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Raman Scattering (raman + scattering)
Kinds of Raman Scattering Terms modified by Raman Scattering Selected AbstractsFabrication of a Macroporous Microwell Array for Surface-Enhanced Raman ScatteringADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Martina Zamuner Abstract Here, a colloidal templating procedure for generating high-density arrays of gold macroporous microwells, which act as discrete sites for surface-enhanced Raman scattering (SERS), is reported. Development of such a novel array with discrete macroporous sites requires multiple fabrication steps. First, selective wet-chemical etching of the distal face of a coherent optical fiber bundle produces a microwell array. The microwells are then selectively filled with a macroporous structure by electroless template synthesis using self-assembled nanospheres. The fabricated arrays are structured at both the micrometer and nanometer scale on etched imaging bundles. Confocal Raman microscopy is used to detect a benzenethiol monolayer adsorbed on the macroporous gold and to map the spatial distribution of the SERS signal. The Raman enhancement factor of the modified wells is investigated and an average enhancement factor of 4,×,104 is measured. This demonstrates that such nanostructured wells can enhance the local electromagnetic field and lead to a platform of ordered SERS-active micrometer-sized spots defined by the initial shape of the etched optical fibers. Since the fabrication steps keep the initial architecture of the optical fiber bundle, such ordered SERS-active platforms fabricated onto an imaging waveguide open new applications in remote SERS imaging, plasmonic devices, and integrated electro-optical sensor arrays. [source] Chemical Nanosensors Based on Composite Molecularly Imprinted Polymer Particles and Surface-Enhanced Raman ScatteringADVANCED MATERIALS, Issue 21 2010Marc Bompart Chemical nanosensors with a submicrometer core,shell composite design, based on a polymer core, a molecularly imprinted polymer (MIP) shell for specific analyte recognition, and an interlayer of gold nanoparticles for signal amplification, are described. SERS measurements on single nanosensors yield detection limits of 10,7,M for the , -blocker propranolol, several orders of magnitude lower than on plain MIP spheres. [source] Highly Surface-roughened "Flower-like" Silver Nanoparticles for Extremely Sensitive Substrates of Surface-enhanced Raman ScatteringADVANCED MATERIALS, Issue 45 2009Hongyan Liang Abstract Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates. [source] Probing the Photothermal Effect of Gold-Based Nanocages with Surface-Enhanced Raman Scattering (SERS),ANGEWANDTE CHEMIE, Issue 52 2009Matthew Rycenga Die Konformation von Molekülen auf der Oberfläche eines Metallnanopartikels reagiert auf Temperaturänderungen und kann durch oberflächenverstärkte Raman-Streuung (SERS) in situ verfolgt werden. Die Anregung des Partikels für die SERS-Messung kann einen photothermischen Effekt auslösen, bei dem das absorbierte Licht als Wärme freigesetzt wird. Aus den SERS-Spektren lassen sich die Änderungen der Oberflächentemperatur während des photothermischen Effekts ableiten (siehe Bild). [source] Direct Evidence of High Spatial Localization of Hot Spots in Surface-Enhanced Raman Scattering,ANGEWANDTE CHEMIE, Issue 52 2009Chang Chen Heiß oder kalt: Die hohe Lokalisierung in SERS-Hotspots lässt sich direkt anhand der selektiven Ablagerung von Raman-Analyten innerhalb und außerhalb von Regionen mit verstärktem Feld in einem Spalt zeigen (siehe Bild). Dies bestätigen Messungen der absoluten SERS-Intensitäten ebenso wie kinetische Studien zum lichtinduzierten Abbau an unterschiedlichen Stellen. [source] Innentitelbild: Label-Free Chemical Imaging of Catalytic Solids by Coherent Anti-Stokes Raman Scattering and Synchrotron-Based Infrared Microscopy (Angew. Chem.ANGEWANDTE CHEMIE, Issue 47 200947/2009) Die katalytische Umsetzung von Thiophenderivaten an Zeolithkristallen wurde mit einer Kombination aus multipler kohärenter Anti-Stokes-Raman-Streuung (CARS) und Synchrotron-basierter IR-Mikroskopie untersucht. In der Zuschrift auf S.,9152,ff. zeigen B.,M. Weckhuysen et,al., dass räumlich hoch aufgelöste chemische Informationen über Reaktanten und Produkte auch ohne Markierung zugänglich sind. Die Schwingungsbanden der CARS- und IR-Spektren belegen Wechselwirkungen zwischen Thiophen und Zeolithgerüst mit anschließender Ringöffnung. [source] Label-Free Chemical Imaging of Catalytic Solids by Coherent Anti-Stokes Raman Scattering and Synchrotron-Based Infrared Microscopy,ANGEWANDTE CHEMIE, Issue 47 2009Marianne Innenaufnahme: Die Kombination aus den beiden im Titel genannten Verfahren während der katalytischen Umsetzung von Thiophenderivaten an Zeolithkristallen ergibt räumlich und zeitlich