Статті в журналах: "Gas oxidations"

1

Korbutowicz, R., and A. Zakrzewski. "Preliminary comparison of three processes of AlN oxidation: dry, wet and mixed ones." Materials Science-Poland 34, no. 1 (March 1, 2016): 157–63. http://dx.doi.org/10.1515/msp-2016-0010.

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AbstractThree methods of AlN layers oxidation: dry, wet and mixed (wet with oxygen) were compared. Some physical parameters of oxidized thin films of aluminum nitride (AlN) layers grown on silicon Si(1 1 1) were investigated by means Energy-Dispersive X-ray Spectroscopy (EDS) and Spectroscopic Ellipsometry (SE). Three series of the thermal oxidations processes were carried out at 1012 °C in pure nitrogen as carrying gas and various gas ambients: (a) dry oxidation with oxygen, (b) wet oxidation with water steam and (c) mixed atmosphere with various process times. All the research methods have shown that along with the rising of the oxidation time, AlN layer across the aluminum oxide nitride transforms to aluminum oxide. The mixed oxidation was a faster method than the dry or wet ones.

2

Akram, Adeeba, Simon J. Freakley, Christian Reece, Marco Piccinini, Greg Shaw, Jennifer K. Edwards, Frédérique Desmedt, et al. "Gas phase stabiliser-free production of hydrogen peroxide using supported gold–palladium catalysts." Chemical Science 7, no. 9 (2016): 5833–37. http://dx.doi.org/10.1039/c6sc01332e.

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Gas phase hydrogen peroxide is postulated to be a key intermediate in many gas phase oxidations. Using Au–Pd catalysts we show it is possible to synthesise H₂O₂ in the gas phase from H₂ and O₂.

3

Yoon, Tae-Ung, Sol Ahn, Ah-Reum Kim, Justin M. Notestein, Omar K. Farha, and Youn-Sang Bae. "Cyclohexene epoxidation with H2O2 in the vapor and liquid phases over a vanadium-based metal–organic framework." Catalysis Science & Technology 10, no. 14 (2020): 4580–85. http://dx.doi.org/10.1039/d0cy00833h.

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4

Pârvulescu, V., V. I. Pârvulescu, G. Popescu, A. Julbe, C. Guizard, and L. Cot. "Gas-solid oxidations with RuO2TiO2 and RuO2SiO2 membranes." Catalysis Today 25, no. 3-4 (August 1995): 385–89. http://dx.doi.org/10.1016/0920-5861(95)00120-5.

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5

Balakotaiah, Vemuri, and David H. West. "Thermal effects and bifurcations in gas phase catalytic partial oxidations." Current Opinion in Chemical Engineering 5 (August 2014): 68–77. http://dx.doi.org/10.1016/j.coche.2014.05.002.

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6

Brönstrup, Mark, Detlef Schröder, and Helmut Schwarz. "Oxidative dealkylation of aromatic amines by "bare" FeO+ in the gas phase." Canadian Journal of Chemistry 77, no. 5-6 (June 1, 1999): 774–80. http://dx.doi.org/10.1139/v99-065.

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The gas-phase oxidations of aniline, N-methylaniline, and N,N-dimethylaniline by FeO+ cation are examined by using mass spectrometric techniques. Although bare FeO+ is capable of hydroxylating aromatic CH bonds, the fate of the oxidation of arylamines is determined by docking of the FeO+ unit at nitrogen. The major reactions of the metastable aniline/FeO+ complex are losses of molecular hydrogen, ammonia, and water, all involving at least one N-H proton. N-alkylation results in a complete shift of the course of the reaction. The unimolecular processes observed can be regarded as initial steps of an oxidative dealkylation of the amines mediated by FeO+. More detailed mechanistic insight is obtained by examining the CH(D) bond activation of N-methyl-N-([D3]-methyl)aniline by bare and ligated FeO+ species. The gas-phase reactions of FeO+ with methylanilines show some similarities to the enzymatic dealkylation of amines by cytochrome P-450. The kinetic isotope effects observed experimentally suggest an electron transfer mechanism for the gas-phase reaction.Key words: mass spectrometry, gas-phase chemistry, iron, dealkylation, N,N-dimethylaniline.

7

Lawless, K. R., J. V. Cathcart, and E. A. Kenik. "In situ oxidation of Ni3Al Alloys." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 542–43. http://dx.doi.org/10.1017/s0424820100104777.

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Ni3Al is subject to dynamic embrittlement when tested in an oxidizing environment; whereas pre-oxidation under stress does not embrittle the alloy. In situ HVEM oxidation studies of several ordered intermetallic (LI2 structure) Ni3Al alloys with small additions of boron and hafnium are reported. AEM studies of the oxidized specimens were also made to fully characterize the microstructure. Specimens were annealed and then electropolished to penetration just prior to insertion in the hot stage of the HVEM. Oxidations were carried out at an oxygen pressure of 13-60 mPa at 750°C. Gas pressure and composition were monitored with a residual gas analyzer. Specimens raised to the operating temperature in the base vacuum (∼0.2 mPa) showed no indication of oxide in the diffraction pattern and were almost entirely free of dislocations.Many of the features of different stages of the oxidation process are shown in Fig. 1. After two minutes exposure to oxygen, a thin, fine-grained, oriented, polycrystalline region of primarily γ-Al2O3 developed at the thinnest regions of the foil (Region A in Fig. 1 and Fig. 2).

8

Papurello, Rocío L., Ana P. Cabello, María A. Ulla, Claudia A. Neyertz, and Juan M. Zamaro. "Microreactor with copper oxide nanostructured films for catalytic gas phase oxidations." Surface and Coatings Technology 328 (November 2017): 231–39. http://dx.doi.org/10.1016/j.surfcoat.2017.08.066.

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9

Yoo, Jin S., Paul S. Lin, and Shari D. Elfline. "Gas-phase oxygen oxidations of alkylaromatics over CVD Fe/Mo/borosilicate molecular sieve. V. Para-selective oxidations of methylaromatics." Applied Catalysis A: General 124, no. 1 (March 1995): 139–52. http://dx.doi.org/10.1016/0926-860x(94)00255-x.

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10

Tuchida, K., Kessaraporn Wathanyu, and S. Surinphong. "Thermal Oxidation Behavior of TiAlCrSiN and AlCrTiN Films on HastelloyX." Advanced Materials Research 486 (March 2012): 400–405. http://dx.doi.org/10.4028/www.scientific.net/amr.486.400.

