CH_3 Detection in Flames Using Photodissociation-Induced Fluorescence

摘要

This paper demonstrates that CH_3 photodissociation occurs in flames when laser radiation around 205 nm is focused even slightly. This photodissociation leads to the formation of CH in the A~2 DELTA elecftronic state. Fluorescence signal issuing from A~2 DELTA CH is shown to be quantitatively representative of CH_3 concentration.Validation is obtained by using chemical kinetic modeling and by comparing 205-nm excited A~2 DELTA CH profile with CH_3 profile measured by molecular beam-mass spectrometry in different methane/ air flames. A spectroscopic discussion is described. It is sshown that the overall photodissociation process may be consistent with the following steps;