The rate constants for the ozone reactions with n-butyl methyl sulfide (n-BMS, CH3CH2CH2CH2SCH3), sec-butyl methyl sulfide (s-BMS, CH3CH2(CH3)CHSCH3) and tert-butyl methyl sulfide (t-BMS, (CH3)3CSCH3) were measured using our smog chamber under supposedly pseudo-first-order conditions at 300±2 K and 760 Torr. The experimental determined rate constants for n-butyl, s-butyl and t-butyl methyl sulfide are (1.23 ± 0.06)×10-19, (5.08 ± 0.19)×10?20 and (2.26 ± 0.14)×10?20 cm3·molecule-1·s-1, respectively. The reactivity-structure relationship of the reactions was discussed and used to illustrate the mechanism of the ozone reaction with thioethers. The results enrich the kinetics data of atmospheric chemistry.
The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters(VmOn+) toward acetylene(C2H2) molecules under gas phase(P,～ 1.14 kPa),under near room temperature(T,～ 350 K) conditions.Association products,VmOnC2H2+(m,n = 2,4;2,6;3,7―8;4,9―11;5,12―13;6,13―16,and 7,17),are observed.The oxidation of C2H2 by(V2O5)+n(n = 1―3) is experimentally identified.The reactivity of(V2O5)+ n decreases as n increases.Density functional theory(DFT) calculations were carried out to interpret the reaction mechanisms.The DFT results indicate that a terminal oxygen atom from V2O5+ can transfer overall barrierlessly to C2H2 at room temperature,which is in agreement with the experimental observation.Other experimental results such as the observation of V2O6C2H+2 and non-observation of V2O7,8C2H+2 in the experiments are also well interpreted based on the DFT calculations.The reactivity of vanadium oxide clusters toward acetylene and other hydrocarbons may be considered in identifying molecular level mechanisms for related heterogeneous catalysis.
A study of the atmospheric photochemical reaction of CF3 radical with CO and O2 was performed by using a homemade ultraviolet photoelectron spectrometer-photoionization mass spectrometer (PES- PIMS). The electronic structures and mechanism of ionization and dissociation of CF3OC(O)OOC(O)- OCF3 were investigated. It was indicated that the two bands on the photoelectron spectrum of CF3OC(O)OOC(O)OCF3 are the result of ionization of an electron from a lone pair of oxygen and a fluo- rine lone pair of CF3 group. The outermost electrons reside in the oxygen lone pair. The experimental and theoretical first vertical ionization energy is 13.21 and 13.178 eV, respectively, with the PES and OVGF method. They are in good agreement. The photo ionization and dissociation processes were discussed with the help of theoretical calculations and PES-PIMS experiment. After ionization, the parent ions prefer the dissociation of the C-O bond and giving the fragments CF3OCO+ and CF3+. It demonstrated that the ultraviolet photoelectron and photoionization mass spectrometer could be ap- plied widely in the study of atmospheric photochemical reaction.
YAO Li1,2, DU Lin1,2, YIN Shi1,2 & GE MaoFa1 1 Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China
