Faraday Discussions of The Chemical Society最新文献_第2页

Indirect information on reactive transition states from conservation of angular momentum 从角动量守恒得到反应跃迁态的间接信息

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100183

C. Leach, A. Tsekouras, P. Vaccaro, R. Zare, Daqing Zhao

引用次数: 5

Hydrogen exchange reaction H + D2 in crossed beams 交叉梁中的氢交换反应H + D2

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100259

L. Schnieder, K. Seekamp-Rahn, F. Liedeker, H. Steuwe, K. Welge

引用次数: 79

Probing the transition state in dissociative adsorption 解离吸附过渡态的探讨

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100425

S. Holloway, X. Chang

{"title":"Probing the transition state in dissociative adsorption","authors":"S. Holloway, X. Chang","doi":"10.1039/DC9919100425","DOIUrl":"https://doi.org/10.1039/DC9919100425","url":null,"abstract":"We have performed calculations for H2 molecules being scattered from a metal surface. The emphasis of the work is aimed at understanding the role of rotational energy on the dissociative adsorption reaction. The time-dependent wavepacket formalism has been employed on a vibrationally adiabatic PES which explicitly contains two rotational degrees of freedom and one translational. The PES is activated (ca. 0.25–1.5 eV) and the value of the barrier depends strongly on the angle that the molecular bond axis makes with the surface. This PES enables a scattering event to be modelled which corresponds to a normally incident beam of hydrogen in the ground vibrational state and the J, mJ rotational state. We have found that the translational energy dependence of the dissociation probability of para- and normal hydrogen is approximately the same. This reflects the fact that the quantum of rotational energy is rather small in comparison to the activation barrier height. More interestingly it has been found that the form chosen for the PES gives rise to effective angular discrimination whereby molecules having only particular orientations will dissociate. This, in turn, gives rise to a characteristic rotational distribution which may be used to explore the symmetry of the dissociative transition state.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"14 1","pages":"425-436"},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81047002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Potential-energy surface control of the NH product state distribution in the decomposition reaction HN3(X 1A′)→ NH(a 1Δ)+ N2(X 1Σ+g) 分解反应HN3(X 1A′)→NH(a 1Δ)+ N2(X 1Σ+g)中NH生成物态分布的势能面控制

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100319

M. Alexander, P. Dagdigian, H. Werner

{"title":"Potential-energy surface control of the NH product state distribution in the decomposition reaction HN3(X 1A′)→ NH(a 1Δ)+ N2(X 1Σ+g)","authors":"M. Alexander, P. Dagdigian, H. Werner","doi":"10.1039/DC9919100319","DOIUrl":"https://doi.org/10.1039/DC9919100319","url":null,"abstract":"A model is presented to explain quantitatively the Λ doublet propensities observed by King, Stephenson, Foy and Casassa in the infrared multiphoton and vibrational overtone decomposition of HN3 to yield NH(a 1Δ) fragments. This Franck–Condon-type model involves the projection of the electronic vibrational wavefunction of the HN⋯NN system at the transition state onto the electronic-rotational wavefunction of the free NH rotor. Ab initio calculations are used to estimate the angular extent of the torsional degrees of freedom which subsequently become converted to rotations of the NH fragment. This model deals explicitly with the two-electron character of the 1Δ state. The experimentally observed ratio of Δ(A′) to Δ(A″)Λ doublet populations vs. the rotational quantum number J of the NH fragment, as well as the observed average rotational excitation of the NH products, are well predicted. In contrast, the observed v, J correlation is not as well predicted. The model presented here represents an advance over those previously developed to explain Λ doublet propensities in that it is based on properties of the specific system under consideration.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"35 1","pages":"319-335"},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83093533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Femtosecond transition-state dynamics 飞秒过渡态动力学

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100207

A. Zewail

引用次数: 105

Energy and structure of the transition states in the reaction OH + CO → H + CO2 OH + CO→H + CO2反应过渡态的能量和结构