aufgelöste chemische Informationen auch ohne Markierungen (siehe Bild). Das reagierende Thiophen befindet sich hauptsächlich im Kristallinneren, während das Produkt in den geraden Poren des Zeoliths gefunden wird. [source] Simultaneous Fluorescence and Raman Scattering from Single Carbon Nanotubes.CHEMINFORM, Issue 48 2003Achim Hartschuh Abstract For Abstract see ChemInform Abstract in Full Text. [source] Preparation and characterization of electrodeposited indium selenide thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2005S. Gopal Abstract Indium Selenide (InSe) thin films were deposited from a mixture of Indium chloride and selenium dioxide in aqueous solution by electrodeposition technique on Indium Tin oxide coated glass substrates. The effects of the parameters during deposition such as current density, deposition potential versus saturated calomel electrode, pH value and concentration of source material were studied. X-ray diffraction studies were carried out on the films to analyze the microstructure using an x-ray diffractometer and were examined by RAMAN spectroscopy. The Raman peak position did not change much with chemical concentrations. Raman scattering due to the (LO) phonon was observed at 211 cm,1. Optical absorption studies were performed with a double beam ultra violet-visible ,NIR spectrophotometer in the wavelength 300,1100 nm. The surface morphology of the layer was examined using a scanning electron micrograph. The composition of the films was studied using an Energy Dispersive Analysis by X-Rays (EDAX). [source] Detection of metastable excited molecules N2(A3,u+) in an atmospheric pressure nitrogen discharge by Raman scatteringELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 6 2010Tetsuo Fukuchi Abstract Raman scattering from metastable excited nitrogen molecules N2(A3,u+) created by an impulse discharge in nitrogen at atmospheric pressure was detected. A pulsed Nd:YAG laser at a wavelength of 266 nm was used as the light source, and Raman scattering from N2(A3,u+) at a wavelength of 277 nm was detected using an interference filter and photomultiplier tube. The filter had sufficient rejection of Rayleigh scattering of laser light at a wavelength of 266 nm and of Raman scattering from ground-state nitrogen molecules N2(X1,g+) at a wavelength of 284 nm. The temporal variation of the signal intensity of Raman scattering from N2(A3,u+) was measured by transmitting the laser light at different time delays relative to sparkover. The results showed that the signal intensity decayed with a time constant of about 200µs. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(6): 34,40, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10205 [source] Surface Nanometer-Scale Patterning in Realizing Large-Scale Ordered Arrays of Metallic Nanoshells with Well-Defined Structures and Controllable PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Shikuan Yang Abstract Surface patterns of nanoshell arrays play an important role in diverse applications including surface-enhanced Raman scattering (SERS) sensors, lithium-ion batteries, solar cells, and optical devices. This paper describes an innovative surface nanopatterning technique for realizing large-scale ordered arrays of metallic spherical nanoshells with well-defined structures. Ag nanoshell arrays are prepared using polystyrene sphere templates by an electrophoretic process in Ag colloidal solutions. The fabricated Ag nanoshell arrays have a high controllability of the structural parameters, including the diameter, the surface roughness, and the intershell spacing, giving rise to the tunable properties of nanoshell arrays. As an example, tunable SERS and localized surface plasmon resonance of the nanoshell arrays are demonstrated by controlling the structural parameters. The surface nanopatterning technique shown in this paper is a general fabrication process in achieving not only metallic nanoshell arrays, but also nanoshell arrays of semiconductors and metallic oxides. [source] Induced SER-Activity in Nanostructured Ag,Silica,Au Supports via Long-Range Plasmon CouplingADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Jiu-Ju Feng Abstract A novel Ag,silica,Au hybrid device is developed that displays a long-range plasmon transfer of Ag to Au leading to enhanced Raman scattering of molecules largely separated from the optically excited Ag surface. A nanoscopically rough Ag surface is coated by a silica spacer of variable thickness from ,1 to 21,nm and a thin Au film of ,25,nm thickness. The outer Au surface is further functionalized by a self-assembled monolayer (SAM) for electrostatic binding of the heme protein cytochrome c (Cyt c) that serves as a Raman probe and model enzyme. High-quality surface-enhanced resonance Raman (SERR) spectra are obtained with 413,nm excitation, demonstrating that the enhancement