The heterogeneity of stem cells represents the main challenge in regenerative medicine development. This issue is particularly pronounced when it comes to the use of primary mesenchymal stem/stromal ...cells (MSCs) due to a lack of identification markers. Considering the need for additional approaches in MSCs characterization, we applied Raman spectroscopy to investigate inter-individual differences between bone marrow MSCs (BM-MSCs). Based on standard biological tests, BM-MSCs of analyzed donors fulfill all conditions for their characterization, while no donor-related specifics were observed in terms of BM-MSCs morphology, phenotype, multilineage differentiation potential, colony-forming capacity, expression of pluripotency-associated markers or proliferative capacity. However, examination of BM-MSCs at a single-cell level by Raman spectroscopy revealed that despite similar biochemical background, fine differences in the Raman spectra of BM-MSCs of each donor can be detected. After extensive principal component analysis (PCA) of Raman spectra, our study revealed the possibility of this method to diversify BM-MSCs populations, whereby the grouping of cell populations was most prominent when cell populations were analyzed in pairs. These results indicate that Raman spectroscopy, as a label-free assay, could have a huge potential in understanding stem cell heterogeneity and sorting cell populations with a similar biochemical background that can be significant for the development of personalized therapy approaches.
Ion beam irradiation is a versatile tool for structural modification and engineering of new materials. In this study, 12‐tungstophosphoric acid (WPA) films of different thickness were spin‐coated on ...platinized silicon substrate and irradiated with low energy hydrogen ions (10 keV) and swift heavy ions (Bi, Xe, and V) with energies up to 710 MeV. The different energy/fluence combinations allowed controllable structural changes that were investigated in detail using Raman and Infrared spectroscopy. For 120‐nm‐thick WPA samples, the irradiation led to the decrease of intensity of the skeletal and W‐Oc‐W bands of Keggin anion in order: Bi < V < Xe (for their applied energy/fluence combination). Also, symmetry change of Keggin anion similar to the one observed in the case of Keggin anions interacting with the supports was observed. For the selected ion beam irradiation parameters, xenon ion beam induced transformation of WPA to polytungstate. For 20‐μm‐thick WPA samples, the irradiation with hydrogen ion beam induced changes of skeletal vibrations and increased individualistic behavior of Keggin anions. As the fluence increased, the amount of the Keggin anions partially transformed to bronze also increased. Irradiation with vanadium also caused transformation to bronze‐like structure but with higher ratio of terminal W=Od bonds. The overall results show clear correlation between degree of structural modification of WPA and the calculated displacement per atom value. These results open possibilities for engineering new catalytically active structures of polyoxometalates with the help of ion beams.
In this study, 12‐tungstophosphoric acid (WPA) films (120 nm and 20 μm) were irradiated with hydrogen (10 keV) and swift heavy ions (Bi, Xe, and V, up to 710 MeV). The different energy/fluence combinations allowed controllable changes, from breaking of symmetry to bronze‐like structures, that were investigated in detail using Raman and Infrared spectroscopy. Structural changes of ion beam irradiated WPA might be beneficial for application in catalysis where the engineered structures can produce additional active sites for different reactions.
The discovery of superconductivity in FeSe led to a new subclass of high-temperature superconductors ? iron chalcogenides. Materials from this group exhibit variety of specific features, from ...superconductivity with relatively high critical temperatures to low-dimensional magnetic properties. This review presents the most important results regarding the iron chalcogenides, with special emphasis on their vibrational properties investigated by means of Raman spectroscopy. Temperature- and/or doping-dependent Raman scattering spectra of iron chalcogenides provide a valuable insight into the complex relationships between the vibrational, electronic and magnetic properties of these materials. The results presented in this review demonstrated that Raman spectroscopy provides new insights which may significantly improve our understanding of the fundamental properties of iron chalcogenides.
