Exploring the mechanism of blue emission from hydrogen combustion

An attempt is made to understand the mechanism of blue emission from hydrogen combustion. Temporal profiles of blue light emitted from high-temperature reactions of H2/O2 mixtures diluted with argon are measured using a high-repetition-rate shock tube coupled with emission spectroscopy. The emissions in the blue region are found to be about three orders of magnitude weaker than and behave differently from the OH* chemiluminescence in the ultraviolet region. With the help of kinetic modeling, the radiative recombination reactions of both H + OH and OH + OH are suggested to be responsible for the blue emission.