Computational study on the mechanism and kinetics for the reaction between HO and -propyl peroxy radical.

The -propyl peroxy radical (-CHO) is the key intermediate during atmospheric oxidation of propane (CH) which plays an important role in the carbon and nitrogen cycles in the troposphere. In this paper, a comprehensive theoretical study on the reaction mechanism and kinetics of the reaction between HO and -CHO was performed at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-311G(d,p) level of theory. Computational results show that the HO + -CHO reaction proceeds on both singlet and triplet potential energy surfaces (PESs).

Mechanism and kinetics of the atmospheric reaction of 1,3,5-trimethylbenzene bicyclic peroxy radical with OH.

The bicyclic peroxy radical (BPR) is the key intermediate during atmospheric oxidation of aromatics. In this paper, the reaction mechanisms and kinetics of the atmospheric reaction of the 1,3,5-trimethylbenzene (1,3,5-TMB) BPR with the OH radical were studied by density functional theory (DFT) and conventional transition-state theory (CTST) calculations. The product channels of formation of the 1,3,5-TMB trioxide (ROOOH), OH-adducts and Criegee intermediate (CI) have been identified, and the geometries and energies of all the stationary points were calculated at the M08-HX/6-311 + g(2df,2p) level of theory.

Improved Chemical Amplification Instrument by Using a Nafion Dryer as an Amplification Reactor for Quantifying Atmospheric Peroxy Radicals under Ambient Conditions.

In our previous work ( Yang et al. Anal. Chem.

The influences of ammonia on aerosol formation in the ozonolysis of styrene: roles of Criegee intermediate reactions.

The influences of ammonia (NH) on secondary organic aerosol (SOA) formation from ozonolysis of styrene have been investigated using chamber experiments and quantum chemical calculations. With the value of [O]/[styrene] ratios between 2 and 4, chamber experiments were carried out without NH or under different [NH]/[styrene] ratios. The chamber experiments reveal that the addition of NH led to significant decrease of SOA yield.

Superconducting-Magnet-Based Faraday Rotation Spectrometer for Real Time in Situ Measurement of OH Radicals at 10 Molecule/cm Level in an Atmospheric Simulation Chamber.

Atmospheric simulation chambers play vital roles in the validation of chemical mechanisms and act as a bridge between field measurements and modeling. Chambers operating at atmospheric levels of OH radicals (10-10 molecule/cm) can significantly enhance the possibility for investigating the discrepancies between the observation and model predications. However, few chambers can directly detect chamber OH radicals at ambient levels.

Removing Water Vapor Interference in Peroxy Radical Chemical Amplification with a Large Diameter Nafion Dryer.

The chemical amplification (PERCA) method has been widely used for measuring peroxy radical concentrations in the troposphere. The accuracy and sensitivity of the method is critically dependent on the chain length (CL)-that is, the number of radical amplification cycles. However, CL decreases strongly with higher relative humidity (RH).

Ultra-sensitive measurement of peroxy radicals by chemical amplification broadband cavity-enhanced spectroscopy.

The PERCA (PEroxy Radical Chemical Amplification) technique, which is based on the catalytic conversion of ambient peroxy radicals (HO and RO, where R stands for any organic chain) to a larger amount of nitrogen dioxide (NO) amplified by chain reactions by adding high concentrations of NO and CO in the flow reactor, has been widely used for total peroxy radical RO* (RO* = HO + ΣRO) measurements. High-sensitivity and accurate measurement of the NO concentration plays a key role in accurate measurement of the RO* concentration. In this paper, we report on the development of a dual-channel chemical amplification instrument, which combined the PERCA method with the incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS), for peroxy radical measurements.

Three-Dimensional Assignment of the Structures of Atomic Clusters: an Example of Au8M (M=Si, Ge, Sn) Anion Clusters.

Identification of different isomer structures of atomic and molecular clusters has long been a challenging task in the field of cluster science. Here we present a three-dimensional (3D) assignment method, combining the energy (1D) and simulated (2D) spectra to assure the assignment of the global minimum structure. This method is more accurate and convenient than traditional methods, which only consider the total energy and first vertical detachment energies (VDEs) of anion clusters.

Experimental and Theoretical Study of Reactions of OH Radicals with Hexenols: An Evaluation of the Relative Importance of the H-Abstraction Reaction Channel.

C6 hexenols are one of the most significant groups of volatile organic compounds with biogenic emissions. The lack of corresponding kinetic parameters and product information on their oxidation reactions will result in incomplete atmospheric chemical mechanisms and models. In this paper, experimental and theoretical studies are reported for the reactions of OH radicals with a series of C6 hexenols, (Z)-2-hexen-1-ol, (Z)-3-hexen-1-ol, (Z)-4-hexen-1-ol, (E)-2-hexen-1-ol, (E)-3-hexen-1-ol, and (E)-4-hexen-1-ol, at 298 K and 1.

Knudsen cell and smog chamber study of the heterogeneous uptake of sulfur dioxide on Chinese mineral dust.

The heterogeneous uptake processes of sulfur dioxide on two types of Chinese mineral dust (Inner Mongolia desert dust and Xinjiang sierozem) were investigated using both Knudsen cell and smog chamber system. The temperature dependence of the uptake coefficients was studied over a range from 253 to 313 K using the Knudsen cell reactor, the initial uptake coefficients decreased with the increasing of temperature for these two mineral dust samples, whereas the steady state uptake coefficients of the Xinjiang sierozem increased with the temperature increasing, and these temperature dependence functions were obtained for the first time. In the smog chamber experiments at room temperature, the steady state uptake coefficients of SO2 decreased evidently with the increasing of sulfur dioxide initial concentration from 1.

Structure, stability, and electronic property of carbon-doped gold clusters Au(n)C- (n = 1-10): a density functional theory study.

The equilibrium geometric structures, relative stabilities, and electronic properties of Au(n)C(-) and Au(n+1)(-) (n = 1-10) clusters are systematically investigated using density functional theory with hyper-generalized gradient approximation. The optimized geometries show that one Au atom capped on Au(n-1)C(-) clusters is a dominant growth pattern for Au(n)C(-) clusters. In contrast to Au(n+1)(-) clusters, Au(n)C(-) clusters are most stable in a quasi-planar or three-dimensional structure because C doping induces the local non-planarity while the rest of the structure continues to grow in a planar mode, resulting in an overall non-2D configuration.

Structural exploration of water, nitrate/water, and oxalate/water clusters with basin-hopping method using a compressed sampling technique.

Exploration of the low-lying structures of atomic or molecular clusters remains a fundamental problem in nanocluster science. Basin hopping is typically employed in conjunction with random motion, which is a perturbation of a local minimum structure. We have combined two different sampling technologies, "random sampling" and "compressed sampling", to explore the potential energy surface of molecular clusters.

[Kinetic studies on the gas-phase reactions of NO3 radicals with three cyclic ethers].

Kinetics of the reaction of NO3 radicals with tetrahydrofuran, 1, 3-dioxolane and 1, 4-dioxane at 298 K +/- 1 K and 1.01 x 10(5) Pa were investigated using a relative rate method in a self-made Teflon chamber. The objective of this study was to assess the possible impact of these volatile organic compounds (VOCs) on the environment by studying their atmospheric degradation kinetics.