. https://doi.org/10.1002/srin.202000051Rinnakkaistallennettu versioPauna, H., Aula, M., Seehausen, J., Klung, J.-S., Huttula, M., & Fabritius, T. (2020). Industrial Ladle Furnace Slag Composition Analysis with Optical Emissions from the Arc. ISIJ International, 60(9), 1985–1992. https://doi.org/10.2355/isijinternational.isijint-2019-676Rinnakkaistallennettu versioAcademic dissertation to be presented with the assent of the Doctoral Training Committee of Technology and Natural Sciences of the University of Oulu for public discussion in the Auditorium L5, on October 30th, 2020, at 12 o'clock noon.Abstract
Electric arc furnaces (EAFs) and ladle furnaces (LFs) are the main recycling units for scrap metal. With lower CO₂ emissions than traditional ore-based steelmaking, the importance of EAFs can be expected to increase in the future. Increasing steel production rates and demand for high-quality and special steels require innovative process control systems to be developed for the steel industry. However, the harsh conditions inside the furnaces set strict requirements for durability and viable data acquisition methods for online measurement systems.
In this thesis, the applicability of optical emission spectroscopy (OES) as an online measurement system for industrial EAFs and LFs is discussed, based on the results from pilot-scale and industrial EAFs, and an industrial LF.
The electric arc has been characterised with OES, plasma diagnostics, and image analysis in the pilot-scale EAF measurements. These studies highlighted the influence of slag composition on the overall properties of the electric arc, the electrical parameters of the furnace, and the arc length{voltage relation. The majority of the atomic emission lines in the electric arc OES spectra were observed to originate from the slag components.
In the industrial EAF campaign, high alloyed steel grade was observed to have high-quality arc spectra within 30 mins before tapping and higher radiative heat transfer compared with the carbon steel grade. The spectra from the carbon steel grade, on the other hand, were used to observe how spectra evolve during slag foaming. Additionally, the molten bath surface temperature was estimated from the OES spectra. The slag composition was evaluated with OES in the industrial LF campaign, indicating that the CaF₂, MgO, and MnO content of the slag could be evaluated from the spectra
Electronic structure calculations applied to spectroscopic studies of some metal atoms
Get PDFAbstractIn this thesis, the electronic structure and electrodynamical processes of atomic mercury and potassium are studied experimentally and theoretically. Experimental measurements were carried out by means of both conventional photoelectron spectroscopy and multielectron coincidence technique utilizing magnetic bottle time-of-flight electron spectrometer together with pulsed synchrotron radiation. The thesis focuses on the theoretical modelling and interpretation of the experimentally observed transitions and binding energies. The calculations were carried out with relativistic multiconfiguration Dirac-Fock (MCDF) and non-relativistic Hartree-Fock (MCHF) methods. Theoretical results were used to interpret the experimental data in order to study the electron binding energy level structure and electron transition dynamics of these atoms.Original papersOriginal papers are not included in the electronic version of the dissertation.Khalal, M. A., Soronen, J., Jänkälä, K., Huttula, S.-M., Huttula, M., Bizau, J.-M., Cubaynes, D., Guilbaud, S., Ito, K., Andric, L., Feng, J., Lablanquie, P., Palaudoux, J., & Penent, F. (2017). Multielectron spectroscopy: energy levels of Kn+and Rbn+ions (n= 2, 3, 4). Journal of Physics B: Atomic, Molecular and Optical Physics, 50(22), 225003. https://doi.org/10.1088/1361-6455/aa90d6Self-archived versionPalaudoux, J., Sheinerman, S., Soronen, J., Huttula, S.-M., Huttula, M., Jänkälä, K., Andric, L., Ito, K., Lablanquie, P., Penent, F., Bizau, J.