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In this paper, the thermal oxidation behavior of TiAlCrSiN and AlCrTiN films coated on hastelloyX substrate, typically used for fuel nozzle in gas turbine engine application, have been studied. The thermal oxidation behavior at 950, 1050 and 1150 °C in controlled atmosphere were investigated. The surface appearance, microstructure, chemical composition and adhesion of films were investigated. The thermal oxidations were observed in all testing conditions showing oxide films at the surface with thicker oxide film at higher temperature. However, spalling of oxide scales was found in both coated and uncoated specimens at 1150°C suggesting the maximum working temperature of < 1150 °C for turbine engine applications. The critical loads corresponding to the full delamination of the thermal oxidation coated specimens were found to be higher than the non-thermal oxidation specimens. The effect of thermal oxidation on damage patterns during scratch tests, i.e. less chipping and cracking for thermal oxidation specimen, were also observed.

11

Li, Haiyan, Matthieu Riva, Pekka Rantala, Liine Heikkinen, Kaspar Daellenbach, Jordan E. Krechmer, Pierre-Marie Flaud, et al. "Terpenes and their oxidation products in the French Landes forest: insights from Vocus PTR-TOF measurements." Atmospheric Chemistry and Physics 20, no. 4 (February 21, 2020): 1941–59. http://dx.doi.org/10.5194/acp-20-1941-2020.

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Abstract. The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) are reported for the first time based on ambient measurements. With the deployment of the Vocus PTR-TOF, we present an overview of the observed gas-phase (oxygenated) molecules in the French Landes forest during summertime 2018 and gain insights into the atmospheric oxidation of terpenes, which are emitted in large quantities in the atmosphere and play important roles in secondary organic aerosol production. Due to the greatly improved detection efficiency compared to conventional PTR instruments, the Vocus PTR-TOF identifies a large number of gas-phase signals with elemental composition categories including CH, CHO, CHN, CHS, CHON, CHOS, and others. Multiple hydrocarbons are detected, with carbon numbers up to 20. Particularly, we report the first direct observations of low-volatility diterpenes in the ambient air. The diurnal cycle of diterpenes is similar to that of monoterpenes and sesquiterpenes but contrary to that of isoprene. Various types of terpene reaction products and intermediates are also characterized. Generally, the more oxidized products from terpene oxidations show a broad peak in the day due to the strong photochemical effects, while the less oxygenated products peak in the early morning and/or in the evening. To evaluate the importance of different formation pathways in terpene chemistry, the reaction rates of terpenes with main oxidants (i.e., hydroxyl radical, OH; ozone, O3; and nitrate radical, NO3) are calculated. For the less oxidized non-nitrate monoterpene oxidation products, their morning and evening peaks have contributions from both O3- and OH-initiated monoterpene oxidation. For the monoterpene-derived organic nitrates, oxidations by O3, OH, and NO3 radicals all contribute to their formation, with their relative roles varying considerably over the course of the day. Through a detailed analysis of terpene chemistry, this study demonstrates the capability of the Vocus PTR-TOF in the detection of a wide range of oxidized reaction products in ambient and remote conditions, which highlights its importance in investigating atmospheric oxidation processes.

12

Gerdes, Robert, Oliver Bartels, Gerhard Schneider, Dieter Wöhrle, and Günter Schulz-Ekloff. "Photooxidation of sulfide, thiol, phenols, and cyclopentadiene by artificial light and solar light irradiation." International Journal of Photoenergy 1, no. 1 (1999): 41–47. http://dx.doi.org/10.1155/s1110662x99000082.

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The photooxidations of the toxic products sulfide, 2-mercaptoethanol and phenols under partial mineralisation in aqueous alkaline solution and the photooxidation of cyclopentadiene in ethanol in order to produce fine chemicals is described. Because the employed photosensitizers such as metal phthalocyanines, a tetraphenylporphyrine, rose bengal or methylene blue absorb in the visible region of light, an inexpensive slide projector was used under laboratory conditions.Experiments under solar radiation were carried out by concentrating the solar light with a reflective satellite bowl. The oxygen consumption over time is measured with a gas burette. The formation of singlet oxygen by energy transfer from the excited photosensitizer followed by oxidation of the substrates is responsible for the photoinduced oxidations. The applicability of the experimental conditions described here for other visible and solar light driven oxidation reactions is obvious.

13

Wu, Chunying, Xiping Zhao, Yingjie Ren, Yinghong Yue, Weiming Hua, Yong Cao, Yi Tang, and Zi Gao. "Gas-phase photo-oxidations of organic compounds over different forms of zirconia." Journal of Molecular Catalysis A: Chemical 229, no. 1-2 (March 2005): 233–39. http://dx.doi.org/10.1016/j.molcata.2004.11.029.

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14

Enea, O. "A porous cell for photo-assisted electro-oxidations in the gas-phase." Electrochimica Acta 41, no. 3 (February 1996): 473–76. http://dx.doi.org/10.1016/0013-4686(95)00319-3.

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15

Gao, Yan, Tao Luan, Tao Lv, and Hong Ming Xu. "The Mo Loading Effect on Thermo Stability and SO₂Oxidation of SCR Catalyst." Advanced Materials Research 573-574 (October 2012): 58–62. http://dx.doi.org/10.4028/www.scientific.net/amr.573-574.58.

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The SCR catalysts were produced with V2O5, WO3, MoO3 and anatase type TiO2. The thermo stability of the catalyst with different MoO3 loading was analyzed with TG-DTG. And the SO2 oxidations were researched with a fixed bed reactor under simulated exhaust gas. The different loadings of MoO3 did not effect on the thermo stability of the catalyst with temperature in the test range of 30~1000 °C. The TG–DTG curves of thermal decomposition process of V2O5-WO3-MoO3/TiO2 catalyst showed three mass loss segments: 1st the evaporation of crystal water from 70 °C to 130 °C; 2nd the decomposition of organics from 180 °C to 350 °C; 3rd the decomposition of impurities from 480 °C to 550 °C. The catalyst loading MoO3 showed higher catalytic selectivity compared to the catalysts without MoO3. MoO3 contained in the catalysts prevented SO2 oxidation, improving the oxidation start temperature and reducing the maximum oxidation.

