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141.
Eri Muramoto Wei Chen Xiwen Jia Cynthia M. Friend Philippe Sautet Robert J. Madix 《Chemical science》2022,13(3):804
With the emergence of methods for computing rate constants for elementary reaction steps of catalytic reactions, benchmarking their accuracy becomes important. The unimolecular dehydrogenation of adsorbed formate on metal surfaces serves as a prototype for comparing experiment and theory. Previously measured pre-exponential factors for CO2 formation from formate on metal surfaces, including Cu(110), are substantially higher than expected from the often used value of kBT/h, or ∼6 × 1012 s−1, suggesting that the entropy of the transition state is higher than that of the adsorbed formate. Herein, the rate constant parameters for formate decomposition on Au(110) and Cu(110) are addressed quantitatively by both experiment and theory and compared. A pre-exponential factor of 2.3 × 1014 s−1 was obtained experimentally on Au(110). DFT calculations revealed the most stable configuration of formate on both surfaces to be bidentate and the transition states to be less rigidly bound to the surface compared to the reactant state, resulting in a higher entropy of activation and a pre-exponential factor exceeding kBT/h. Though reasonable agreement is obtained between experiment and theory for the pre-exponential factors, the activation energies determined experimentally remain consistently higher than those computed by DFT using the GGA–PBE functional. This difference was largely erased when the metaGGA–SCAN functional was applied. This study provides insight into the underlying factors that result in the relatively high pre-exponential factors for unimolecular decomposition on metal surfaces generally, highlights the importance of mobility for the transition state, and offers vital information related to the direct use of DFT to predict rate constants for elementary reaction steps on metal surfaces.The underlying factors that result in the high pre-exponential factors for formate decomposition on Au and Cu(110) surfaces and the origins of differences between experiment and theory that may arise are reported. 相似文献
142.
143.
Eri Asakawa Jun-ichi Kamoshita Akio Sugamoto Isamu Watanabe 《The European Physical Journal C - Particles and Fields》2000,14(2):335-345
We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process
at the energy around the mass poles of the Higgs bosons. It is found that interference between H and A with small mass gap, as well as the ones between Higgs bosons and continuum, contributes to the cross section, if the photon
beams are polarized and if we observe the helicity of the top quarks. It is demonstrated in the framework of the minimal supersymmetric
extension of the standard model that the H and A contributions can be sizable at future colliders for small values of . The methods to measure the CP-parity of the Higgs boson are also presented. The statistical significance of detecting the Higgs signals and measuring the
Higgs CP-parity is evaluated.
Received: 16 December 1999 / Revised version: 30 January 2000 / Published online: 6 April 2000 相似文献
144.
E. Asakawa A. Sugamoto I. Watanabe 《The European Physical Journal C - Particles and Fields》2000,17(2):279-284
In the s-channel Higgs-boson exchange processes, the interference between the amplitudes for CP-even and CP-odd Higgs bosons is sizable, if the helicities of the initial and final particles are properly fixed and if the mass difference
between these bosons is not much larger than their decay widths. We discuss this interference effect in the process . Examining the effect gives us information on the CP-parity for the Higgs bosons and on the sign of the product of the coupling constants for the and vertices. The feasibility of observing the interference effect in future muon colliders is evaluated in the framework of
the minimal supersymmetric extension of the standard model as an example. 相似文献
145.
Angela Mammana Dr. Gennaro Pescitelli Dr. Tomohiro Asakawa Dr. Steffen Jockusch Dr. Ana G. Petrovic Dr. Regina R. Monaco Dr. Roberto Purrello Prof. Nicholas J. Turro Prof. Koji Nakanishi Prof. George A. Ellestad Dr. Milan Balaz Prof. Nina Berova Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):11765-11765
146.
Furuta T Sakai M Hayashi H Asakawa T Kataoka F Fujii S Suzuki T Suzuki Y Tanaka K Fishkin N Nakanishi K 《Chemical communications (Cambridge, England)》2005,(36):4575-4577
An artificial phospholipid, possessing saturated alkyl chains as a membrane anchor and protein recognition site as well as an Fe(III)-EDTA moiety as a protein cleavable polar head group, was designed and synthesized based on the amidite method for the purpose of examination of cleavage of integral membrane proteins. 相似文献
147.
Miyazaki A Asakawa T Nakano Y Balint I 《Chemical communications (Cambridge, England)》2005,(29):3730-3732
On the surface of morphologically controlled Pt nanoparticles, statistically rich in [100] crystalline facet, nitrite ions were reduced by H2 to N2 with high selectivity. 相似文献
148.
Achievement of more than 100 mW of pure continuous-wave deep-ultraviolet radiation at 213 nm has been demonstrated in an efficient all-solid-state laser system that uses two Brewster-cut CsLiB6O10 (CLBO) crystals. The first crystal is used for 266-nm generation by external resonant doubling of 532-nm radiation from a frequency-doubled Nd:YVO4 laser. Subsequent sum-frequency mixing is performed in a second CLBO crystal placed in a diode-pumped Nd:YAG laser cavity to mix the single-pass 266-nm output with circulating 1064-nm light. 相似文献
149.
Central pseudorapidity gaps in events with a leading antiproton at the fermilab tevatron pp collider
Acosta D Affolder T Akimoto H Albrow MG Ambrose D Amidei D Anikeev K Antos J Apollinari G Arisawa T Artikov A Asakawa T Ashmanskas W Azfar F Azzi-Bacchetta P Bacchetta N Bachacou H Badgett W Bailey S De Barbaro P Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Barone M Bauer G Bedeschi F Behari S Belforte S Bell WH Bellettini G Bellinger J Benjamin D Bensinger J Beretvas A Berryhill J Bhatti A Binkley M Bisello D Bishai M Blair RE Blocker C Bloom K Blumenfeld B Blusk SR Bocci A Bodek A 《Physical review letters》2003,91(1):011802
We report a measurement of the fraction of events with a large pseudorapidity gap deltaeta within the pseudorapidity region available to the proton dissociation products X in p+p-->p+X. For a final state p of fractional momentum loss xi(p) and 4-momentum transfer squared t(p) within 0.063 is found to be 0.246+/-0.001 (stat)+/-0.042 (syst) [0.184+/-0.001 (stat)+/-0.043 (syst)]. Our results are compared with gap fractions measured in minimum bias pp collisions and with theoretical expectations. 相似文献
150.
Acosta D Affolder T Akimoto H Albrow MG Ambrose D Amidei D Anikeev K Antos J Apollinari G Arisawa T Artikov A Asakawa T Ashmanskas W Azfar F Azzi-Bacchetta P Bacchetta N Bachacou H Badgett W Bailey S De Barbaro P Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Barone M Bauer G Bedeschi F Behari S Belforte S Bell WH Bellettini G Bellinger J Benjamin D Bensinger J Beretvas A Berryhill J Bhatti A Binkley M Bisello D Bishai M Blair RE Blocker C Bloom K Blumenfeld B Blusk SR Bocci A Bodek A 《Physical review letters》2003,90(13):131801
We report a search for the production of long-lived charged massive particles in a data sample of 90 pb(-1) of square root[s]=1.8 TeV pp collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of O(1) pb are derived using two reference models, a stable quark and a stable scalar lepton. 相似文献