-M., Guilbaud, S., & Cubaynes, D. (2015). Valence Auger decay following 3s photoionization in potassium. Physical Review A, 92(1). https://doi.org/10.1103/physreva.92.012510Huttula, S.-M., Soronen, J., Huttula, M., Penent, F., Palaudoux, J., Andric, L., & Lablanquie, P. (2015). Auger decay of core valence double photoionized states in atomic mercury. Journal of Physics B: Atomic, Molecular and Optical Physics, 48(11), 115001. https://doi.org/10.1088/0953-4075/48/11/115001Soronen, J., Aho, S.-M., Huttula, M., Penent, F., Palaudoux, J., Andric, L., & Lablanquie, P. (2021). Photoionization and subsequent Auger decay of atomic potassium 2s subshell. Manuscript in preparation.OsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Khalal, M. A., Soronen, J., Jänkälä, K., Huttula, S.-M., Huttula, M., Bizau, J.-M., Cubaynes, D., Guilbaud, S., Ito, K., Andric, L., Feng, J., Lablanquie, P., Palaudoux, J., & Penent, F. (2017). Multielectron spectroscopy: energy levels of Kn+and Rbn+ions (n= 2, 3, 4). Journal of Physics B: Atomic, Molecular and Optical Physics, 50(22), 225003. https://doi.org/10.1088/1361-6455/aa90d6Rinnakkaistallennettu versioPalaudoux, J., Sheinerman, S., Soronen, J., Huttula, S.-M., Huttula, M., Jänkälä, K., Andric, L., Ito, K., Lablanquie, P., Penent, F., Bizau, J.-M., Guilbaud, S., & Cubaynes, D. (2015). Valence Auger decay following 3s photoionization in potassium. Physical Review A, 92(1). https://doi.org/10.1103/physreva.92.012510Huttula, S.-M., Soronen, J., Huttula, M., Penent, F., Palaudoux, J., Andric, L., & Lablanquie, P. (2015). Auger decay of core valence double photoionized states in atomic mercury. Journal of Physics B: Atomic, Molecular and Optical Physics, 48(11), 115001. https://doi.org/10.1088/0953-4075/48/11/115001Soronen, J., Aho, S.-M., Huttula, M., Penent, F., Palaudoux, J., Andric, L., & Lablanquie, P. (2021). Photoionization and subsequent Auger decay of atomic potassium 2s subshell. Manuscript in preparation.Academic Dissertation to be presented with the assent of the Doctoral Training Committee of Technology and Natural Sciences of University of Oulu for public discussion in the Auditorium IT115, on September 10th, 2021, at 12 o’clock noon.Abstract
In this thesis, the electronic structure and electrodynamical processes of atomic mercury and potassium are studied experimentally and theoretically. Experimental measurements were carried out by means of both conventional photoelectron spectroscopy and multielectron coincidence technique utilizing magnetic bottle time-of-flight electron spectrometer together with pulsed synchrotron radiation. The thesis focuses on the theoretical modelling and interpretation of the experimentally observed transitions and binding energies. The calculations were carried out with relativistic multiconfiguration Dirac-Fock (MCDF) and non-relativistic Hartree-Fock (MCHF) methods. Theoretical results were used to interpret the experimental data in order to study the electron binding energy level structure and electron transition dynamics of these atoms
Experimental studies of the structural, dynamical and electronic properties of clusters and nanoparticles
Get PDFAbstractIn this thesis, properties of freestanding atomic/molecular clusters are experimentally addressed using various synchrotron radiation and electron ionization based electron and ion spectroscopic methods. The work focuses on water clusters with and without dopant atoms/molecules, including ≲3nm sized [H₂O]N, [H₂O]N[KCl]M, [H₂O]NArM and ArN clusters. The surface properties of larger 100–200nm sized MgCl₂/CaCl₂ and MgBr₂/NaBr nanoparticles generated from precursor solution droplets are also investigated. The experiments provide fundamental level information on the particles’ chemical and structural composition in relation to their formation conditions, electronic properties, and dynamical response to ionizing radiation. Instrumentation was also developed for the generation and characterization of the clusters.Original papersOriginal papers are not included in the electronic version of the dissertation.Pelimanni, E., Saak, C.