Heterogeneous reactions between NO3 and N2O5 and diethyl sebacate (DES), glycerol, oleic acid (OA), linoleic acid (LA), and conjugated linoleic acid (CLA) were studied to understand better nighttime aerosol chemistry. The reactive uptake coefficient of NO3 on the liquid alkenoic acids (OA, LA, and CLA) was found to be >0.07, which is higher than previous results for unsaturated organics, including alkenoic acids. This reaction could potentially be an important loss process of particle-phase unsaturated organic compounds in the atmosphere and in laboratory secondary organic aerosol studies. The reactive uptake coefficient of N2O5 on liquid glycerol was also found to be relatively large with a value of (3.2-8.5)x10(-4), suggesting that N2O5 heterogeneous reactions with alcohols may also be atmospherically relevant. For all measurements with OA, CLA, and DES, the reactive uptake coefficients decreased significantly upon freezing. One possible explanation is that the liquid reaction is due to both a surface reaction and a bulk reaction and that the freezing process significantly decreases the importance of any bulk reactions. NO3 reactive uptake coefficients for liquid-phase compounds decreased in magnitude in the order: alkenoic acids>DES>glycerol. This is different compared to previous gas-phase studies and the difference may be due to the large viscosity of glycerol compared to the other organic compounds studied. N2O5 reactive uptake coefficients for liquid-phase compounds decreased in magnitude in the order: glycerol>LA>DES congruent with OA congruent with CLA.

No abstract

The insulation characteristics and decomposition components of C4F7N/N2 gas mixture, a potential substitute for SF6, were first explored by breakdown experiments/gas chromatography–mass spectrometer. The structural properties of C4F7N molecule and the decomposition mechanism of C4F7N/N2 gas mixture were analyzed based on the density functional theory calculation and ReaxFF molecular dynamics simulation. We found that C4F7N/N2 mixture has great self-recovery performance. The decomposition of C4F7N in a discharge mainly produces CF4, C2F6, C3F8, CF3CN, C2F4, C3F6, and C2F5CN, among which the relative content of C2F6, CF4, and CF3CN is higher. ReaxFF-MD simulations show that CF3, CN, F, and C3F7 are the four main free radicals produced by C4F7N. The decomposition characteristics of N2 are better than that of C4F7N. The addition of N2 has a certain buffering effect to avoid the massive decomposition of C4F7N. The global warming potential value of a gas mixture containing 20% C4F7N decreased by 94.32% compared with SF6. Relevant results not only reveal the decomposition characteristics of C4F7N/N2 mixture in a discharge comprehensively, but also provide a reference for engineering application and emission of a C4F7N/N2 gas mixture.

No abstract

No abstract