16

Tsona, Narcisse Tchinda, and Lin Du. "A potential source of atmospheric sulfate from O2−-induced SO2 oxidation by ozone." Atmospheric Chemistry and Physics 19, no. 1 (January 17, 2019): 649–61. http://dx.doi.org/10.5194/acp-19-649-2019.

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Abstract. It was formerly demonstrated that O2SOO− forms at collisions rate in the gas phase as a result of SO2 reaction with O2-. Here, we present a theoretical investigation of the chemical fate of O2SOO− by reaction with O3 in the gas phase, based on ab initio calculations. Two main mechanisms were found for the title reaction, with fundamentally different products: (i) formation of a van der Waals complex followed by electron transfer and further decomposition to O2 + SO2 + O3- and (ii) formation of a molecular complex from O2 switching by O3, followed by SO2 oxidation to SO3- within the complex. Both reactions are exergonic, but separated by relatively low energy barriers. The products in the former mechanism would likely initiate other SO2 oxidations as shown in previous studies, whereas the latter mechanism closes a path wherein SO2 is oxidized to SO3-. The latter reaction is atmospherically relevant since it forms the SO3- ion, hereby closing the SO2 oxidation path initiated by O2-. The main atmospheric fate of SO3- is nothing but sulfate formation. Exploration of the reactions kinetics indicates that the path of reaction (ii) is highly facilitated by humidity. For this path, we found an overall rate constant of 4.0×10-11 cm3 molecule−1 s−1 at 298 K and 50 % relative humidity. The title reaction provides a new mechanism for sulfate formation from ion-induced SO2 oxidation in the gas phase and highlights the importance of including such a mechanism in modeling sulfate-based aerosol formation rates.

17

Bartusik, Dorota, David Aebisher, BiBi Ghafari, Alan M. Lyons, and Alexander Greer. "Generating Singlet Oxygen Bubbles: A New Mechanism for Gas–Liquid Oxidations in Water." Langmuir 28, no. 5 (January 20, 2012): 3053–60. http://dx.doi.org/10.1021/la204583v.

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18

Kouridaki, Antonia, and Kevin Huvaere. "Singlet oxygen oxidations in homogeneous continuous flow using a gas–liquid membrane reactor." Reaction Chemistry & Engineering 2, no. 4 (2017): 590–97. http://dx.doi.org/10.1039/c7re00053g.

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19

Chang, Chung-Liang, Tser-Sheng Lin, and Hsin-Chung Lu. "Catalytic elimination of carbon monoxide in gas streams by thermal and ozone oxidations." Reaction Kinetics and Catalysis Letters 89, no. 1 (October 2006): 105–13. http://dx.doi.org/10.1007/s11144-006-0092-5.

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20

Miura, Masahiro, Klaus Schultheis, and Karl Griesbaum. "Heterogeneously catalyzed gas phase oxidations of 1,3-pentadiene-cyclodimers and of related substances." Applied Catalysis A: General 87, no. 2 (August 1992): 241–54. http://dx.doi.org/10.1016/0926-860x(92)80059-l.

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21

Gaya, Ndepana A., Victor Charles, Innocent Joseph, and Hitler Louis. "A review on CO oxidation, methanol synthesis, and propylene epoxidation over supported gold catalysts." Catalysis for Sustainable Energy 6, no. 1 (January 1, 2019): 13–37. http://dx.doi.org/10.1515/cse-2019-0003.

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Abstract The aim of this general review is to give an overview of the reaction pathways involving the transformation of carbon monoxide (CO), methanol synthesis and propylene epoxidation using gold (Au) and gold supported clusters. Over the catalyst system of Nano-gold (Au/SiO2), the process of methane to methanol was also highlighted. A reaction mechanism proposed, indicated that molecular oxygen was consumed in the oxidation–reduction cycle. Consequently, methane oxidation to methanol can be achieved as a green chemical process. The system can also be used in other green chemical processes of liquid phase or gas phase oxidations. Methanol is expected to be a potential solution to the partial deployment of fossil source-based economies. Moreover, it is a recognized energy carrier that is better than other alternatives in terms of transportation, storage and reuse. New or improved catalysts for methanol production are likely to be discovered in the near future.

22

Tuchida, K., K. Wathanyu, Chiraporn Auechalitanukul, and S. Surinphong. "High Temperature Performance of TiAlON Thin Films." Advanced Materials Research 622-623 (December 2012): 690–94. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.690.

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In this paper, the thermal oxidation behavior, adhesion and tribological properties of TiAlON films coated on hastelloyX substrate, typically used for fuel nozzle in gas turbine engine application, have been studied. The uncoated and coated samples were heated to different temperatures, i.e. 950, 1050 and 1150 °C in the controlled atmosphere. The surface appearance, microstructure, chemical composition and adhesion of films were investigated. The thermal oxidations were observed in all testing conditions showing thicker oxide film at higher temperature. However, spalling of oxide scales was found in hastelloyX and TiAlON coated at 1150°C suggesting the maximum working temperature of < 1150 °C. The critical loads corresponding to the full delamination of the thermal oxidation coated specimens were found to be higher than the non-thermal oxidation specimens. The effect of thermal oxidation on damage patterns during scratch tests, i.e. less chipping and cracking for thermal oxidation specimen, were also observed. The tribological properties were also investigated under different load under room temperature and 600 and 1000°C. The results suggested significant improvement in wear resistance of coated sample especially at low load at all temperatures.

23

Henglein, A. "Sonolysis of Carbon Dioxide, Nitrous Oxide and Methane in Aqueous Solution." Zeitschrift für Naturforschung B 40, no. 1 (January 1, 1985): 100–107. http://dx.doi.org/10.1515/znb-1985-0119.

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Water was irradiated with ultrasonic waves under an argon atmosphere which contained small amounts of carbon dioxide, nitrous oxide or methane. The yield of the products was measured as a function of the composition of the gas atmosphere. Maximum yields were observed at a few per cent of the added polyatomic gas. No chemical effects occurred in the irradiation under an atmosphere of pure CO2 , N2O or CH4. It is concluded that the gas mixture in the tiny gas bubbles, in which the chemical effects are brought about, is not in Henry’s equilibrium with the aqueous gas solution.The main product of the sonolysis of CO2 is CO, a small amount of formic acid also being formed. The sonolysis is explained by both the attack of H atoms from the sonolysis of water and direct decomposition of CO2 due to the high temperatures existing in compressed gas bubbles. The main products of the sonolysis of N2O are nitrogen, nitrite and nitrate. N2O enhances the rate of various oxidations such as that of iodide, nitrite and propanol-2. In the methane containing solution, a lot of hydrogen is produced, the main oxidation products being ethane, ethylene, C3- and C4-hydrocarbons and carbon monoxide. A mechanism is postulated which involves both the attack on methane by radicals from the decomposition of water and thermal decomposition of methane. The local radical concentrations are so high that a methane molecule may undergo multiple radical attack. The similarity between sonolytic reactions and reactions occurring in flames is emphasized

24

Shustov, Gennady V., and Arvi Rauk. "Dioxirane oxidation of nitrosoamines. An ab initio study." Canadian Journal of Chemistry 77, no. 1 (January 1, 1999): 74–85. http://dx.doi.org/10.1139/v98-217.

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Pathways for oxidation of the parent nitrosoamine 2, nitrosodimethylamine 3, and anti- nitrosoethylmethylamine 4 by the parent dioxirane 1 have been explored computationally using the B3LYP hybrid density functional theoretical method in conjunction with the 6-31G* and 6-311+G** basis sets. Oxygen transfer from 1 to the nitrogen of the NO group (NO oxidation), yielding nitroamines 5,7, and 10, has the lowest activation barrier (15, 12.8, and 12 kcal mol-1 for 2, 3, and anti-4, respectively). Oxidation of the amine nitrogen (N oxidation) in 2, 3 leads to nitric oxide and nitroxyl radicals 6, 8 and is characterized by the highest activation energy: 28.5 kcal mol-1 for 2, 22.3 kcal mol-1 for 3. The potential barrier to hydroxylation of the methyl groups in 3 (CH oxidation) is intermediate - ca. 19 kcal mol-1. Introduction of a methyl group to the carbon reaction centre decreases the activation barrier of the anti-CH oxidation by 2-3 kcal mol-1. In 3, a gas-phase small preference for anti-CH oxidation over syn-CH oxidation, 0.1 kcal mol-1, is predicted to increase dramatically to 4.7 kcal mol-1 when the reaction is carried out in a dielectric medium (acetone, IPCM model). In general, polar solvents (CH2Cl2, acetone) lower the activation barriers for the NO, N, and CH oxidations, more so for the species of higher polarity than those of lower polarity (reactive complexes (1+3), (1+anti-4), transition state anti,syn-TSCH(1+4)]. However, the chemoselectivity (EaNO <Eaanti-CH <Easyn-CH <EaN) in the polar solvents is predicted to be the same as in the gas phase.Key words: dioxirane, nitrosoamines, oxidation, ab initio, omputation.

25

Leclerc, Arnaud, Mohamad Alamé, Daniel Schweich, Patrick Pouteau, Cyril Delattre, and Claude de Bellefon. "Gas–liquid selective oxidations with oxygen under explosive conditions in a micro-structured reactor." Lab on a Chip 8, no. 5 (2008): 814. http://dx.doi.org/10.1039/b717985e.

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26

SIMANDAN, Tiberiu, Jing SUN, and Thomas A. DIX. "Oxidation of DNA bases, deoxyribonucleosides and homopolymers by peroxyl radicals." Biochemical Journal 335, no. 2 (October 15, 1998): 233–40. http://dx.doi.org/10.1042/bj3350233.

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DNA base oxidation is considered to be a key event associated with disease initiation and progression in humans. Peroxyl radicals (ROO•) are important oxidants found in cells whose ability to react with the DNA bases has not been characterized extensively. In this paper, the products resulting from ROO• oxidation of the DNA bases are determined by gas chromatography/MS in comparison with authentic standards. ROO• radicals oxidize adenine and guanine to their 8-hydroxy derivatives, which are considered biomarkers of hydroxyl radical (HO•) oxidations in cells. ROO• radicals also oxidize adenine to its hydroxylamine, a previously unidentified product. ROO• radicals oxidize cytosine and thymine to the monohydroxy and dihydroxy derivatives that are formed by oxidative damage in cells. Identical ROO• oxidation profiles are observed for each base when exposed as deoxyribonucleosides, monohomopolymers and base-paired dihomopolymers. These results have significance for the development, utilization and interpretation of DNA base-derived biomarkers of oxidative damage associated with disease initiation and propagation, and support the idea that the mutagenic potential of N-oxidized bases, when generated in cellular DNA, will require careful evaluation. Adenine hydroxylamine is proposed as a specific molecular probe for the activity of ROO• in cellular systems.

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Wu, Chunying, Yinghong Yue, Xingyi Deng, Weiming Hua, and Zi Gao. "Investigation on the synergetic effect between anatase and rutile nanoparticles in gas-phase photocatalytic oxidations." Catalysis Today 93-95 (September 2004): 863–69. http://dx.doi.org/10.1016/j.cattod.2004.06.087.

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28

MIURA, M., K. SCHULTHEIS, and K. GRIESBAUM. "ChemInform Abstract: Heterogeneously Catalyzed Gas-Phase Oxidations of 1,3-Pentadiene- Cyclodimers and of Related Substances." ChemInform 23, no. 48 (August 21, 2010): no. http://dx.doi.org/10.1002/chin.199248106.

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29

Pillar-Little, Elizabeth, and Marcelo Guzman. "An Overview of Dynamic Heterogeneous Oxidations in the Troposphere." Environments 5, no. 9 (September 7, 2018): 104. http://dx.doi.org/10.3390/environments5090104.

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Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric transport. The resulting complex mixture of organic aerosol has variable physical and chemical properties that contribute further to the uncertainty of these species modifying the radiative budget. Correlations between oxidative processing and increased absorptivity, hygroscopicity, and cloud condensation nuclei activity have been observed, but the mechanisms behind these phenomena have remained unexplored. Herein, we review environmentally relevant heterogeneous mechanisms occurring on interfaces that contribute to the processing of aerosols. Recent laboratory studies exploring processes at the aerosol–air interface are highlighted as capable of generating the complexity observed in the environment. Furthermore, a variety of laboratory methods developed specifically to study these processes under environmentally relevant conditions are introduced. Remarkably, the heterogeneous mechanisms presented might neither be feasible in the gas phase nor in the bulk particle phase of aerosols at the fast rates enabled on interfaces. In conclusion, these surface mechanisms are important to better understand how organic aerosols are transformed in the atmosphere affecting the environment.

