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The gas-phase organic compounds resulting from OH-initiated photooxidation of isoprene have been investigated on-line by VUV photoionization mass spectrometry based on synchrotron radiation for the first time. The photoionization efficiency curves of the corresponding gaseous products as well as the chosen standards have been deduced by gating the interested peaks in the photoionization mass spectra while scanning the photon energy simultaneously, which permits the identification of the pivotal gaseous products of the photooxidation of isoprene, such as formaldehyde (10.84 eV), formic acid (11.38 eV), acetone (9.68 eV), glyoxal (9.84 eV), acetic acid (10.75 eV), methacrolein (9.91 eV), and methyl vinyl ketone (9.66 eV). Proposed reaction mechanisms leading to the formation of these key products were discussed, which were completely consistent with the previous works of different groups. The capability of synchrotron radiation photoionization mass spectrometry to directly identify the chemical composition of the gaseous products in a simulation chamber has been demonstrated, and its potential application in related studies of atmospheric oxidation of ambient volatile organic compounds is anticipated.

Density functional theory and conventional transition state theory (TST) are employed to investigate the reaction of Cl with toluene. Eight different reaction paths are considered, corresponding to side chain, three possible ring hydrogen abstraction and four kinds of different Cl addition. The calculated results indicate that the reaction proceeds almost exclusively through hydrogen abstraction at room temperature, and is predicted to occur dominantly at the side chain position, and the calculated overall rate constant at the CCSD(T)/6-311++G(d,p)//BHandHLYP/6-311++G(d,p) is 6.49 × 10−11 cm3 molecule−1 s−1, showing a reasonably good agreement with the available experimental results. Although negligible at low temperature, at 1000 K ring hydrogen abstraction accounts for about 20% of the total abstraction reaction, and the total hydrogen abstraction makes up for about 98% of the total reaction above 800 K, indicating that hydrogen abstraction is the dominant channel for the Cl-toluene reaction at high temperatures, which is different from the OH-toluene reaction. This study may provide useful information on understanding the mechanistic features of Cl-initiated oxidation of toluene.

Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.

The composition of products formed from photooxidation of the aromatic hydrocarbon toluene was investigated. The OH-initiated photooxidation experiments were conducted by irradiating toluene/CH3ONO/NO/air mixtures in a smog chamber, the gaseous products were detected under the supersonic beam conditions by utilizing vacuum ultraviolet photoionization mass spectrometer using synchrotron radiation in real-time. And an aerosol time-of-flight mass spectrometer was used to provide on-line measurements of the individual secondary organic aerosol particle resulting from irradiating toluene. The experimental results demonstrated that there were some differences between the gaseous products and that of particle-phase, the products of glyoxal, 2-hydroxyl-3-oxo-butanal, nitrotoluene, and methyl-nitrophenol only existed in the particle-phase. However, furane, methylglyoxal, 2-methylfurane, benzaldehyde, cresol, and benzoic acid were the predominant photooxidation products in both the gas phase and particle phase.

The OH hydrogen abstraction and addition with m -xylene have been studied in the range of 298–1000 K using quantum chemistry methods. The geometries and frequencies of the reactants, transition states and products have been performed at BHandHLYP/6-311++G(d,p) level, and single-point calculation for all the stationary points were carried out at CCSD(T) calculations of the optimized structures with the same basis set. Eight different reaction paths are considered, corresponding to side chain, three possible ring hydrogen abstraction and four kinds different OH addition. The results of the theoretical study indicate that the reaction proceeds almost exclusively through OH addition at room temperature, and is predicted to occur dominantly at the ortho position, and the calculated overall rate constant is 2.60 × 10 −11 cm 3 molecule −1 s −1 , showing the agreement with available experimental data extremely. Despite unimportance at low temperature, at 1000 K ring hydrogen abstraction accounts for about 70% of the total abstraction reaction, and the whole hydrogen abstraction makes up for 3% of the total reaction. This study may provide useful information on understanding the mechanistic features of OH-initiated oxidation of m -xylene.

