Raman microspectrometry

Originally, Raman microspectrometry was developed to improve the Raman detection sensibility to small samples containing a limited number of molecules scattering the light. The intensity of the signal delivered by a spectrometer detector excited by a Raman line at the wavelength X can be expressed as  

When a small volume of matter is examined, compensation for the decreased number of molecules N in the probed volume and increase of the detection 

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Thus, when such problems appeared, we used Raman microspectrometry to identify the salt hydrates and to measure... 

G. Penel, G. Leroy, C. Rey, B. Sombret, J.P. Huvenne, E. Bres, Infrared and Raman microspectrometry study of fluor- fluor-hydrox- and hydroxy-apatite powders, J. Mater. Sci. Mater. Med. 8 (1997) 271-276. 

Merlin, J., Statoua, A., and Brouillard, R., Investigation of the in vivo organization of anthocyanins using resonance Raman microspectrometry. Phytochemistry 24, 1575, 1985. 

Combined elastic and confocal Raman microspectrometry experiments were carried out by Yaroslavsky et al. [10] to investigate the spatially resolved scattering behavior along the visual axis of human donor lenses ranging in age from 20 to 68 years. They explored the relation between local protein content and local intensity of elastically scattered light, and compared their results with protein scattering behavior from a model that assumes... 

Raman microspectroscopy results from coupling of an optical microscope to a Raman spectrometer. The high spatial resolution of the confocal Raman microspectrometry allows the characterization of the structure of food sample at a micrometer scale. The principle of this imaging technique is based on specific vibration bands as markers of Raman technique, which permit the reconstruction of spectral images by surface scanning on an area. 

Microspectrometry is an indispensable technique in criminalistic analyses, being a combination of optical microscopy and spectrometry. Microscopy creates, records and interprets magnified images, whereas spectrometry uses emission, absorption and reflection of radiant energy by matter to determine its structure, properties and composition. On the basis of the type of energy applied, microspectrometry can be divided into IR, visual and ultraviolet (UV-vis), and Raman microspectrometry. This group also includes X-ray microspectrometry, in which an electron microscope takes the place of an optical microscope. Infrared and Raman microspectrometry enable determination and comparison of the chemical composition of studied samples UV-vis microspectrometry serves to compare the colour of samples in an objective way that is independent of the observer and X-ray microspectrometry allows determination of the elemental composition. 

Figure 12.16 illustrates how Raman microspectrometry can be used to image nanophase distribution in nanosized materials. We will present the case of SiC fibers for aerospace applications, prepared with different technologies. These... 

FIGURE 12.17 Spectral in-line scan (2 pm step) of a composite cross section. Spectra were recorded from one NLM202 fiber to another, through the aluminosilicate + (Zr02 Ge02) tailored interface and the mullite matrix. (Reprinted from Colomban, R, Raman microspectrometry and imaging of ceramic fibers in CMCs and MMCs, 103, 517, 2000. With permission from The American Ceramic Society.)... 

Lagugne Labarthet F, Bruneel JL, Rodriguez V, Sourisseau C. 2004. Chromophore orientations in surface relief gratings with second order nonlinearity as studied by confocal polarized Raman microspectrometry. J Phys Chem B 108(4) 1267 1278. 

Penel G, Leroy N, Van Landuyt P, Flautre B, Hardouin P, Lemaitre J, et al. Raman microspectrometry studies of brushite cement in vivo evolution in a sheep model. Bone. 1999 Aug 25(2 Suppl) 81S S. 

R. Baddour-Hadjean, J.-P. Pereira-Ramos, Raman Microspectrometry Applied to the Study of Electrode Materials for Lithium Batteries, Chem. Rev. (Washington, DC, U. S.) 2009,110, 1278-1319. 

Baddour-Hadjean, R. and Pereira-Ramos, J.P. (2009) Raman microspectrometry applied to the study of electrode materials for lithium batteries. Chemical Reviews, 110, 1278-1319. 

To obtain deeper insights into such guest exchange processes in urea inclusion compounds, confocal Raman microspectrometry has been exploited as an in situ probe (Figure 29) to yield information on the spatial distribution of the original and new guest molecules within the crystal, and to establish details of how the spatial distribution of... 

Figure 29 Schematic representation of the experimental assembly for in situ Raman microspectrometry studies of guest exchange in a urea inclusion compound, comprising the single crystal of the urea inclusion compound (green), initially containing 1,8-dibromooctane guest molecules, attached to a reservoir containing liquid pentadecane (blue).

Sobanska S, Hwang H, Choel M, Jung H-J, Eom H-J, Kim H, Barbillat J, Ro C-U (2012) Investigation of the chemical mixing state of individual Asian dust particles by the combined use of electron probe X-ray microanalysis and Raman microspectrometry. Anal Chem... 

The techniques mentioned so far provide no direct spatially resolved information on the chemical composition of materials. Various established analytical techniques, such as secondary-ion mass spectrometry (SIMS), X-ray photoelectron spectrometry (XPS), and infrared (IR) and Raman microspectrometry, can be used to carry out local compositional studies. In the case of SIMS and XPS, the sample needs to be held in high vacuum, while in IR and Raman microspectrometry, the resolution is limited by the relatively large wavelength... 

The above-described examples are applications presently performed in major gemmological laboratories. As Raman microspectrometry is a relatively new method in gemmology, all possibilities of gemstone detection are probably not exhausted yet. With new gemstone treatments such as the treatment of color in diamond, a rising awareness of those treatments in the gemstone trade, and smaller and more affordable instruments, it is safe to assume that a Raman microspectrometer will soon be a standard instrument in all major gemmological laboratories. 

Raman microspectrometry can be apphed to the study of membrane systems in contact with Hquid solutions or gases and it can allow the visualization of ionic species, solvent, or membrane structure [20, 33—44]. However, the cell used for investigation must be specifically designed in order to obtain the best optical coupling between the system under study and the spectrometer. 

Experimental studies of the membrane transport by confocal Raman microspectrometry can be carried out only in some specific cases. Amongst various... 

A.V., and Prasad, P.N. (2010) Nonlinear optical imaging and Raman microspectrometry of the cell nucleus throughout the cell cycle. Biophys.., 99, 3483-3491. 

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