Characterisation of Imogolite by Microscopic and Spectroscopic Methods
Résumé
The main techniques needed to characterise imogolite are reviewed. The global quality of an imogolite sample can be assessed by a simple visual inspection. It should be transparent and should display some birefringence if sufficiently concentrated when observed between crossed polarisers. To gain a deep knowledge about a particular sample, the most often used techniques are infrared (IR) spectroscopy, transmission electronic microscopy (TEM) and X-ray diffraction. The main results are reviewed and some less commonly used techniques are also described. It is stressed that emerging techniques (namely, cryo-TEM and small-angle X-ray scattering) are particularly useful for assessing the global shape and the diameter of imogolite samples. Some characterisation developments are still needed, especially for obtaining reliable and fast measurements of the nanotube length distribution.