Search results for "RAMAN"
showing 10 items of 1328 documents
Spectrally selective holographic optical elements based on a thick polymer medium with diffusional amplification
2000
A thick rigid polymer recording medium with self-amplification of holograms owing to diffusion of phenanthrenequinone molecules was used to find efficient holographic optical elements with high-spectral-selectivity interference filters and multiple demultiplexers. Several examples of practical applications are briefly described in this paper, showing the benefits of such optical elements for the fields of astronomy, spectroscopy and communication technologies.
Host-guest interactions for extracting antibiotics with a γ-cyclodextrin poly(glycidyl-co-ethylene dimethacrylate) hybrid sorbent
2021
Abstract A procedure for the solid-phase extraction of antibiotics (enoxacin, ofloxacin, norfloxacin, ciprofloxacin, and sparfloxacin) in water has been developed. The sorbent used is based on a poly(glycidyl-co-ethylene dimethacrylate) network, whose previously modified surface has been functionalized with γ-cyclodextrin through a click-chemistry reaction. The architecture of the material has been characterized by thermogravimetric analysis, N2 adsorption-desorption, Raman spectroscopy, confocal microscopy, and scanning electron microscopy, showing good capability to be used as a filler for extraction cartridges. The optimization of the extraction methodology shows good intra-day and inter…
Spectroscopic behavior of metal–drug complexes. Infrared spectra of Cu(II) dimer complexes with acetazolamide (H2acm) and an analogue sulfonamide (B-…
1999
Abstract The infrared spectra of the drugs H2acm and B-H2ats, and their copper(II) dimer complexes with stoichiometries [Cu(acm)(NH3)2(OH2)]2·H2O and [Cu(B-ats)(NH3)2]2 are reported and discussed. The Raman spectra of H2acm and B-H2ats are also reported. An assignment of H2acm and B-H2ats modes in the complexes is proposed in comparison with the modes of the free ligands. The spectral modifications due to the deprotonation and coordination effects are analyzed. The ν(N–H) modes of the sulfonamido, carbonamido and Nring–H of the imine tautomer have been accurately assigned. Important information about the S–O and S–N vibrations has been obtained.
Imidazolium functionalized carbon nanotubes for the synthesis of cyclic carbonates: reducing the gap between homogeneous and heterogeneous catalysis
2016
Single walled carbon nanotubes (SWCNTs) were functionalized with imidazolium salts bearing vinyl functionalities. An extremely high loading of active species was achieved through a straightforward one-pot procedure involving self-assembly of the imidazolium moieties followed by radical initiated polymerization of the double bonds. The materials were extensively characterized by transmission electron microscopy, Raman spectroscopy, nitrogen physisorption and combustion chemical analysis. The imidazolium functionalized SWCNTs displayed excellent catalytic activity for the reaction of CO2 and epoxides to produce cyclic carbonates as demonstrated by the excellent turnover numbers (TON). Moreove…
Experimental and theoretical studies on corals. I. Toward understanding the origin of color in precious red corals from Raman and IR spectroscopies a…
2009
An attempt to explain the origin of the vivid red color in precious pink and red corals was undertaken. Raman and IR spectroscopies were applied to characterize white, pink and red corals. The position of the Raman signal near 1500 cm −1 of some corals and pearls was associated by several authors with the presence of the mixture of all-trans-polyenic pigments, containing 6 – 16 conjugated C C bonds or β-carotenoids. This hypothesis was examined theoretically by performing extensive B3LYP-DFT calculations of vibrational spectra of the model polyenic compounds. The B3LYP/6-311++G ∗∗ predicted positions of the dominating Raman mode depend on the number of C Cu nits (Cn parameter) and can be ac…
Dunham coefficients of 14N2 from CARS measurements of high vibrational states in a low-pressure discharge
1988
Spectroscopic constants of the X1Σg+ ground state of 14N2 are deduced from CARS spectra recorded in a 4 Torr d.c. N2 glow discharge. Vibrational states up to ν = 14 have been observed but only the 11 lower levels which have a good signal-to-noise ratio have been processed. The Dunham constants that were deduced yield vibrational band centre positions in good agreement with those of Lofthus and Krupenie.
Elaboration and characterization of organic/inorganic hybrid nanoporous material incorporating Keggin-type Mo-Si polyanions
2007
A novel nanoporous (pore size of 11 nm in average, BET surface area of 30 m2/g, pore volume of 300 mm3/g) hybrid inorganic-organic material was synthesized using the solid-phase interaction at room temperature of plant-originated phenylpropanoid polymer lignin and a Keggin-type heteropolyanion [SiMo12O40]4-. The partly reduction of Mo(VI) to Mo(V) and complexes formation between lignin and polyanion have been established by EPR, FT-IR and Raman spectroscopy. The XRD pattern and FT-IR spectrum of the hybrid material and indicates that [SiMo12O40]4- anion maintains the Keggin structure.
Effects of isotopic substitution on the conformational properties of polymeric aqueous solutions
2000
Abstract This work deals with a side-by-side comparison between the PEO conformational properties in H 2 O and D 2 O. The gyration radius, evaluated by SANS, the hydrodynamic radius, evaluated by PCS, and the Raman D-LAM band analysis furnish valuable information on the structural arrangement of the molecules. The findings clearly show different behavioural properties of the polymer in H 2 O and D 2 O.
Characterisation of the glycosidic linkage by infrared and Raman spectroscopy in the C-H stretching region: α,α-trehalose and α,α-trehalose-2,3,4,6,6…
1991
Abstract I.r. and Raman spectra of solid α,α-trehalose and α,α-trehalose- 2,3,4,6,6-d 10 in the C-H and C-D stretching regions are recorded. The experimental data are reproduced satisfactorily by normal co-ordinate and i.r. absorption intensity calculations which take into account the specific interactions of each C-H hydrogen with nearby oxygen lone-pairs. The relevance of the region 2800–3000 cm −1 in α,α-trehalose- 2,3,4,6,6-d 10 for the study of the conformational properties of the inter-glycosidic linkage is discussed.
Disorder Classification of the Vibrational Spectra of Modern Glasses
2021
Using the coherent-potential approximation in heterogeneous-elasticity theory with a log-normal distribution of elastic constants for the description of the Raman spectrum and the temperature dependence of the specifi?c heat, we are able to reconstruct the vibrational density of states and characteristic descriptors of the elastic heterogeneity of a wide range of glassy materials. These descriptors are the non-affi?ne contribution to the shear modulus, the mean-square fluctuation of the local elasticity, and its correlation length. They enable a physical classification scheme for disorder in modern, industrially relevant glass materials. We apply our procedure to a broad range of real-world…