results exclusively from excitation of Ag surface plasmons. The enhancement factor is estimated to be 2,×,104,8,×,103 for a separation of Cyt c from the Ag surface by 28,47,nm, corresponding to an attenuation of the enhancement by a factor of only 2,6 compared to Cyt c adsorbed directly on a SAM-coated Ag electrode. Upon immobilization of Cyt c on the functionalized Ag,silica,Au device, the native structure and redox properties are preserved as demonstrated by time- and potential-dependent SERR spectroscopy. [source] Plasmonic Crystals: A Platform to Catalog Resonances from Ultraviolet to Near-Infrared Wavelengths in a Plasmonic LibraryADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Hanwei Gao Abstract Surface plasmons are responsible for a variety of phenomena, including nanoscale optical focusing, negative refraction, and surface-enhanced Raman scattering. Their characteristic evanescent electromagnetic fields offer opportunities for sub-diffraction imaging, optical cloaking, and label-free molecular sensing. The selection of materials for such applications, however, has been traditionally limited to the noble metals Au and Ag because there has been no side-by-side comparison of other materials. This feature article describes recent progress on manipulating surface plasmons from ultraviolet to near-infrared wavelengths using plasmonic crystals made from 2D nanopyramidal arrays. A library of plasmon resonances is constructed in the form of dispersion diagrams for a series of unconventional and new composite plasmonic materials. These resonances are tuned by controlling both intrinsic factors (unit cell shape, materials type) and extrinsic factors (excitation conditions, dielectric environment). Finally, plasmonic crystals with reduced lattice symmetries are fabricated as another means to tailor resonances for broadband coupling. [source] Tailored Plasmonic Gratings for Enhanced Fluorescence Detection and Microscopic ImagingADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Xiaoqiang Cui Abstract The ability to precisely control the pattern of metallic structures at the micro- and nanoscale for surface plasmon coupling has been demonstrated to be essential for signal enhancement in fields such as fluorescence and surface-enhanced Raman scattering. In the present study, a series of silver coated gratings with tailored duty ratio and depth and a periodical pitch of 400,nm are designed and implemented. The influence of the grating profile on plasmonic properties and the corresponding enhancement factor are investigated by angular scanning measurement of reflectivity and fluorescence intensity and by finite difference time domain simulation. The application of the substrate in the enhanced fluorescence imaging detection of labeled protein is also investigated. This substrate has a wide range of potential applications in areas including biodiagnostics, imaging, sensing, and photovoltaic cells. [source] Fabrication of a Macroporous Microwell Array for Surface-Enhanced Raman ScatteringADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Martina Zamuner Abstract Here, a colloidal templating procedure for generating high-density arrays of gold macroporous microwells, which act as discrete sites for surface-enhanced Raman scattering (SERS), is reported. Development of such a novel array with discrete macroporous sites requires multiple fabrication steps. First, selective wet-chemical etching of the distal face of a coherent optical fiber bundle produces a microwell array. The microwells are then selectively filled with a macroporous structure by electroless template synthesis using self-assembled nanospheres. The fabricated arrays are structured at both the micrometer and nanometer scale on etched imaging bundles. Confocal Raman microscopy is used to detect a benzenethiol monolayer adsorbed on the macroporous gold and to map the spatial distribution of the SERS signal. The Raman enhancement factor of the modified wells is investigated and an average enhancement factor of 4,×,104 is measured. This demonstrates that such nanostructured wells can enhance the local electromagnetic field and lead to a platform of ordered SERS-active micrometer-sized spots defined by the initial shape of the etched optical fibers. Since the fabrication steps keep the initial architecture of the optical fiber bundle, such ordered SERS-active platforms fabricated onto an imaging waveguide open new applications in remote SERS imaging, plasmonic devices, and integrated electro-optical sensor arrays. [source] Nanoporous Copper with Tunable Nanoporosity for SERS ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Lu-Yang Chen Abstract Nanostructured materials with designable microstructure and controllable physical and chemical properties are highly desired for practical applications in nanotechnology. In this