Abstract
Formaldehyde (H2CO) is one of the key intermediate species in the initial state of combustion and is also a harmful exhaust constituent, especially in alcohol combustion. A detailed understanding of the reaction system of H2CO can be obtained by comparison between measured and calculated density profiles. LIF is often used for in-situ measurement of flame but the estimation of quenching effects under atmospheric pressure is difficult (1). The electronic band spectrum of H2CO has been discussed in many papers (1,2), but most spectral experiments were performed under low pressure at room temperature. Also the red shaded branch of 350nm band which is important for the YAG THG has been seldom used for measurement.