Atmospheric Pressure Acetylene Detection by UV Photo-Fragmentation and Induced C 2 Emission

Abstract

Detection of C₂H₂ via UV photo-fragmentation, followed by monitoring the C₂d³Π_g–a³Π_u fluorescence, is explored at atmospheric pressure and at temperatures of 295 K, 600 K, and 800 K, for excitation wavelengths 210 to 240 nm using a broadband laser source (~3 cm⁻¹ fwhm). At the lower temperature, C₂ emissions correlate closely with C₂H₂ Ã←X absorption bands, and the excitation spectra suggest a higher-transition probability for the v″ ₄ = 2 and 3 states than for the v″ ₄ = 0 and 1 states. As temperature increases, the excitation spectra exhibit a higher nonresonant background.