article, it is reported that nanoporous copper with a tunable nanopore size can be fabricated by controlling the dealloying process. The influence of acid concentration and etching potential on the formation of nanoprosity is systematically investigated. With optimal etching conditions, the nanopore sizes can be tailored from ,15 to ,120,nm by controlling the dealloying time. It is found that the tunable nanoporosity leads to significant improvements in surface-enhanced Raman scattering (SERS) of nanoporous copper and peak values of SERS enhancements for both rhodamine 6G and crystal violet 10B molecules are observed at a pore size of ,30,50,nm. This study underscores the effect of complex three-dimensional nanostructures on physical and chemical properties and is helpful in developing inexpensive SERS substrates for sensitive instrumentations in molecular diagnostics. [source] Nanoaggregate-Embedded Beads as Novel Raman Labels for BiodetectionADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Ping-Ji Huang Abstract Novel Raman tags called nanoaggregate-embedded beads (NAEBs) have been developed. NAEBs are silica-coated, dye-induced aggregates of a small number of metal nanoparticles. In this work, the Raman reporters used to induce aggregation of gold nanoparticles include strongly binding dyes such as XRITC, TRITC, and DTDC and weakly binding dyes such as R6G. Surface-enhanced Raman scattering (SERS) signal from a single NAEB can be detected. This study also demonstrates that these SERS-active beads can be used as Raman tags for bio-detection. [source] Synthesis and Optical Properties of Europium-Doped ZnS: Long-Lasting Phosphorescence from Aligned Nanowires,ADVANCED FUNCTIONAL MATERIALS, Issue 11 2005C. Cheng Abstract Quasi-aligned Eu2+ -doped wurtzite ZnS nanowires on Au-coated Si wafers have been successfully synthesized by a vapor deposition method under a weakly reducing atmosphere. Compared with the undoped counterpart, incorporation of the dopant gives a modulated composition and crystal structure, which leads to a preferred growth of the nanowires along the [010] direction and a high density of defects in the nanowire hosts. The ion doping causes intense fluorescence and persistent phosphorescence in ZnS nanowires. The dopant Eu2+ ions form an isoelectronic acceptor level and yield a high density of bound excitons, which contribute to the appearance of the radiative recombination emission of the bound excitons and resonant Raman scattering at higher pumping intensity. Co-dopant Cl, ions can serve not only as donors, producing a donor,acceptor pair transition with the Eu2+ acceptor level, but can also form trap levels together with other defects, capture the photoionization electrons of Eu2+, and yield long-lasting (about 4,min), green phosphorescence. With decreasing synthesis time, the existence of more surface states in the nanowires forms a higher density of trap centers and changes the crystal-field strength around Eu2+. As a result, not only have an enhanced Eu2+ 4f65d1,4f7 intra-ion transition and a prolonged afterglow time been more effectively observed (by decreasing the nanowires' diameters), but also the Eu2+ related emissions are shifted to shorter wavelengths. [source] Formation of Oxynitride as the Photocatalytic Enhancing Site in Nitrogen-Doped Titania Nanocatalysts: Comparison to a Commercial Nanopowder,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005X. Chen Abstract A nitrogen-doped TiO2 nanocolloid has been successfully prepared and its properties compared with the commercially available TiO2 nanomaterial, Degussa P25. Several characterization techniques, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Raman scattering, and UV-visible reflectance spectra, are combined in order to determine the crystal phase and grain size, shape, degree of nitrogen incorporation, and nature of the resultant oxynitride chemical bonding on the surface and in the bulk. The high relative photocatalytic activity of the nitrogen doped-TiO2 nanocolloid is evaluated through a study of the decomposition of methylene blue under visible light excitation. The ease and degree of substitutional-insertional nitrogen doping is held accountable for the significant increase in photocatalytic activity in the porous nanocolloid versus the nitrided commercial nanopowder. It is suggested that the nitrogen incorporation produces an NO bonding region as evidenced by the resulting XPS spectrum. [source] Influence of Side-Chain Structure and Irradiation Condition on Photoalignment of Ladder-Like Polysiloxane Films,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005H.