30

Moussa, Samar G., and Barbara J. Finlayson-Pitts. "Reaction of gas phase OH with unsaturated self-assembled monolayers and relevance to atmospheric organic oxidations." Physical Chemistry Chemical Physics 12, no. 32 (2010): 9419. http://dx.doi.org/10.1039/c000447b.

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31

Mao, Xinyu, Alexandre C. Foucher, Eric A. Stach, and Raymond J. Gorte. "“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition." Inorganics 7, no. 9 (September 12, 2019): 113. http://dx.doi.org/10.3390/inorganics7090113.

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LaCoO3 films were deposited onto MgAl2O4 powders by atomic layer deposition (ALD) and then used as catalyst supports for Pt. X-ray diffraction (XRD) showed that the 0.5 nm films exhibited a perovskite structure after redox cycling at 1073 K, and scanning transmission electron microscopy and elemental mapping via energy-dispersive X-ray spectroscopy (STEM/EDS) data demonstrated that the films covered the substrate uniformly. Catalysts prepared with 3 wt % Pt showed that the Pt remained well dispersed on the perovskite film, even after repeated oxidations and reductions at 1073 K. Despite the high Pt dispersion, CO adsorption at room temperature was negligible. Compared with conventional Pt on MgAl2O4, the reduced forms of the LaCoO3-containing catalyst were highly active for the CO oxidation and water gas shift (WGS) reactions, while the oxidized catalysts showed much lower activities. Surprisingly, the reduced catalysts were much less active than the oxidized catalysts for toluene hydrogen. Catalysts prepared from thin films of Co3O4 or La2O3 exhibited properties more similar to Pt/MgAl2O4. Possible reasons for how LaCoO3 affects properties are discussed.

32

Park, Yeo, Hee Yoo, Min Song, Dong-Heon Lee, and Seung Lee. "Biocatalytic Oxidations of Substrates through Soluble Methane Monooxygenase from Methylosinus sporium 5." Catalysts 8, no. 12 (November 26, 2018): 582. http://dx.doi.org/10.3390/catal8120582.

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Methane, an important greenhouse gas, has a 20-fold higher heat capacity than carbon dioxide. Earlier, through advanced spectroscopy and structural studies, the mechanisms underlying the extremely stable C–H activation of soluble methane monooxygenase (sMMO) have been elucidated in Methylosinus trichosporium OB3b and Methylococcus capsulatus Bath. Here, sMMO components—including hydroxylase (MMOH), regulatory (MMOB), and reductase (MMOR)—were expressed and purified from a type II methanotroph, Methylosinus sporium strain 5 (M. sporium 5), to characterize its hydroxylation mechanism. Two molar equivalents of MMOB are necessary to achieve catalytic activities and oxidized a broad range of substrates including alkanes, alkenes, halogens, and aromatics. Optimal activities were observed at pH 7.5 for most substrates possibly because of the electron transfer environment in MMOR. Substitution of MMOB or MMOR from another type II methanotroph, Methylocystis species M, retained specific enzyme activities, demonstrating the successful cross-reactivity of M. sporium 5. These results will provide fundamental information for further enzymatic studies to elucidate sMMO mechanisms.

33

Otsuka, Kiyoshi, Yasuo Shimizu, Ichiro Yamanaka, and Takayuki Komatsu. "Wacker type and ?-allyl type oxidations of propylene controlled by fuel cell system in the gas phase." Catalysis Letters 3, no. 5-6 (1989): 365–69. http://dx.doi.org/10.1007/bf00771264.

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34

Yoo, Jin S., John A. Donohue, Mark S. Kleefisch, Paul S. Lin, and Shari D. Elfline. "Gas-phase oxygen oxidations of alkylaromatics over chemical vapor deposited Fe/Mo/borosilicate molecularsieve, Fe/Mo/DBH." Applied Catalysis A: General 105, no. 1 (November 1993): 83–105. http://dx.doi.org/10.1016/0926-860x(93)85135-c.

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35

Macartney, Donal H. "The oxidation of hydrogen peroxide by tris(polypyridine) complexes of osmium(III), iron(III), ruthenium(III), and nickel(III) in aqueous media." Canadian Journal of Chemistry 64, no. 9 (September 1, 1986): 1936–42. http://dx.doi.org/10.1139/v86-319.

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The stoichiometry and kinetics of the oxidation of hydrogen peroxide by tris(2,2′-bipyridine) and tris(4,4′-dimethyl-2,2′-bipyridine) complexes of osmium(III), iron(III), ruthenium(III), and nickel (III) were studied in acidic and neutral aqueous media at 25 °C and I = 0.50 M (LiCF3SO3). The reaction 2M(bpy)33+ + H2O2 → 2M(bpy)32+ + O2 + 2H+ is observed with quantitative yields of dioxygen gas. The observed rate constants displayed an inverse acid dependence over the pH range 6.0–8.5; kobsd = k1 + k2K1/[H+], attributed to the oxidations of H2O2(k1) and HO2− (k2). An application of the Marcus theory relationship to the cross-reaction data gave a self-exchange rate constant of 10−2–10−1 M−1 s−1 for the HO2−/HO2 couple. The electron exchange rate constant is evaluated in terms of the inner-sphere and solvent reorganizational barriers and is compared to values reported for other small molecule couples. Rate and activation parameters for the reduction of the nickel(III) complexes by the hydroxide ion have been determined and are compared with the corresponding values for other metal tris(poly pyridine) complexes.

36

Li, Y. P., H. Elbern, K. D. Lu, E. Friese, A. Kiendler-Scharr, Th F. Mentel, X. S. Wang, A. Wahner, and Y. H. Zhang. "Updated aerosol module and its application to simulate secondary organic aerosols during IMPACT campaign May 2008." Atmospheric Chemistry and Physics 13, no. 13 (July 3, 2013): 6289–304. http://dx.doi.org/10.5194/acp-13-6289-2013.

