Search results for "absorption spectroscopy"
showing 10 items of 828 documents
Microstructure and magnetic properties of colloidal cobalt nano-clusters
2010
The magnetic response of nanometer sized Co nanoparticles (NP) prepared using reverse micelle solutions are presented. The use of complementary structural and morphological probes (like transmission electron microscopy, high resolution electron microscopy, X-ray absorption spectroscopy) allowed to relate the magnetic properties to the size, morphology, composition and atomic structure of the nanoparticles. All data agree on the presence of a coreshell structure of NPs made of a metallic Co core surrounded by a thin Co-oxide layer. The coreshell microstructure of NPs affects its magnetic response mainly raising the anisotropy constant. (C) 2010 Elsevier B.V. All rights reserved.
Al driven peculiarities of local coordination and magnetic properties in single phase Alx CrFeCoNi high entropy alloys
2021
The authors thank the Helmholtz-Zentrum Berlin for the provision of access to synchrotron radiation facilities and allocation of synchrotron radiation at the PM2-VEKMAG, BAMline, and UE46_PGM-1 beamlines of BESSY II at HZB as well as measurement time for magnetometry at HZB CoreLab for Quantum Materials. A. S. acknowledges personal funding from CALIPSOplus project (the Grant Agreement no. 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020). The financial support for the VEKMAG project and the PM2-VEKMAG beamline by the German Federal Ministry for Education and Research (Nos. BMBF 05K10PC2, 05K10WR1, 05K10KE1) and by HZB is cordially acknowledged by all co-author…
Infrared laser threshold magnetometry with a NV doped diamond intracavity etalon
2019
International audience; We propose a hybrid laser system consisting of a semiconductor external cavity laser associated to an intra-cavity diamond etalon doped with nitrogen-vacancy color centers. We consider laser emission tuned to the infrared absorption line that is enhanced under the magnetic field dependent nitrogen-vacancy electron spin resonance and show that this architecture leads to a compact solid-state magnetometer that can be operated at room-temperature. The sensitivity to the magnetic field limited by the photon shot-noise of the output laser beam is estimated to be less than 1 pT/ √ Hz. Unlike usual NV center infrared magnetometry, this method would not require an external f…
Role of Shallow Electron Traps in the Fast Transient Optical Phenomena of Alkali Halide Crystals
2002
We present additional evidences that the same shallow electron traps-atomic alkali impurity centres [M + ] c 0 e - are responsible for both classes (A and B) of the transient IR-absorption bands: (A) bands with maximum at 0.27-0.36 eV in NaCl, KCl, KBr, KI and RbCl (due to shallow electron traps or bound polarons) and (B) bands with maximum at 0.15-0.36 eV in NaI, NaBr, NaCl:I, KCl:I, KBr:I, RbCl:I and RbBr:I (due to on-centre STE or on-centre STE localised at iodine dimer). Both classes of the IR bands have the same location, similar shape (both exactly coincide for KCl:I and KCl at 10 or 80 K), half-width, vibration structure. It is established that the same Mollwo-Ivey plot curves E o =a…
The influence of Zn$^{2+}$ ions on the local structure and thermochromic properties of Cu$_{1-x}$Zn$_x$MoO$_4$ solid solutions
2021
I. P., A. K. and A. K. would like to thank the support of the Latvian Council of Science project No. lzp-2019/1-0071. I.P. acknowledges the L‘OREAL Baltic “For Women In Science” Program with the support of the Latvian National Commission for UNESCO and the Latvian Academy of Sciences. The experiment at the PETRA III synchrotron was performed within project No. I-20190277 EC. The synchrotron experiments have been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2…
Calculation of vibrationally resolved absorption and fluorescence spectra of the rylenes
2020
A generating function method was used to simulate the vibrationally resolved absorption and emission spectra of perylene, terrylene and quaterrylene. This method operates on the basis of adiabatic excitation energies and electronic ground and excited state vibrational frequencies. These parameters were calculated using density functional theory with the PBE0 functional for perylene and terrylene and with the BH-LYP functional for quaterrylene. The vertical excitation energies of the lower excited states were calculated using functionals with differing amounts of Hartree-Fock exchange. The optimal functional for each molecule was chosen by comparing these energies to literature excitation en…
Synthesis and characterization of GaN/ReS2, ZnS/ReS2 and ZnO/ReS2 core/shell nanowire heterostructures
2020
This research was funded by the ERDF project “Smart Metal Oxide Nanocoatings and HIPIMS Technology”, project number: 1.1.1.1/18/A/073. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².
Local structure relaxation in nanocrystalline Ni1−xO thin films
2014
Abstract Non-stoichiometric nickel oxide (Ni 1 − x O) thin films were prepared by DC magnetron sputtering technique in mixed Ar/O 2 atmosphere and studied by synchrotron radiation Ni K-edge x-ray absorption spectroscopy, x-ray diffraction and scanning electron microscopy. The use of advanced modelling technique, combining classical molecular dynamics with ab initio multiple-scattering extended x-ray absorption fine structure calculations, allowed us to describe the structure relaxation and dynamics in nanocrystallites and to estimate their size and the concentration of nickel vacancies.
Metal-free organic dyes with di(1-benzothieno)[3,2-b:2′,3′-d]pyrrole as an auxiliary donor for efficient dye-sensitized solar cells: Effect of the mo…
2019
Abstract A series of novel di(1-benzothieno)[3,2-b:2′,3′-d]pyrrole (DBTP)-based organic dyes (WL5-10) with D-D-π-A or D-D-A-π-A configurations are designed and the relationship between the properties and molecular configurations of these organic dyes are studied systematically. WL5,7–8 with D-D-π-A configuration incorporating triphenylamine or phenothiazine as donor and DBTP as auxiliary donor and WL9-10 with D-D-A-π-A configuration incorporating benzothiadiazole as an auxiliary acceptor are synthesized to study the effect of the molecular engineering on the photovoltaic performance. WL5,7–8 exhibit similar absorption spectra and high molar extinction coefficient. Especially, the dye WL5 wi…
Dithienopyrrolobenzothiadiazole-based organic dyes for efficient dye-sensitized solar cells
2014
Four novel D–π–A metal-free organic dyes DTP1–4 containing a dithienopyrrolobenzothiadiazole (DTPBT) unit were synthesized and applied in dye-sensitized solar cells, where DTPBT was employed as a π-spacer for the first time. The photophysical, electrochemical and photovoltaic properties of the dyes were systematically investigated. The dyes DTP1–4 showed broad absorption spectra and high molar extinction coefficient, resulting in high light harvesting efficiency. In addition, the impacts of donors and the thiophene unit as an additional π-spacer were also studied. The results showed that the dye DTP4 with triphenylamine as the donor exhibited better photovoltaic performance than DTP1–3 with…