-M., Michailoudi, G., Prisle, N., Huttula, M., & Patanen, M. (2022). Solvent and cosolute dependence of Mg surface enrichment in submicron aerosol particles. Physical Chemistry Chemical Physics, 24(5), 2934–2943. https://doi.org/10.1039/D1CP04953DSelf-archived versionPelimanni, E., Hautala, L., Hans, A., Kivimäki, A., Kook, M., Küstner-Wetekam, C., Marder, L., Patanen, M., & Huttula, M. (2021). Core and valence level photoelectron spectroscopy of nanosolvated kcl. The Journal of Physical Chemistry A, 125(22), 4750–4759. https://doi.org/10.1021/acs.jpca.1c01539Self-archived versionPelimanni, E., Hans, A., Heikura, E., Huttula, M., & Patanen, M. (2022). Efficient neutralization of core ionized species in an aqueous environment. Physical Chemistry Chemical Physics, 24(19), 11646–11653. https://doi.org/10.1039/D2CP01178FSelf-archived versionOsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Pelimanni, E., Saak, C.-M., Michailoudi, G., Prisle, N., Huttula, M., & Patanen, M. (2022). Solvent and cosolute dependence of Mg surface enrichment in submicron aerosol particles. Physical Chemistry Chemical Physics, 24(5), 2934–2943. https://doi.org/10.1039/D1CP04953DRinnakkaistallennettu versioPelimanni, E., Hautala, L., Hans, A., Kivimäki, A., Kook, M., Küstner-Wetekam, C., Marder, L., Patanen, M., & Huttula, M. (2021). Core and valence level photoelectron spectroscopy of nanosolvated kcl. The Journal of Physical Chemistry A, 125(22), 4750–4759. https://doi.org/10.1021/acs.jpca.1c01539Rinnakkaistallennettu versioPelimanni, E., Hans, A., Heikura, E., Huttula, M., & Patanen, M. (2022). Efficient neutralization of core ionized species in an aqueous environment. Physical Chemistry Chemical Physics, 24(19), 11646–11653. https://doi.org/10.1039/D2CP01178FRinnakkaistallennettu versioAcademic Dissertation to be presented with the assent of the Doctoral Training Committee of Technology and Natural Sciences of the University of Oulu, for public discussion in the Auditorium IT116, on June 8th, 2022, at 13 o’clock.Abstract
In this thesis, properties of freestanding atomic/molecular clusters are experimentally addressed using various synchrotron radiation and electron ionization based electron and ion spectroscopic methods. The work focuses on water clusters with and without dopant atoms/molecules, including ≲3nm sized [H₂O]N, [H₂O]N[KCl]M, [H₂O]NArM and ArN clusters. The surface properties of larger 100–200nm sized MgCl₂/CaCl₂ and MgBr₂/NaBr nanoparticles generated from precursor solution droplets are also investigated. The experiments provide fundamental level information on the particles’ chemical and structural composition in relation to their formation conditions, electronic properties, and dynamical response to ionizing radiation. Instrumentation was also developed for the generation and characterization of the clusters
Computational characterization of photoionization and fragmentation processes of aminobenzoic acids
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Ab initio quantum chemistry methods are used to characterize the electronic structure of aminobenzoic acid isomers and interpret their experimentally observed spectroscopic features. Aminobenzoic acids are composed of a benzene ring with amino and carboxylic functional groups. The relative stability and differences in fragmentation processes between the isomers are studied by sampling the potential energy surface. Excited states modeling is used to calculate vibrationally resolved photoelectron spectra and interpret features of the Auger electron spectrum. Experimental data was gathered using valence and core level photoelectron spectroscopy as well as electron-ion co incidence techniques at a synchrotron facility. Original papers Abid, A. R., Veteläinen, O., Boudjemia, N., Pelimanni, E., Kivimäki, A., Alatalo, M., Huttula, M., Björneholm, O., & Patanen, M. (2023). Forming bonds while breaking old ones: Isomer-dependent formation of h3 o+ from aminobenzoic acid during x-ray-induced fragmentation. The Journal of Physical Chemistry A, 127(6), 1395–1401. https://doi.org/10.1021/acs.jpca.2c06869 https://doi.org/10.1021/acs.jpca.2c06869 