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Abstract. The formation of Secondary organic aerosol (SOA) was simulated with the Secondary ORGanic Aerosol Model (SORGAM) by a classical gas-particle partitioning concept, using the two-product model approach, which is widely used in chemical transport models. In this study, we extensively updated SORGAM including three major modifications: firstly, we derived temperature dependence functions of the SOA yields for aromatics and biogenic VOCs (volatile organic compounds), based on recent chamber studies within a sophisticated mathematic optimization framework; secondly, we implemented the SOA formation pathways from photo oxidation (OH initiated) of isoprene; thirdly, we implemented the SOA formation channel from NO3-initiated oxidation of reactive biogenic hydrocarbons (isoprene and monoterpenes). The temperature dependence functions of the SOA yields were validated against available chamber experiments, and the updated SORGAM with temperature dependence functions was evaluated with the chamber data. Good performance was found with the normalized mean error of less than 30%. Moreover, the whole updated SORGAM module was validated against ambient SOA observations represented by the summed oxygenated organic aerosol (OOA) concentrations abstracted from aerosol mass spectrometer (AMS) measurements at a rural site near Rotterdam, the Netherlands, performed during the IMPACT campaign in May 2008. In this case, we embedded both the original and the updated SORGAM module into the EURopean Air pollution and Dispersion-Inverse Model (EURAD-IM), which showed general good agreements with the observed meteorological parameters and several secondary products such as O3, sulfate and nitrate. With the updated SORGAM module, the EURAD-IM model also captured the observed SOA concentrations reasonably well especially those during nighttime. In contrast, the EURAD-IM model before update underestimated the observations by a factor of up to 5. The large improvements of the modeled SOA concentrations by updated SORGAM were attributed to the mentioned three modifications. Embedding the temperature dependence functions of the SOA yields, including the new pathways from isoprene photo oxidations, and switching on the SOA formation from NO3 initiated biogenic VOC oxidations, contributed to this enhancement by 10, 22 and 47%, respectively. However, the EURAD-IM model with updated SORGAM still clearly underestimated the afternoon SOA observations up to a factor of two.

37

Yoo, Jin S., Chin Choi-Feng, and John A. Donohue. "Gas-phase oxygen oxidations of alkylaromatics over chemical vapor deposited Fe/Mo/borosilicate molecular sieve, Fe/Mo/DBH." Applied Catalysis A: General 118, no. 1 (October 1994): 87–101. http://dx.doi.org/10.1016/0926-860x(94)80091-x.

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38

Albonetti, S., L. Dal Pozzo, and F. Trifirò. "Oxidation Catalysis in Clean Technologies for Fine Chemicals." Eurasian Chemico-Technological Journal 3, no. 4 (July 10, 2017): 221. http://dx.doi.org/10.18321/ectj572.

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The role of heterogeneous catalysis for the production of fine chemicals is reviewed with particular interest for the oxidation in a wide range of aspects of this kind of processes: reaction of oxygen insertion, oxidative dehydrogenation and nitrogen insertion (with ammonia and oxygen). In this review are examined the main processes industrially applied and the best research perspectives in the field of heterogeneous oxidation catalysis for the synthesis of fine chemicals. It is an important point of view in relation with the typical parameters of this field of industrial chemistry and in relation with the driving force of environmental friendly technologies (the line guides of green chemistry) to substitute traditional processes. It is examined either the possibility of the use of gas phases, that is better on an economical and plant point of view, with molecular oxygen, nitrous oxide (it is a very specific oxidant, and it is active in mild conditions) and with the technique of short bed reactor to minimise the effects of the consecutive oxidation reaction particularly on aromatic side chains. Or the use of liquid phases, very useful to work in mild conditions with not stable reagents, with hydrogen peroxide and other alternative oxidants such as regenerable organic hydroperoxides. In the liquid phase reactions it is posed a particular interest in the oxidations carried out with the use of metal doped zeolites, with special attention to tianiasilica catalysts such as TS-1 with the new developments of hydrogen peroxide in situ generation; and heteropoly compounds.

39

Huang, D., X. Zhang, Z. M. Chen, Y. Zhao, and X. L. Shen. "The kinetics and mechanism of an aqueous phase isoprene reaction with hydroxyl radical." Atmospheric Chemistry and Physics 11, no. 15 (August 1, 2011): 7399–415. http://dx.doi.org/10.5194/acp-11-7399-2011.

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Abstract. Aqueous phase chemical processes of organic compounds in the atmosphere have received increasing attention, partly due to their potential contribution to the formation of secondary organic aerosol (SOA). Here, we analyzed the aqueous OH-initiated oxidation of isoprene and its reaction products including carbonyl compounds and organic acids, regarding the acidity and temperature as in-cloudy conditions. We also performed a laboratory simulation to improve our understanding of the kinetics and mechanisms for the products of aqueous isoprene oxidation that are significant precursors of SOA; these included methacrolein (MACR), methyl vinyl ketone (MVK), methyl glyoxal (MG), and glyoxal (GL). We used a novel chemical titration method to monitor the concentration of isoprene in the aqueous phase. We used a box model to interpret the mechanistic differences between aqueous and gas phase OH radical-initiated isoprene oxidations. Our results were the first demonstration of the rate constant for the reaction between isoprene and OH radical in water, 1.2 ± 0.4) × 1010 M−1 s−1 at 283 K. Molar yields were determined based on consumed isoprene. Of note, the ratio of the yields of MVK (24.1 ± 0.8 %) to MACR (10.9 ± 1.1%) in the aqueous phase isoprene oxidation was approximately double that observed for the corresponding gas phase reaction. We hypothesized that this might be explained by a water-induced enhancement in the self-reaction of a hydroxy isoprene peroxyl radical (HOCH2C(CH3)(O2)CH = CH2) produced in the aqueous reaction. The observed yields for MG and GL were 11.4 ± 0.3 % and 3.8 ± 0.1 %, respectively. Model simulations indicated that several potential pathways may contribute to the formation of MG and GL. Finally, oxalic acid increased steadily throughout the course of the study, even after isoprene was consumed completely. The observed yield of oxalic acid was 26.2 ± 0.8 % at 6 h. The observed carbon balance accounted for ~50 % of the consumed isoprene. The presence of high-molecular-weight compounds may have accounted for a large portion of the missing carbons, but they were not quantified in this study. In summary, our work has provided experimental evidence that the availably abundant water could affect the distribution of oxygenated organic compounds produced in the oxidation of volatile organic compounds.

