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papers from the latest issue:
Vibrational spectroscopic study of poly(dimethylsiloxane)-ZnO nanocomposites
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): L. Bistričić , V. Borjanović , L. Mikac , V. Dananić
A series of poly(dimethylsiloxane)-zinc oxide (PDMS-ZnO) nanocomposites having different concentrations of ZnO nanoparticles (0, 1, 5, 10 and 20wt%) have been prepared. Raman and FTIR-ATR spectroscopic analysis was performed in order to determine the interaction between the ZnO nanoparticles and PDMS polymer matrix. Density functional theory (DFT) using the (B3-LYP)/6-311++G(2df,2p) method was used to investigate the vibrational spectra of PDMS. A complete vibrational assignment is supported by the normal coordinate analysis, calculated Raman activities as well as IR intensities. The presence of ZnO nanoparticles in PDMS gives rise to significant differences in relative intensities of the characteristic vibrational bands with respect to the cross-linked polymer. The changes in relative intensities of Raman bands, as well as swelling measurements, were used to explain the effect of ZnO nanoparticles on the cross-linked structure of PDMS nanocomposites. It is established that ZnO nanoparticles influence the cross-linking density of the polymer matrix.
Source:Vibrational Spectroscopy, Volume 68
Author(s): L. Bistričić , V. Borjanović , L. Mikac , V. Dananić
A series of poly(dimethylsiloxane)-zinc oxide (PDMS-ZnO) nanocomposites having different concentrations of ZnO nanoparticles (0, 1, 5, 10 and 20wt%) have been prepared. Raman and FTIR-ATR spectroscopic analysis was performed in order to determine the interaction between the ZnO nanoparticles and PDMS polymer matrix. Density functional theory (DFT) using the (B3-LYP)/6-311++G(2df,2p) method was used to investigate the vibrational spectra of PDMS. A complete vibrational assignment is supported by the normal coordinate analysis, calculated Raman activities as well as IR intensities. The presence of ZnO nanoparticles in PDMS gives rise to significant differences in relative intensities of the characteristic vibrational bands with respect to the cross-linked polymer. The changes in relative intensities of Raman bands, as well as swelling measurements, were used to explain the effect of ZnO nanoparticles on the cross-linked structure of PDMS nanocomposites. It is established that ZnO nanoparticles influence the cross-linking density of the polymer matrix.
Spectroscopic analysis of pigments and inks in manuscripts: I. Byzantine and post-Byzantine manuscripts (10–18th century)
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Irena Nastova , Orhideja Grupče , Biljana Minčeva-Šukarova , Melih Ozcatal , Lenče Mojsoska
Pigments and inks used in six Byzantine manuscripts (covering the period from 10th to 15th century) and one 18th century post-Byzantine manuscript have been analyzed, using micro-Raman spectroscopy, ATR-FT-infrared spectroscopy and SEM–EDS. Micro-Raman spectroscopy allowed fast and in situ analysis of majority of pigments and inks used, except for the purple-red organic pigment, brown-purple ink and metallic pigments (silver and gold). The nature of the organic purple-red pigment and organic purple ink was revealed applying ATR-FTIR. In the analysis of the metallic pigment (silver and gold) as well as additional technique in characterizing organic purple-red dye and ink, SEM–EDS was used. Varieties of inks were used in the manuscripts. Gold and silver inks were used for capital letters and for emphasizing certain paragraphs. Red ink was identified as madder in illuminated manuscripts and as vermilion in simple texts. Gall ink was identified as black-brown ink in most of the manuscripts. In 18th century manuscript logwood was identified while in the 12th century manuscript, goethite was used as ink. The analysis of the pigments and inks revealed that over the course of 5 centuries, the pigments used for decoration in Byzantine manuscripts remained similar and traditional (mineral and organic), with pronounced variations in the 18th century post-Byzantine manuscript.
