Atmospheric pressure acetylene detection by UV photo-fragmentation and induced C2 emission.

Detection of C(2)H(2) via UV photo-fragmentation, followed by monitoring the C(2) d(3)Π(g)-a(3)Π(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, C(2) emissions correlate closely with C(2)H(2) 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.