The state-resolved reactivity of CH 4 in its totally symmetric C-H stretch vibration ( 1 ) has been measured on a Ni(100) surface. Methane molecules were accelerated to kinetic energies of 49 and 63:5 kJ=mol in a molecular beam and vibrationally excited to 1 by stimulated Raman pumping before surface impact at normal incidence. The reactivity of the symmetric-stretch excited CH 4 is about an order of magnitude higher than that of methane excited to the antisymmetric stretch ( 3 ) reported by Juurlink et al. [Phys. Rev. Lett. 83, 868 (1999)] and is similar to that we have previously observed for the excitation of the first overtone (2 3 ). The difference between the state-resolved reactivity for 1 and 3 is consistent with predictions of a vibrationally adiabatic model of the methane reaction dynamics and indicates that statistical models cannot correctly describe the chemisorption of CH 4 on nickel.Activated dissociation of molecules on a metal surface is a fundamental step in many catalytic processes. An important example is the chemisorption of methane on nickel to form surface-bound methyl and hydrogen; this reaction is the rate-limiting step in steam reforming, which is the principal process for industrial hydrogen production. The importance of this process has incited a number of studies, both theoretical and experimental, directed towards understanding the detailed mechanism of methane chemisorption [1-15]. Molecular-beam experiments have shown that methane chemisorption on nickel is a direct process, activated by translational and vibrational energy [1,2]. More recent state-resolved experiments investigating the reactivity of CH 4 excited to the antisymmetric stretch fundamental vibration ( 3 ) [6] and first overtone (2 3 ) [9] on Ni(100) have found that energy in 3 promotes the reaction with similar efficacy as kinetic energy along the surface normal. Furthermore, Juurlink et al. [6] have shown that CH 4 with excitation in 3 contributes less than 2% to the activated chemisorption of thermally excited methane [2]. They conclude that vibrational modes other than 3 must play a significant role in methane reactivity under thermal conditions. Theoretical treatments of methane chemisorption include statistical [11,12] as well as dynamical models [3,4,7,8,13]. While the statistical approach excludes the possibility of mode-specific reactivity, it has been claimed to reproduce the results of both thermally averaged and eigenstate-resolved measurements for CH 4 on Ni(100) [11,12]. On the other hand, simplified dynamical models for gas-surface reactions suggest the possibility of mode specificity [7,8]. For reactions that occur entirely in the gas phase, more realistic dynamical calculations find that the symmetric-stretch vibration is generally more efficient than the antisymmetric stretch in promoting reaction [16 -22], and this has been confirmed, in part, by experiments [18,23].We have previously reported vibrational mode-specific chemisorption of CD 2 H 2 on Ni(100), where we demon-strated the difference in re...

Quantum state-resolved sticking coefficients on Pt(111) and Ni(111) surfaces have been measured for CH4 excited to the first overtone of the antisymmetric C-H stretch (2nu3) at well-defined kinetic energies in the range of 10-90 kJ/mol. The ground-state reactivity of CH4 is approximately 3 orders of magnitude lower on Ni(111) than on Pt(111) for kinetic energies in the range of 10-64 kJ/mol, reflecting a difference in barrier height of 28+/-6 kJ/mol. 2nu3 excitation of CH4 increases its reactivity by more than 4 orders of magnitude on Ni(111), whereas on Pt(111) the reactivity increase is lower by 2 orders of magnitude. We discuss the observed differences in the state-resolved reactivity for the ground state and 2nu3 excited state of methane in terms of a difference in barrier height and transition state location for the dissociation reaction on the two metal surfaces.

Electrochemical carbon dioxide (CO 2 )r eduction reaction (CO 2 RR) is an attractive approach to deal with the emission of CO 2 and to produce valuable fuels and chemicals in ac arbon-neutral way.M any efforts have been devoted to boost the activity and selectivity of high-value multicarbon products (C 2+ )o nC u-based electrocatalysts.H owever,C ubased CO 2 RR electrocatalysts suffer from poor catalytic stability mainly due to the structural degradation and loss of active species under CO 2 RR condition. To date,most reported Cu-based electrocatalysts present stabilities over dozenso f hours,w hich limits the advance of Cu-based electrocatalysts for CO 2 RR. Herein, ap orous chlorine-doped Cu electrocatalyst exhibits high C 2+ Faradaic efficiency (FE) of 53.8 %at À1.00 Vv ersus reversible hydrogen electrode (V RHE ). Importantly,the catalyst exhibited an outstanding catalytic stability in long-term electrocatalysis over 240 h. Experimental results show that the chlorine-induced stable cationic Cu 0 /Cu + species and the well-preserved structure with abundant active sites are critical to the high FE of C 2+ in the long-term run of electrochemical CO 2 reduction.

The reactivity of methane (CH(4)) on Pt(110)-(1 x 2) has been studied by quantum state-resolved surface reactivity measurements. Ground state reaction probabilities, S(0)(v=0) congruent with S(0)(laser-off), as well as state-resolved reaction probabilities S(0)(2nu(3)), for CH(4) excited to the first overtone of the antisymmetric C-H stretch (2nu(3)) have been measured at incident translational energies in the range of 4-64 kJ/mol. We observe S(0)(2nu(3)) to be up to three orders of magnitude higher than S(0)(v=0), demonstrating significant vibrational activation of CH(4) dissociation on Pt(110)-(1 x 2) by 2nu(3) excitation. Furthermore, we explored the azimuthal and polar incident angle dependence of S(0)(2nu(3)) and S(0)(v=0) for a fixed incident translational energy E(t)=32 kJ/mol. For incidence perpendicular to the missing row direction on Pt(110)-(1 x 2) and polar angles theta>40 degrees, shadowing effects prevent the incident CH(4) molecules from impinging into the trough sites. Comparison of this polar angle dependence with reactivity data for incidence parallel to the missing rows yields state-resolved site specific reactivity information consistent with a Pt(110)-(1 x 2) reactivity that is dominated by top layer Pt atoms located at the ridge sites. A comparison of S(0)(v=0) measured on Pt(110)-(1 x 2) and Pt(111) yields a lower average barrier for Pt(110)-(1 x 2) by 13.7+/-2.0 kJ/mol.

Understanding the rules of life is one of the most important scientific endeavours and has revolutionised both biology and biotechnology. Remarkable advances in observation techniques allow us to investigate a broad range of complex and dynamic biological processes in which living systems could exploit quantum behaviour to enhance and regulate biological functions. Recent evidence suggests that these non-trivial quantum mechanical effects may play a crucial role in maintaining the non-equilibrium state of biomolecular systems. Quantum biology is the study of such quantum aspects of living systems. In this review, we summarise the latest progress in quantum biology, including the areas of enzyme-catalysed reactions, photosynthesis, spin-dependent reactions, DNA, fluorescent proteins, and ion channels. Many of these results are expected to be fundamental building blocks towards understanding the rules of life.

Proton transfer along the hydrogen bonds of DNA can lead to the creation of short-lived, but biologically relevant point mutations that can further lead to gene mutation and, potentially, cancer.

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The dissociative adsorption of cyclopentadiene (C(5)H(6)) on Cu(111) yields a cyclopentadienyl (Cp) species with strongly anionic characteristics. The Cp potential energy surface and frictional coupling to the substrate are determined from measurements of dynamics of the molecule together with density functional calculations. The molecule is shown to occupy degenerate threefold adsorption sites and molecular motion is characterized by a low diffusional energy barrier of 40±3 meV with strong frictional dissipation. Repulsive dipole-dipole interactions are not detected despite charge transfer from substrate to adsorbate.