Absolute UV absorption cross sections of dimethyl substituted Criegee intermediate (CH 3 ) 2 COO

The absolute absorption cross sections of (CH 3 ) 2 COO under a jet-cooled condition were measured via laser depletion to be (1.32 ± 0.10) × 10 −17 cm 2 molecule −1 at 308 nm and (9.6 ± 0.8) × 10 −18 cm 2 molecule −1 at 352 nm. The peak UV cross section is estimated to be (1.75 ± 0.14) × 10 −17 cm 2 molecule −1 at 330 nm, according to the UV spectrum of (CH 3 ) 2 COO (Huang et al., 2015) scaled to the absolute cross section at 308 nm.