Source:Vibrational Spectroscopy, Volume 68
Author(s): Irena Nastova , Orhideja Grupče , Biljana Minčeva-Šukarova , Melih Ozcatal , Lenče Mojsoska
Pigments and inks used in six Byzantine manuscripts (covering the period from 10th to 15th century) and one 18th century post-Byzantine manuscript have been analyzed, using micro-Raman spectroscopy, ATR-FT-infrared spectroscopy and SEM–EDS. Micro-Raman spectroscopy allowed fast and in situ analysis of majority of pigments and inks used, except for the purple-red organic pigment, brown-purple ink and metallic pigments (silver and gold). The nature of the organic purple-red pigment and organic purple ink was revealed applying ATR-FTIR. In the analysis of the metallic pigment (silver and gold) as well as additional technique in characterizing organic purple-red dye and ink, SEM–EDS was used. Varieties of inks were used in the manuscripts. Gold and silver inks were used for capital letters and for emphasizing certain paragraphs. Red ink was identified as madder in illuminated manuscripts and as vermilion in simple texts. Gall ink was identified as black-brown ink in most of the manuscripts. In 18th century manuscript logwood was identified while in the 12th century manuscript, goethite was used as ink. The analysis of the pigments and inks revealed that over the course of 5 centuries, the pigments used for decoration in Byzantine manuscripts remained similar and traditional (mineral and organic), with pronounced variations in the 18th century post-Byzantine manuscript.
Temperature dependence of the microstructure of 1-butyl-3-methylimidazolium tetrafluoroborate in aqueous solution
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Huiyong Wang , Jianji Wang , Lamei Zhang
Many applications of ionic liquids (ILs) are closely related with their microstructure in mixtures. For example, morphology and pore size of the MCM-41 prepared in aqueous ILs are greatly dependent on the aggregation behavior of the ILs in water. Therefore, the study on the microstructure of ILs in aqueous solutions is of great importance. In this work, 1H NMR, dynamic light scattering and attenuated total reflection infrared spectroscopy have been used to investigate the temperature effect on the structures of aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) solutions. It was shown that the size of the IL aggregates becomes larger with decreasing temperature. When the system temperature is below the upper critical solution temperature (UCST) of the binary mixture at about 4°C, the aggregate size of the IL is larger than 1000nm. Additionally, the two-dimensional IR results reveal that at low IL concentrations, H2O can interact with [BF4]− prior to the CH groups of the imidazolium ring, whereas cation and anion of the IL tend to form aggregate at high IL concentrations. With the decrease of temperature, the interactions between cation and anion of the IL become stronger, but those between the IL and water become weaker, thereby resulting in the growth of the aggregate of cation with anion of the IL. This result may give a reasonable explanation for the origin of the UCST behavior of aqueous [C4mim][BF4] solution.
Source:Vibrational Spectroscopy, Volume 68
Author(s): Huiyong Wang , Jianji Wang , Lamei Zhang
Many applications of ionic liquids (ILs) are closely related with their microstructure in mixtures. For example, morphology and pore size of the MCM-41 prepared in aqueous ILs are greatly dependent on the aggregation behavior of the ILs in water. Therefore, the study on the microstructure of ILs in aqueous solutions is of great importance. In this work, 1H NMR, dynamic light scattering and attenuated total reflection infrared spectroscopy have been used to investigate the temperature effect on the structures of aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) solutions. It was shown that the size of the IL aggregates becomes larger with decreasing temperature. When the system temperature is below the upper critical solution temperature (UCST) of the binary mixture at about 4°C, the aggregate size of the IL is larger than 1000nm. Additionally, the two-dimensional IR results reveal that at low IL concentrations, H2O can interact with [BF4]− prior to the CH groups of the imidazolium ring, whereas cation and anion of the IL tend to form aggregate at high IL concentrations. With the decrease of temperature, the interactions between cation and anion of the IL become stronger, but those between the IL and water become weaker, thereby resulting in the growth of the aggregate of cation with anion of the IL. This result may give a reasonable explanation for the origin of the UCST behavior of aqueous [C4mim][BF4] solution.
