Abstract: Combretastatin-A2 (CA2), a potential anticancer drug in advanced preclinical development, is extracted from the medicinal plant Combretum caffrum. The NIR-FT Raman and FT-IR spectral studies of the molecule were carried out and ab initio calculations performed at the B3LYP/6-31G(d) level to derive the equilibrium geometry as well as the vibrational wavenumbers and intensities of the spectral bands. The vibrational analysis showed that the molecule has a similar geometry as that of cis-stilbene, and has undergone steric repulsion resulting in twisting of the phenyl ring with respect to the ethylenic plane. Vibrational analysis was used to investigate the lowering of the stretching modes, and enhancement of infrared band intensities of the C–H stretching modes of Me2 may be attributed to the electronic effects caused by back-donation and induction from the oxygen atom. Analysis of phenyl ring modes shows that the CA2 stretching mode 8 and the aromatic C–H in-plane bending mode are equally active as strong bands in both IR and Raman spectra, which can be interpreted as the evidence of intramolecular charge transfer (ICT) between the OH and OCH3groups via conjugated ring path and is responsible for bioactivity of the molecule. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: The phonon dispersions of graphene and graphene layers are theoretically investigated within fifth-nearest-neighbor force-constant approach. Based on their symmetry groups, the number of Raman- and infrared-active modes at the Γ point is given. Interatomic force constants are recalculated by fitting them to experimental phonon energy dispersion curves. Wavenumbers of optically active modes are presented as a function of number of layers (n). Our calculated results reproduce well the experimental data of G peak for graphene (1587 cm−1) and graphite (1581.6 cm−1) and clearly give the relation that ωG = 1581.6 + 11/(1 + n1.6). Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: Surface-enhanced Raman spectroscopy (SERS) has been suggested as a powerful tool to identify bacteria, drawing from its high fingerprint (vibrational) information content, its extreme sensitivity (down to the single molecule level) and its obliviousness to the aqueous environment intrinsic to biological systems. We review here in a comparative manner the various studies that attempted to utilize SERS for this important goal in light of the work carried out by our own group over the past 10 years or so. We show that SERS has an additional major advantage, namely, it introduces a new dimension of selectivity, which, on the one hand, makes it even more suitable as an analytical tool, but on the other hand, it requires gaining control of the precise manner in which the SERS-active metal centers are produced and brought into contact with the micro-organism. Our emphasis in this review is on understanding the spectra in terms of the nature of the SERS-active centers and their placement within the bacterium. On the interpretation and assignment of the spectra, we constantly keep in mind the final goal of bacteria identification. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: Raman spectroscopic studies of a range of naturally occurring carotenoids in over 50 specimens of plant tissue and a range of standard extracts have been undertaken, and the characteristic bands of CC and CC stretching and CCH bending have been recorded. Comparison of the spectroscopic data with the chemical assignment of the carotenoids from chemical extraction of the plant tissues reveals that there is a problem in the interpretation of the spectroscopic data which can be attributed to significant wavenumber shifts, particularly in the CC stretching band wavenumber, for carotenoids in the organic tissues arising from molecular interactions between the carotenoid and its host matrix. The simple identification of carotenoids in biological tissues on the basis of comparison with the standard spectra of extracted material must be made with caution; the progressive shift in wavenumber of the CC stretching band in the conjugated polyene chain of carotenoids with the number of CC groups, and hence the identification of the carotenoid, cannot be unambiguously interpreted for the range of materials studied here. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: We have been able to observe the surface-enhanced Raman scattering (SERS) from 4-mercaptopyridine (4-Mpy) molecules adsorbed on ZnO nanocrystals, which display 103 enhancement factors (EFs). An excitation wavelength-dependent behavior is clearly observed. Another molecule BVPP is also observed to have surface-enhanced Raman signals. The chemical enhancement is most likely responsible for the observed enhancement, since plasmon resonances are ruled out. The research is important not only for a better understanding of the SERS mechanism, but also for extension of the application of Raman spectroscopy to a variety of adsorption problems on a semiconductor surface. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: Raman spectroscopy has evolved into an important fast, direct and nondestructive technique in pharmaceutical analysis. Usually, the focus in this field is mainly on the active ingredients and not on the excipients present in the drugs. A collection of Raman spectra of widely used pharmaceutical excipients is presented in this article, which can serve as a reference for the interpretation of Raman spectra during drug analysis (including classical qualitative and quantitative pharmaceutical analysis, counterfeit tracing and process analytical technology (PAT) applications). The 43 analyzed excipients can be classified into seven categories: mono- and disaccharides (dextrose, lactitol, maltitol, lactose and sucrose), polysaccharides (microcrystalline cellulose, methylcellulose (MC), carboxymethylcellulose (CMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), wheat starch, maltodextrin, primojel, tragacanth and pectin), polyalcohols (propylene glycol, erythritol, xylitol, mannitol and sorbitol), carboxylic acids and salts (alginic acid, glycine, magnesium stearate, sodium acetate and sodium benzoate), esters (arachis oil, lubritab, dibutyl sebacate, triacetin, Eudragit E100 and Eudragit RL100), inorganic compounds (calcium phosphate, talc, anatase and rutile (TiO2), calcium carbonate, magnesium carbonate, sodium bicarbonate and calcium sulfate) and some unclassified products [gelatin, macrogol 4000 (polyethylene glycol (PEG), polyvinyl pyrrolidone and sodium lauryl sulfate]. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: NSFC [10625418, 20703032]; MOST [2006DFBO2020, 2007CB936800, 2009CB930703]; CAS; CSIC [2008601039]; MEC [FIS2007-66711-c01-01]; Natural Science Foundation of Fujian Province of China [E0710028]

Abstract: The development of fast identification techniques of viruses is an ongoing important research topic. Conventional virus detection and identification is generally based on various different microbiological methods. However, these techniques are not suitable for the analysis of single virus particles. Therefore, our goal is to establish tip-enhanced Raman scattering (TERS), providing vibrational spectroscopic information with a spatial resolution less than 50 nm, to characterize single viruses at a molecular level. Here we report, to the best of our knowledge for the first time, about TERS spectra of a tobacco mosaic virus, showing the great capability of this technique. However, the application of the TERS technique for a rapid and direct detection of different species of single viruses is under development, which is useful for a wide range of analytical fields. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: Multi-walled carbon nanotube (MWCNT) filters have been recently synthesised which have specific molecular filtering capabilities and good mechanical strength. Optical and scanning electron microscopy (SEM) reveals the formation of highly aligned arrays of bundles of carbon nanotubes having lengths up to 500 µm. The Raman spectra of this material along with four other carbonaceous materials, commercially available single-walled carbon nanotubes (SWCNTs) and MWCNTs, graphitised porous carbon (Carbotrap) and graphite have been recorded using two-excitation wavelengths, 532 and 785 nm, and analysed for band positions and shape with special emphasis paid to the D-, G- and G′-bands. A major difference between the different MWCNT varieties analysed is that G-bands in the MWCNT filters exhibit almost no dispersion, whereas the other MWCNTs show a noticeable dispersive behaviour with a change in the excitation wavelength. Spectral features similar to those of the MWCNT filter varieties were observed for the Carbotrap material. From the line shape analysis, the intensity ratio, ID/IG, of the more ordered MWCNT filter material using the integral G-band turns out to be two times lower than that of the less ordered MWCNT filter product at both excitation wavelengths. This parameter can, therefore, be used as a measure of the degree of MWCNT alignment in filter varieties, which is well supported also by our SEM study. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: We report for the first time the tip-enhancement of resonance Raman scattering using deep ultraviolet (DUV) excitation wavelength The tip-enhancement was successfully demonstrated with an aluminum-coated silicon tip that acts as a plasmonic material in DUV wavelengths Both the crystal violet and adenine molecules, which were used as test samples, show electronic resonance at the 266-nm excitation used in the experiments With results demonstrated here, molecular analysis and imaging with nanoscale spatial resolution in DUV resonance Raman spectroscopy can be realized using the tip-enhancement effect Copyright © 2009 John Wiley & Sons, Ltd

Abstract: We have investigated the potential of Raman spectroscopy with excitation in the visible spectral range (VIS Raman) as a tool for the classification of different vegetable oils and the quantification of adulteration of virgin olive oil as an example. For the classification, principal component analysis (PCA) was applied, where 96% of the spectral variation was characterized by the first two components. A significant similarity between sunflower oil and extra-virgin olive oil was found using this approach. Therefore, sunflower oil is a potential candidate for adulteration in most commercially available olive oils. Beside the classification of the different vegetable oils, we have successfully applied Raman spectroscopy in combination with partial least-squares (PLS) regression analysis for very fast monitoring of adulteration of extra-virgin olive oil with sunflower oil. Different mixtures of extra-virgin olive oil with three different sunflower oil types were prepared between 5 and 100% (v/v) in 5% increments of sunflower oil. While in the present context the adulteration usually refers to the addition of reasonable amounts of the adulterant (given the similarity with the basic product), we show that the technique proposed can also be used for trace analysis of the adulterant. Without using techniques like surface-enhanced Raman scattering (SERS), a quantitative detection limit down to 500 ppm (0.05%) could be achieved, a limit irrelevant for adulteration in commercial terms but significant for trace analysis. The qualitative detection limit even was at considerably lower concentration values. Based on PCA, a clear discrimination between pure extra-virgin olive oil and olive oil adulterated with sunflower oil was achieved. The adulterant content was successfully determined using PLS regression with a high correlation coefficient and small root mean-square error for both prediction and validation. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: During surface-enhanced Raman scattering (SERS), molecules exhibit a significant increase in their Raman signals when attached, or in very close vicinity, to gold or silver nanostructures. This effect is exploited as the basis of a new class of optical labels. Here we demonstrate robust and sensitive SERS labels as probes for imaging live cells. These hybrid labels consist of gold nanoparticles with Rose Bengal or Crystal Violet attached as reporter molecules. These new labels are stable and nontoxic, do not suffer from photobleaching, and can be excited at any excitation wavelength, even in the near infrared. SERS labels can be detected and imaged through the specific Raman signatures of the reporters. In addition, surface-enhanced Raman spectroscopy in the local optical fields of the gold nanoparticles also provides sensitive information on the immediate molecular environment of the label in the cell and allows imaging of the native constituents of the cell. This is demonstrated by images based on a characteristic Raman line of the reporter as well as by displaying lipids based on the SERS signal of the CH deformation/bending modes at ∼1470 cm−1. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: Titanium dioxide nanocrystals were prepared by the wet chemical method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman scattering (RS) and photoluminescence techniques. The XRD pattern shows the formation of single phase anatase structure of average sizes ∼7 nm (sample A) and ∼15 nm (sample B) for two samples. Additionally, TEM and RS were used to confirm the anatase crystal structure for both samples. The PL spectra show that the intensity of the sample A is more than that of sample B, which has been attributed to defect(s) and particle size variation. A modified phonon confinement model incorporating particle size distribution function and averaged dispersion curves for two most dispersive phonon branch (Γ-X direction) have been used to interpret the size effect in Raman spectra. The obtained Raman peak shift and full width at half-maximum agree well with the experimental data. Our observations suggest that the phonon confinement effects are responsible for a significant shift and broadening for the Raman peaks. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: Surface-enhanced Raman spectroscopy (SERS) coupled with dendritic silver nanosubstrates was used in this study for rapid detection and characterization of restricted antibiotics. Dendritic silver nanosubstrates were prepared through a simple replacement reaction and stored in deionized water for months. SERS methods with near-IR excitation at 785 nm using silver nanosubstrates were evaluated for detection of three restricted antibiotics (i.e. enrofloxacin, ciprofloxacin, and chloramphenicol) prepared in standard solutions. SERS was capable of identifying and characterizing three antibiotics quickly and accurately. Silver dendrites exhibit satisfactory and consistent performance with an analytical enhancement factor of ∼104. The limit of detection and limit of quantification for antibiotics could reach the level of 20 ppb. Silver dendrites can be kept in deionized water for up to 6 months with no signs of degradation in SERS performance. These results demonstrate a great potential of using SERS coupled with silver dendrites for rapid detection, classification, and quantification of chemical contaminants. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: Inspired by the discovery of bismuth metal used as a pigment in a fifteenth century illuminated manuscript, the identification of bismuth compounds by Raman spectroscopy is investigated. Raman spectra of bismuth metal powder, bismuth (III) sulfide (Bi2S3) and bismuth (III) oxide (α-Bi2O3) are presented. The influence of excitation laser wavelength is explored, along with the laser-induced oxidation of bismuth to α-Bi2O3 and β-Bi2O3. The implication of these results with respect to the selection of appropriate analytical protocols in the investigation of bismuth pigments in works of art is discussed. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: The hydrogenated diamond-like carbon (DLCH) film with 1-µm thickness is deposited by direct hydrocarbon gas ion beam method on silicon wafer and annealed at 400 °C. Detailed Raman spectra feature are fitted from nine sets of different peak fitting functions, including Gaussian, Lorentzian and Breit-Wigner-Fano (BWF) functions. These fitting results obtained from a two-peak combination show some specific variances on the G peak position, FWHMG and ID/IG ratio for as-deposited and as-annealed DLCH films. The most popular two-peak fitting method with full Gaussian function tends to exhibit a higher ratio of the G peak position shift and higher ID/IG ratio than others fitting methods, the drastic difference among the most popular G (G) & G (D) and B (G) & L (D) schemes also have brought out in ID/IG ratio. However, for a more complex four-peak Gaussian function fitting Raman spectra, the ID/IG ratio is close to that of a two-peak fitting function with a mixture functions of BWF (G) and L (D). Furthermore, a series of systematic peak fitting procedures and comparisons of Raman spectra have been discussed in this study. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: This article reviews the analytic techniques for Raman spectroscopic imaging with emphasis on chemometrics. Key information included in Raman spectra is often distributed broadly throughout the dataset. It is possible to condense the information into a very compact matrix representation by a chemometric technique of factor analysis such as principal component analysis (PCA) or self-modeling curve resolution (SMCR). PCA yields two matrices called scores and loadings which complementarily represent the entire features broadly distributed in the dataset. This concept can be further extended to other forms of data transformation schemes, including bilinear data decomposition based on SMCR analysis. SMCR offers a firmer model which is chemically or physically interpretable. The information derived from these techniques readily brings useful insight into building a mechanistic model for understanding complex phenomena studied by Raman spectroscopy. Illustrative examples are given for applications of both PCA and SMCR to Raman imaging of pharmaceutical tablets. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: We present a high-throughput method for fabricating large arrays of surface-enhanced Raman scattering (SERS) active gold dimers. Using a large-area/low-cost nanopatterning method in conjunction with a meniscus force deposition technique, we were able to create large arrays of uniformly spaced nanoclusters comprising two 60-nm gold nanospheres. Raman measurements of a thiophenol monolayer deposited on smaller scale arrays of aligned dimers yielded enhancement factors as high as 10(9). Polarization-control led measurements show spectral peak heights to be 10-100 times smaller when the incident beam is polarized perpendicularly to the dimer axis, confirming that the measured enhancements arise from the 'hot spots' between the two nanospheres. Copyright (C) 2009 John Wiley & Sons, Ltd.

Abstract: Raman spectra in solid and 1 M solution of L-cysteine and surface-enhanced Raman scattering (SERS) spectra of this molecule in the zwitterionic form, by using colloidal silver nanoparticles, have been recorded. Density functional theory with the B3LYP functional was used for the optimizations of the ground state geometries and simulation of the vibrational spectrum of this amino acid. The SERS spectrum with a large silver cluster as a model metallic surface was simulated for the first time. Taking into account the experimental and calculated Raman and SERS vibrations and the corresponding assignments, as well as a comparison of force constants and geometrical parameters between the free zwitterion cysteine and the one in the presence of the colloidal silver nanoparticles, we can confirm the presence of gauche (PH) and trans (PN) rotamers in the solid state, the formation of a SS bond in the solution state, the dissociation of the peptide bond and mixing of rotamers because of the SERS effect, and the relative importance of the interaction of sulphyldryl, NH3+, and carboxylate groups with the metallic surface. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: A simple synthesis method of silver nanoparticles and its application as an active surface-enhanced Raman spectroscopy (SERS) colloid are presented in this work. The photoreduction of AgNO3 in presence of sodium citrate (NaCit) was carried out by irradiation with different light sources (UV, white, blue, cyan, green, and orange) at room temperature. The evaluation of silver nanoparticles obtained as a function of irradiation time (1–24 h) and light source was followed by UV-visible absorption spectroscopy. This light-modification process results in a colloid with distinctive optical properties that can be related to the size and shape of the particles. The Ag colloids, as prepared, were employed as active colloids in SERS. Pyridine and caffeine were used as test molecules. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: In this paper, pure and Zn-doped TiO2 nanoparticles (NPs) with various content of Zn were prepared by a sol–hydrothermal method and were employed as active substrates for surface-enhanced Raman scattering (SERS). On the 3% Zn-doped TiO2 substrate, 4-mercaptobenzoic acid(4-MBA) molecules exhibit a higher SERS intensity by a factor of 6, as compared with the native enhancement of 4-MBA adsorbed on undoped TiO2 NPs. Moreover, the higher SERS activity was still observed on the 3% Zn-doped TiO2 NPs at temperature even up to 125 °C. These results indicate that an appropriate amount of Zn doping can improve the SERS performances of TiO2 SERS-active substrates. The introduction of Zn dopant can enrich the surface states (defects) of TiO2 and improve the separation efficiency of photo-generated charge carriers (electrons and holes) in TiO2, according to measurements of X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and photoluminescence, which are responsible for the influence of Zn dopant on the improved SERS performances of TiO2 NPs. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: Supported lipid structures and human cells (human dermal derived keratinocyte, HaCaT) were investigated using tip-enhanced Raman spectroscopy (TERS) to use the high spatial resolution capabilities of TERS, which is assumed to be less than 10 nm, to determine specific components on the cell surface. As lipids are a main component of cellular membranes, the correlation of spectral properties of pure lipids with respect to the complex biological sample was investigated. Induced by dynamic structural changes as well as nanoscale effects, a particular spectral feature of the lipid TERS spectra is found to vary, and a similar spectral deviation appears among the TERS spectra measured on the cell. Modifications of the cell surface alone cannot cause such behaviour. In contrast to soft lipid agglomerates, the cells were fixed and therefore hampered for intrinsic structural changes. Hence, the main contribution for the cell TERS spectra variation results from nanoscale effects, determined by different spectral characteristics compared to conventional Raman spectroscopy. The present results demonstrate the capability of TERS to provide a detailed and fast insight into the composition of the cell surface, even allowing the detection of single components. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: A selection of 23 rare glass objects, mostly enameled, of various provenance and age, from the 5th century BC to the 19th century AD including the Western and Islamic Middle Ages but with a focus on 16th–18th century Venetian and French ‘facon de Venise’ artefacts, have been studied on-site at the Sevres museum or at the laboratory. The Raman signatures of the transparent or opacified glass matrix and of enameled decorations are discussed and compared to those previously recorded on ceramics and stained glasses. The Raman parameters allow discrimination between 2 groups (with some variations) of glass bodies, belonging to mixed Ca–Na and Ca-containing Na-rich silicates, with some exceptions. Most enamels are instead lead-based glasses, but we also found enamels having a composition close to that of the glass body. Most of the pigment signatures are similar to those recorded on ceramic glazes, which proves the link between the two technologies. A particular emphasis was given to the identification of white opacification techniques. Very specific signatures could question the authenticity of some artefacts, and at least in two cases, arguments have been found to identify a fake or embellished artefact. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: This paper reports a systematic study of the composition and the temperature-dependent-Raman spectra of Zr4+-rich BaZrxTi1−xO3 (BZT) ceramic compositions (0.50⩽x⩽1.00). On the basis of the dielectric behavior of Zr rich BZT ceramics, the observed relaxor behavior has been hypothesized as a result of increasing long-range interactions of nanosized, Ti4+-rich polar regions in a Zr4+-rich nonpolar matrix. Beyond an optimum concentration of BaTiO3 (BT) in the nonpolar matrix of BaZrO3 (x⩽0.75), a critical size and density of the polar regions is reached when the polar clusters start showing the relaxor like behavior, which finally show classical relaxor behavior for compositions with x = 0.5 and 0.6. This hypothesis is strongly supported from the Raman data on Zr-rich BZT presented in this paper. Well-defined BT Raman spectra for 5% BT in BZT composition were recorded, which followed completely up to the 50% Ti addition in the BZT samples. The temperature-dependent Raman spectra collected on the BZT ceramics far beyond the dielectric transition temperatures supported the existence of the nano-polar BT regions, like in typical relaxor samples. The full width at half-maximum (FWHM), integrated intensity of the peaks in the Raman spectra has been analyzed to further support the conclusions. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract: We demonstrate nano-scale optical analysis of graphene layers by tip-enhanced near-field Raman spectroscopy (TERS). In this technique, the spatial resolution ∼30 nm is realized by the near-field probe which acts as a nano-light source. From the intensity change of the Raman band of silicon generated from the near-field probe, we can conveniently estimate the edge boundaries and the number of stacking layers. TERS measurement across the layer edges reveals the nano-scale properties of the material as well as the existence of local defects and edge boundaries. The intensity change of the G-band shows the step-like behavior that follows the layer boundary, whereas the two components in 2D peak show more complex behaviors even inside layers. The peak fluctuation in the 2D band also suggests the local stress distribution due to interlayer interactions. An excess charge effect is observed through the correlation between the peak position and the width of the G-band and their nano-scale distribution within a layer is revealed. Besides the vibrational analysis, we successfully performed the estimation of the number of layers in two-dimensional imaging by the same experimental platform, which allows us high-throughput nondestructive identification of graphene layers critical for the evaluation of this material especially in future device applications. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: Vibrational bands of L-tryptophan which was adsorbed on Ag nanoparticles (∼10 nm in diameter) have been investigated in the spectral range of 200 – 1700 cm −1 using surface-enhanced Raman scattering (SERS) spectroscopy. Compared with the normal Raman scattering (NRS) of L-tryptophan in either 0.5 M aqueous solution (NRS-AS) or solid powder (NRS-SP), the intensified signals by SERS have made the SERS investigation at a lower molecular concentration (5 × 10 −4 M) possible.Abinitio calculations at the B3LYP/6-311G level have been carried out to predict the optimal structure and vibrational wavenumbers for the zwitterionic form of L-tryptophan. Facilitated with the theoretical prediction, the observed vibrational modes of L-tryptophan in the NRS-AS, NRS-SP, and SERS spectra have been analyzed. In the spectroscopic observations, there are no significant changes for the vibrational bands of the indole ring in either NRS-AS, NRS-SP, or SERS. In contrast, spectral intensities involving the vibrations of carboxylate and amino groups are weak in NRS-AS and NRS-SP, but strong in SERS. The intensity enhancement in the SERS spectrum can reach 10 3 –1 0 4 -fold magnification. On the basis of spectroscopic analysis, the carboxylate and amino groups of L-tryptophan are determined to be the preferential terminal groups to attach onto the surfaces of Ag nanoparticles in the SERS measurement. Copyright c � 2008 John Wiley & Sons, Ltd.

