Detection of oh in an atmospheric flame at 1.5μm using optical frequency comb spectroscopy

Abstract

We report broadband detection of OH in a premixed CH4/air flat flame at atmospheric pressure using cavity-enhanced absorption spectroscopy based on an Er:fiber femtosecond laser and a Fourier transform spectrometer. By taking ratios of spectra measured at different heights above the burner we separate twenty OH transitions from the largely overlapping water background. We retrieve from fits to the OH lines the relative variation of OH concentration and flame temperature with a height above the burner and compare them with the 1D simulations of flame structure.