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| 2. |
- Baranovskiy, A. E., et al.
(författare)
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Electronic structure, bulk and magnetic properties of MB6 and MB12 borides
- 2007
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 442:1-2, s. 228-230
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Tidskriftsartikel (refereegranskat)abstract
- The bulk and magnetic properties of MB6 and MB12 were investigated on the basis of first principles electronic structure calculations. The elastic constants were measured for ZrB12, HoB12, ErB12, TmB12, LuB12, YB6 and LaB6 compounds at low temperatures. The calculated equations of states and balanced crystal orbital overlap populations have allowed to analyse bonding and magnetic properties of MB6 and MB12 .
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| 3. |
- Grechnev, G. E., et al.
(författare)
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Electronic structure and bulk properties of MB6 and MB12 borides
- 2008
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 34:11, s. 921-929
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio band structure calculations are carried out for the higher borides MB6 and MB12. High-precision measurements of the elastic constants are performed for the compounds ZrB12, HoB12, ErB12, TmB12, LuB12, YB6 and LaB6 at low temperatures. The bulk properties of the borides are analyzed on the basis of the calculated equations of states and balanced crystal orbital overlap populations. Our calculations indicate that hexaborides with divalent metals, CaB6, SrB6, BaB6, and YbB6, are semiconductors with small energy gaps. The metallic MB6 hexaborides with trivalent M atoms are found to possess larger bulk moduli values. For dodecaborides the bulk moduli are found to be higher for MB12 with increased filling of the conduction band (ZrB12, HfB12, UB12) in comparison with M3+B12 compounds. The total energy calculations for different magnetic configurations in YbB12 point to the possibility of antiferromagnetic coupling between Yb3+ ions.
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| 4. |
- Ignatova, K., et al.
(författare)
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Reversible exchange bias in epitaxial V2O3/Ni hybrid magnetic heterostructures
- 2022
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Ingår i: Journal of Physics. - : Institute of Physics (IOP). - 0953-8984 .- 1361-648X. ; 34:49
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present a temperature and angular dependent study of the structural and magnetic properties in highly crystalline V2O3/Ni/Zr magnetic heterostructure films. Our investigation focuses on the coupling between the ferromagnetic Ni layer and V2O3 layer which undergoes an antiferromagnetic/paramagnetic phase transition coupled to the structural phase transition of the material at around 150 K. Structural investigations using x-ray diffraction reveal highly crystalline films of a quality which has previously not been reported in the literature. The Ni layers display an absence of in-plane magnetic anisotropy owing to the highly textured (1 1 1) layering of the Ni films on the underlying V2O3(0 0 0 1) oriented layer. During the transition we observe a strain related enhancement of the coercivity and the onset of a weak exchange bias for cooling under an external magnetic field. Heating the films to above the transition temperature, the exchange bias in the Ni is removed and can be reversed upon subsequent cooling under an inverted external magnetic field. Using temperature dependent polarized neutron reflectometry we investigate the film structure at the interface, capturing the magnetic and nuclear profiles.
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| 5. |
- da Cruz, Vinicius Vaz, et al.
(författare)
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Nuclear dynamics in resonant inelastic X-ray scattering and X-ray absorption of methanol
- 2019
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 150:23
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Tidskriftsartikel (refereegranskat)abstract
- We report on a combined theoretical and experimental study of core-excitation spectra of gas and liquid phase methanol as obtained with the use of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The electronic transitions are studied with computational methods that include strict and extended second-order algebraic diagrammatic construction [ADC(2) and ADC(2)-x], restricted active space second-order perturbation theory, and time-dependent density functional theory-providing a complete assignment of the near oxygen K-edge XAS. We show that multimode nuclear dynamics is of crucial importance for explaining the available experimental XAS and RIXS spectra. The multimode nuclear motion was considered in a recently developed "mixed representation" where dissociative states and highly excited vibrational modes are accurately treated with a time-dependent wave packet technique, while the remaining active vibrational modes are described using Franck-Condon amplitudes. Particular attention is paid to the polarization dependence of RIXS and the effects of the isotopic substitution on the RIXS profile in the case of dissociative core-excited states. Our approach predicts the splitting of the 2a RIXS peak to be due to an interplay between molecular and pseudo-atomic features arising in the course of transitions between dissociative core- and valence-excited states. The dynamical nature of the splitting of the 2a peak in RIXS of liquid methanol near pre-edge core excitation is shown. The theoretical results are in good agreement with our liquid phase measurements and gas phase experimental data available from the literature. (C) 2019 Author(s).
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| 6. |
- Dahle, Charlotte, et al.