The OH hydrogen abstraction and addition with ethylbenzene have been studied in the range 298–1000 K using quantum chemistry methods. The geometries and frequencies of the reactants, transition states, and products were performed at BH and HLYP/6-311++G(d,p) level, single point calculation for all the stationary points were carried out at CCSD(T) calculations of the optimized structures with the same basis set. Nine different reaction paths are considered corresponding to two side chain, three possible ring hydrogen abstraction, and four kinds different OH addition. The results of the theoretical study indicate that at the room temperature the reaction proceeds almost exclusively through OH addition, and is predicted to occur dominantly at the ortho position, the calculated overall rate constant is 6.72 × 10−12 cm3 molecule−1 s−1, showing a very good agreement with available experimental data. Although negligible at low temperature, at 1000 K ring hydrogen abstraction accounts for about 32% of the total abstraction reaction, and the whole hydrogen abstraction makes up for 30% of the total reaction. This study may provide useful information on understanding the mechanistic features of OH-initiated oxidation of ethylbenzene. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

The scalable synthesis of two-dimensional (2D) hexagonal boron nitride (h-BN) is of great interest for its numerous applications in novel electronic devices. Highly-crystalline h-BN films, with single-crystal sizes up to hundreds of microns, are demonstrated via a novel Ni foam assisted technique reported here for the first time. The nucleation density of h-BN domains can be significantly reduced due to the high boron solubility, as well as the large specific surface area of the Ni foam. The crystalline structure of the h-BN domains is found to be well aligned with, and therefore strongly dependent upon, the underlying Pt lattice orientation. Growth-time dependent experiments confirm the presence of a surface mediated self-limiting growth mechanism for monolayer h-BN on the Pt substrate. However, utilizing remote catalysis from the Ni foam, bilayer h-BN films can be synthesized breaking the self-limiting effect. This work provides further understanding of the mechanisms involved in the growth of h-BN and proposes a facile synthesis technique that may be applied to further applications in which control over the crystal alignment, and the numbers of layers is crucial., Comment: 18 pages, 7 figures

The reaction mechanism for ethylbenzene with OH radical and O2 was investigated by density functional theory (DFT) method. The structures, energetics, and relative stability of OH-ethylbenzene reaction intermediate radicals have been determined, and their activation barriers have been analyzed to assess the energetically favorable pathways to propagate the ethylbenzene oxidation. The results of the theoretical study indicate that OH addition is predicted to occur dominantly at the ortho position, with branching ratios of 0.53, 0.31, 0.10, and 0.06 for ortho, para, meta, and ipso additions, respectively, and the calculated overall rate constant is 1.24 × 10−11 cm3 molecule−1 s−1, showing a very good agreement with available experimental data. Under atmospheric conditions, oxygen is expected to add to the ethylbenzene-OH adducts forming ethylbenzene peroxy radicals. And subsequent ring closure of the peroxyl radicals to form bicyclic radicals. With relatively low barriers, isomerization of the ethylbenzene bicyclic radicals to more stable epoxide radicals likely occurs, competing with O2 addition to form bicyclic peroxy radicals. The study provides thermochemical data for assessment of the photochemical production potential of ozone and formation of toxic products and secondary organic aerosol from ethylbenzene photooxidation.

Since the reform and opening policy, the construction of rural area in China has become more and more important. The idea of establishing green villages needs to be accepted and recognized by the public. The hot summer and cold winter zone combines two contradictory weather conditions that is cold winter and hot summer. So the living conditions are limited. In response to this climate, residents extensively use electric heaters or air conditioning to adjust the indoor temperature, resulting in energy waste and environmental pollution. In order to improve the living conditions of residents, rural area energy conservation has been put on the agenda. Based on the present situation and energy consumption analysis of the rural buildings in the hot summer and cold winter zone, this article puts forward several energy saving paths from government, construction technology and so on

Secondary organic aerosol (SOA) formation from hydroxyl radical (OH*) initiated photooxidation of alpha-pinene was investigated in a home-made smog chamber. The size distribution of SOA particles was measured using aerodynamic particle sizer spectrometer. The effects of illumination intensity and light application time on SOA formation for alpha-pinene were evaluated. Experimental results show that the concentration of SOA particles increased significantly with an increasing of illumination intensity, and the light application time, the concentration, and the size of SOA particles were also increased. In addition, the factors influencing the formation of SOA were discussed. In addition, this article compared the effect of alpha-pinene with that of toluene, and discussed the contribution of alpha-pinene to SOA formation.

