Detection of OH in a flame by degenerate four-wave mixing

Abstract
The detection of OH in a laminar premixed air–methane flame by degenerate four-wave mixing (DFWM) is The detection reported. The four-wave mixing spectrum was recorded in the region of the R1, R2 band heads of the (0, 0) 2∑–2Π transition, showing clearly resolved rotational structure. Applications of the DFWM technique to combustion are discussed. As an example, the distribution of sodium atoms in a sodium-seeded flame has been diagnostics measured using a 90° geometry to enhance spatial resolution.