(författare)
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Antibodies against deamidated gliadin peptides identify adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase
- 2010
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Ingår i: Alimentary Pharmacology and Therapeutics. - : Blackwell Publishing Ltd. - 0269-2813 .- 1365-2036. ; 32:2, s. 254-260
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Tidskriftsartikel (refereegranskat)abstract
- Background This study was done to evaluate the diagnostic utility of antibodies against deamidated gliadin peptides compared to traditional markers for coeliac disease. Aim To evaluate diagnostic utility of antibodies against deamidated gliadin peptide (DGP). Methods Sera from 176 adults, referred for endoscopy without previous analysis of antibodies against tissue transglutaminase (tTG) or endomysium (EmA), were retrospectively analysed by ELISAs detecting IgA/IgG antibodies against DGP or a mixture of DGP and tTG, and compared with IgA-tTG and EmA. Seventy-nine individuals were diagnosed with coeliac disease. Results Receiver operating characteristic analyses verified the manufacturers cut-off limits except for IgA/IgG-DGP/ tTG. In sera without IgA deficiency, the sensitivity was higher for IgA/IgG-DGP (0.85-0.87) compared with IgA-tTg (0.76) and EmA (0.61). All tests showed high specificity (0.95-1.00). Eighteen coeliac disease-sera were negative regarding IgA-tTG, nine of which were positive for IgA/IgG-DGP. Sera from coeliac disease-patients greater than70 years were more often negative for IgA-tTG (50%) and IgA/IgG-DGP (36%) than younger patients (15% and 8% respectively) (P less than 0.01). Three of the four IgA-deficient patients were positive in the IgA/IgG-DGP assay. Conclusions In this study of patients unselected regarding IgA-tTg/EmA, thus unbiased in this respect, IgA/IgG-DGP identified adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase. Serology is often negative in elderly patients with coeliac disease; a small bowel biopsy should therefore be performed generously before coeliac disease is excluded.
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| 10. |
- Ignatova, V.A., et al.
(författare)
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Quantification problems in depth profiling of PWR steels using Ar+ ion sputtering and XPS analysis
- 2006
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Ingår i: Microscopy and Microanalysis. ; 12:5, s. 432-437
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Tidskriftsartikel (refereegranskat)abstract
- The oxide scales of AISI 304 formed in boric acid solutions at 300°C and pH = 4.5 have been studied using X-ray photoelectron spectroscopy (XPS) depth profiling. The present focus is depth profile quantification both in depth and chemical composition on a molecular level. The roughness of the samples is studied by atomic force microscopy before and after sputtering, and the erosion rate is determined by measuring the crater depth with a surface profilometer and vertical scanning interferometry. The resulting roughness (20–30 nm), being an order of magnitude lower than the crater depth (0.2–0.5 [mu]m), allows layer-by-layer profiling, although the ion-induced effects result in an uncertainty of the depth calibration of a factor of 2. The XPS spectrum deconvolution and data evaluation applying target factor analysis allows chemical speciation on a molecular level. The elemental distribution as a function of the sputtering time is obtained, and the formation of two layers is observed—one hydroxide (mainly iron–nickel based) on top and a second one deeper, mainly consisting of iron–chromium oxides.
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| 11. |
- Kuklin, A. V., et al.
(författare)
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Strong Topological States and High Charge Carrier Mobility in Tetraoxa[8]circulene Nanosheets
- 2018
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:38, s. 22216-22222
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Tidskriftsartikel (refereegranskat)abstract
- Here we report structural and electronic properties of a new family of two-dimensional covalent metal-free organic frameworks based on tetraoxa[8]circulene with different types of fusing. All nanosheets demonstrate high thermodynamic stability and unique electronic properties depending on the fusing type. Among three types of nanosheets, only two demonstrate semiconducting properties exhibiting 1.37 and 1.84 eV direct band gaps, while another one is found to be a semimetal, which hosts strong topological states and enhances the band gap (∼87 meV) induced by spin-orbit coupling that exceeds by several orders of magnitude that gap in graphene. Tetraoxa[8]circulene-based nanosheets are also predicted to be good organic semiconductors due to a clearly observable quantum confinement effect on the band gap size in oligomers and relatively low effective masses, which result in high carrier mobility. Owing to the versatility of chemical design, these materials have the potential to expand applications beyond those of graphene.
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| 12. |
- Liu, J. -C, et al.
(författare)
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Time-resolved study of recoil-induced rotation by X-ray pump - X-ray probe spectroscopy
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:11, s. 6627-6638
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Tidskriftsartikel (refereegranskat)abstract
- Modern stationary X-ray spectroscopy is unable to resolve rotational structure. In the present paper, we propose to use time-resolved two color X-ray pump-probe spectroscopy with picosecond resolution for real-time monitoring of the rotational dynamics induced by the recoil effect. The proposed technique consists of two steps. The first short pump X-ray pulse ionizes the valence electron, which transfers angular momentum to the molecule. The second time-delayed short probe X-ray pulse resonantly excites a 1s electron to the created valence hole. Due to the recoil-induced angular momentum the molecule rotates and changes the orientation of transition dipole moment of core-excitation with respect to the transition dipole moment of the valence ionization, which results in a temporal modulation of the probe X-ray absorption as a function of the delay time between the pulses. We developed an accurate theory of the X-ray pump-probe spectroscopy of the recoil-induced rotation and study how the energy of the photoelectron and thermal dephasing affect the structure of the time-dependent X-ray absorption using the CO molecule as a case-study. We also discuss the feasibility of experimental observation of our theoretical findings, opening new perspectives in studies of molecular rotational dynamics.
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