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排序方式: 共有138条查询结果,搜索用时 31 毫秒
41.
Maik Dreyer Dr. Daniel Cruz Dr. Ulrich Hagemann Dr. Patrick Zeller Dr. Markus Heidelmann Dr. Soma Salamon Dr. Joachim Landers Anna Rabe Dr. Klaus Friedel Ortega Dr. Sharif Najafishirtari Prof. Dr. Heiko Wende Prof. Dr. Nils Hartmann Dr. Axel Knop-Gericke Prof. Dr. Robert Schlögl Prof. Dr. Malte Behrens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):17127-17144
Perovskites are interesting oxidation catalysts due to their chemical flexibility enabling the tuning of several properties. In this work, we synthesized LaFe1−xCoxO3 catalysts by co-precipitation and thermal decomposition, characterized them thoroughly and studied their 2-propanol oxidation activity under dry and wet conditions to bridge the knowledge gap between gas and liquid phase reactions. Transient tests showed a highly active, unstable low-temperature (LT) reaction channel in conversion profiles and a stable, less-active high-temperature (HT) channel. Cobalt incorporation had a positive effect on the activity. The effect of water was negative on the LT channel, whereas the HT channel activity was boosted for x>0.15. The boost may originate from a slower deactivation rate of the Co3+ sites under wet conditions and a higher amount of hydroxide species on the surface comparing wet to dry feeds. Water addition resulted in a slower deactivation for Co-rich catalysts and higher activity in the HT channel state. 相似文献
42.
Robert S. Wilson-Kovacs Xue Fang Maximilian J. L. Hagemann Dr. Henry E. Symons Prof. Charl F. J. Faul 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(3):e202103443
The number and type of new supramolecular polymer (SMP) systems have increased rapidly in recent years. Some of the key challenges faced for these novel systems include gaining full control over the mode of self-assembly, the creation of novel architectures and exploring functionality. Here, we provide a critical overview of approaches related to perylene-based SMPs and discuss progress to exert control over these potentially important SMPs through chemical modification of the imide substituents. Imide substitutions affect self-assembly behaviour orthogonally to the intrinsic optoelectronic properties of the perylene core, making for a valuable approach to tune SMP properties. Several recent approaches are therefore highlighted, with a focus on controlling 1) morphology, 2) H- or J- aggregation, and 3) mechanism of growth and degree of aggregation using thermodynamic and kinetic control. Areas of potential future exploration and application of these functional SMPs are also explored. 相似文献
43.
Vibrational spectra of BH(4)(-) and its isotopic analogues in a crystalline environment of alkali metals cations (K(+), Rb(+), Cs(+)) have been investigated beyond the harmonic approximation using a variational approach supported by computations of B3LYP type anharmonic force fields. From the comparison of the observed and simulated IR spectra, the influence of the anharmonic couplings on the band position and on the relative intensity of the allowed vibrational transitions is discussed. Here, the effect of the crystalline environment induces a blue shift of about 50 and 100 cm(-1) respectively for the bending and stretching modes of BH(4)(-). Furthermore, anharmonic effects, which are exclusively well reproduced by a variational approach, are needed to yield reliable positions and relative amplitudes of IR allowed combination and overtone transitions. This leads to theoretical results fitting their experimental counterpart between 6 and 30 cm(-1) in the investigated series. 相似文献
44.
45.
M. Kmiecik A. Maj B. Herskind A. Bracco R.A. Bark M. Bergström F. Camera G. Hagemann N. Hashimoto A. Holm S. Leoni T. Saitoh T.S. Tveter 《The European Physical Journal A - Hadrons and Nuclei》1998,1(1):11-13
The decay of 170W* formed in reactions with two different projectile - target combinations was studied. The observed differences in the average
number of emitted neutrons suggest an entrance channel effect at the highest excitation energy and angular momentum. It may
be explained by different excitation energies of the equilibrated system, resulting from the emission of pre-equilibrium α-particles
during a longer fusion time, in the more symmetric reaction.
Received: 30 October 1997 相似文献
46.