We report temperature‐dependent Raman scattering and magnetization studies of van der Waals ferromagnetic compound CrSi0.8Ge0.1Te3. Magnetic susceptibility measurements revealed dominant ...ferromagnetic interactions below TC which shift to the lower values due to the presence of vacancies. A Raman active mode, additional to the ones predicted by symmetry in the parent compounds, has been observed. This Ag symmetry mode most likely emerges as a consequence of the atomic vacancies on Si/Ge site. Presence of the strong spin–phonon coupling at temperature around 210 K is indicated by deviations from conventional phonon self‐energy temperature dependence of all analysed modes.
We report temperature‐dependent Raman scattering and magnetization studies of van der Waals ferromagnetic compound CrSi0.8Ge0.1Te3. Magnetic susceptibility measurements revealed dominant ferromagnetic interactions below TC which shift to the lower values due to the presence of vacancies.
The scope of this paper is temperature dependence of Raman spectra in several nanocrystalline materials and iron‐based single‐crystals. The Raman results presented and analyzed here are related to ...TiO2 nanopowders (with dominant anatase and brookite phase) and ZnxCd1−xSe single layers measured at different temperatures. Temperature‐dependent Raman spectra of iron‐based sulphides and selenides (BaFe2S3 and BaFe2Se3), as well as alkali‐doped iron selenides (KxFe2−ySe2 and K0.8Fe1.8Co0.2Se2) are also analyzed. A physical model, including thermal expansion as well as three‐ and four‐phonon anharmonic effects, is used to quantitatively analyze temperature evolution of the characteristic Raman mode self‐energies for the materials of interest. It is demonstrated how this model can be used as a tool for predicting the temperature of structural and phase transitions, with critical scrutany of its limitations.
Presented results show how temperature‐dependent Raman scattering measurements could be used in the analysis of temperature variation of structural, morphological, compositional, electronic, and/or magnetic material properties. A model including quasiharmonical and anharmonical contributions is used to quantitatively analyze experimental temperature dependence of energy and linewidth of the characteristic Raman modes of nanostructured and iron‐based materials.
Abstract
We report temperature‐dependent Raman scattering and magnetization studies of van der Waals ferromagnetic compound CrSi
0.8
Ge
0.1
Te
3
. Magnetic susceptibility measurements revealed ...dominant ferromagnetic interactions below
T
C
which shift to the lower values due to the presence of vacancies. A Raman active mode, additional to the ones predicted by symmetry in the parent compounds, has been observed. This
A
g
symmetry mode most likely emerges as a consequence of the atomic vacancies on Si/Ge site. Presence of the strong spin–phonon coupling at temperature around 210 K is indicated by deviations from conventional phonon self‐energy temperature dependence of all analysed modes.
We present a single-step route to generate ordered nanocomposite thin films of secondary phase inclusions (Mn3O4) in a pristine perovskite matrix (LaMnO3) by taking advantage of the complex phase ...diagram of manganese oxides. We observed that in samples grown under vacuum growth conditions from a single LaMnO3 stoichiometric target by Pulsed Laser Deposition, the most favourable mechanism to accommodate Mn2+ cations is the spontaneous segregation of self-assembled wedge-like Mn3O4 ferrimagnetic inclusions inside a LaMnO3 matrix that still preserves its orthorhombic structure and its antiferromagnetic bulk-like behaviour. A detailed analysis on the formation of the self-assembled nanocomposite films evidences that Mn3O4 inclusions exhibit an epitaxial relationship with the surrounding matrix that it may be explained in terms of a distorted cubic spinel with slight (~9º) c-axis tilting. Furthermore, a Ruddlesden-Popper La2MnO4 phase, helping to the stoichiometry balance, has been identified close to the interface with the substrate. We show that ferrimagnetic Mn3O4 columns influence the magnetic and transport properties of the nanocomposite by increasing its coercive field and by creating local areas with enhanced conductivity in the vicinity of the inclusions.
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