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Smart Optical Spectroscopy for the Analysis of Nanomaterials

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12.06.2006

Raman spectrometry is a very elegant technique to study nanomaterials since it investigates the matter at a sub-nanometer scale, i.e. the scale of the chemical bonds.

Each Raman peak corresponds to a specific vibration and provides information (even on heterogeneous materials) such as the phases nature, distribution, residual stress,….

Since the Raman scattering efficiency depends on the polarisability of the electronic cloud, it can be very sensitive to light elements involved in covalent bonds, which is a valuable advantage, when compared to X-ray-based techniques (EDS, micro-probe,…).

Despite these advantages, the rise of Raman and Rayleigh imaging is still limited due to the huge time they require and to a lack of real control on the resolution. The deconvolution of the images by the spot shape allows to improve the “xy” resolution down to the diffraction limit (~wavelength/2). A comparison between Rayleigh imaging and AFM shows that under specific conditions Rayleigh analysis is a competitive alternative to AFM for nearly (sub)micronic resolution range.

“Smart” images i.e. images of physical (strain, strength, height, …) or chemical parameters (e.g. corrosion) can be obtained owing for the development of models that link Raman parameters to physical/chemical parameters.

Philippe Colomban | Source: alphagalileo
Further information: www.microscopy-analysis.com/cgi-bin/item.cgi?ap=1&id=271
www.glvt-cnrs.fr

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