P. Bringel H. Hübel H. Amro M. Axiotis D. Bazzacco S. Bhattacharya R. Bhowmik J. Domscheit G.B. Hagemann D.R. Jensen Th. Kröll S. Lunardi D.R. Napoli A. Neußer S.C. Pancholi C.M. Petrache G. Schönwaßer A.K. Singh C. Ur 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):155-158
High-spin states in 161Lu and 162Lu have been investigated using the GASP γ-ray spectrometer array. Excited states in these nuclei have been populated through
the 100Mo(65Cu, xn) reaction at a beam energy of 260 MeV. Four presumably triaxial superdeformed bands, three in 162Lu and one in 161Lu, have been observed. This is the first evidence for triaxial superdeformation in the two isotopes.
Received: 18 October 2002 / Accepted: 21 November 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: bringel@iskp.uni-bonn.de
RID="b"
ID="b"Present address: Wright Nuclear Structure Laboratory, Yale University, New Haven, CT 06520, USA.
RID="c"
ID="c"Present address: Physik Department, Technische Universit?t München, James Franck Str., D-85748 Garching, Germany.
Communicated by D. Schwalm 相似文献
47.
48.
L. Carlén S. Jónsson J. Krumlinde J. Lyttkens N. Roy H. Ryde S. Strömberg W. Waluś G.B. Hagemann B. Herskind 《Nuclear Physics A》1982,381(1):155-172
Energy levels in 153Er have been populated in the reaction 144Sm(12C. 3n)153Er. Isotopically enriched targets were bombarded with 53–65 MeV 12C ions and the emitted γ-ray and conversion electron spectra were investigated. From studies of excitation functions. γ- coincidences, γ-ray multiplicities, delayed γ-radiation and angular distributions, the level scheme of 153Er has been constructed. The properties of the energy levels are discussed and compared with the results of calculations with a deformed shell model. The remarkable similarities and some important discrepancies of the level structure, when compared with adjacent, N = 85 nuclides, are emphasized. 相似文献
49.
D.L. Hillis J.D. Garrett O. Christensen B. Fernandez G.B. Hagemann B. Herskind B.B. Back F. Folkmann 《Nuclear Physics A》1979,325(1):216-268
The moments of the γ-ray multiplicity distributions as a function of evaporation residue and of Eγ have been determined from γ-multiplicity measurements for the 116, 120, 122, 124Sn(40Ar, xn) reactions at 161 ≦ E(Ar) ≦ 236 MeV and for the 76Ge(86Kr, xn) reaction at 314 ≦ E(Kr) ≦ 376 MeV. Even at the highest incident energies where lgr ≈ 120 units, it is not possible to populate nuclei with l > 65 units, the limiting l predicted for a rotating liquid drop. For the lowest incident energies these data are in agreement with the decay of a compound system. At the highest incident energy, however, significant deviations are observed from the expected decay of an equilibrated system. Such deviations are indicative of pre-equilibrium particle decay. Statistical calculations utilizing the code GROG12 are used to substantiate these conclusions. No evidence for a lower l-cut in the population of the compound system is observed; however, these data would not be sensitive to an lcut ? 10 units. The moments of inertia extracted from the edge of the “collective E2 bump” in the 〈Mγ〉 versus Eγ data are in agreement with those predicted for a rotating liquid drop. The average multiplicity of the noncompound processes is estimated to be 8–11 for lgr ? 100 units and increasing to 21 for lgr ? 120 units. 相似文献
50.
G.B. Hagemann R. Broda B. Herskind M. Ishihara S. Ogaza H. Ryde 《Nuclear Physics A》1975,245(1):166-188
First and higher order multiple coincidence rates have been measured for the γ-rays from 16O induced reactions on targets of 148,150Nd at various bombarding energies. Average values and shape parameters for the γ-ray multiplicity distributions have been extracted from the data. The multiplicities are connected to angular momentum through complete fusion cross sections, and conclusions are drawn on spin distributions of entry states in the final nuclei as well as on the decay pattern from these states. 相似文献