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Chemical Imaging (chemical + imaging)
Selected AbstractsInnentitelbild: 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] The Use of Optical Fiber Bundles Combined with Electrochemistry for Chemical ImagingCHEMPHYSCHEM, Issue 2 2003Sabine Szunerits Dr. Abstract The present Review describes the progress made in using imaging optical fiber bundles for fluorescence and electrochemical-initiated chemiluminescence imaging. A novel optoelectrochemical micro-ring array has been fabricated and demonstrated for concurrent electrochemical and optical measurements. The device comprises optical fibers coated with gold via electroless gold deposition and assembled in a random array format. The design yielded an array of approximately 200 micro-ring electrodes, where interdiffusional problems were minimized. The inner diameter of the ring electrode is fixed by the diameter of the individual optical fibers (25 ,m), while the outer radius is determined by the thickness of the deposited gold. While all the fibers are optically addressable, they are not all electrochemically addressable. The resolution of this device is in the tens of micrometers range, determined by the diameter of the optical fiber (25 ,m) and by the spacing between each electrically connected fiber. For the purpose of having well-behaved microelectrode characteristics, this spacing was designed to be larger than 60 ,m. The array was characterized using ferrocyanide in aqueous solution as a model electroactive species to demonstrate that this microelectrode array format exhibits steady-state currents at short response times. This device has potential application to be used as an optoelectronic sensor, especially for the electrolytic generation and transmission of electrochemiluminescence, and was used to demonstrate that electrochemically generated luminescent products can be detected with the fiber assembly. [source] Three-Dimensional Atomic Force Microscopy , Taking Surface Imaging to the Next LevelADVANCED MATERIALS, Issue 26-27 2010Mehmet Z. Baykara Abstract Materials properties are ultimately determined by the nature of the interactions between the atoms that form the material. On surfaces, the site-specific spatial distribution of force and energy fields governs the phenomena encountered. This article reviews recent progress in the development of a measurement mode called three-dimensional atomic force microscopy (3D-AFM) that allows the dense, three-dimensional mapping of these surface fields with atomic resolution. Based on noncontact atomic force microscopy, 3D-AFM is able to provide more detailed information on surface properties than ever before, thanks to the simultaneous multi-channel acquisition of complementary spatial data such as local energy dissipation and tunneling currents. By illustrating the results of experiments performed on graphite and pentacene, we explain how 3D-AFM data acquisition works, what challenges have to be addressed in its realization, and what type of data can be extracted from the experiments. Finally, a multitude of potential applications are discussed, with special emphasis on chemical imaging, heterogeneous catalysis, and nanotribology. [source] Analysis of video images from a gas,liquid transfer experiment: a comparison of PCA and PARAFAC for multivariate image analysisJOURNAL OF CHEMOMETRICS, Issue 7 2003Stephen P. Gurden Abstract The use of chemical imaging is a developing area which has potential benefits for chemical systems where spatial distribution is important. Examples include processes in which homogeneity is critical, such as polymerizations, pharmaceutical powder blending and surface catalysis, and dynamic processes such as the study of diffusion rates or the transport of environmental pollutants. Whilst single images can be used to determine chemical distribution patterns at a given point in time, dynamic processes can be studied using a sequence of images measured at regular time intervals, i.e. a movie. Multivariate modeling of image data can help to provide insight into the important chemical factors present. However, many issues of how best to apply these models remain unclear, especially when the data arrays involved have four or five different dimensions (height, width, wavelength, time, experiment number, etc.). In this paper we describe the analysis of video images recorded during an experiment to investigate the uptake of CO2 across a free air,water interface. The use of PCA and PARAFAC for the analysis of both single images and movies is described and some differences and similarities are highlighted. Some other image transformation techniques, such as chemical mapping and histograms, are found to be useful both for pretreatment of the raw data and for dimensionality reduction of the data arrays prior to further modeling. Copyright © 2003 John Wiley & Sons, Ltd. [source] Facing the challenge of biosample imaging by FTIR with a synchrotron radiation sourceJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2010Cyril Petibois Fourier-transform infrared (FTIR) synchrotron radiation (SR) microspectroscopy is a powerful molecular probe of biological samples at cellular resolution (<10,µm). As the brilliance of SR is 100,1000 times higher than that of a conventional Globar source, FTIR microscopes are now available in almost all advanced SR facilities around the world. However, in spite of this superior performance, the expected