ABSTRACT
In recent years, Raman spectroscopy has emerged as a powerful analytical tool to identify and quantify the components of gas mixtures in continuous and nonconsumptive fashion. Although the Raman effect has been known since 1928, its use has mainly been constrained to fundamental research regarding the structure and characteristics of molecules for a long time. When monochromatic laser light is guided into a gas sample, most photons pass the volume without any interaction and remain unaltered. Quantum mechanical selection rules govern the transitions. The occurring bands and branches and their spectral positions are the characteristics for the scattering molecule. The uncertainty of the energy levels leads to natural line broadening. Together with other homogeneous broadening effects such as the pressure broadening, this would lead to Lorentzian-shaped spectral lines. One strategy is based on a multipass cavity used as sample container.
