Femtosecond laser filamentation for sensing combustion intermediates: A comparative study

We demonstrate experimental evidences that femtosecond filament-induced clean fingerprint fluorescence can indeed be employed to characterize the combustion intermediates in flames. By comparing the emission spectra obtained from an ethanol-air flame by femtosecond filament excitation, nanosecond laser-breakdown excitation, as well as without any laser excitation, it is found that the filament-induced fluorescence in the combustion flame mainly results from the interaction of femtosecond laser pulses with the combustion intermediates such as OH, CH, and C-2 existing in the combustion, but not from the fragmentation of parent ethanol molecules. (C) 2014 Elsevier B. V. All rights reserved.