With the help of Raman spectroscopy it is possible to quickly determine the material composition of an unknown surface. For example, it is possible to distinguish between the rutile and anatase geometries of titanium dioxide using Raman spectroscopy, as well as to differentiate between single-layer, double-layer or multilayer graphene layers.

But not only composition and structure can be measured, it is also possible to determine crystallinity, layer thickness or temperature, depending on the sample. Compressive or tensile forces also often lead to a shift in the position of the Raman lines.

Not all materials and molecules are Raman active. In order to use Raman spectroscopy, the polarisability of the material must change with rotation or vibration.

At ICAN we use the inVia confocal Raman microscope from Renishaw. This instrument delivers powerful performance and many measurement modes while being very user-friendly. Two lasers, with wavelengths of 532nm and 633nm, are available on the microscope.

Figure 1: Spatially resolved image of a titanium dioxide (TiO2) surface. The light blue background is the light microscope image (20x magnification) of the surface. The dark blue and yellow areas represent the Raman signal intensity of the two geometries rutile and anatase of the TiO2.