-W. Gu Abstract In this paper we consider the photo-induced aligning capability of various ladder-like polysiloxane-based photoalignment films,which could be used in liquid-crystal displays,bearing different photoreactive side chains, i.e., laterally grafted cinnamate/azobenzene-based dual photoreactive side chains with a short or longer spacer, and terminally fixed coumarin-containing side chains. Results from polarized optical microscopy (POM), Fourier-transform infrared (FTIR) spectroscopy, surface-enhanced Raman scattering (SERS), atomic force microscopy (AFM), etc., are integrated to elucidate the influence of side-chain structure and the irradiation conditions on the photoalignment of ladder-like polysiloxane films. It is demonstrated that the film containing the dual photoreactive group with a longer spacer exhibits better alignment properties. Reasonably, the concerted photoreactions of the dual photoreactive group and the longer spacer are beneficial to the cooperative motion of chromophores at the "domain level", resulting in improved alignment facility and stability. The complicated effects of irradiation conditions and moderate annealing are also discussed. High-quality alignment of the polysilsesquioxane (LPS)-based photoalignment film LPS-CA11 with a longer spacer between the LPS main chain and cinnamoyl/azobenzene side chains can be achieved only within an optimal range of exposure (5,8,J,cm,2), while the pretilt angles can be adjusted in the range 0.5°,7° by varying the incident light intensity. Additionally, moderate annealing before and after illumination can markedly improve the alignment uniformity by self-healing of defects. [source] Improved SERS Performance from Au Nanopillar Arrays by Abridging the Pillar Tip Spacing by Ag SputteringADVANCED MATERIALS, Issue 37 2010Zhulin Huang Ag-capped Au nanopillar arrays on a resin supporter (see left upper figure), with a typical adjacent pillar tip gap of 10 nm, show obviously higher surface-enhanced Raman scattering (SERS) sensitivity (right column in red) than that of the bare Au nanopillar array while using 10 nM R6G as probe molecules. The large-area Ag-capped Au nanopillar array has potential in trace detection of special chemicals. [source] Highly Surface-roughened "Flower-like" Silver Nanoparticles for Extremely Sensitive Substrates of Surface-enhanced Raman ScatteringADVANCED MATERIALS, Issue 45 2009Hongyan Liang Abstract Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates. [source] Carbon Nanotube Fibers: Monitoring a Micromechanical Process in Macroscale Carbon Nanotube Films and Fibers (Adv. Mater.ADVANCED MATERIALS, Issue 5 20095/2009) The evaluation of mechanical properties of carbon nanotube (CNT) fibers is inherently difficult. On p. 603, Sishen Xie and co-workers report that Raman scattering,a generic methodology independent of mechanical measurements,can be used to determine the interbundle strength and microscopic failure process for various CNT macroarchitectures. Raman data are used to predict the moduli of CNT films and fibers, and to illustrate the influences of the twisting geometries on the fibers' mechanical performances. [source] Monitoring a Micromechanical Process in Macroscale Carbon Nanotube Films and FibersADVANCED MATERIALS, Issue 5 2009Wenjun Ma The evaluation of mechanical properties of carbon nanotube (CNT) fibers is inherently difficult. Here, Raman scattering,a generic methodology independent of mechanical measurements,is used to determine the interbundle strength and microscopic failure process for various CNT macroarchitectures. Raman data are used to predict the moduli of CNT films and fibers, and to illustrate the influences of the twisting geometries on the fibers' mechanical performances. [source] Synthesis and Optical Properties of Tetrapod-Like ZnSSe Alloy Nanostructures,ADVANCED MATERIALS, Issue 17 2008Haiyang Xu Tetrapod-like ZnS1,xSex alloy nanostructures (T-ZnS1,xSex) of different compositions (0,,,x,,,1) are synthesized by chemical vapor deposition. Their composition-dependent Raman scattering and cathodoluminescence are studied. The single-crystal T-ZnS1,xSex nanostructures exhibit strong and narrow near-band-edge emissions that can be continuously tuned from 330,459,nm (see figure). [source] Photo-Induced Orientation of a Film of Ladderlike Polysiloxane Bearing Dual Photoreactive Side Groups,ADVANCED MATERIALS, Issue 16 2003H.W. Gu A newly designed ladder-like polysiloxane (LPS) containing dual photoreactive side groups has been synthesized for the purpose of generating high-quality photo-alignment layers with controllable pretilt angle (,,1,7°, see Figure and cover). Integrated spectroscopic methods of UV dichroism, surface-enhanced Raman scattering (SERS), and FT-IR are used together for the first time to elucidate the photo-alignment mechanism and the real cause of the high pretilt angle. [source] Use of vibrational spectroscopy to study protein and DNA structure, hydration, and binding of biomolecules: A combined theoretical and experimental approachINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2006K. J. Jalkanen Abstract We report on our work with vibrational absorption, vibrational circular dichroism, Raman scattering, Raman optical activity, and surface-enhanced Raman spectroscopy to study protein and DNA structure, hydration, and the binding of ligands, drugs, pesticides, or herbicides via a combined theoretical and experimental approach. The systems we have studied systematically are the amino acids (L -alanine, L -tryptophan, and L -histidine), peptides (N -4271 acetyl L -alanine N,-methyl amide, N -acetyl L -tryptophan N,-methyl amide, N -acetyl L -histidine N,-methyl amide, L -alanyl L -alanine, tri- L -serine, N -acetyl L -alanine L -proline L -tyrosine N,-methyl amide, Leu-enkephalin, cyclo-(gly- L -pro)3, N -acetyl (L -alanine)nN,-methyl amide), 3-methyl indole, and a variety of small molecules (dichlobenil and 2,6-dochlorobenzamide) of relevance to the protein systems under study. We have used molecular mechanics, the SCC-DFTB, SCC-DFTB+disp, RHF, MP2, and DFT methodologies for the modeling studies with the goal of interpreting the experimentally measured vibrational spectra for these molecules to the greatest extent possible and to use this combined approach to understand the structure, function, and electronic properties of these molecules in their various environments. The application of these spectroscopies to biophysical and environmental assays is expanding, and therefore a thorough understanding of the phenomenon from a rigorous theoretical basis is required. In addition, we give some exciting and new preliminary results which allow us to extend our methods to even larger and more complex systems. The work presented here is the current state of the art to this ever and fast changing field of theoretical spectroscopic interpretation and use of VA, VCD, Raman, ROA, EA, and ECD spectroscopies. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Low-temperature phase transformation and phonon confinement in one-dimensional Ta2O5 nanorodsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2010Rupesh S. Devan The thermochromic phase transformations of one-dimensional Ta2O5 nanorods have been analyzed at elevated temperatures ranging from 80 to 300,K. The nanorods, grown in a large-area high-density array, are 14,22,nm wide and approximately 500,nm long. The array contained ,93.5% of the orthorhombic (,) phase and ,6.5% of the tetragonal (,) phase. Low-temperature X-ray diffraction results showed complex and polymorphic thermochromic phase transformations of the ,(001), ,(101) and ,(103) lattice planes of the nanorods, which incorporate (i) ,-to-, (,,,), (ii) ,,,,, and (iii) ,,, phase transitions. In comparison with the Raman scattering of three-dimensional bulk powder and two-dimensional thin films of Ta2O5, there were concurrent Raman blue- and redshifts in the one-dimensional Ta2O5 nanorods, indicating that the molecular vibrations of the nanorods were confined owing to the reduction of size and dimension. [source] Anomalous conformational properties of PEO in H2O and D2O by SANS, PCS and Raman scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000C. Branca PEO solutions in water and heavy water have been investigated using SANS, PCS and Raman spectroscopy. The employement of these techniques allows to carry out a comparison between the diffusive properties of PEO/H2O and PEO/D2O systems, in order to study the coil conformation dependence on temperature and concentration. The data reveal the different conformational properties of PEO in the two solvents which have been attributed to a different solvent quality of H2O and D2O. These results provide evidence to the fact that the properties of macromolecules, even of simple structure, can be influenced by the isotopic composition of the solvent. [source] Signal generation and Raman-resonant imaging by non-degenerate four-wave mixing under tight focusing conditionsJOURNAL OF BIOPHOTONICS, Issue 3 2010Tyler Weeks Abstract The authors demonstrate Raman-resonant imaging based on the simultaneous generation of several nonlinear frequency mixing processes resulting from a 3-color coherent anti-Stokes Raman scattering (CARS) experiment. The interaction of three coincident short-pulsed laser beams simultaneously generates both 2-color (degenerate) CARS and 3-color (non-degenerate) CARS signals, which are collected and characterized spectroscopically , allowing for resonant, doubly-resonant, and non-resonant contrast mechanisms. Images obtained from both 2-color and 3-color CARS signals are compared and found to provide complementary information. The 3-color CARS microscopy scheme provides a versatile multiplexed modality for biological imaging, which may extend the capabilities of label-free non-linear microscopy, e.g. by probing multiple Raman resonances. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||