65 research outputs found
Raman spectroscopy study of the switchable phases metal-organic frameworks DUT-8(Ni)
Acknowledgments: I.S.,V.B., S.K. thank the DFG for financial support (FOR 2433); A.K., S.K., A.V. thank the Russian Foundation for Basic Research for financial support (18-02-00754)
Cubic to cubic phase transition in (NH4)3SnF7 ferroelastic crystal β Raman scattering study
This work was supported by Russian Foundation for Basic Research (Grant N 17-02-00920)
Nature of phase transitions in ammonium oxofluorovanadates, a vibrational spectroscopy study of (NH4)3VO2F4 and (NH4)3VOF5
Two ammonium oxofluorovanadates, (NH4)3VO2F4 and (NH4)3VOF5, have been in-vestigated by temperature-dependent infrared and Raman spectroscopy methods to determine the nature of phase transitions (PT) in these compounds. Dynamics of quasioctahedral groups was simulated within the framework of semi-empirical approach, which justified the cis-conformation of VO2F43β (C2v) and the C4v geometry of VOF53β. The observed infrared and Raman spectra of both compounds at room temperature (RT) revealed the presence at least of two crystallographically independent octahedral groups. The first order PT at elevated temperatures is connected with a complete dynamic disordering of these groups with only single octahedral state. At lower temperatures, the octahedra are ordered and several octahedral states appear. This PT is the most pronounced in the case of (NH4)3VOF5, when at least seven independent VOF53β octahedra are present in the structure below 50 K, in accordance with the Raman spec-tra. Ammonium groups do not take part in PTs at higher and room temperatures but their reorientational motion freezes at lower temperatures
Magnon mode in Ξ±βMnS Raman spectrum
ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ ΡΠΏΠ΅ΠΊΡΡΡ ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ ΡΠ°ΡΡΠ΅ΡΠ½ΠΈΡ ΠΌΠΎΠ½ΠΎΡΡΠ»ΡΡΠΈΠ΄Π° ΠΌΠ°ΡΠ³Π°Π½ΡΠ° (Ξ±βMnS) ΡΠΎ ΡΡΡΡΠΊΡΡΡΠΎΠΉ NaCl Π² ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΠΎΠΌ ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»Π΅ 5β300 Π. ΠΡΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
ΡΠ΅ΠΌΠΏΠ΅ΠΏΠ΅ΡΠ°ΡΡΡΠ°Ρ
ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ Π½ΠΎΠ²ΡΠΉ ΠΏΠΈΠΊ 22 cmβ1. Π’Π΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½Π°Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΡΡΠΎΠ³ΠΎ ΠΏΠΈΠΊΠ° ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΎΡΠ½Π΅ΡΡΠΈ Π΅Π³ΠΎ ΠΊ ΠΌΠ°Π³Π½ΠΎΠ½Π½ΠΎΠΉ ΠΌΠΎΠ΄Π΅ ΠΏΡΠΈ k = 0. ΠΡΠΎ Ρ
ΠΎΡΠΎΡΠΎ ΡΠΎΠ³Π»Π°ΡΡΠ΅ΡΡΡ Ρ Π²ΠΎΠ»Π½ΠΎΠ²ΡΠΌ ΡΠΈΡΠ»ΠΎΠΌ ΠΌΠ°Π³Π½ΠΎΠ½Π°, ΡΠ°ΡΡΡΠΈΡΠ°Π½Π½ΠΎΠ³ΠΎ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠ½ΠΎΠ³ΠΎ ΠΏΠ°ΠΊΠ΅ΡΠ° Munich SPRKKR
Polarized Raman spectroscopy of delta-BiB3O6 at 7β350 K
BiB3O6 crystal has been characterized by Raman spectroscopy. Polarized low-frequency spectra have been obtained. Temperature measurements have been carried out in range 7β350 K. Raman spectra have been numerically simulated with lady software package. The results of experiment confirmed the contribution of the Bi3+ ions and BO4 groups in nonlinear optical properties of BiB3O6. The studied crystal is a promising medium for up- and down-Raman laser-frequency converters
Polarized Raman spectroscopy of delta-BiB3O6 at 7β350 K
BiB3O6 crystal has been characterized by Raman spectroscopy. Polarized low-frequency spectra have been obtained. Temperature measurements have been carried out in range 7β350 K. Raman spectra have been numerically simulated with lady software package. The results of experiment confirmed the contribution of the Bi3+ ions and BO4 groups in nonlinear optical properties of BiB3O6. The studied crystal is a promising medium for up- and down-Raman laser-frequency converters
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