Vacuum ultraviolet (VUV) dissociative photoionization of isoprene in the energy region 8.5-18 eV was investigated with photoionization mass spectroscopy (PIMS) using synchrotron radiation (SR). The ionization energy (IE) of isoprene as well as the appearance energies (AEs) of its fragment ions C(5)H(7) (+), C(5)H(5) (+), C(4)H(5) (+), C(3)H(6) (+), C(3)H(5) (+), C(3)H(4) (+), C(3)H(3) (+) and C(2)H(3) (+) were determined with photoionization efficiency (PIE) curves. The dissociation energies of some possible dissociation channels to produce those fragment ions were also determined experimentally. The total energies of C(5)H(8) and its main fragments were calculated using the Gaussian 03 program and the Gaussian-2 method. The IE of C(5)H(8), the AEs for its fragment ions, and the dissociation energies to produce them were predicted using the high-accuracy energy model. According to our results, the experimental dissociation energies were in reasonable agreement with the calculated values of the proposed photodissociation channels of C(5)H(8).

The interconversion between the two distinct isomers of methyl vinyl ether (MVE), the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the subsequent fragmentation were studied using quantum chemical methods at the BHandHLYP/6–311++G(d,p) level of theory for optimized geometries and frequency calculations and at the QCISD/6–31G(d,p) level for the single point energy calculations. The rate coefficients were calculated for the temperature range 280–440 K by using the canonical transition state theory (TST). For ozone addition to MVE, there are two different possibilities discussed on the basis of two different possible orientations for ozone attack. The results of the theoretical study indicate that although the synperiplanar-MVE is 7.11 kJ/mol more stable than the antiperiplanar-MVE, the antiperiplanar-MVE plays a more important role in formation of the primary ozonides because the primary ozonides formed from the ozone addition antiperiplanar-MVE are more stable and the energy barriers corresponding to transition states are lower. The interconversion between the primary ozonides formed from the ozone addition to antiperiplanar-MVE is the most accessible compared with the transformations between other primary ozonides. The cleavage of the primary ozonides mainly leads to the formation of the CH2OO, which is in agreement with the experimental estimates. The calculated overall rate constant for the ozone-initiated reactions is 4.8×10−17cm3/(molecules) at 298.15 K, which agrees with the experimental value for ethyl vinyl ether.

A theoretical study of the mechanism and kinetics of the toluene-OH adduct I (2-methyl-hydroxycyclohexadienyl radical intermediate, generated from the reaction of OH with toluene) with O 2 is presented. The geometries of the reactants, transition states and products were optimized at B3LYP/6-31G(d,p) level. The single-point calculations for all the stationary points were carried out at the B3LYP/6-311++G (2df,2pd) level using the B3LYP/6-31G(d,p) optimized geometries. The results of the theoretical study indicate that the major product is o-cresol, and the minor product is the 2-methyl-hydroxycyclohexadienyl peroxyl radical V. And the overall rate constant for I and O 2 reaction is 5.21 × 10 −16 cm 3 molecule −1 s −1 at the room temperature, showing a very good agreement with available experimental data. This study may provide useful information on understanding the mechanistic features of OH-initiated oxidation of toluene.