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100305

M. Frost, P. Sharkey, Ian W. M. Smith

{"title":"Energy and structure of the transition states in the reaction OH + CO → H + CO2","authors":"M. Frost, P. Sharkey, Ian W. M. Smith","doi":"10.1039/DC9919100305","DOIUrl":"https://doi.org/10.1039/DC9919100305","url":null,"abstract":"Two, quite different, experimental studies have been carried out on the reaction between OH and CO at low total pressures. In the first, rate constants have been determined at 82 and 106 K. At the lower temperature, measurements were made at 2 and 5 Torr total pressure, yielding k=(1.0 ± 0.12)× 10–13 cm3 molecule–1 s–1 and (0.91 ± 0.1)× 10–13 cm3 molecule–1 s–1, respectively. At 106 K and 4 Torr, k=(0.98 ± 0.08)× 10–13 cm3 molecule–1 s–1. Theoretical considerations show that the reaction must be in its low-pressure limit, yielding H + CO2, and that the vibrational ground-state adiabatic barrier to formation of HOCO must be <200 cm–1, significantly lower than estimated previously.In the second series of experiments, a tunable diode laser has been used to observe transient absorptions on transitions in the ν3 infrared bands of the CO2 product of the reaction, when it is initiated by flash photolysis at room temperature. There is no excitation of the ν3 mode, and the overall vibrational distribution corresponds to an averaged vibrational energy yield of only 6%. It is concluded that energy is released largely as repulsion following passage through a transition state in which the OCO angle is ca. 171° and the O—C, C—O bond distances are very similar to those in isolated CO2.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"20 1","pages":"305-317"},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72998491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 78

Two-colour sub-Doppler circular dichroism: a four-vector correlation molecular dynamics experiment for inelastic and reactive collisions 双色亚多普勒圆二色性:非弹性和反应性碰撞的四向量相关分子动力学实验

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100091

T. Collins, A. J. McCaffery, M. Wynn

引用次数: 4

Professor R. B. Bernstein: an appreciation 伯恩斯坦教授:谢谢

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100001

A. Buckingham

引用次数: 5

Photochemistry of adsorbed molecules. Part 10.—Harpooning a fixed target: charge transfer from Ag or K substrates to halide adsorbates 吸附分子的光化学。第10部分。-鱼叉固定目标:电荷从Ag或K底物转移到卤化物吸附剂

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100451

S. Dixon-Warren, E. Jensen, J. Polanyi, G. Xu, Shihe Yang, H. Zeng

{"title":"Photochemistry of adsorbed molecules. Part 10.—Harpooning a fixed target: charge transfer from Ag or K substrates to halide adsorbates","authors":"S. Dixon-Warren, E. Jensen, J. Polanyi, G. Xu, Shihe Yang, H. Zeng","doi":"10.1039/DC9919100451","DOIUrl":"https://doi.org/10.1039/DC9919100451","url":null,"abstract":"In part 1 of this paper we report direct evidence for the process of charge-transfer photodissociation (CT/PDIS), namely the formation of negatively charged photofragments from a halide adsorbed on a metal substrate. The system was CCl4/Ag(111). The observation was that 1 µJ cm–2 of laser radiation with photon energies in excess of a threshold hν0≈ 5 eV, approximately equal to the work function of the substrate, gave rise to a readily detectable flux of Cl– leaving the surface, attributable to a harpooning process CCl4/Ag(111)+hν→ CCl–4/Ag(111)→ Cl–(g)+ CCl3/Ag(111). In part 2 the cross-section, σ(CT/PDIS), is reported over the range 193–700 nm incident wavelength for charge-transfer photodissociation of HI and HBr adsorbed on 2–3 monolayers of K deposited on Ag(110) or LiF(001). The observed shift in threshold photon energy, Δhν0, to higher energy in going from HI(ads) to HBr(ads) was in the direction expected for dissociative electron attachment (DA). There was evidence of a significant tunnelling regime for CT/PDIS of HI/Ag but not for HBr/Ag, a finding that can be understood in terms of DA.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"18 1","pages":"451-463"},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82383566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 27

Metal–metal and metal–hydrogen reactive transition states 金属-金属和金属-氢反应过渡态

Faraday Discussions of The Chemical Society Pub Date : 1991-01-01 DOI: 10.1039/DC9919100097

W. Stwalley, P. Kleiber, K. Sando, A. Lyyra, Li Li, S. Ananthamurthy, S. Bililign, He Wang, J. X. Wang, V. Zafiropulos

引用次数: 2