Self-archived version Veteläinen, O., Babayan, M., Rahman Abid, A., Kukk, E., Pihlava, L., Urpelainen, S., Huttula, M., Kivimäki, A., Alatalo, M., & Patanen, M. (2024). Valence photoelectron spectra of aminobenzoic acid molecules: A combined theoretical and experimental study. Journal of Physics B: Atomic, Molecular and Optical Physics, 57(22), 225101. https://doi.org/10.1088/1361-6455/ad83b0 https://doi.org/10.1088/1361-6455/ad83b0 Self-archived version Veteläinen, O., Babayan, M., Pihlava, L., Abid, A. R., Kivimäki, A., Kukk, E., Walsh, N., Urpelainen, S., Björneholm, O., Huttula, M., Alatalo, M., Patanen, M., & Díaz-Tendero, S. (2025). Hydrogen migration reactions via low internal energy pathways in aminobenzoic acid dications. Physical Chemistry Chemical Physics, 27(18), 9884–9894. https://doi.org/10.1039/D5CP00415B https://doi.org/10.1039/d5cp00415b Self-archived version Osajulkaisut Abid, A. R., Veteläinen, O., Boudjemia, N., Pelimanni, E., Kivimäki, A., Alatalo, M., Huttula, M., Björneholm, O., & Patanen, M. (2023). Forming bonds while breaking old ones: Isomer-dependent formation of h3 o+ from aminobenzoic acid during x-ray-induced fragmentation. The Journal of Physical Chemistry A, 127(6), 1395–1401. https://doi.org/10.1021/acs.jpca.2c06869 https://doi.org/10.1021/acs.jpca.2c06869 Rinnakkaistallennettu versio Veteläinen, O., Babayan, M., Rahman Abid, A., Kukk, E., Pihlava, L., Urpelainen, S., Huttula, M., Kivimäki, A., Alatalo, M., & Patanen, M. (2024). Valence photoelectron spectra of aminobenzoic acid molecules: A combined theoretical and experimental study. Journal of Physics B: Atomic, Molecular and Optical Physics, 57(22), 225101. https://doi.org/10.1088/1361-6455/ad83b0 https://doi.org/10.1088/1361-6455/ad83b0 Rinnakkaistallennettu versio Veteläinen, O., Babayan, M., Pihlava, L., Abid, A. R., Kivimäki, A., Kukk, E., Walsh, N., Urpelainen, S., Björneholm, O., Huttula, M., Alatalo, M., Patanen, M., & Díaz-Tendero, S. (2025). Hydrogen migration reactions via low internal energy pathways in aminobenzoic acid dications. Physical Chemistry Chemical Physics, 27(18), 9884–9894. https://doi.org/10.1039/D5CP00415B https://doi.org/10.1039/d5cp00415b Rinnakkaistallennettu versio Academic Dissertation to be presented with the assent of the Faculty of Science, University of Oulu, Finland for public discussion in the Auditorium L5, on June 6th, 2025, at noon 12 o’clock (EEST).Abstract
Ab initio quantum chemistry methods are used to characterize the electronic structure of aminobenzoic acid isomers and interpret their experimentally observed spectroscopic features. Aminobenzoic acids are composed of a benzene ring with amino and carboxylic functional groups. The relative stability and differences in fragmentation processes between the isomers are studied by sampling the potential energy surface. Excited states modeling is used to calculate vibrationally resolved photoelectron spectra and interpret features of the Auger electron spectrum. Experimental data was gathered using valence and core level photoelectron spectroscopy as well as electron-ion co incidence techniques at a synchrotron facility
Electronic and photocatalytic properties of transition metal decorated molybdenum disulfide
Get PDFAbstractThis thesis is dedicated to realizations and physical understanding of electronic and photocatalytic properties after decorating transition metals to the semiconducting molybdenum disulfide. Synthesized via facile wet chemical methods, the MoS₂-Au, MoS₂-Au-Ni and MoS₂-Ag-Ni composites were formed as binary or ternary compounds. The Au nanoparticles are stably joined to the MoS₂ matrix without deteriorating layered structures of the host. After introducing the Au nanoglue as a common buffer, a metallic contact is reached between Ni and MoS₂, and attributed to new electron migration channel via MoS₂ edge contact. Adapting the Ag as the buffer element can attach the Ni to the basal plane of the MoS₂ beside edge contact. The Ni-Ag-MoS₂ composite effectively splits water under visible light irradiation and produce hydrogen. The