Label free non-invasive imaging of topically applied actives in reconstructed human epidermis by confocal Raman spectroscopy
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Franziska D. Fleischli , Stephanie Mathes , Christian Adlhart
Raman spectroscopy has become a versatile tool for the in vivo characterization of skin. Here we describe use of Raman spectroscopy for high resolution optical cross sectioning to resolve skin constituents and administered drugs at the cellular level. Percutaneous penetration is typically studied using permeation cells with biopsies of animals or human skin. Although this technique provides valuable clinical data, little insight is gained in the microstructure of drug penetration (intercellular or transcellular) or in the mode of action of applied vehicles or penetration enhancers. Therefore, a Raman microspectroscopic method was combined with a confocal scanning setup to image the microstructure of commercially available skin models (SkinEthic®) and the spatial distribution of penetrated actives. The models’ microstructure was scanned without any special treatment or environment such as cutting, staining, freezing, or application of vacuum. The non-invasive Raman images reveal the layered structure of stratum corneum. This in particular for lipids while water tends to be more evenly distributed. When penetration of the hydrophilic active glycerol and the lipophilic octyl methoxycinnamate, OMC, was studied, a strong correlation between the local distribution of skin constituents and the hydrophilic/lipophilic character of the active was observed.
Source:Vibrational Spectroscopy, Volume 68
Author(s): Franziska D. Fleischli , Stephanie Mathes , Christian Adlhart
Raman spectroscopy has become a versatile tool for the in vivo characterization of skin. Here we describe use of Raman spectroscopy for high resolution optical cross sectioning to resolve skin constituents and administered drugs at the cellular level. Percutaneous penetration is typically studied using permeation cells with biopsies of animals or human skin. Although this technique provides valuable clinical data, little insight is gained in the microstructure of drug penetration (intercellular or transcellular) or in the mode of action of applied vehicles or penetration enhancers. Therefore, a Raman microspectroscopic method was combined with a confocal scanning setup to image the microstructure of commercially available skin models (SkinEthic®) and the spatial distribution of penetrated actives. The models’ microstructure was scanned without any special treatment or environment such as cutting, staining, freezing, or application of vacuum. The non-invasive Raman images reveal the layered structure of stratum corneum. This in particular for lipids while water tends to be more evenly distributed. When penetration of the hydrophilic active glycerol and the lipophilic octyl methoxycinnamate, OMC, was studied, a strong correlation between the local distribution of skin constituents and the hydrophilic/lipophilic character of the active was observed.
High-pressure Raman scattering of MgMoO4
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): M.N. Coelho , P.T.C. Freire , M. Maczka , C. Luz-Lima , G.D. Saraiva , W. Paraguassu , A.G. Souza Filho , P.S. Pizani
In this paper, we present results of high-pressure Raman scattering studies in β-MgMoO4 from atmospheric to 8.5GPa. The experiments were carried out using methanol–ethanol as pressure medium. By analyzing the pressure dependence of the Raman data (change in the number of lattice modes, splitting of bands and wavenumber discontinuities) we were able to observe a phase transition undergone by the β-MgMoO4 at 1.4GPa, which is only completed at ∼5GPa. The transition was observed to be irreversible and the modifications in the Raman spectra were attributed to the changes in coordination of Mo ions from tetrahedral to octahedral. The transition possibly changes the original C2/m symmetry to C2/m or to P2/c. Implication on the phase transition for similar molybdate structures, such as α-MnMoO4, is also highlighted.
Source:Vibrational Spectroscopy, Volume 68
Author(s): M.N. Coelho , P.T.C. Freire , M. Maczka , C. Luz-Lima , G.D. Saraiva , W. Paraguassu , A.G. Souza Filho , P.S. Pizani
In this paper, we present results of high-pressure Raman scattering studies in β-MgMoO4 from atmospheric to 8.5GPa. The experiments were carried out using methanol–ethanol as pressure medium. By analyzing the pressure dependence of the Raman data (change in the number of lattice modes, splitting of bands and wavenumber discontinuities) we were able to observe a phase transition undergone by the β-MgMoO4 at 1.4GPa, which is only completed at ∼5GPa. The transition was observed to be irreversible and the modifications in the Raman spectra were attributed to the changes in coordination of Mo ions from tetrahedral to octahedral. The transition possibly changes the original C2/m symmetry to C2/m or to P2/c. Implication on the phase transition for similar molybdate structures, such as α-MnMoO4, is also highlighted.
