Raman Spectrometer

Description

Application:

• Raman spectrometer is used to track molecular structural changes, variations of concentrations in compounds, identify changes in crystallinity, identify phase changes in polymers, identify molecular orientation.
• It is widely used in the food and beverage industry, pharmaceutical industry, oil and gas and healthcare industry.

Principle:

Raman Spectrometer is used to study the interaction between the light source and the sample. In the Raman Spectrometer, the sample is illuminated with a laser light of single wavelength and the scattered Raman photons are dispersed on the detector. The intensity of the scattered photons are plotted as a spectrum. The elastically scattered photons called Rayleigh scattered photons have the same wavelength as incident light. However some incident light interacts with the sample and the wavelength shifts lower or higher (red or blue). The red shifted photons are called Stokes shifted. This shift is due to the interaction of the photon with the electron cloud of the functional groups present in the sample. Thus an electron gets excited to the virtual state. This then relaxes into an excited vibrational or rotational state thus causing the photon to lose its energy and this is called Raman scattering. This loss of energy indicates the functional group, the structure of the molecule it has interacted with and the types of atoms present. Some vibrational and rotational motions in molecules don’t exhibit Raman scattering effect because of the difference in polarizability. These do not show up in the Raman spectra.