Imaging, Raman

Raman spectroscopy is attractive as an examination technique for ceramic and polymeric materials because it can simply examine them by illuminating their surfaces regardless of sample thickness and form. Raman microscopy is even more attractive because it can examine a microscopic area with diameters in the order of 1 /xm. Raman microscopy is increasingly used for materials characterization, including  

Raman microscopy is able to determine phases for polymorphic solids at the microscopic level. This is its advantage over conventional X-ray diffraction spectrometry in which the sample volume cannot be too small. Phase identification with Raman spectroscopy uses 

Polymorphic Materials Phase 1 Bands (cm ) Phase 2 Bands (cm ) 

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Plenary 7(5. N I Koroteev et al, e-mail address Koroteev nik.phys.iusu.su (CARS/CSRS, CAHRS, BioCARS). A survey of the many applications of what we call the Class II spectroscopies from third order and beyond. 2D and 3D Raman imaging. Coherence as stored infonuation, quantum infonuation (the qubit ). Uses tenus CARS/CSRS regardless of order. BioCARS is fourtli order in optically active solutions. 

With a special optical system at the sample chamber, combined with an imagir system at the detector end, it is possible to construct two-dimensional images of the sample displayed in the emission of a selected Raman line. By imaging from their characteristic Raman lines, it is possible to map individual phases in the multiphase sample however, Raman images, unlike SEM and electron microprobe images, have not proved sufficiently useful to justify the substantial cost of imaging optical systems. 

To summarize, we have shown here that enhanced electric-field distribution in metal nanoparticle assemblies can be visualized on the nanoscale by a near-field two-photon excitation imaging method. By combining this method and near-field Raman imaging, we have clearly demonstrated that hot spots in noble metal nanoparticle assemblies make a major contribution to surface enhanced Raman scattering. 

Spatially Resolved Resonance Raman Imaging of Macular Pigment.95... 

SPATIALLY RESOLVED RESONANCE RAMAN IMAGING OF MACULAR PIGMENT... 

FIGURE 6.7 (a) Schematics of experimental setup used for in vivo resonance Raman imaging, RRI, of MP... 

Gellermann W, Ermakov IV, McClane RW, and Bernstein PS (2002b), Raman imaging of human macular pigments, Opt. Lett. 27 833-835. 

Sharifzadeh M, Zhao DY, Bernstein PS, and Gellermann W (2008), Resonance Raman Imaging of macular pigment distributions in the human retina, J. Opt. Soc. Am. A 25 947-957. 

Global Raman imaging can be a fast and simple technique, providing high lateral spatial resolution (down to the diffraction limit corresponding with the excitation laser wavelength) images of the sample of interest. There are several techniques available. 

Figure 3 Global Raman imaging Experimental setup and example image of a silicon wafer with letter E printed on it. Image taken at 520 cm 1 (Silicon Raman mode).

There is a number of alternative Raman imaging techniques these include using the Hadamard transform technique [25-27], and such as fibre-bundle image compression, which however is not yet commercially available [26-31]. However in the latter approach, the laser power on the sample could be high, since the beam is not defocused, and the possibility of sample damage increases. 

The theoretical lateral spatial resolution achievable with Raman imaging using the optical arrangements of our system (50 x objective with NA = 0.75, 633 nm HeNe laser) should be about 1 pm. In this investigation the resolution is worse than predicted. In practice, sample drift during long acquisition times, uneven surface structures and penetration of laser light into the material worsen the lateral spatial resolution to a value of about 2 pm (estimated). 

The Raman images in Figure 7 show that PTFE clusters in the sample are between 8 and 20 pm in diameter [46]. These results have also been confirmed by FTIR imaging and SEM [47]. 

Figure 10 Global Raman image of PTFE distribution in PA-matrix image taken at 731 cm- Left white light micrograph center Raman image right the same image after image enhancement and edge detection.

Fig. 10.4 Fossilized cellular filamentous microorganisms (two examples of Primaevifilum amoenum). They are 3.456 billion years old and come from the Apex chert region in northwestern Australia. As well as the original images, drawings and the Raman spectra and Raman images, which indicate that the fossils have a carbonaceous (organic) composition, are shown. With kind permission of J. W. Schopf...

Deckert V., Zeisel D., Zenobi R., Vo-Dinh T., Near-field surface enhanced Raman imaging of dye-labeled DNA with 100-nm resolution, Anal. Chem. 1998 70 2646-2650. 

V. Tishkova, P.-l. Raynal, P. Puech, A. Lonjon, M. Le Fournier, P. Demont, E. Flahaut, W. Bacsa, Electrical conductivity and Raman imaging of double wall carbon nanotubes in a polymer matrix, Compos. Sci. Technol., vol. 71, pp. 1326-1330, 2011. 

L. Zhang, M. Henson and S. Sekulic, Multivariate data analysis for Raman imaging of a model pharmaceutical tablet. Anal Chim. Acta, 545(2), 262-278 (2005). 

Uzunbajakava, N., Lenferink, A., Kraan, Y, Volokhina, E., Vrensen, G., Greve, J., and Otto, C. 2003. Nonresonant confocal Raman imaging of DNA and protein distribution in apop-totic cells. Biophys. J. 84 3968-81. 

Hayazawa, N., Inouye, Y, Sekkat, Z., and Kawata, S. 2002. Near-held Raman imaging of organic molecules by an apertureless metallic probe scanning optical microscope. J. Chem. Phys. 117 1296-1301. 

Jiang, C., Zhao, J., Therese, H. A., Friedrich, M., and Mews, A. 2003. Raman imaging and spectroscopy of heterogeneous individual carbon nanotubes. J. Phys. Chem. B 107 8742 5. 

Fiber Bundles Fiber bundles are used for Raman imaging. Several optical fibers are grouped together, each analyzing a specific sample area [13]. A 3D data cube is... 

Thus Raman imaging is a useful tool for detecting small API particles on the surface of pharmaceutical solid forms. It may even be the most suitable chemical imaging technique for API mapping due to its low spatial resolution (up to 0.5 pm/ pixel) and the polymorphism of the spectral information. 

FIGURE 11 Raman images at specific wavelengths and reference spectra (image size 325 pm x 270pm white higher absorbance, black lower absorbance). 

Parameters Raman Imaging Infrared Imaging Near-Infrared Imaging... 

Gift, A. D., Ma, J., Haber, K. S., McClain, B. L., and Ben-Amotz, D. (1999), Near-infrared Raman imaging microscope based on fiber-bundle image compression, J. Raman Spectrosc., 30,757-765. 

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