51. Characterization of electrochemical processes in metal-organic batteries by X-ray Raman spectroscopyMartin Sundermann, Hlynur Gretarsson, Robert Dominko, Urban Košir, Jan Bitenc, Alen Vižintin, Marko Petric, Matjaž Žitnik, Klemen Bučar, Iztok Arčon, Ava Rajh, Matjaž Kavčič, 2022, izvirni znanstveni članek Opis: X-ray Raman spectroscopy (XRS) is an emerging
spectroscopic technique that utilizes inelastic scattering of hard Xrays
to study X-ray absorption edges of low Z elements in bulk
material. It was used to identify and quantify the amount of
carbonyl bonds in a cathode sample, in order to track the redox
reaction inside metal−organic batteries during the charge/
discharge cycle. XRS was used to record the oxygen K-edge
absorption spectra of organic polymer cathodes from different
multivalent metal−organic batteries. The amount of carbonyl bond
in each sample was determined by modeling the oxygen K-edge
XRS spectra with the linear combination of two reference compounds that mimicked the fully charged and the fully discharged
phases of the battery. To interpret experimental XRS spectra, theoretical calculations of oxygen K-edge absorption spectra based on
density functional theory were performed. Overall, a good agreement between the amount of carbonyl bond present during different
stages of battery cycle, calculated from linear combination of standards, and the amount obtained from electrochemical
characterization based on measured capacity was achieved. The electrochemical mechanism in all studied batteries was confirmed to
be a reduction of double carbonyl bond and the intermediate anion was identified with the help of theoretical calculations. X-ray
Raman spectroscopy of the oxygen K-edge was shown to be a viable characterization technique for accurate tracking of the redox
reaction inside metal−organic batteries.
Najdeno v: ključnih besedah
Ključne besede: X-ray Raman spectroscopy, meta-organic batteries, oxygen K-edge XANES, electrochemical processes
Objavljeno: 24.03.2022; Ogledov: 836; Prenosov: 14
 Polno besedilo (1,75 MB)
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52. Monitoring of chemical processes at the atomic level by X-ray absorption spectrometry using extremely bright synchrotron radiation sourcesIztok Arčon, vabljeno predavanje na konferenci brez natisa Opis: X-ray absorption spectroscopy (XAS) is a powerful tool for characterisation of local structure and chemical state of selected elements in different new functional materials and biological or environmental samples. The XAS spectroscopy is based on extremely bright synchrotron radiation X-rays sources, which allow precise characterisation of bulk, nanostructured or highly diluted samples. The rapid development of extremely bright synchrotron sources of X-ray and ultraviolet light in recent years has opened new possibilities for research of matter at the atomic or molecular level, indispensable in the development of new functional nanostructured materials with desired properties. The lecture will present the possibilities offered by X-ray absorption spectroscopy with synchrotron light for ex-situ and in-situ or operando characterization of various functional porous and other nanomaterials before, after and during their operation. With the operando micro-XANES and EXAFS methods it is possible to track changes in the valence states and local structures of selected elements in different energy storage materials or in various (photo)catalysts, during chemical reactions under controlled reaction conditions, thus gaining insight into the dynamic functional properties and reaction mechanisms of these materials. New synchrotron light sources also opened the possibility of combining X-ray absorption or emission spectroscopy and microscopy with a resolution of up to a few tens of nanometres, crucial for analysis of environmental and biological samples on sub-cellular level, to understand the mechanisms of uptake, transport, accumulation, and complexation of metal cations on subcellular level in various plant tissues or accumulation in environment, to develop effective remediation approaches.
Najdeno v: ključnih besedah
Povzetek najdenega: ...X-ray absorption spectroscopy (XAS) is a powerful tool for characterisation...