Abstract: A versatile and efficient tip-enhanced spectroscopic imaging technique based on a parabolic mirror (PM) assisted near-field optical microscope is demonstrated. The replacement of the conventional objective lens with a parabolic mirror allows the non-restricted investigation of sample materials regarding their opacity. In addition, an improved signal collection efficiency and effective excitation of the longitudinal plasmonic oscillation in the tip apex are obtained. The capabilities of PM-assisted tip-enhanced Raman (TER) and photoluminescence (PL) imaging in distinguishing the individual domains made of different chemical components in poly (3-hexythiophene)/[6, 6]-penyl-C61 butyric acid methyl ester (P3HT/PCBM) solar cell blend film and in the investigation of the plasmonic properties of geometrically well-defined Au cones are demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract: The surface-enhanced Raman scattering (SERS) of sodium alginates and their hetero- and homopolymeric fractions obtained from four seaweeds of the Chilean coast was studied. Alginic acid is a copolymer of β-D-mannuronic acid (M) and α-L guluronic acid (G), linked 1 → 4, forming two homopolymeric fractions (MM and GG) and a heteropolymeric fraction (MG). The SERS spectra were registered on silver colloid with the 632.8 nm line of a He – Ne laser. The SERS spectra of sodium alginate and the polyguluronate fraction present various carboxylate bands which are probably due to the coexistence of different molecular conformations. SERS allows to differentiate the hetero- and homopolymeric fractions of alginic acid by characteristic bands. In the fingerprint region, all the poly-D-mannuronate samples present a band around 946 cm −1 assigned to C – O stretching, and C –C–H and C –O–H deformation vibrations, a band at 863 cm −1 assigned to deformation vibration of β-C1 –H group, and one at 799 – 788 cm −1 due to the contributions of various vibration modes. Poly-L-guluronate spectra show three characteristic bands, at 928 – 913 cm −1 assigned to symmetric stretching vibration of C – O – C group, at 890 – 889 cm −1 due to C –C–H , skeletal C – C, and C – O vibrations, and at 797 cm −1 assigned to α C1 – H deformation vibration. The heteropolymeric fractions present two characteristic bands in the region with the more important one being an intense band at 730 cm −1 due to ring breathing vibration mode. Copyright c � 2009 John Wiley & Sons, Ltd.

Abstract: We describe the chemical and electromagnetic enhancements of surface-enhanced resonance Raman scattering (SERRS) for the pyridine molecule absorbed on silver clusters, in which different incident wavelength regions are dominated by different enhancement mechanisms. Through visualization we theoretically investigate the charge transfer (CT) between the molecule and the metal cluster, and the charge redistribution (CR) within the metal on the electronic intracluster collective oscillation excitation (EICOE). The CT between the metal and the molecule in the molecule-metal complex is considered as an evidence for chemical enhancement to SERRS. CR within the metal on EICOE is considered as an evidence for the electromagnetic enhancement by collective plasmons. For the incident wavelength from 300 to 1000 nm, the visualized method of charge difference density can classify the different wavelength regions for chemical and electromagnetic enhancement, which are consistent with the formal fragmented experimental studies. Copyright (C) 2008 John Wiley & Sons, Ltd.