40

Huang, D., X. Zhang, Z. M. Chen, Y. Zhao, and X. L. Shen. "The kinetics and mechanism of an aqueous phase isoprene reaction with hydroxy radical." Atmospheric Chemistry and Physics Discussions 11, no. 3 (March 11, 2011): 8515–51. http://dx.doi.org/10.5194/acpd-11-8515-2011.

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Abstract. Aqueous phase chemical processes of organic compounds in the atmosphere have received increasing attention, partly due to their potential contribution to the formation of secondary organic aerosol (SOA). Here, we analyzed the aqueous oxidation of isoprene in clouds and its reaction products, including carbonyl compounds and organic acids. We also performed a laboratory simulation to improve our understanding of the kinetics and mechanisms for the products of aqueous isoprene oxidation that are significant precursors of SOA; these included methacrolein (MACR), methyl vinyl ketone (MVK), methyl glyoxal (MG), and glyoxal (GL). We used a novel chemical titration method to monitor the concentration of isoprene in the aqueous phase. We used a box model to interpret the mechanistic differences between aqueous- and gas-phase OH radical-initiated isoprene oxidations. Our results were the first demonstration of the rate constant for the reaction between isoprene and OH radical in water, 3.50 (± 0.98) × 109 M−1 s−1 at 283 K. Molar yields were determined based on consumed isoprene. Of note, the ratio of the yields of MVK (18.9 ± 0.8%) to MACR (9.0 ± 1.1%) in the aqueous phase isoprene oxidation was approximately double that observed for the corresponding gas phase reaction. We hypothesized that this might be explained by a water-induced enhancement in the self-reaction of a hydroxy isoprene peroxyl radical (HOCH2C(CH3)(O2)CH = CH2) produced in the aqueous reaction. The observed yields for MG and GL were 11.4 ± 0.3% and 3.8 ± 0.1%, respectively. Model simulations indicated that several potential pathways may contribute to the formation of MG and GL. Finally, oxalic acid increased steadily throughout the course of the study, even after isoprene was consumed completely. The observed yield of oxalic acid was 26.2 ± 0.8% at 6 h. The observed carbon balance accounted for ~50% of the consumed isoprene. The presence of high-molecular-weight compounds may have accounted for a large portion of the missing carbons, but they were not quantified in this study. In summary, our work has provided experimental evidence that condensed water could affect the distribution of oxygenated organic compounds produced in the oxidation of volatile organic compounds. If volatile organic compounds like isoprene and terpenes undergo aqueous oxidation to a larger extent than considered previously, the contribution of their atmospheric aqueous oxidation should be considered when constructing future models of the global SOA budget.

41

Barnes, Stephen, Erin M. Shonsey, Shannon M. Eliuk, David Stella, Kerri Barrett, Om P. Srivastava, Helen Kim, and Matthew B. Renfrow. "High-resolution mass spectrometry analysis of protein oxidations and resultant loss of function." Biochemical Society Transactions 36, no. 5 (September 19, 2008): 1037–44. http://dx.doi.org/10.1042/bst0361037.

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MS, with or without pre-analysis peptide fractionation, can be used to decipher the residues on proteins where oxidative modifications caused by peroxynitrite, singlet oxygen or electrophilic lipids have occurred. Peroxynitrite nitrates tyrosine and tryptophan residues on the surface of actin. Singlet oxygen, formed by the interaction of UVA light with tryptophan, can oxidize neighbouring cysteine, histidine, methionine, tyrosine and tryptophan residues. Dose–response inactivation by 4HNE (4-hydroxynonenal) of hBAT (human bile acid CoA:amino acid N-acyltransferase) and CKBB (cytosolic brain isoform of creatine kinase) is associated with site-specific modifications. FT-ICR (Fourier-transform ion cyclotron resonance)–MS using nanoLC (nano-liquid chromatography)–ESI (electrospray ionization)–MS or direct-infusion ESI–MS with gas-phase fractionation identified 14 4HNE adducts on hBAT and 17 on CKBB respectively. At 4HNE concentrations in the physiological range, one member of the catalytic triad of hBAT (His362) was modified; for CKBB, although all four residues in the active site that were modifiable by 4HNE were ultimately modified, only one, Cys283, occurred at physiological concentrations of 4HNE. These results suggest that future in vivo studies should carefully assess the critical sites that are modified rather than using antibodies that do not distinguish between different modified sites.

42

Kim, Saewung, Dianne Sanchez, Mark Wang, Roger Seco, Daun Jeong, Stacey Hughes, Barbara Barletta, et al. "OH reactivity in urban and suburban regions in Seoul, South Korea – an East Asian megacity in a rapid transition." Faraday Discussions 189 (2016): 231–51. http://dx.doi.org/10.1039/c5fd00230c.

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South Korea has recently achieved developed country status with the second largest megacity in the world, the Seoul Metropolitan Area (SMA). This study provides insights into future changes in air quality for rapidly emerging megacities in the East Asian region. We present total OH reactivity observations in the SMA conducted at an urban Seoul site (May–June, 2015) and a suburban forest site (Sep, 2015). The total OH reactivity in an urban site during the daytime was observed at similar levels (∼15 s⁻¹) to those previously reported from other East Asian megacity studies. Trace gas observations indicate that OH reactivity is largely accounted for by NO_X (∼50%) followed by volatile organic compounds (VOCs) (∼35%). Isoprene accounts for a substantial fraction of OH reactivity among the comprehensive VOC observational dataset (25–47%). In general, observed total OH reactivity can be accounted for by the observed trace gas dataset. However, observed total OH reactivity in the suburban forest area cannot be largely accounted for (∼70%) by the trace gas measurements. The importance of biogenic VOC (BVOCs) emissions and oxidations used to evaluate the impacts of East Asian megacity outflows for the regional air quality and climate contexts are highlighted in this study.

43

Kolb, G., V. Hessel, V. Cominos, C. Hofmann, H. Löwe, G. Nikolaidis, R. Zapf, et al. "Selective oxidations in micro-structured catalytic reactors—For gas-phase reactions and specifically for fuel processing for fuel cells." Catalysis Today 120, no. 1 (January 2007): 2–20. http://dx.doi.org/10.1016/j.cattod.2006.07.021.