Ključne besede: X-ray absorption spectroscopy, EXAFS, XANES, synchrotron radiation sources, operando
Objavljeno: 15.12.2021; Ogledov: 902; Prenosov: 0
Polno besedilo (287,07 KB) |
53. Ultrafast relaxation of photoexcited superfluid He nanodropletsD.M. Neumark, A. Hernando, O. Gessner, C. Grazioli, P. Finetti, M. Drabbels, M. Di Fraia, M. Devetta, A. Demidovich, M. Coreno, C. Callegari, A. Ciavardini, P. O'Keeffe, M. Mudrich, A.C. LaForge, Y. Ovcharenko, P. Piseri, O. Plekan, K.C. Prince, R. Richter, M.P. Ziemkiewicz, T. Moller, J. Eloranta, M. Pi, M. Barranco, F. Stienkemeier, 2020, izvirni znanstveni članek Najdeno v: ključnih besedah
Povzetek najdenega: ...density functional theory, dipole, excitation, ionization, photoelectron spectroscopy, photoexcitation, photon, simulation, ultraviolet radiation, ultrafast photoemis...
Ključne besede: helium, helium nanodroplet, nanomaterial, density functional theory, dipole, excitation, ionization, photoelectron spectroscopy, photoexcitation, photon, simulation, ultraviolet radiation, ultrafast photoemission, free electron laser, ultrafast spectrscopy
Objavljeno: 20.01.2022; Ogledov: 895; Prenosov: 0
Polno besedilo (2,39 MB) |
54. Experimental and Theoretical Photoemission Study of Indole and Its Derivatives in the Gas PhaseO. Plekan, H. Sa'adeh, A. Ciavardini, C. Callegari, G. Cautero, C. Dri, M. Di Fraia, K.C. Prince, R. Richter, R. Sergo, L. Stebel, M. Devetta, D. Faccialà, C. Vozzi, L. Avaldi, P. Bolognesi, M.C Castrovilli, D. Catone, M. Coreno, F. Zuccaro, E. Bernes, G. Fronzoni, D. Toffoli, 2020, izvirni znanstveni članek Najdeno v: ključnih besedah
Povzetek najdenega: ...of gases, Ionization potential, Molecular orbitals, Photoelectron spectroscopy, Photoelectrons, Photoemission, Photoionization, Photons, Polycyclic aromatic hy...
Ključne besede: Binding energy, Calculations, Core levels, Electronic structure, Ionization of gases, Ionization potential, Molecular orbitals, Photoelectron spectroscopy, Photoelectrons, Photoemission, Photoionization, Photons, Polycyclic aromatic hydrocarbons, X rays
Objavljeno: 21.01.2022; Ogledov: 907; Prenosov: 0
Polno besedilo (2,23 MB) |
55. Structure and population of complex ionic species in FeCl[sub]2 aqueous solution by X-ray absorption spectroscopyMatjaž Valant, Iztok Arčon, Uroš Luin, 2022, izvirni znanstveni članek Opis: Technologies for mass production require cheap and abundant materials such as ferrous chloride (FeCl2). The literature survey shows the lack of experimental studies to validate theoretical conclusions related to the population of ionic Fe-species in the aqueous FeCl2 solution. Here, we present an in situ X-ray absorption study of the structure of the ionic species in the FeCl2 aqueous solution at different concentrations (1–4 molL−1) and temperatures (25–80 ◦C). We found that at low temperature and low FeCl2 concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five water molecules at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical water molecule is substituted by a chlorine ion to yield a neutral Fe[Cl2(H2O)4]0. The observed substitutional mechanism is facilitated by the presence of the intramolecular hydrogen bonds as well as entropic reasons. The transition from the single charged Fe[Cl(H2O)5]+ to the neutral Fe[Cl2(H2O)4]0 causes a significant drop in the solution conductivity, which well correlates with the existing conductivity models.
Najdeno v: ključnih besedah
Ključne besede: structure, population, ionic species, aqueous ferrous chloride, in situ X-ray absorption spectroscopy
Objavljeno: 24.01.2022; Ogledov: 873; Prenosov: 26
 Polno besedilo (0,00 KB)
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56. Order fluctuation induced tunable light emission from carbon nano systemSankararaman S, Swapna Mohanachandran Nair Sindhu, 2019, izvirni znanstveni članek Opis: The paper reports the thermal-induced order fuctuations, in a carbon nanosystem with carbon nanotubes (CNTs) synthesized
by the incomplete combustion of gingelly oil. The sample annealed at diferent temperatures (30–400 °C) is subjected to
various morphological and spectroscopic characterizations. The ultraviolet–visible spectroscopic and thermogravimetric
analyses reveal the CNTs in the sample. The high-resolution transmission electron microscopy (HR-TEM) also confrms the
formation of CNTs in the sample. The Raman spectrum and X-ray difraction pattern show the signature of multi-walled
to single-walled CNT transformation and thus an order fuctuation on annealing. The quantum yield of the sample, measured by integrating sphere method, yields 46.15% at an emission wavelength of 575 nm. When the excitation wavelength
is varied from 350 to 510 nm, the CIE coordinate moves from the white region to the yellowish-green region. The varying
amount of CNTs in the soot, upon annealing is found to vary the luminescence emission from the sample. The study reveals
the thermal-induced oscillatory order in carbon nanosystem with carbon nanotubes (CNTs) leading to tunable excitation/
thermal-dependent luminescence emission and thereby suggesting the possibility of converting the futile soot for fruitful
applications in photonics and nanoelectronics.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Raman spectroscopy,Thermogravimetric analysis, CIE plot, Quantum yield, gingelly oil...
Ključne besede: Carbon nanosystem, Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Raman spectroscopy, Thermogravimetric analysis, CIE plot, Quantum yield, gingelly oil
Objavljeno: 05.07.2022; Ogledov: 334; Prenosov: 0
Polno besedilo (1,82 MB) |
57. Particulate Exhaust Analysis from Internal Combustion EnginesSwapna Mohanachandran Nair Sindhu, 2017, kratki znanstveni prispevek Opis: Today the world is worried over the particulate emission from various forms of internal combustion engines. The present work is an attempt to understand the constituents of the particulate emission and its possible use. The particulate exhaust matter containing carbonaceous soot produced from the combustion of
fuel containing hydrocarbons shows the presence of significant amount of carbon Nanomaterials. Hydrocarbons are the most widespread precursors among carbon sources employed in the production of carbon nanotubes (CNTs) and carbon
nanoparticles (CNPs). Carbon nanotubes find application in fuel cells providing improved performance. The soot particles collected from the internal combustion diesel engines are cleaned, powdered and analyzed by various techniques. The
CNPs are characterized by Field Emission Scanning Electron Microscopy (FESEM), X-Ray Powder Diffraction (XRD), Energy Dispersive X ray diffraction (EDS), Raman Spectroscopy, Photoluminescence spectroscopy (PL), Power spectrum and CIE
plot. X Ray Diffraction and Raman spectroscopic analysis show the presence of carbon nanotubes in the amorphous materials.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Energy Dispersive X ray diffraction (EDS), Raman Spectroscopy, Photoluminescence spectroscopy (PL), Power spectrum and CIE...
Ključne besede: HydrocarbonsL Carbon nanotubes, Diesel engines, CIE plot, EDX, Raman spectroscopy
Objavljeno: 30.06.2022; Ogledov: 397; Prenosov: 0
Polno besedilo (672,31 KB) |
58. Acclimatisation through thermal diffusivity tuning of coconut oil – A mode mismatched dual-beam thermal lens studySwapna Mohanachandran Nair Sindhu, 2022, izvirni znanstveni članek Opis: Background: Ayurvedic medicinal oils traditionally prepared by blending herbal extracts in different
compositions are commonly used for treatment and improving health. The estimation of the thermal
properties of medicinal oils is essential for practical applications.
Objective: The present work aims to expound the ability of medicinal oils for the acclimatization of body
temperature by determining its thermal diffusivity and thereby providing a validation to the traditional
knowledge.
Materials and methods: The medicinal oils are prepared by incorporating black pepper (Piper nigrum),
aloe vera (Aloe barbadensis), hibiscus bud (Hibiscus rosa-sinensis) and Ocimum sanctum in coconut oil
base. The samples are subjected to thermal diffusivity study using the mode-mismatched dual-beam
thermal lens technique.