Effect of thermal annealing on the microstructure of P3HT thin film investigated by RAIR spectroscopy
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Linlin An , Yongxin Duan , Yuan Yuan , Lijuan Zhou , Jianming Zhang
The influence of thermal annealing on the structural ordering and orientation rearrangement of as cast P3HT thin film (<100nm) has been studied by reflection absorption infrared spectroscopy (RAIR). In order to erase the effect of temperature on the spectral intensity, two thermal procedures have been used to investigate the annealing-induced structural change of P3HT thin film. One is the continuous heating mode, in which the RIAR spectra were in situ collected during the heating process. The other is the stepwise heating mode, that is the isothermal annealing, and the spectra were ex situ collected at room temperature after the thermal treatment. It is found that thermal annealing can enhance the π–π interaction in P3HT crystal domain, whereas the improvement on the degree of crystallinity is not so obviously. Meanwhile, our results suggest that annealing-induced structural rearrangement on π–π stacking is irreversible, whereas the change on hexyl side chain packing is reversible.
Source:Vibrational Spectroscopy, Volume 68
Author(s): Linlin An , Yongxin Duan , Yuan Yuan , Lijuan Zhou , Jianming Zhang
The influence of thermal annealing on the structural ordering and orientation rearrangement of as cast P3HT thin film (<100nm) has been studied by reflection absorption infrared spectroscopy (RAIR). In order to erase the effect of temperature on the spectral intensity, two thermal procedures have been used to investigate the annealing-induced structural change of P3HT thin film. One is the continuous heating mode, in which the RIAR spectra were in situ collected during the heating process. The other is the stepwise heating mode, that is the isothermal annealing, and the spectra were ex situ collected at room temperature after the thermal treatment. It is found that thermal annealing can enhance the π–π interaction in P3HT crystal domain, whereas the improvement on the degree of crystallinity is not so obviously. Meanwhile, our results suggest that annealing-induced structural rearrangement on π–π stacking is irreversible, whereas the change on hexyl side chain packing is reversible.
Immobilised gold nanostars in a paper-based test system for surface-enhanced Raman spectroscopy
29 July 2013,
09:01:11
Publication date: September
2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Dora Mehn , Carlo Morasso , Renzo Vanna , Marzia Bedoni , Davide Prosperi , Furio Gramatica
Paper-based SERS active substrates were prepared adsorbing spherical and star-shaped gold nanoparticles on a standard filter paper support. Besides the deposition conditions, morphological parameters of the particles were found to strongly affect the enhancer properties of the substrates. The developed substrate was tested regarding surface homogeneity as well as in the quantitative analysis of malachite green, – a well documented Raman reporter dye – and proved to be capable also to detect the oxidation products of apomorphine, a well-known drug molecule used in Parkinson's disease. This material is simple to prepare, easy to handle and dispose and as such it could be a perfect target for further development of a new family of mass-produced, cheap solid SERS substrates.
Source:Vibrational Spectroscopy, Volume 68
Author(s): Dora Mehn , Carlo Morasso , Renzo Vanna , Marzia Bedoni , Davide Prosperi , Furio Gramatica
Paper-based SERS active substrates were prepared adsorbing spherical and star-shaped gold nanoparticles on a standard filter paper support. Besides the deposition conditions, morphological parameters of the particles were found to strongly affect the enhancer properties of the substrates. The developed substrate was tested regarding surface homogeneity as well as in the quantitative analysis of malachite green, – a well documented Raman reporter dye – and proved to be capable also to detect the oxidation products of apomorphine, a well-known drug molecule used in Parkinson's disease. This material is simple to prepare, easy to handle and dispose and as such it could be a perfect target for further development of a new family of mass-produced, cheap solid SERS substrates.
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