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Shang Y, Ning H, Shi J, Wu Y, Luo SN. Effects of Anharmonicity, Recrossing, Tunneling, and Pressure on the H-Abstractions from Dimethylamine by Triplets O and O 2. J Phys Chem A 2022; 126:825-833. [PMID: 35134298 DOI: 10.1021/acs.jpca.1c09556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rate constants of the H-abstraction reactions from dimethylamine (DMA) by triplets O and O2 are theoretically determined with the canonical variational transition-state theory (CVT). By comparing the barrier heights and reaction energies obtained from different density-functional theory methods to those computed from the gold-standard method CCSD(T)/CBS(T-Q), we identify the M08-HX/ma-TZVP method as the best with a mean unsigned deviation of 1.0 kcal mol-1. On the basis of the optimized geometries and frequencies with the selected method, the rate constants are calculated using the CVT method combined with the multistructural torsional anharmonicity and small-curvature tunnelling (MS-CVT/SCT) options in the temperature range 200-2000 K. The calculations show that OH and HO2 are mainly produced from the direct abstraction from the C-H bond. The multistructural torsional anharmonicity has a large contribution to the rate constants, and the effects of recrossing and tunneling at the N-site are more important than those at C-site. Additionally, given the formation of reactant complex between DMA and triplet O, the H-abstraction channel is not favored at high pressure. Our calculations with both the Polyrate and MESS codes agree with the reported data within the uncertainty.
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Affiliation(s)
- Yanlei Shang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China.,The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610027, P. R. China
| | - Hongbo Ning
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
| | - Jinchun Shi
- The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610027, P. R. China
| | - Yi Wu
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Sheng-Nian Luo
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
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Kovach T, Boyd S, Garcia A, Fleischer A, Vega K, Hilfiker R, Shertok J, Mehan M, Gupta SK, Takacs GA. Surface Modification of Polybenzimidazole (PBI) with Microwave Generated Vacuum Ultraviolet (VUV) Photo-Oxidation. CURRENT MICROWAVE CHEMISTRY 2021. [DOI: 10.2174/2213335608666210908123730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Polybenzimidazole (PBI) is used in high temperature proton exchange
membrane fuel cells (HT-PEMFCs) and redox flow batteries, where proton transfer occurs with
the nitrogen-containing groups in PBI, and in aerospace applications exposed to oxygen and radiation.
Objective:
The objective is to investigate VUV photo-oxidation of PBI for the first time in order to
incorporate polar functional groups on the surface to potentially enhance proton conductivity in
HT-PEMFCs.
Methods:
A low-pressure microwave discharge of Ar generated 104.8 and 106.7 nm vacuum UV
(VUV) radiation to treat PBI with VUV photo-oxidation. Analysis was done with X-ray
Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), water contact angle
(WCA) and Thermal Gravimetric Analysis (TGA) to detect changes in chemistry, surface roughness,
hydrophilicity, and adhesion, respectively.
Results :
XPS showed: an increase in the O concentration up to a saturation level of 15 ± 1 at %; a
decrease of the C concentration by about the same amount; and little change in the N concentration.
With increasing treatment time, there were significant decreases in the concentrations of C-C
sp2, C-C sp3 and C=N groups, and increases in the concentration of C=O, O-C=O, O-(C=O)-O, CN,
and N-C=O containing moieties. The water contact angle decreased from 83° for pristine PBI
down to 43°, making the surface more hydrophilic, primarily due to the oxidation, since AFM detected
no significant changes in surface roughness. TGA analysis showed an improvement of water
adhesion to the treated surface.
Conclusion:
Microwave generated VUV photo-oxidation is an effective technique for oxidizing
the surface of PBI and increasing hydrophilicity.
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Affiliation(s)
- Timothy Kovach
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Samuel Boyd
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Anthony Garcia
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Andrew Fleischer
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Katerine Vega
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Regina Hilfiker
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Joel Shertok
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
| | - Michael Mehan
- Xerox Analytical Services, Xerox Corporation, Webster, NY, United States
| | - Surendra K. Gupta
- Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY, United States
| | - Gerald A. Takacs
- School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, United States
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Babadi AS, Tang-Kong R, McIntyre PC. Link between Gas Phase Reaction Chemistry and the Electronic Conductivity of Atomic Layer Deposited Titanium Oxide Thin Films. J Phys Chem Lett 2021; 12:3625-3632. [PMID: 33825465 DOI: 10.1021/acs.jpclett.1c00115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In situ monitoring of gas phase composition reveals the link between the changing gas phase chemistry during atomic layer deposition (ALD) half-cycle reactions and the electronic conductivity of ALD-TiO2 thin films. Dimethylamine ((CH3)2NH, DMA) is probed as the main product of both the TDMAT and water vapor half-reactions during the TDMAT/H2O ALD process. In-plane electronic transport characterization of the ALD grown films demonstrates that the presence of DMA, a reducing agent, in the ALD chamber throughout each half-cycle is correlated with both an increase in the films' electronic conductivity, and observation of titanium in the 3+ oxidation state by ex situ X-ray photoelectron spectroscopy analysis of the films. DMA annealing of as-grown TiO2 films in the ALD chamber produces a similar effect on their electronic characteristics, indicating the importance of DMA-induced oxygen deficiency of ALD-TiO2 in dictating the electronic conductivity of as-grown films.
