DIRECT MEASUREMENT OF (CH2)-C-1 IN FLAMES BY CAVITY RINGDOWN LASER-ABSORPTION SPECTROSCOPY

Singlet methylene is an important combustion intermediate, but has rem ained difficult to measure in flames. Cavity ringdown laser absorption spectroscopy (CRLAS) allows the sensitive and selective detection of (CH2)-C-1 with good spatial resolution. Singlet methylene has been det ected by CRLAS in a series of rich, low-pressure methane flames with s toichiometries of 1.0, 1.2, 1.4 and 1.6. The measured relative concent ration profiles are compared with laminar flame models utilizing detai led chemical reaction mechanisms. The data show good agreement with mo dels at stoichiometries of 1.0 and 1.2, but increasingly poor agreemen t at richer stoichiometries. (C) 1998 Elsevier Science B.V. All rights reserved.