The laser induced fluorescence excitation spectrum (LIF) and the ultraviolet absorption spectrum (TA) of the acetonyl radical (CH 3C(O)CH2) were remeasured by using the time-resolved fast discharge flow (DF) and laser flash photolysis (LP) experimental techniques (T = 298 K). The absorption cross section of σ(acetonyl, 207 nm) = (3.16 ± 0.61) x 10-18 cm2 molecule-1 was determined calibrated against the acetyl-peroxyl radical (CH3C(O) O2) in LP/TA measurements. The kinetics of the reactions of CH 3C(O)CH2 with the open shell reaction partners O 2 (1), NO (2), NO2 (3) and H (4) were studied by using the DF method with LIF detection of the acetonyl radical at 298 ± 1 K and 2.85 ± 0.05 mbar He pressure. The rate constants for the overall reactions were determined in units of cm3 molecule-1 s-1 to be k1 = (3.49 ± 0.51) × 10 -13, k2 = (1.04 ± 0.19) × 10-11, k3 = (3.25 ± 0.65) × 10-11 and k4 ≥ 3 × 10-10 with 2σ accuracy given. The acetonyl radical was found to react similarly to alkyl radicals by comparison with literature results. A reduced reactivity was observed toward O2 and NO that might be attributed to the resonance stabilisation of the acetonyl radical. No such effect was observed for the NO2 and H atom reactions.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry