Presented here are authoritative and up-to-date assessments of the homogenous and heterogenous chemical and physical processes occuring in the troposphere and stratosphere, especially during the "ozone hole" event. The book begins with an overview of atmospheric chemistry, followed by reviews of relevant homogenous reactions in the gas phase and the microphysics and physical chemistry of heterogenous processes that occur on, or in aerosols, rain and ice. Low temperature laboratory studies are compared with related fieldwork measurements, particularly in relation to the formation and composition of polar stratospheric clouds. Also discussed are measurements in glacial ice. Finally chemical modelling of the troposphere and stratosphere, including heterogenous processes, is reviewed.
We demonstrate time-resolved frequency comb spectroscopy (TRFCS), a new broadband absorption spectroscopy technique for the study of trace free radicals on the microsecond timescale. We apply TRFCS to study the time-resolved, mid-infrared absorption of the deuterated hydroxyformyl radical trans-DOCO, an important short-lived intermediate along the OD + CO reaction path. Directly after photolysis of the chemical precursor acrylic acid-d1, we measure absolute trans-DOCO product concentrations with a sensitivity of 5 × 10(10) cm(-3) and observe its subsequent loss with a time resolution of 25 μs. The multiplexed nature of TRFCS allows us to detect simultaneously the time-dependent concentration of several other photoproducts and thus unravel primary and secondary chemical reaction pathways.
Catalysts which comprise silica are rendered less susceptible to physical damage during processing with aqueous liquids by pre-steaming them.