Raman Spectra: Typical Raman scattering spectra collected from the HPGB facility in hydrogen-air flames at 10 atm pressure. The top spectrum shows data from a fuel-lean flame, the middle from a stoichiometric flame, and the bottom from a fuel-rich flame. Note that the spectra cover the entire visible range from 400 nm to 700 nm and provide adequate spectral resolution and signal-to-noise (> 10,000:1) for the development of a calibration database. The interpretation of the above Raman scattering spectra then provide a quantitative measurement of chemical species concentration and thermodynamic temperature.