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Affiliation(s)
- Aein S Babadi
- Department of Materials Science & Engineering, Stanford University, Stanford, California 94305, United States
| | - Robert Tang-Kong
- Department of Materials Science & Engineering, Stanford University, Stanford, California 94305, United States
| | - Paul C McIntyre
- Department of Materials Science & Engineering, Stanford University, Stanford, California 94305, United States
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Bourgalais J, Caster KL, Durif O, Osborn DL, Le Picard SD, Goulay F. Product Detection of the CH Radical Reactions with Ammonia and Methyl-Substituted Amines. J Phys Chem A 2019; 123:2178-2193. [PMID: 30803230 DOI: 10.1021/acs.jpca.8b11688] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reactions of the methylidyne (CH) radical with ammonia (NH3), methylamine (CH3NH2), dimethylamine ((CH3)2NH), and trimethylamine ((CH3)3N) have been investigated under multiple collision conditions at 373 K and 4 Torr. The reaction products are detected by using soft photoionization coupled to orthogonal acceleration time-of-flight mass spectrometry at the Advanced Light Source (ALS) synchrotron. Kinetic traces are employed to discriminate between CH reaction products and products from secondary or slower reactions. Branching ratios for isomers produced at a given mass and formed by a single reaction are obtained by fitting the observed photoionization spectra to linear combinations of pure compound spectra. The reaction of the CH radical with ammonia is found to form mainly imine, HN═CH2, in line with an addition-elimination mechanism. The singly methyl-substituted imine is detected for the CH reactions with methylamine, dimethylamine, and trimethylamine. Dimethylimine isomers are formed by the reaction of CH with dimethylamine, while trimethylimine is formed by the CH reaction with trimethylamine. Overall, the temporal profiles of the products are not consistent with the formation of aminocarbene products in the reaction flow tube. In the case of the reactions with methylamine and dimethylamine, product formation is assigned to an addition-elimination mechanism similar to that proposed for the CH reaction with ammonia. However, this mechanism cannot explain the products detected by the reaction with trimethylamine. A C-H insertion pathway may become more probable as the number of methyl groups increases.
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Affiliation(s)
- Jeremy Bourgalais
- LATMOS/IPSL , UVSQ Université Paris-Saclay , Sorbonne Université, CNRS, 78280 Guyancourt , France
| | - Kacee L Caster
- Department of Chemistry , West Virginia University , Morgantown , West Virginia 26506 , United States
| | - Olivier Durif
- Astrophysique de Laboratoire , Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251 , F-35000 Rennes , France
| | - David L Osborn
- Combustion Research Facility, Mail Stop 9055 , Sandia National Laboratories , Livermore , California 94551 , United States
| | - Sebastien D Le Picard
- Astrophysique de Laboratoire , Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251 , F-35000 Rennes , France
| | - Fabien Goulay
- Department of Chemistry , West Virginia University , Morgantown , West Virginia 26506 , United States
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Ausfelder F, McKendrick KG. The Dynamics of Reactions of O(3P) Atoms with Saturated Hydrocarbons and Related Compounds. PROGRESS IN REACTION KINETICS AND MECHANISM 2019. [DOI: 10.3184/007967400103165164] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We review the experimental and theoretical work which has been carried out on the dynamics of reactions of O(3P) with saturated hydrocarbons and related systems. We concentrate primarily on gas phase reactions, but also cover in less detail the more limited work on condensed phase and interfacial reactions. Although O(3P) + saturated alkane reactions are the primary focus, the dominant features of their dynamics are compared and contrasted with those of unsaturated alkanes, functionalised alkanes, and inorganic hydrides (including silanes, germanes, H2S, and hydrogen halides). The principal experimental techniques are reviewed. The experimentally determined quantities are identified, including excitation functions, OH rovibrational and fine-structure partitioning, the rather limited equivalent results for the organic radical co-product, and differential cross-sections. The dynamical conclusions that have been inferred are discussed and compared with the predictions of various levels of theory from semi-empirical models through to rigorous ab initio treatments. For many organic systems, most of the evidence points to OH being formed via a direct abstraction mechanism in which the O(3P) atom attacks along an isolated C–H bond. Outstanding problems with this basic interpretation and gaps in the current knowledge base are identified.
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Affiliation(s)
- Florian Ausfelder
- Department of Chemisty, The University of Edinburgh, Edinburgh EH9 3JJ, UK
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Tanaka N, Oike J, Shibuya K, Kudoh S, Nakata M. Visible light induced oxygen atom transfer from NO2 to (CH3)3N in a cryogenic ar matrix. RESEARCH ON CHEMICAL INTERMEDIATES 1998. [DOI: 10.1163/156856798x00366] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Tanaka N, Oike J, Kajii Y, Shibuya K, Nakata M. Photoinduced dehydrogenation reaction of CH3NH2 by NO2 in a cryogenic Ar matrix. Identification of the CH2 = NH · H2O complex. Chem Phys Lett 1995. [DOI: 10.1016/0009-2614(94)01305-f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kleinermanns K, Luntz AC. Molecular beam‐laser induced fluorescence experiments on hydrogen abstraction from amines by O(3P). J Chem Phys 1982. [DOI: 10.1063/1.444254] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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9
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Atkinson R. Comments on ?predicting gas phase organic molecule reaction rates using linear free energy correlations. I. O(3P) and OH addition and abstraction reactions? INT J CHEM KINET 1980. [DOI: 10.1002/kin.550121009] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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