A laboratory study was performed to investigate the composition of secondary organic aerosol (SOA) products from photooxidation of the aromatic hydrocarbon p-xylene. The experiments were conducted by irradiating p-xylene/CH 3 ONO/NO/air mixtures in a home-made smog chamber. The aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the size and the chemical composition of individual secondary organic aerosol particles in real-time. According to a large number of single aerosol diameters and mass spectra, the size distribution and chemical composition of SOA were determined statistically. Experimental results showed that aerosol created by p-xylene photooxidation is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e. PM2.5), and aromatic aldehyde, unsaturated dicarbonys, hydroxyl dicarbonys, and organic acid are major product components in the SOA after 2 hours photooxidation. After aging for more than 8 hours, about 10% of the particle mass consists of oligomers with a molecular mass up to 600 daltons. The possible reaction mechanisms leading to these products are also proposed.

The reaction mechanism for o-xylene with OH radical and O2 was studied by density functional theory (DFT) method. The geometries of the reactants, intermediates, transition states, and products were optimized at B3LYP/6-31G(d,p) level. The corresponding vibration frequencies were calculated at the same level. The single-point calculations for all the stationary points were carried out at the B3LYP/6-311++G(2df,2pd) level using the B3LYP/6-31G(d,p) optimized geometries. Reaction energies for the formation of the aromatic intermediate radicals have been obtained to determine their relative stability and reversibility, and their activation barriers have been analyzed to assess the energetically favorable pathways to propagate the o-xylene oxidation. The results of the theoretical study indicate that OH addition to o-xylene forms ipso, meta, and para isomers of o-xylene-OH adducts, and the ipso o-xylene adduct is the most stable among these isomers. Oxygen is expected to add to the o-xylene-OH adducts forming o-xylene peroxy radicals. And subsequent ring closure of the peroxyl radicals to form bicyclic radicals. With relatively low barriers, isomerization of the o-xylene bicyclic radicals to more stable epoxide radicals likely occurs, competing with O2 addition to form bicyclic peroxy radicals. The study provides thermochemical data for assessment of the photochemical production potential of ozone and formation of toxic products and secondary organic aerosol from o-xylene photooxidation. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008

Five aromatic hydrocarbons – benzene, toluene, ethylbenzene, p-xylene and 1,2,4-trimethylbenzene – were selected to investigate the laser desorption/ionization mass spectra of secondary organic aerosols (SOA) resulting from OH-initiated photooxidation of aromatic compounds. The experiments were conducted by irradiating aromatic hydrocarbon/CH3ONO/NO X mixtures in a home-made smog chamber. The aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the aerodynamic size and chemical composition of individual secondary organic aerosol particles in real-time. Experimental results showed that aerosol created by aromatics photooxidation is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e. PM2.5), and different aromatic hydrocarbons SOA mass spectra have eight same positive laser desorption/ionization mass spectra peaks: m/z = 18, 29, 43, 44, 46, 57, 67, 77. These mass spectra peaks may come from the fragment ions of the SOA products: oxo-carboxylic acids, aldehydes and ketones, nitrogenated organic compounds, furanoid and aromatic compounds. The possible reaction mechanisms leading to these products were also discussed.

We report on the first demonstration of the study of photo-induced reaction products in a smog chamber by means of wavelength modulated off-axis integrated cavity output spectroscopy (WM-OA-ICOS) at 1.511 μm. The preliminary results of the photolysis of methyl nitrite (CH 3 ONO) are presented which demonstrates the ability of our system for the degradation mechanisms studies of atmospheric relevant organic compounds.

