Raman microspectroscopy

In a medium without translation symmetry, the wavevector conservation rule breaks down, and the Raman spectrum again is expected to display features reflecting the density of states of the particular excitation. A generic Raman spectrometer consists of a monochromatic light source for sample illumination, collection optics for redirection of the scattered light into the wavelength analyser and the detector. Integration of a Raman spectrometer with a microscope provides higher spatial resolution suitable for performing Raman analysis on very small regions of a sample. The spatial resolution that the Raman instrumentation can achieve depends on the optical systems used for light delivery and collection. The chapter outlines of the general approach to phase and stress analysis by means of Raman microspectroscopy, using silicon (Si) as the reference material because of the utmost importance of Si for this type of research. In general, mechanical strain may shift the frequencies of the Raman modes and lift their degeneracy.