Raman microscopes are very powerful tools, they provide a non-invasive and non-destructive technique that can investigate materials. The Department of Physics houses a Jobin-Yvon LabRam HR Raman microscope which serves the needs of research workers in the department and can provide specialist services to industry.
When light passes through a material, some of it is absorbed and some of it is scattered. Nearly all of the scattered light has identically the same frequency as the incident light; this is called elastic scattering or Rayleigh scattering. However, a tiny fraction of the scattered light is shifted in frequency; this process is called Raman scattering and the associated frequency shift is called the Raman shift.
Raman scattering is caused by the light interacting with some kind of oscillation inside the material, and the Raman shift measures the frequency of the oscillation involved. Many kinds of oscillations produce Raman shifts, e.g. molecular vibrations and rotations; a complex structure like an organic compound can oscillate in many ways and can therefore produce a complicated Raman spectrum.
This can all be analysed by using a Raman Microscope, samples are placed under the instrument's microscope and illuminated by a focussed laser beam. Back-scattered light is collected and analysed and a useful spectrum from a single spot on the sample may be produced in seconds.