The hydroxycyclohexadienyl peroxy radicals (HOC6H6O2) produced from the reaction of OH-benzene adduct with O2 were studied with density functional theory (DFT) calculations to determine their characteristics. The optimized geometries, vibrational frequencies, and total energies of 2-hydroxycyclohexadienyl peroxy radical IIs and 4-hydroxycyclohexadienyl peroxy radical IIIs were calculated at the following theoretical levels, B3LYP/6-31G(d), B3LYP/6-311G(d,p), and B3LYP/6-311+G(d,p). Both were shown to contain a red-shifted intramolecular hydrogen bond (OH … OH bond). According to atoms-in-molecules (AIM) analysis, the intramolecular hydrogen bond in the 2-hydroxycyclohexadienyl peroxy radical IIs is stronger than that one in 4-hydroxycyclohexadienyl peroxy radical IIIs, and the former is the most stable conformation among its isomers. Generally speaking, hydrogen bonding in these radicals plays an important role to make them more stable. Based on natural bond orbital (NBO) analysis, the stabilization energy between orbitals is the main factor to produce red-shifted intramolecular hydrogen bond within these peroxy radicals. The hyperconjugative interactions can promote the transfer of some electron density to the OH antibonding orbital, while the increased electron density in the OH antibonding orbital leads to the elongation of the OH bond and the red shift of the OH stretching frequency. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Aging of secondary organic aerosol (SOA) particles formed from OH- initiated oxidation of ethylbenzene in the presence of high mass (100-300μg/m(3)) concentrations of (NH4)2SO4 seed aerosol was investigated in a home-made smog chamber in this study. The chemical composition of aged ethylbenzene SOA particles was measured using an aerosol laser time-of-flight mass spectrometer (ALTOFMS) coupled with a Fuzzy C-Means (FCM) clustering algorithm. Experimental results showed that nitrophenol, ethyl-nitrophenol, 2,4-dinitrophenol, methyl glyoxylic acid, 5-ethyl-6-oxo-2,4-hexadienoic acid, 2-ethyl-2,4-hexadiendioic acid, 2,3-dihydroxy-5-ethyl-6-oxo-4-hexenoic acid, 1H-imidazole, hydrated N-glyoxal substituted 1H-imidazole, hydrated glyoxal dimer substituted imidazole, 1H-imidazole-2-carbaldehyde, N-glyoxal substituted hydrated 1H-imidazole-2-carbaldehyde and high-molecular-weight (HMW) components were the predominant products in the aged particles. Compared to the previous aromatic SOA aging studies, imidazole compounds, which can absorb solar radiation effectively, were newly detected in aged ethylbenzene SOA in the presence of high concentrations of (NH4)2SO4 seed aerosol. These findings provide new information for discussing aromatic SOA aging mechanisms.

Three methyl-hydroxycyclohexadienyl peroxy radicals with intramolecular H-bonds were studied at B3LYP/6-31G(d), B3LYP/6-311+G(d,p) and B3LYP/6-311++G(2d,2p) levels, respectively. 2-hydroxy-1-methyl-cyclohexadienyl peroxy radical (II), 2-hydroxy-3-methyl-cyclohexadienyl peroxy radical (III), and 4-hydroxy-3-methyl-cyclohexadienyl peroxy radical (IV) exhibit red-shifted O–H⋯O H-bond. From the AIM analysis, it becomes evident that 2-hydroxy-3-methyl-cyclohexadienyl peroxy radical (III) intramolecular O–H⋯O H-bond is the strongest. This represents that 2-hydroxy-3-methyl-cyclohexadienyl peroxy radical (III) is the most stable isomer. It is clear that hydrogen bonding plays a role in stabilizing the peroxy radicals: the hydrogen bond lengths are 1.9804, 1.9566, and 2.4457 A for (II), (III), and (IV), respectively, correlating with their relative stability. From the NBO analysis, it becomes evident that three red-shifted intramolecular H-bonds can be explained on the basis of the two opposite effects: hyperconjugation and rehybridization. The hyperconjugation is slightly dominant and overshadows the rehybridization in the O–H⋯O H-bond.

A laboratory study was carried out to investigate the secondary organic aerosol (SOA) products from photooxidation of the aromatic hydrocarbon toluene. The experiments were conducted by irradiating toluene/CH 3 ONO/NO/air mixtures in a home-made smog chamber. The aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the size and the chemical composition of individual secondary organic aerosol particles in real-time. According to a large number of single aerosol diameters and mass spectra, we obtained the size distribution and chemical composition of SOA statistically. Expeperimental results showed that aerosol created by toluene photooxidation is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e. PM2.5), and the predominant components of aerosol are furane, methyl glyoxylic acid, phenol, benzaldehyde, benzyl alcohol, cresol, 3-hydroxy-2,4-dioxo-pentanal, methyl nitrophenol, and 5-hydroxy-4,6-dioxo-2-heptenal. The possible reaction mechanisms leading to these products were also discussed.