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44

Li, Y. P., H. Elbern, K. D. Lu, E. Friese, A. Kiendler-Scharr, Th F. Mentel, X. S. Wang, A. Wahner, and Y. H. Zhang. "Updated aerosol module and its application to simulate secondary organic aerosols during IMPACT campaign May 2008." Atmospheric Chemistry and Physics Discussions 13, no. 3 (March 6, 2013): 5961–6005. http://dx.doi.org/10.5194/acpd-13-5961-2013.

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Abstract. The formation of Secondary organic aerosol (SOA) was simulated with the Secondary ORGanic Aerosol Model (SORGAM) by a classical gas-particle partitioning concept, using the two-product model approach, which is widely used in chemical transport models. In this study, we extensively updated SORGAM including three major modifications: firstly, we derived temperature dependence functions of the SOA yields for aromatics and biogenic VOCs, based on recent chamber studies within a sophisticated mathematic optimization framework; secondly, we implemented the SOA formation pathways from photo oxidation (OH initiated) of isoprene; thirdly, we implemented the SOA formation channel from NO3-initiated oxidation of reactive biogenic hydrocarbons (isoprene and monoterpenes). The temperature dependence functions of the SOA yields were validated against available chamber experiments. Moreover, the whole updated SORGAM module was validated against ambient SOA observations represented by the summed oxygenated organic aerosol (OOA) concentrations abstracted from Aerosol Mass Spectrometer (AMS) measurements at a rural site near Rotterdam, the Netherlands, performed during the IMPACT campaign in May 2008. In this case, we embedded both the original and the updated SORGAM module into the EURopean Air pollution and Dispersion-Inverse Model (EURAD-IM), which showed general good agreements with the observed meteorological parameters and several secondary products such as O3, sulfate and nitrate. With the updated SORGAM module, the EURAD-IM model also captured the observed SOA concentrations reasonably well especially those during nighttime. In contrast, the EURAD-IM model before update underestimated the observations by a factor of up to 5. The large improvements of the modeled SOA concentrations by updated SORGAM were attributed to the mentioned three modifications. Embedding the temperature dependence functions of the SOA yields, including the new pathways from isoprene photo oxidations, and switching on the SOA formation from NO3 initiated biogenic VOCs oxidations contributed to this enhancement by 10%, 22% and 47%, respectively. However, the EURAD-IM model with updated SORGAM still clearly underestimated the afternoon SOA observations up to a factor of two. More work such as to improve the simulated OH concentrations under high VOCs and low NOx concentrations, further including the SOA formation from semi-volatile organic compounds, the correct aging process of aerosols, oligomerization process and the influence on the biogenic SOA by the anthropogenic SOA, are still required to fill the gap.

45

Bandosz, Teresa J. "Beyond Adsorption: The Effect of Sulfur Doping on Emerging Applications of Nanoporous Carbons." Eurasian Chemico-Technological Journal 18, no. 4 (February 18, 2017): 233. http://dx.doi.org/10.18321/ectj466.

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Recently we have directed our attention to new applications of “old” materials, nanoporous carbons, as photocatalysts for oxidation of dibenzothiophenes, as water splitting catalysts, as gas sensors and as photosensitizers. Our inspiration was in graphene science. We found that both surface chemistry and porosity are crucial factors determining the specific performance. Since the effects are synergistic, it is not possible to totally separate the influence of these two factors. In terms of photoactivity and photosensitivity, surface chemistry was found as having the predominant effect on the catalytic performance. Sulfur containing groups were indicated as playing a major role in these processes. Of course physical adsorption was necessary to take place on the surface before further reactions promoted by absorption of photons occurred. Since some level of conductivity of the carbon matrix is important for an electron transfer, formation of radicals, and active oxygen species, the presence of sp2 graphitic dots of 10 nm in size in the carbon matrix enhanced the photoactive performance. In the case of gas sensing where the reversibility of the signal is important, physical adsorption was a predominant factor. Here the specific polar or electrostatic interactions enhance the sensitivity and affect markedly the selectivity. A minireview of our recent work on these two emerging topics, photoactivity of carbon and their sensing application, is presented in this paper. The emphasis is on the importance of both, specific surface chemistry and developed porosity. The latter is a unique factor, which differentiates the performance of porous carbons from that of nanoforms of carbons such as graphene or carbon nanotubes. Keywords: nanoporous carbon, photoactivity, catalytic oxidations, water splitting, gas sensing, surface chemistry, porosity, photosensitivity

46

Varma, R. M., S. M. Ball, T. Brauers, H. P. Dorn, U. Heitmann, R. L. Jones, U. Platt, et al. "Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers." Atmospheric Measurement Techniques 6, no. 11 (November 19, 2013): 3115–30. http://dx.doi.org/10.5194/amt-6-3115-2013.

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Abstract. Broadband optical cavity spectrometers are maturing as a technology for trace-gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulfate particles, the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using the Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

47

Varma, R. M., S. M. Ball, T. Brauers, H. P. Dorn, U. Heitmann, R. L. Jones, U. Platt, et al. "Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers." Atmospheric Measurement Techniques Discussions 6, no. 4 (July 22, 2013): 6685–727. http://dx.doi.org/10.5194/amtd-6-6685-2013.

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Abstract. Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulphate particles the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

48

Yoo, Jin S. "Gas-phase oxygen oxidations of alkylaromatics over CVD Fe/Mo/borosilicate molecular sieve VI. Effects of para-substituents in toluene derivatives." Applied Catalysis A: General 135, no. 2 (February 1996): 261–71. http://dx.doi.org/10.1016/0926-860x(95)00253-7.

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49

Yoo, Jin S., Paul S. Lin, and Shari D. Elfline. "Gas-phase oxygen oxidations of alkylaromatics over CVD Fe/Mo/borosilicate molecular sieve. II. The role of carbon dioxide as a co-oxidant." Applied Catalysis A: General 106, no. 2 (December 1993): 259–73. http://dx.doi.org/10.1016/0926-860x(93)80181-o.

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50

YOO, J. S., C. CHOI-FENG, and J. A. DONOHUE. "ChemInform Abstract: Gas-Phase Oxygen Oxidations of Alkyl Aromatics over Chemical Vapor Deposited Fe/Mo/Borosilicate Molecular Sieve, Fe/Mo/DBH. Part 4. Effect of Supporting Matrix on p-Xylene Oxidation." ChemInform 26, no. 13 (August 18, 2010): no. http://dx.doi.org/10.1002/chin.199513052.

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