Confocal micro-Raman
providing sub-micron capabilities
The use of optimized microscope objectives, careful selection of the most appropriate laser wavelength, and specialized mapping acquisition enables Raman microscopy to push towards the true optical limit of resolution- the far field diffraction limit.
Measurements of Nanowire structures, show that they may be observed and analyzed in the sub-micron scale. Here, 190 nm nanowire structures are determined by the polarized Raman analysis on a LabRAM system.
Single GaN nanowire with different polarization.
Raman image of GaN nanowire,
courtesy of D Talaga, F Lagugne Labarthet,
Bordeaux university
Not all samples will enable the spatial resolution to reach the sub-micron level - particularly those that are transparent and where there is significant interaction between the laser and the sample, (as the interaction of Raman scattering and of the laser beam with these samples can be quite complex).
However, with increasing types and numbers of samples, Raman microscopy can be pushed towards its limits and with relatively straight forward equipment and operation. Thus, features on the 500 nm, or even 200 nm realm may be distinguished.
Confocal Raman microscope systems from HORIBA Jobin Yvon.