Aerosol laser time-of-flight mass spectrometer was used to measure the aged 1,3,5- trimethylbenzene secondary organic aerosol in the presence of NaNO3 in real-time. Nitrogen-containing compounds were detected and reaction mechanisms were discussed.

Black phosphorus is a layered material stacked together by weak van der Waals force with a direct bandgap and highly anisotropic electrical characteristics. Most of the previous reports focus on the low-field mobility of transistors based on SiO2 back gate dielectrics. Recently, black phosphorus transistors encapsulated with hexagonal boron nitride have been demonstrated with greatly improved mobility at low temperatures. However, this approach requires multiple dry transfer methods using both black phosphorus and boron nitride flakes, which are only available in small crystal sizes. Here, we demonstrated high performance black phosphorus transistors using atomic layer deposited high-κ HfO2 as a back gate dielectric. The maximum drain current density reaches 480 μA/μm at 300 K and a record high drain current 906 μA/μm at 20 K in a short channel 100 nm device based on HfO2, exhibiting excellent current-carrying capability and high field strength. Moreover, a side-by-side comparison on important figures-of-...

Building sector is the main contributor to total energy consumption and the associated CO2 emissions. The enforcement of energy efficient building is considered as the most successful strategy for CO2 emission reduction and energy saving during the life cycle of the building, while the application of suitable green building products plays an important role in facilitating energy efficient building promotion. This article proposes a comprehensive evaluation method for assessing the green performance of building products. The analytic hierarchy process is employed to determine the weights of evaluation indices, while the gray relational analysis is used to find the optimal product. A hypothetical case study is presented and the result shows that the sequence of the size of green performance is: product 3> product 1> product 2> product 4. Meanwhile, the proposed methods are proved feasible for scheme selection. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1389–1395, 2014

Secondary organic aerosol (SOA) formed from C1-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by C1-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 microm (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.

A new method is presented for measuring the electric parameters in dielectric barrier discharge (DBD), and the effect of barrier on discharge is investigated. Results show that the number of discharge current is variable in different half period of applied voltage, and the current pulse width is in the range of 160 to 280ns. The discharge power increases monotonously with the applied voltage, and the maximum power is 22.62w, which corresponding power density of 5.76w/cm 3 . The electric field in the gas gap decreases monotonously with the increase of gas gap, and the optimum work condition is proposed in DBD.

Combined with the climatic characteristics of hot-summer and cold-winter area, describe the current requirements and energy saving in buildings of the rural residential in the hot-summer and cold-winter area of China. In the view of the appropriate energy-saving and insulation technology applied on walls, windows, roof and other parts of the building, and introduce the application of some relevant building energy-saving technology especially for the hot-summer and cold-winter area of China, in order to improve the performance of Energy Saving of the Rural Residential in the hot-summer and cold-winter area, reduce building energy consumption and improve the farmers' living condition.

Smog chamber experiments were performed to investigate the composition of products formed from photooxidation of aromatic hydrocarbon ethylbenzene. Vacuum ultraviolet photoionization mass spectrometer and aerosol time-of-flight mass spectrometer were used to measure the products in the gas and particle phases in real-time. Experimental results demonstrated that ethylphenol methylglyoxal, phenol, benzaldehyde, and 2-ethylfurane were the predominant photooxidation products in both the gas and particle phases. However, there were some differences between detected gas phase products and those of particle phase, for example 2-ethylfurane, ethylglyoxylic acid, nitroethylbenzene, 3,4-dioxopentanal and ethyl-nitrophenol were only existing in the particle-phase The possible reaction mechanisms leading to these products were also discussed and proposed.

