The photolytic cage effect is studied over a wide density range of several bath gases in the laser flash photolysis of iodine at 694.3 nm. Particular attention is paid to measurements in the ‘‘simple’’ solvents Xe and Kr, which are compared with molecular dynamics calculations. Measurements in polyatomic gases and liquids are also reported, as well as the variation of the cage effect with temperature and applied magnetic field. While measuring the cage effect under such a wide variety of conditions, we simultaneously obtain the second order rate constants for iodine atom combination, which help to establish the detailed mechanism of this elementary chemical reaction.

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Sensitive and reliable analysis of alkylphosphonic acids (APAs) and 2-(N,N-dialkylamino)ethanesulfonic acids (SAs), the degradation products of chemical warfare agents (CWAs), is one of the most important tasks for verification of the Chemical Weapons Convention (CWC). Unambiguous identification of these chemicals is required in a variety of environmental matrices, including soil and water. These acids with low volatility are very polar, and efficient and reliable methylation methods for their derivatization are needed for analysis with gas chromatography–mass spectrometry (GC–MS). In this study, the derivatization conditions for trimethylsilyldiazomethane (TMSDAM) methylation were optimized for rapid GC–MS screening. Optimized methylation of APAs and SAs with TMSDAM was compared with methylation with diazomethane. The TMSDAM methylation of SAs and benzilic acid was further compared with silylation with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide. The significance and necessity of cation exchange prior to derivatization and analysis were tested on samples with a high inorganic background. A recommendation to use the method for methylation of water samples and aqueous extracts using TMSDAM is given. The robustness of the method was illustrated by the successful identification of APAs and SAs in aqueous samples from proficiency tests organized by the Organisation for the Prohibition of Chemical Weapons.