Abstract

Spontaneous Raman spectroscopy (SRS) has been used in combustion diagnostics to measure gas temperature and species concentration.^1–7 SRS is an inelastic process in which the scattered light undergoes a frequency change characteristic of the internal energy levels of the irradiated molecules. SRS is easy to implement as a fieldable system, because it is a relatively simple and inexpensive technique. The Raman signal can be collected in the backward direction which makes SRS suitable for industrial applications using only one optical port. However, it suffers from low collection efficiency due to its isotropy scattered signal. Recent Raman studies with pulsed lasers and gated detection have shown a great improvement in the sensitivity of SRS technique.^1,2

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