excellent photocatalytic activity is attributed to effective charge migration through dangling bonds at the MoS2-Ag-Ni alloy interface and the activation of MoS₂ basal planes.Original papersOriginal papers are not included in the electronic version of the dissertation.Cao, W., Pankratov, V., Huttula, M., Shi, X., Saukko, S., Huang, Z., & Zhang, M. (2015). Gold nanoparticles on MoS₂ layered crystal flakes. Materials Chemistry and Physics, 158, 89–95. https://doi.org/10.1016/j.matchemphys.2015.03.041Shi, X., Posysaev, S., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., … Cao, W. (2018). Metallic Contact between MoS₂ and Ni via Au Nanoglue. Small, 14(22), 1704526. https://doi.org/10.1002/smll.201704526Self-archived versionShi, X., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., Zeeshan, F., … Cao, W. (2018). Quantification of bonded Ni atoms for Ni-MoS₂ metallic contact through X-ray photoemission electron microscopy. Microscopy and Microanalysis, 24(S2), 458−459. https://doi.org/10.1017/S1431927618014526Self-archived versionX. Shi, M. Zhang, W. Cao, X. Wang, M. Huttula. (2018). Efficient photocatalytic hydrogen evolution via activated multilayer MoS₂. Manuscript in preparation.Shi, X., Huang, Z., Huttula, M., Li, T., Li, S., Wang, X., … Cao, W. (2018). Introducing Magnetism into 2D Nonmagnetic Inorganic Layered Crystals: A Brief Review from First-Principles Aspects. Crystals, 8(1), 24. https://doi.org/10.3390/cryst8010024Self-archived versionOsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Cao, W., Pankratov, V., Huttula, M., Shi, X., Saukko, S., Huang, Z., & Zhang, M. (2015). Gold nanoparticles on MoS₂ layered crystal flakes. Materials Chemistry and Physics, 158, 89–95. https://doi.org/10.1016/j.matchemphys.2015.03.041Shi, X., Posysaev, S., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., … Cao, W. (2018). Metallic Contact between MoS₂ and Ni via Au Nanoglue. Small, 14(22), 1704526. https://doi.org/10.1002/smll.201704526Rinnakkaistallennettu versioShi, X., Huttula, M., Pankratov, V., Hoszowska, J., Dousse, J.-C., Zeeshan, F., … Cao, W. (2018). Quantification of bonded Ni atoms for Ni-MoS₂ metallic contact through X-ray photoemission electron microscopy. Microscopy and Microanalysis, 24(S2), 458−459. https://doi.org/10.1017/S1431927618014526Rinnakkaistallennettu versioX. Shi, M. Zhang, W. Cao, X. Wang, M. Huttula. (2018). Efficient photocatalytic hydrogen evolution via activated multilayer MoS₂. Manuscript in preparation.Shi, X., Huang, Z., Huttula, M., Li, T., Li, S., Wang, X., … Cao, W. (2018). Introducing Magnetism into 2D Nonmagnetic Inorganic Layered Crystals: A Brief Review from First-Principles Aspects. Crystals, 8(1), 24. https://doi.org/10.3390/cryst8010024Rinnakkaistallennettu versioAcademic Dissertation to be presented with the assent of the Faculty of Science, University of Oulu for public discussion in the Auditorium Saalastinsali, on September 12th, 2018, at 12 o’clock noon.Abstract
This thesis is dedicated to realizations and physical understanding of electronic and photocatalytic properties after decorating transition metals to the semiconducting molybdenum disulfide. Synthesized via facile wet chemical methods, the MoS₂-Au, MoS₂-Au-Ni and MoS₂-Ag-Ni composites were formed as binary or ternary compounds. The Au nanoparticles are stably joined to the MoS₂ matrix without deteriorating layered structures of the host. After introducing the Au nanoglue as a common buffer, a metallic contact is reached between Ni and MoS₂, and attributed to new electron migration channel via MoS₂ edge contact. Adapting the Ag as the buffer element can attach the Ni to the basal plane of the MoS₂ beside edge contact. The Ni-Ag-MoS₂ composite effectively splits water under visible light irradiation and produce hydrogen. The excellent photocatalytic activity is attributed to effective charge migration through dangling bonds at the MoS2-Ag-Ni alloy interface and the activation of MoS₂ basal planes
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
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