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The kinetics of the gas phase reactions of the Criegee intermediate CH 2 OO with O 3 and IO have been studied at 296 K and 300 Torr through simultaneous measurements of CH 2 OO, the CH 2 OO precursor (CH 2 I 2 ), O 3 , and IO using flash photolysis of CH 2 I 2 /O 2 /O 3 /N 2 mixtures at 248 nm coupled to time-resolved broadband UV absorption spectroscopy. Experiments were performed under pseudo-first-order conditions with respect to O 3 , with the rate coefficients for reactions of CH 2 OO with O 3 and IO obtained by fitting to the observed decays of CH 2 OO using a model constrained to the measured concentrations of IO. Fits were performed globally, with the ratio between the initial concentration of O 3 and the average concentration of IO varying in the range 30-700, and gave k CH2OO+O3 = (3.6 ± 0.8) × 10 -13 cm 3 molecule -1 s -1 and k CH2OO+IO = (7.6 ± 1.4) × 10 -11 cm 3 molecule -1 s -1 (where the errors are at the 2σ level). The magnitude of k CH2OO+O3 has a significant effect on the steady state concentration of CH 2 OO in chamber studies. Atmospheric implications of the results are discussed.

The reaction between CH 3 O 2 and OH radicals has been shown to be fast and to play an appreciable role for the removal of CH 3 O 2 radials in remote environments such as the marine boundary layer. Two different experimental techniques have been used here to determine the products of this reaction. The HO 2 yield has been obtained from simultaneous time-resolved measurements of the absolute concentration of CH 3 O 2 , OH, and HO 2 radicals by cw-CRDS. The possible formation of a Criegee intermediate has been measured by broadband cavity enhanced UV absorption. A yield of ϕ HO 2 = (0.8 ± 0.2) and an upper limit for ϕ Criegee = 0.05 has been determined for this reaction, suggesting a minor yield of methanol or stabilized trioxide as a product. The impact of this reaction on the composition of the remote marine boundary layer has been determined by implementing these findings into a box model utilizing the Master Chemical Mechanism v3.2, and constraining the model for conditions found at the Cape Verde Atmospheric Observatory in the remote tropical Atlantic Ocean. Inclusion of the CH 3 O 2 +OH reaction into the model results in up to 30% decrease in the CH 3 O 2 radical concentration while the HO 2 concentration increased by up to 20%. Production and destruction of O 3 are also influenced by these changes, and the model indicates that taking into account the reaction between CH 3 O 2 and OH leads to a 6% decrease of O 3 .

The kinetics of the OH + glyoxal, (HCO)2, reaction have been studied in N2 and N2/O2 bath gas from 5-80 Torr total pressure and 212-295 K, by monitoring the OH decay via laser induced fluorescence (LIF) in excess (HCO)2. The following rate coefficients, kOH+(HCO)2 = (9.7 ± 1.2), (12.2 ± 1.6), and (15.4 ± 2.0) × 10(-12) cm(3) molecule(-1) s(-1) (where errors represent a combination of statistical errors at the 2σ level and estimates of systematic errors) were measured in nitrogen at temperatures of 295, 250, and 212 K, respectively. Rate coefficient measurements were observed to be independent of total pressure but decreased following the addition of O2 to the reaction cell, consistent with direct OH recycling. OH yields, ΦOH, for this reaction were quantified experimentally for the first time as a function of total pressure, temperature, and O2 concentration. The experimental results have been parametrized using a chemical scheme where a fraction of the HC(O)CO population promptly dissociates to HCO + CO, the remaining HC(O)CO either dissociates thermally or reacts with O2 to give CO2, CO, and regenerate OH. A maximum ΦOH of (0.38 ± 0.02) was observed at 212 K, independent of total pressure, suggesting that ∼60% of the HC(O)CO population promptly dissociates upon formation. Qualitatively similar behavior is observed at 250 K, with a maximum ΦOH of (0.31 ± 0.03); at 295 K, the maximum ΦOH decreased further to (0.29 ± 0.03). From the parametrization, an OH yield of ΦOH = 0.19 is calculated for 295 K and 1 atm of air. It is shown that the proposed mechanism is consistent with previous chamber studies. While the fits are robust, experimental evidence suggests that the system is influenced by chemical activation and cannot be fully described by thermal rate coefficients. The atmospheric implications of the measurements are briefly discussed.

The essential oil content and the composition of subterranean parts of two valerian (Valeriana officinalis, L.) cultivars Select and Anthose, from certified commercial organic fields, were determined by hydrodistillation, followed by gas chromatography (GC) and GC/mass spectrometry analysis. Eight and fourteen month old cv. Select had 0.67 and 0.87% essential oil, while similar aged cv. Anthose contained 0.97 and 1.1% essential oil. Forty-three and fifty-three components from cv. Select and cv. Anthose oils were detected, respectively. The oil composition significantly varied due to the cultivar type, plant age, and/or harvesting time. The major components for cv. Select were valerenal, bornyl acetate, 15-acetoxy valeranone, valerenic acid, and camphene, while cv. Anthose had valerenal, (-)-bornyl acetate, alpha-humulene, camphene, 15-acetoxy valeranone, and valerenic acid. With further aging of the plants, the valerenal, valerenic acid, and alpha-humulene contents increased. The oil of cv. Select had a strong antimicrobial effect against Aspergillus niger, Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae, while cv. Anthose showed low or no activity against all test microbes, including Pseudomonas aeruginosa, suggesting that the inhibitory activity of valerian oil depends on the cultivar and its developmental stage. The oil profile of our cultivars did not match the literature proposed chemotype profiles.