Raman mapping

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. 

Stress in crystalline solids produces small shifts, typically a few wavenumbers, in the Raman lines that sometimes are accompanied by a small amount of line broadening. Measurement of a series of Raman spectra in high-pressure equipment under static or uniaxial pressure allows the line shifts to be calibrated in terms of stress level. This information can be used to characterize built-in stress in thin films, along grain boundaries, and in thermally stressed materials. Microfocus spectra can be obtained from crack tips in ceramic material and by a careful spatial mapping along and across the crack estimates can be obtained of the stress fields around the crack. ... 

Baranska, M. et al.. Identification of secondary metabolites in medicinal and spice plants by NIR FT Raman microspectroscopic mapping. Analyst, 129, 926, 2004. 

Figure 2.7 (a) Tip-enhanced near-field Raman spectral mapping ofthe adenine nanocrystal at 30 nm intervals, (b) Raman intensity distribution of two major bands at 739 cm and 1328cm. ... 

Inorganic Compounds. The Raman microprobe has been used by Berg and Kerridge (2000) to obtain computer mappings of the structures of salt eutectics solidified from their melts. In contrast to metallic eutectics, which commonly occur... 

In ocular applications, Raman spectroscopy can quickly and objectively assess composite lutein and zeaxanthin concentrations of macular pigment using spatially averaged, integral measurements or images that quantify and map the complete MP distribution with high spatial resolution. Importantly, both variants can be validated with HPLC methods in excised human eyecups and in animal models. 

All considerations for measurements of single spot Raman spectra also hold for mapping because the measuring technique is essentially identical. The spatial resolution in a map depends also on the distance between the single points and can be altered from map to map. By increasing the distance, the spatial resolution... 

In transmission mode a spatial resolution of about 15-20 pm can be achieved with infrared microscopes [32]. This is generally sufficient to properly identify such as small impurities, inclusions, gels or single components of multilaminate foils. Similar to Raman spectroscopy, line profiles or maps over larger sample areas can be performed. 

The samples were collected from the cathodes 2.5 cm away from the current collector tab, washed in pure dimethyl carbonate (DMC), and soaked in DMC for 30 minutes after removal from Li-ion cells inside an argon-filled glove box. This procedure removed electrolyte salt from the electrode to prevent its reaction with air and moisture. An integrated Raman microscope system Labram made by ISA Groupe Horiba was used to analyze and map the cathode surface structure and composition. The excitation source was an internal He-Ne (632 nm) 10 mW laser. The power of the laser beam was adjusted to 0.1 mW with neutral filters of various optical densities. The size of the laser beam at the sample was 1.2 pm. 

Zhu T., Yu H.Z., Wang J., Wang Y.Q., Cai S.M., Liu Z.F., Two-dimensional surface enhanced Raman mapping of differently prepared gold substrates with an azobenzene self-assembled monolayer, Chem. Phys. Lett. 1997 265 334-340. 

IR and Raman line shapes have been measured for H0D/H20. They peak near 2500 cm 1 and have line widths in the 160 to 180 cm 1 range. Corcelli et al. [151] calculated these line shapes using the approaches described in Section III.C, for the SPC/FQ model, for temperatures of 10 90°C, finding quite good agreement with experiment. More recently, we have extended the method involving the quadratic electric field map for HOD/D20 [98] to HOD/H20 [52] and have calculated IR and unpolarized Raman line shapes. These line shapes, in comparison with experimental line shapes [12, 52], are shown in Fig. 7. Agreement between theory and experiment is excellent for both the IR and Raman. 

W.-T. Cheng, S.-Y. Lin and M.-J. Li, Raman microspectroscopic mapping or thermal system used to investigate milling-induced solid-state conversion of famotidine polymorphs, J. Raman Spectrosc., 38, 1595-1601... 

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