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151.
Steffen Cychy Sebastian Lechler Zijian Huang Michael Braun Ann Cathrin Brix Peter Blümler Corina Andronescu Friederike Schmid Wolfgang Schuhmann Martin Muhler 《催化学报》2021,42(12):2206-2215
在碱性甘油电氧化反应中,利用电化学傅里叶变换衰减全反射谱红外光谱法,研究了薄膜流动池中滴注硼酸镍催化剂负载量对玻碳电极性能的影响.连续操作的径向流动池包括一个位于内反射元件上方50μm的钻孔电极,可实现红外光谱分析.这是在确定条件下对电催化剂进行简便和可重复筛选的一个适合的方法,同时还提供了对复杂反应(如甘油氧化)产物选择性的检测.通过对泵送电解液进行更耗时的定量高效液相色谱分析,结果表明,衰减全反射红外光谱法可快速鉴定产物.在层流条件下,水中使用0.1 M甘油和1 M KOH,流速为5μL min-1时,甘油转化率较高.转化率和选择性取决于催化剂的负载量,负载量又决定了催化剂层的厚度和粗糙度.由于在更粗糙的膜中停留时间更长有利于再吸附和C-C键断裂,因此当负载量最高达210μg cm-2时,甘油转化率为73%且甲酸选择性接近80%.当最低负载量为13μg cm-2时,甘油转化率达到63%,甲酸选择性降至60%,相应地,C2物种(如乙醇酸盐)选择性较高,为8%.因此,只有催化剂负载量较低时才能形成几微米厚度范围内的薄膜,此时才适合进行优质催化剂的筛选. 相似文献
152.
Dr. Bodo Hattendorf Bianca Gusmini Dr. Ladina Dorta Prof. Dr. Robert S. Houk Prof. Dr. Detlef Günther 《Chemphyschem》2016,17(17):2640-2644
Doubly charged diatomic ions MAr2+ where M=Mg, Ca, Sr or Ba have been observed by mass spectrometry with an inductively coupled plasma ion source. Abundance ratios are quite high, 0.1 % for MgAr2+, 0.4 % for CaAr2+, 0.2 % for SrAr2+ and 0.1 % for BaAr2+ relative to the corresponding doubly charged atomic ions M2+. It is assumed that these molecular ions are formed through reactions of the doubly charged metal ions with neutral argon atoms within the ion source. Bond dissociation energies (D0) were calculated and agree well with previously published values. The abundance ratios MAr+/M+ and MAr2+/M2+ generally follow the predicted bond dissociation energies with the exception of MgAr2+. Mg2+ should form the strongest bond with Ar [D0 (MgAr2+)=124 to 130 kJ mol?1] but its relative abundance is similar to that of the weakest bound BaAr2+ (D0=34 to 42 kJ mol?1). The relative abundances of the various MAr2+ ions are higher than those expected from an argon plasma at T=6000 K, indicating that collisions during ion extraction reduce the abundance of the MAr2+ ions relative to the composition in the source. The corresponding singly charged MAr+ ions are also observed but occur at about three orders of magnitude lower intensity than MAr2+. 相似文献
153.
We construct an Enriques surface X over Q with empty étale-Brauer set (and hence no rational points) for which there is no algebraic Brauer–Manin obstruction to the Hasse principle. In addition, if there is a transcendental obstruction on X, then we obtain a K3 surface that has a transcendental obstruction to the Hasse principle. 相似文献
154.
155.
A. S. Kuznetsov R. W. E. van de Kruijs M. A. Gleeson K. Schmid F. Bijkerk 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(4):563-566
Mo/Si multilayer mirrors were exposed to deuterium ions with well-defined energies in order to gain insight into the effects
of Extreme UV light driven plasma generation on reflective elements in commercial lithography equipment. Post-irradiation
analysis by Rutherford Backscattering Spectrometry showed erosion of both Mo and Si layers for the highest energy 50 eV/D
and exposure time 5.4 × 104 s. Nuclear Reaction Analysis revealed detectable deuterium retention for energies ⩾25 eV/D. Surface analysis by X-ray Photoelectron
Spectroscopy showed erosion of the first Si layer for energies ⩾5 eV/D. Inferences on the spatial distribution of trapped
deuterium are made on the basis of available data regarding deuterium retention in the materials in question. 相似文献
156.
Anna Hayer Tanguy Van Regemorter Bianca Höfer Chris S. K. Mak David Beljonne Anna Köhler 《Journal of Polymer Science.Polymer Physics》2012,50(5):361-369
Although carbazole‐containing copolymers are frequently used as hole‐transporting host materials for polymer organic light‐emitting diodes (OLEDs), they often suffer from the formation of undesired exciplexes when the OLED is operated. The reason why exciplexes sometimes form for electrical excitation, yet not for optical excitation is not well understood. Here, we use luminescence measurements and quantum chemical calculations to investigate the mechanism of such exciplex formation for electrical excitation (electroplex formation) in a carbazole–pyridine copolymer. Our results suggest that the exciplex is formed via a positively charged interchain precursor complex. This complex is stabilized by interactions that involve the nitrogen lone pairs on both chain segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
157.
158.
Julien Labaune J. Bianca Jackson Kaori Fukunaga Jeffrey White Laura d’Alessandro Alison Whyte Michel Menu Gerard Mourou 《Applied Physics A: Materials Science & Processing》2011,105(1):5-9
Terahertz Time Domain Imaging has been used in the last few years for the investigation of cultural heritage. In this article,
the authors demonstrate the possibility to apply it for the investigation of clay artifacts. Tomographic images were obtained
of a model in reflection, and an Egyptian vessel in transmission. 相似文献
159.
Samy Chammaa Dr. Bianca Sperl Anke G. Roth Aybike Yektaoglu Steffen Renner Dr. Thorsten Berg Prof. Dr. Christoph Arenz Prof. Dr. Athanassios Giannis Prof. Dr. Tudor I. Oprea Dr. Daniel Rauh Dr. Markus Kaiser Dr. Herbert Waldmann Prof. Dr. 《Angewandte Chemie (International ed. in English)》2010,49(21):3666-3670
160.
C. Haefeli M.A. Ivanov M. Schmid 《The European Physical Journal C - Particles and Fields》2008,53(4):549-557
We investigate three-flavour chiral perturbation theory including virtual photons in the limit in which the strange quark
mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of
two-flavour chiral perturbation theory. In particular, we work out the strange quark mass dependence of the electromagnetic
two-flavour low-energy constants C and ki. We expect that these relations will be useful for a more precise determination of the electromagnetic low-energy constants.
PACS 11.30.Rd; 12.39.Fe; 13.40.Dk; 13.40.Ks 相似文献