The UV absorption spectrum of the simplest Criegee intermediate CH2OO

SO2 scavenging and self-reaction of CH2OO were utilized for the decay of CH2OO to extract the absorption spectrum of CH2OO under bulk conditions. Absolute absorption cross sections of CH2OO at 308.4 and 351.8 nm were obtained from laser-depletion measurements in a jet-cooled molecular beam. The peak cross section is (1.23 +/- 0.18) x 10(-17) cm(2) at 340 nm.