| 1. |
- Kolczewski, C., et al.
(författare)
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Detailed study of pyridine at the C1s and N1s ionization thresholds : The influence of the vibrational fine structure
- 2001
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 115:14, s. 6426-6437
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Tidskriftsartikel (refereegranskat)abstract
- High resolution, vibrationally resolved, near-edge x-ray absorption fine structure (NEXAFS) spectra at the C 1s and N 1s ionization thresholds of pyridine and deuterated d(5)-pyridine in the gas phase have been recorded. The high resolution of 65 meV (150 meV) at the C s (N 1s) ionization thresholds reveals vibrational structures in the spectra. Detailed ab initio and density functional theory (DFT) calculations were performed to interpret the experimental spectra and to assign the observed peaks. In particular we focused on the previously unexplained intensity ratio for the two components of the C1s -->1 pi* transition. For this transition the vibrational structure is included through a linear coupling model in the DFT calculations and leads to the experimentally observed similar to2:3 intensity ratio between the two pi* components in the C1s spectrum rather than the similar to3:2 ratio obtained without vibrational effects. After inclusion of relaxation effects in the excited states, in addition to the vibrational effects, both theoretical methods yield almost perfect agreement with experiment.
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| 2. |
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| 3. |
- Chen, G., et al.
(författare)
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Energy-Cascaded Upconversion in an Organic Dye-Sensitized Core/Shell Fluoride Nanocrystal
- 2015
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 15:11, s. 7400-7407
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Tidskriftsartikel (refereegranskat)abstract
- Lanthanide-doped upconversion nanoparticles hold promises for bioimaging, solar cells, and volumetric displays. However, their emission brightness and excitation wavelength range are limited by the weak and narrowband absorption of lanthanide ions. Here, we introduce a concept of multistep cascade energy transfer, from broadly infrared-harvesting organic dyes to sensitizer ions in the shell of an epitaxially designed core/shell inorganic nanostructure, with a sequential nonradiative energy transfer to upconverting ion pairs in the core. We show that this concept, when implemented in a core-shell architecture with suppressed surface-related luminescence quenching, yields multiphoton (three-, four-, and five-photon) upconversion quantum efficiency as high as 19% (upconversion energy conversion efficiency of 9.3%, upconversion quantum yield of 4.8%), which is about ∼100 times higher than typically reported efficiency of upconversion at 800 nm in lanthanide-based nanostructures, along with a broad spectral range (over 150 nm) of infrared excitation and a large absorption cross-section of 1.47 × 10-14 cm2 per single nanoparticle. These features enable unprecedented three-photon upconversion (visible by naked eye as blue light) of an incoherent infrared light excitation with a power density comparable to that of solar irradiation at the Earth surface, having implications for broad applications of these organic-inorganic core/shell nanostructures with energy-cascaded upconversion.
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| 6. |
- Minkov, Ivaylo, et al.
(författare)
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Core-excitations of naphthalene : Vibrational structure versus chemical shifts
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 121:12, s. 5733-5739
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Tidskriftsartikel (refereegranskat)abstract
- The initial state chemical shifts and vibrational fine structure of core excitations of naphthalene were analyzed using high-resolution x-ray photoelectron emission (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectra. The carbon atoms at peripheral sites were found to experience a small chemical shift and exhibit similar charge-vibrational coupling. The C-H stretching modes provide significant contributions to overall shape of spectra in the XPS spectra. The results show that vibrational fine structure dominates by particular C-C stretching modes, and in XPS of C2 and C3 sites also by high-energy C-H stretching modes.
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| 7. |
- Moiseenko, V. E., et al.
(författare)
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Stellator research at IPP KIPT : Status and prospects
- 2019
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Ingår i: PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. - : KHARKOV INST PHYSICS & TECHNOLOGY. - 1562-6016. ; :1, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- Features of the recent Uragan-2M campaign are reviewed together with some theoretical advances. They include experiments with B4C limiter, studies of various 1. . . 20 kHz oscillations, development of a new in-situ diagnostics for wall conditions, i.e. the thermal desorption probe, the improved numerical model of RF plasma production in stellarators in the ion cyclotron and electron-cyclotron frequency ranges, a new positive-definite form of time-harmonic Maxwell's equations and plasma start-up studies.
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| 8. |
- Plashkevych, O., et al.
(författare)
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Vibronic structure fingerprints in NEXAFS : a theoretical study of 2-mercaptobenzoxazole
- 2000
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Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 327:02-jan, s. 7-12
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Tidskriftsartikel (refereegranskat)abstract
- We use 2-mercaptobenzoxazole to study the notion of vibronic fine structure fingerprints in near-edge X-ray absorption fine structure (NEXAFS). It is shown that connected and non-connected carbons in the phenyl ring of the 2-mercaptobenzoxazole molecule give mutually similar excitation patterns and patterns similar to the one in free benzenewas while the 5-ring carbon is distinctly different in this respect. The simulated vibronic bands give an unambiguous assignment of the full NEXAFS spectrum at the carbon K-edge.
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| 9. |
- Ratke, L., et al.
(författare)
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Lead-free bearing alloys for engine applications results of the ESA-MAP project MONOPHAS
- 2007
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Ingår i: Transactions of the Indian Institute of Metals. - 0019-493X. ; 60:2-3, s. 103-111
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Tidskriftsartikel (refereegranskat)abstract
- Recent developments to reduce fuel consumption, emission and air pollution, size and weight of engines for automotive, truck, ship propulsion and electrical power generation lead to temperature and load conditions within engines that cannot be provided by conventional bearings. Therefore a European project has been established to develop a technically usable aluminium based lead free bearing material with sufficient hardness, wear and friction properties and good corrosion resistance to be produced with semi-continuous casting process. The paper describes the scientific challenges, approaches to tackle the solidification and casting problems and presents some illustrative research results.
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