Results: The study reveals that the incorporation of black pepper (Piper nigrum), having hot potency
(Ushna veerya), to the base fluid lowers the thermal diffusivity value, suggesting its potential in heat-trapping. The addition of aloe vera (Aloe barbadensis), hibiscus bud (Hibiscus rosa-sinensis), and
O. sanctum dissipates heat energy quickly, thus increases the thermal diffusivity of coconut oil revealing a
cold potency (Sheeta veerya). The study provides a validation for traditional knowledge and delineates
the possiblity of thermal diffusivity tuning of the base fluids.
Conclusion: The thermal diffusivity tuning through incorporation of herbal extracts can effectively be
used to acclimatize the human body temperature with the surroundings. A higher thermal diffusivity
value induces a cooling effect and the lower value causes heating effect. This, opens up the possibility of
using thermally tuned oils depending on climate and geographical location.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Ayurveda, Acclimatization, Medicinal oils, Thermal lens spectroscopy
Thermal diffusivity...
Ključne besede: Ayurveda, Acclimatization, Medicinal oils, Thermal lens spectroscopy
Thermal diffusivity
Objavljeno: 04.07.2022; Ogledov: 297; Prenosov: 0
Polno besedilo (998,33 KB) |
59. Concentration-dependent thermal duality of hafnium carbide nanofluid for heat transfer applicationsV. Gokul, Mohanachandran Nair Sindhu Swapna, Vimal Raj, H. V. Saritha Devi, Sankaranarayana Iyer Sankararaman, 2021, izvirni znanstveni članek Opis: he mode mismatch dual-beam thermal lens technique is a sensitive tool for studying the nanofuids’ thermal difusivity in thermal engineering. The work reports
the low-temperature green synthesis of hafnium carbide (HfC) using rice four as a natural carbon precursor and its potential in heat transfer nanofuids by studying the concentration-dependent thermal difusivity. The structure characterisations confirm the formation of HfC, whose refractory nature is revealed through the high thermal stability observed in the thermogravimetric analysis. The Tauc plot analysis shows direct bandgap energy of 2.92 eV. The fuorescence study suggests bluish-pink emission with CIE coordinates (0.271, 0.263). The existence of the critical concentration of HfC in the nanofuid decides its suitability for heat transfer or heat trap applications indicating a concentration-dependent thermal duality. Thus, the study is signifcant as it overcomes the major drawbacks of the existing methods of the synthesis of refractory HfC, using toxic chemical and costly equipment for heat transfer applications.
Najdeno v: ključnih besedah
Ključne besede: hafnium carbide, hydrothermal synthesis, rice flour, thermal lens spectroscopy
Objavljeno: 04.07.2022; Ogledov: 331; Prenosov: 0
Polno besedilo (1,50 MB) |
60. Time series analysis of duty cycle induced randomness in thermal lens systemSwapna Mohanachandran Nair Sindhu, 2020, izvirni znanstveni članek Opis: The present work employs time series analysis, a proven powerful mathematical tool, for investigating the complex molecular dynamics of the thermal lens (TL) system induced by the duty cycle (C) variation. For intensity modulation, TL spectroscopy commonly uses optical choppers. The TL formation involves complex molecular dynamics that vary with the input photothermal energy, which is implemented by varying the duty cycle of the chopper. The molecular dynamics
is studied from the fractal dimension (D), phase portrait, sample entropy (S), and Hurst exponent (H) for different duty cycles. The increasing value of C is found to increase D and S, indicating that the system is becoming complex and less deterministic, as evidenced by the phase portrait analysis. The value of H less than 0.5 conforms the evolution of the TL system to more anti-persistent nature with C. The increasing value of C increases the enthalpy of the system that appears as an increase in full width at half maximum of the refractive index profile. Thus the study establishes that the sample entropy and thermodynamic entropy are directly related.
Najdeno v: ključnih besedah
Povzetek najdenega: ...cycle (C) variation. For intensity modulation, TL spectroscopy commonly uses optical choppers. The TL formation...
Ključne besede: Time series analysis
Fractal analysis
Photothermal lens spectroscopy
Fractal dimension
Hurst exponent
Sample entropy
Objavljeno: 05.07.2022; Ogledov: 337; Prenosov: 0
Polno besedilo (1,30 MB) |
