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31.
J. Mark Parnis Kaitlynn A. King Matthew G. K. Thompson 《Journal of mass spectrometry : JMS》2013,48(11):1224-1231
The chemistry of ionized acetone:Ar mixtures under varied ionizing electron density conditions has been studied using matrix‐isolation techniques. Gaseous acetone diluted in excess argon gas was subjected to electron bombardment with 300 eV electrons at currents between 20 and 200 μA. Linear wire ‘pin’ and metal ‘plate’ electron collector geometries were employed, allowing a wide range of electron density conditions to be explored. The products of subsequent reaction processes were matrix isolated and analyzed by Fourier transform infrared absorption spectroscopy. Products included methane, ketene, 1‐propen‐2‐ol (the enol isomer of acetone), CO, HCO, ethane, ethane, acetylene and CCCO. Product absolute and relative yields varied with acetone number density, the choice of anode geometry and the rate of electron bombardment. The overall chemistry observed is rationalized in terms of mechanistic steps involving unimolecular cation decomposition, ion–molecule reactions, radical–radical reactions and dissociative recombination processes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
32.
Pieter Bouckenooge Oliver Bauer Kathrin Eckhard Herman Terryn 《Surface and interface analysis : SIA》2020,52(4):174-184
In this paper, the behaviour of the industrial applied Ti/Zr conversion coating (CC) pretreatment on rolled automotive aluminium samples (AA5182) is analysed. Due to its nanometre lateral and depth resolution, Auger electron spectroscopy (AES) is used to analyse the CC distribution at surface cathodic intermetallic particles. As a result of its high surface sensitivity, the AES technique is very susceptible to differences in the top contamination layer thickness. It is demonstrated that AES point measurements performed on aluminium model samples coated with 1.5 and 3 nm of Ti (oxide) layer cannot differentiate the two-layer thicknesses if a difference in the top contamination thickness is not taken into account. A data analysis methodology is introduced, based on the ratio of normalized peak areas (enrichment ratios), to eliminate the effect of the contamination layer thickness. The experimental validation of the methodology is performed on the model samples, demonstrating errors of 2% on the enrichment ratios on similar samples with different contamination layer thicknesses, while the conventional spectra quantification results in errors of 49%. The methodology is also theoretically substantiated within certain constraints. By the use of the AES methodology, an enriched Ti and Zr deposition is confirmed at the cathodic intermetallic particles at the surface of the industrial no-rinse CC sprayed automotive aluminium sheet samples. 相似文献
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34.
基于瞬态光电压和瞬态光电流技术研究了锌掺杂的TiO2染料敏化太阳能电池中电子复合及传输的动力学行为.通过实验获得了不同阳极掺杂条件下的电子复合时间常数与电子收集时间常数,考察了锌掺杂对电池阳极材料导带能级和电子俘获态的影响.研究结果表明,锌的掺杂在提高TiO2导带能级的同时延长了俘获态电子的复合时间常数,从而大大提高了电池的开路电压. 相似文献
35.
研究了染料敏化太阳能电池(DSCs)中N3/Al2O3/N749交替组装结构的作用. 该结构使用Al2O3作为介质层吸附第二层染料, 可以有效拓宽DSCs的光响应范围, 提高电池的光电转化效率. UV-Vis 吸收光谱和单色光转换效率(IPCE)谱测试结果表明, 相对于单一染料, 使用交替组装结构的电池光响应范围变宽. 电流-电压(I-V)曲线结果表明, 该结构有效增加了DSCs 电池的光电转化效率, 从单一N3 和N749 染料的4.22%和3.09%增加到了5.75%, 分别增加了36%和86%. 为了研究该结构的作用机理, 本文对其界面修饰作用及界面电子过程进行了讨论. 暗电流测试结果表明交替组装结构可以有效阻止电荷复合过程; 电化学阻抗谱(EIS)结果表明在黑暗条件下, N3/Al2O3/N749结构可以提高界面电阻, 从而抑制电荷复合过程; 本文建立了等效电路模型, 并使用该模型讨论了交替组装结构的界面电子过程; 调制强度光电流谱(IMPS)和调制强度光电压谱(IMVS)的结果表明该结构可以提高电子寿命和改善电子扩散. 相似文献
36.
A two‐step reaction scheme leading to singlet carbene species that can be detected under matrix conditions for the reaction of Zr(3F) with either CH3F or CH3CN 下载免费PDF全文
Ana E. Torres Guadalupe Castro Ricardo Pablo‐Pedro Fernando Colmenares 《Journal of computational chemistry》2014,35(11):883-890
The results obtained from CASSCF‐MRMP2 calculations are used to rationalize the singlet complexes detected under matrix‐isolation conditions for the reactions of laser‐ablated Zr(3F) atoms with the CH3F and CH3CN molecules, without invoking intersystem crossings between electronic states with different multiplicities. The reaction Zr(3F) + CH3F evolves to the radical products ZrF· + ·CH3. This radical asymptote is degenerate to that emerging from the singlet channel of the reactants Zr(1D) + CH3F because they both exhibit the same electronic configuration in the metal fragment. Hence, the caged radicals obtained under cryogenic‐matrix conditions can recombine through triplet and singlet paths. The recombination of the radical species along the low‐multiplicity channel produces the inserted structures H3C? Zr? F and H2C?ZrHF experimentally detected. For the Zr(3F) + CH3CN reaction, a similar two‐step reaction scheme involving the radical fragments ZrNC· + ·CH3 explains the presence of the singlet complexes H3C? Zr? NC and H2C?Zr(H)NC revealed in the IR‐matrix spectra upon UV irradiation. © 2014 Wiley Periodicals, Inc. 相似文献
37.