The spatial-temporal correlation in dielectric barrier discharge is difficult to be studied in the mixed gas of air and argon. In this paper, a simple optical method is introduced to study the temporal correlation intensity between micro-discharge filaments in dielectric barrier discharges at different air concentration in mixed gas of air and argon. The relation of the breakdown voltage and air concentration ( Χ ) is measured. It's found that the breakdown voltage increases as the air concentration increasing. The experimental results show that the diameter and discharge duration of the filament decrease with the air concentration increasing, at the same time the coherence of the discharge moments of the filaments weakens with the air concentration increasing. The experimental results can be explained with the theory of electron drifting. In addition, the accumulated charges on dielectric surface created by the filament discharge create a field within very time when the duration is small, which against the filament breakdown in its neighboring region. So the coherence of the discharge moments of the filaments can't be realized. While the accumulation of the surface charges will last a long time when the duration of the filament discharge is big, the breakdown can take place in the neighboring region of the filament in the duration, which would be the factor to the coherence of the discharge moments.

In this paper, Aerosol time-of-flight mass spectrometer optical particle size measurement system optimization and influencing factors are studied. Optimized the distance between nozzle and the skimmer, using a shorter wavelength light source measurement, Aerosol particle size measurement from the previous limit of 260 nm to 120 nm. Study found that the particles scattered light intensity is connected with light intensity and wavelength of the light source. particle size measurements using shorter laser wavelengths or greater energy, which can measure smaller size diameter within certain range. combining particle beam focusing aerodynamic lens system device, the particle size of air the time-resolved measurement of 256 / min, Measurement of time-resolved mass spectrometry to 170 / min, MS hit rate of 64.5%.

Hydroxyl radical (.OH)-initiated photooxidation reaction of toluene was carried out in a self-made smog chamber. Four individual seed aerosols such as ammonium sulfate, ammonium nitrate, sodium silicate and calcium chloride, were introduced into the chamber to assess their influence on the growth of secondary organic aerosols (SOA). It was found that the low concentration of seed aerosols might lead to high concentration of SOA particles. Seed aerosols would promote rates of SOA formation at the start of the reaction and inhibit its formation rate with prolonging the reaction time. In the case of ca. 9000 pt/cm3 seed aerosol load, the addition of sodium silicate induced a same effect on the SOA formation as ammonium nitrate. The influence of the four individual seed aerosols on the generation of SOA decreased in the order of calcium chloride>sodium silicate and ammonium nitrate>ammonium sulfate.

An inexpensive resonant photoacoustic spectrometer based on a low-power distributed feedback diode laser and wavelength modulation spectroscopy is developed. This sensor has been applied to the detection of acetylene (C2H2) using a properly designed photoacoustic cell operating on its second longitudinal mode. The minimum detectable limit of about 10 parts-per-million volume (signal to noise ratio = 1) is achieved at atmospheric pressure, and the pressure and laser power linear dependence of the photoacoustic signal is also investigated. Moreover, in this paper we also describe some basic theory of gas photoacoustic spectroscopy. © 2005 Elsevier B.V. All rights reserved.

We develop a system to measure the elemental composition of unprepared samples using laser-induced breakdown spectroscopy (LIBS) in our laboratory, which can be used for the determination of elements in solids, liquids and aerosols. A description of the instrumentation, including laser, sample chamber and detection, is followed by a brief discussion. The time-resolved LIBS of aluminum at atmospheric pressure is presented. At the end, the possibilities and later uses of this technique are briefly discussed.

A home-made Single Aerosol Laser Mass Spectrometer (SALMS) was utilised to provide on-line measurements of the sizes and molecular compositions of Secondary Organic Aerosols (SOAs) from irradiating toluene in the smog chamber. Results demonstrate that variations in reaction conditions make a little difference in the size and chemical composition distributions of SOAs. According to the reaction mechanisms, some aromatic ring-retaining and ring-opening products have been tentatively identified. Compounds from the H-abstraction pathways contribute more to the aromatic ring-reserved products. Those ring opening products could be produced from OH-addition pathways via two important intermediate species 6-oxo-2,4-heptadienal and 5-methyl-6-oxo-2,4-hexadienal isomers.