A kinetic study of the CH2OO Criegee intermediate self- reaction, reaction with SO2 and unimolecular reaction using cavity ring-down spectroscopy: Supplementary Information

A 106-cm long, nearly confocal cavity with high reflectivity mirrors (R >99.9% at 355 nm, r = 100 cm) was used for the cavity ring down spectrometer. Probe laser radiation was passed through one of the mirrors into the cavity. The probe radiation was generated by spatially filtering the frequency doubled fundamental output from a dye laser. Spatial filtering used a pinhole and lens assembly. A New Focus 1801 photodiode detector measured the decay profile of the light transmitted from the cavity. Signal from the photodiode was digitized using a LeCroy Waverunner 6030 oscilloscope (8 bit, 350 MHz, 2.5 GSamples/s). A BNC 555 digital delay-pulse generator was used to change the delay between probe and photolysis lasers.