Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy.

Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) is a technique that is capable of simultaneously measuring temperature and species mole fractions of N(2), O(2), H(2), C(2)H(4), CO, and CO(2). WIDECARS is designed for measurements of all the major species (except water) in supersonic combustion flows fueled with hydrogen and hydrogen/ethylene mixtures. The two lowest rotational energy levels of hydrogen detectable by WIDECARS are H(2) S(3) and H(2) S(4). The detection of these lines gives the system the capability to measure temperature and species concentrations in regions of flow containing pure hydrogen fuel at room temperature.