James E. Castle 《Surface and interface analysis : SIA》2022,54(4):455-464
The Auger parameter (AP) is a value extracted from the X-ray photoelectron spectrum (XPS) by addition of the binding energy of a photoelectron, for a given element in the spectrum, to the kinetic energy of the Auger electron emitted as the resulting hole in the electronic structure is filled by an electron from one of the outer orbitals. The value of the AP is sensitive to the polarization of electrons in the orbitals of neighbouring ions towards the photo-ionized atom and is thus related to other opto-electronic properties of the material. A correlation had been shown between the refractive index and the AP of aluminosilicates and thus the ability to compare, on a single chart, the AP's of the Al and Si ions gave important structural information. This comparison was made possible by normalising the individual APs to a common zero-point. In this contribution, the methodology employed is extended to a wider range of elements. The resulting ability, to compare and contrast the normalised AP, thus generated, greatly enhances the information available from XPS and thus relates it directly to the polarizability of the material's structure. 相似文献
38.
通常认为缺陷加速黑磷的非辐射电子-空穴复合,阻碍器件性能的持续提高。实验打破了这一认识。采用含时密度泛函理论结合非绝热分子动力学,我们发现P-P伸缩振动驱动非辐射电子-空穴复合,使纳米孔修饰的单层黑磷的激发态寿命比完美体系延长了约5.5倍。这主要归因于三个因素。一,纳米孔结构不但没有在禁带中引入深能级缺陷,而且由于价带顶下移使带隙增加了0.22 eV。二,除了带隙增加,纳米孔减小了电子和空穴波函数重叠,并抑制了原子核热运动,从而使非绝热耦合降低至完美体系的约1/2。三,退相干时间比完美体系延长了1.5倍。前两个因素战胜了第三个因素,使纳米孔结构激发态寿命延长至2.74 ns,而其在完美体系中约为480 ps。我们的研究表明可以制造合理数量和形貌的缺陷,如纳米孔,降低黑磷非辐射电子-空穴复合,提高光电器件效率。这一研究对于理解和调控黑磷和其它二维材料的激发态性质有重要意义。 相似文献
39.
Organic solar cells (OSCs) harvesting indoor light are highly promising for emerging technologies, such as internet of things. Herein, the photovoltaic performance of PTB7-Th:PC71BM solar cells constructed using “optimized (with 1,8-diiodooctane (DIO))” and “non-optimized (without DIO)” processing conditions are compared for indoor and outdoor applications. We find that in comparison to the “optimized” solar cell, the “non-optimized” solar cell is less efficient under simulated solar light illumination (100 mW cm−2, spectral range 350–1100 nm), owing to significant bimolecular charge carrier recombination losses. However, under simulated indoor illumination (3.28 mW cm−2, spectral range 400–700 nm), bimolecular recombination losses are effective suppressed, thus the power conversion efficiency of the solar cell without DIO was increased to 14.7 %, higher than that of the solar cell with DIO (14.2 %). These results suggest that the common strategy used to optimize the OSCs could be undesired for indoor OSCs. We demonstrate that the efforts for realizing the desired “morphology” of the active layer for the outdoor OSCs may be unnecessary for indoor OSCs, allowing us to realize high-efficiency indoor OSCs using a non-halogenated solvent. 相似文献
40.
Haiyang Cui Prof. Dr. Karl-Erich Jaeger Dr. Mehdi D. Davari Prof. Dr. Ulrich Schwaneberg 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(8):2789-2797
The CompassR (computer-assisted recombination) rule enables, among beneficial substitutions, the identification of those that can be recombined in directed evolution. Herein, a recombination strategy is systematically investigated to minimize experimental efforts and maximize possible improvements. In total, 15 beneficial substitutions from Bacillus subtilis lipase A (BSLA), which improves resistance to the organic cosolvent 1,4-dioxane (DOX), were studied to compare two recombination strategies, the two-gene recombination process (2GenReP) and the in silico guided recombination process (InSiReP), employing CompassR. Remarkably, both strategies yielded a highly DOX-resistant variant, M4 (I12R/Y49R/E65H/N98R/K122E/L124K), with up to 14.6-fold improvement after screening of about 270 clones. M4 has a remarkably enhanced resistance in 60 % (v/v) acetone (6.0-fold), 30 % (v/v) ethanol (2.1-fold), and 60 % (v/v) methanol (2.4-fold) compared with wild-type BSLA. Molecular dynamics simulations revealed that attracting water molecules by charged surface substitutions is the main driver for increasing the DOX resistance of BSLA M4. Both strategies and obtained molecular knowledge can likely be used to improve the properties of other enzymes with a similar α/β-hydrolase fold. 相似文献