Infrared detection of Criegee intermediates

In this mini-review article, we present the recent progress of utilizing three types of infrared (IR) spectroscopic tools to investigate the chemistry of Criegee intermediates (CIs). The first part of this article described a recent work of Wang et al., which utilized rapid-scan FTIR to detect CIs created from ozonolysis. The second part of this article describes the advantages of quantum cascade lasers (QCLs) used as novel IR spectroscopic tools to probe CIs and the key concepts of experimental implementations. We also summarize the works of Chang and co-workers, which utilized distributed feedback QCLs with thermal chirping to detect the simplest CI, CH2OO, and the subsequent kinetics measurements, such as reactions of CH2OO with ozone, CH3SH, and dimethyl sulfoxide. In the last part of this article, we described the key ideas of external-cavity QCLs coupled with off-axis integrated cavity output spectroscopy, which was proposed by Chung et al., and also the latest progress on determination of the band strength of CH2OO and its rate coefficient with O-3.