advances in IR SR microscopy have not yet been realised, particularly with regard to bio-analytical studies of single cells and soft tissues. In recent decades solid-state array detectors have revolutionized the fields of molecular spectroscopy and chemical imaging, and now new IR focal plane array detectors implemented at ultra-bright SR facilities will extend the performance and overcome the existing limitations, possibly allowing IR SR instrumentation to achieve the highest sensitivity and resolution of molecular imaging. The impact of IR imaging on large tissue area and the complexity of the analysis are discussed. In view of the high brilliance of SR sources, a comparison of published microscope images is given. Finally, it is briefly outlined how an optimized combination of IR instrumentation and SR optical systems could reach the expected advantages of a SR-based FTIR imaging system. [source] The use of FT-IR microspectroscopic mapping to study the effects of enzymatic retting of flax (Linum usitatissimum L) stems,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2002David S Himmelsbach Abstract Fourier transform infrared (FT-IR) microspectroscopic mapping was investigated as a tool to study the effects of enzymatic retting of flax stems. The FT-IR technique permitted the elucidation of the relative loss or changes in the distribution of key chemical components after treatment with enzymes or enzyme/chelator mixtures in association with visible changes in structure. Cross-sections of Ariane flax stems were treated with SP 249 (a pectinase-rich enzyme mixture from Novo Nordisk) at 0.5, 0.7 or 1.0,ml,l,1 concentration in pH 5 acetate buffer for 6,h at 40,°C. Flax stems treated with 0.5 or 0.7,ml,l,1 SP 249 and 50,mM oxalic acid as a chelator were also investigated by the technique. The results indicated that treatment with 0.5,ml,l,1 SP 249 alone was ineffective in releasing the fibre bundles from the surrounding tissue, but the release was increased by the addition of 50,mM oxalic acid as a likely chelator for the cations of pectate salts. However, the IR spectra of the bundles indicated that an insoluble oxalate salt remained on the tissue after this treatment. Increasing the concentration of SP 249 to 0.7,ml,l,1 plus 50,mM oxalic acid was effective in releasing the fibre bundles and generating some ultimate fibres with no detectable oxalate expectate salt residues. Increasing the SP 249 concentration to 1.0,ml,l,1 without using oxalic acid was effective in separating the fibre bundles into ultimate (individual) fibres, leaving no pectate salt residue and only a trace of pectic esters and/or acids. The use of infrared mapping, or so-called chemical imaging, is shown to have advantages over visible imaging alone in that it can detect and locate the chemical species present after each treatment in relation to the anatomical features of the flax stem. This analytical tool shows promise as a technique by which to study the effects of enzymatic treatment of natural fibre materials. Published in 2002 for SCI by John Wiley & Sons, Ltd [source] THE APPLICATION OF TIME-OF-FLIGHT SECONDARY ION MASS SPECTROMETRY (ToF-SIMS) TO THE CHARACTERIZATION OF OPAQUE ANCIENT GLASSES*ARCHAEOMETRY, Issue 6 2009F. J. M. RUTTEN Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used, for the first time, for the characterization of opaque ancient glasses. Isotope-specific chemical imaging with sub-micron resolution enabled the separate analysis of opacifiying inclusions and the surrounding glass matrix. Phase identification has been demonstrated and quantification of the matrix composition has been investigated by use of Corning Glass Standard B as a model. Trace element detection limits are typically in the range 0.5,5.0 ppm atomic,in favourable cases down to 0.01 ppm. For the analysis of inclusions in particular, this has the potential to provide new information of use in establishing provenance and trade routes by ,fingerprinting' as well as the investigation of manufacturing techniques, as demonstrated by comparisons between glasses and with EDX data from the same samples. [source] Hybrid Rayleigh, Raman and two-photon excited fluorescence spectral confocal microscopy of living cellsJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2010Vishnu Vardhan Pully Abstract A hybrid fluorescence,Raman confocal microscopy platform is presented, which integrates low-wavenumber-resolution Raman imaging, Rayleigh scatter imaging and two-photon fluorescence (TPE) spectral imaging, fast ,amplitude-only' TPE-fluorescence imaging and high-spectral-resolution Raman imaging. This multi-dimensional fluorescence,Raman microscopy platform enables rapid imaging along the fluorescence emission and/or Rayleigh scatter dimensions. It is shown that optical contrast in these images can be used to select an area of interest prior to subsequent investigation with high spatially and spectrally resolved Raman imaging. This new microscopy platform combines the strengths of Raman ,chemical' imaging with light scattering microscopy and fluorescence microscopy and provides new modes of correlative light microscopy. Simultaneous acquisition of TPE hyperspectral fluorescence imaging and Raman imaging illustrates spatial relationships of fluorophores, water, lipid and protein in cells. The fluorescence,Raman microscope is demonstrated in an application to living human bone marrow stromal stem cells. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||