With laser-induced fluorescence, images of the distribution of intermediate species in flames usually have been taken under the condition that the excitation electronic state and emission electronic state are the same. We have successfully photographed two-dimensional CH distribution in a natural gas/oxygen flame through a 431-nm bandpass filter with A-state emission by means of C-state excitation (312 nm). This method provides a smaller signal than the A-state excitation method does but is free from the scattering of the pumping laser beam surrounding the burner nozzle and Rayleigh scattering. Furthermore, this method gives us the opportunity to observe semiquantitative CH distribution.
© 1992 Optical Society of America
Akira Hirano, Masamichi Ippommastu, and Masahide Tsujishita, "Two-dimensional digital imaging of the CH distribution in a natural gas/oxygen flame at atmospheric pressure and detection of A-state emission by means of C-state excitation," Opt. Lett. 17, 303-304 (1992)