(1) by 248-nm photolysis of acetone CH₃C(O)CH₃, methyl ethyl ketone CH₃C(O)C₂H₅, and biacetyl CH₃C(O)C(O)CH₃, and

(2) by the reaction of acetaldehyde CH₃CHO with Cl atoms (Cl₂ photolysis or discharge flow tube) or with OH radicals (H₂O₂ or O₃/H₂O photolysis)

The absorption spectra were measured using cavity ring-down spectroscopy

The spectrum obtained with the H₂O₂ photolysis source was used as a reference and fitted to the polynomial

σ(λ) = A + Bλ + Cλ² + Dλ³ + Eλ⁴

leading to the parameters
(σ in units of cm² molecule^-1, λ in nm)

A = -6.6124×10^-17
B = 4.1946×10^-19
C = -9.865×10^-23
D = 1.02141×10^-24
E = -3.93411×10^-28

The listed absorption cross sections have been calculated at 0.5-nm intervals using the empirical fit