Coverage Dependent Dissociative Adsorption of HCl on Au(111)

Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface chemistry.Despite tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage initial sticking probabilities(So).To find the origin of the large experiment-theory discrepancy,we have revisited the dissociative adsorption of HCl on Au(111)with a newly designed molecular beam-surface apparatus.The zero-coverage So derived from Cl-coverage measurements with varying HCl doses agree well with previous ones.However,we notice a sharp change of the coverage/dose slope with the HCl dosage at the low coverage regime,which may result in some uncertainties to the fitted So value.This seems consistent with a coverage-dependence of the dissociation barrier predicted by density functional theory at low Cl-coverages.Our results reveal the potential inconsistency of utilizing simulations with finite coverage to compare against experimental data with zero coverage in this system,and provide guidance for improving both experiment and theory in this regard.

Reaction probabilities of ClONO_2 on ice

The reaction probabilities of ClONO\-2 on ice surface were determined by using a flow tube reactor attached with a photoionization detector. The growth rate of HOCl was used to obtain reaction probabilities. The measured reaction probabilities depended on temperature and flow velocity. The reaction proceeded efficiently at temperature range of 190K to 200K. The reaction probability was 0 0023 at 198K ( v =100 cm/s). The result was in good agreement with that of Abbatt et al.

Dynamics of the Au+H2 reaction by time-dependent wave packet and quasi-classical trajectory methods

Dynamics of the Au + H2 reaction are studied using time-dependent wave packet(TDWP) and quasi-classical trajectory(QCT) methods based on a new potential energy surface [Int. J. Quantum Chem. 118 e25493(2018)]. The dynamic properties such as reaction probability, integral cross section, differential cross section and the distribution of product are studied at state-to-state level of theory. Furthermore, the present results are compared with the theoretical studies available.The results indicate that the complex-forming reaction mechanism is dominated in the reaction in the low collision energy region and the abstract reaction mechanism plays a dominant role at high collision energies. Different from previous theoretical calculations, the side-ways scattering signals are found in the present work and become more and more apparent with increasing collision energy.

The Quantum Scattering Study for Ion-pair Formation Reaction Na+I_2→Na^+I_2^- with the LCAC-SW method

The selected-state probabilities of collinear ion-pair formation process Na+I2→Na++I2-on Aten-Laming-Los two-State potential energy surface have been calculated by using LCAC-SW method. The results show that reaction probabilities are oscillatory with collision energy; the threshold energy of this ioniZation reaction is 2.8 ev, which is in modest agreement with experimental result.

Exact quantum dynamics study of the H(^(2)S)+SiH^(+)(X^(1)Σ^(+))reaction on a new potential energy surface of SiH_(2)^(+)(X^(2)A_(1))

Based on a new global potential energy surface of SiH_(2)^(+)(X^(2)A_(1)),the exact quantum dynamical calculation for the H(^(2)S)+SiH^(+)(X^(1)Σ^(+))→H_(2)+Si^(+)reaction has been carried out by using the Chebyshev wave packet method.The initial state specified(νi=0,ji=0)probabilities,integral cross sections(ICS)and thermal rate constants of the title reaction are calculated.All partial wave contributions up to J=90 are calculated in exact quantum calculation including the full Coriolis coupling(CC)effect.The dynamical behaviors of probabilities,ICSs and rate constants are found to be in accord with an exothermic reaction without potential barrier.By comparing the probabilities of CC with the corresponding centrifugal sudden(CS)approximation ones,it can be concluded that neglecting CC effect will decrease the collision time,increase the amplitude of oscillation and lead to overestimation or underestimation of the reaction probability.For ICSs and rate constants,it is found that the deviation of CC and CS ICSs is small in the most of collision energy range except for the range of 0 eV-0.05 eV,while the deviation of both rate constants is considerable in the temperature range of 16 K-1000 K.

Time-Dependent Quantum Wave Packet Calculation for Reaction S-(^(2)P)+H_(2)(^(1)∑_(g)^(+))→SH-(^(1)∑)+H(^(2)S) on Ab Initio Potential Energy Surface

The time-dependent wave packet propagation method was applied to investigate the dynamic behaviours of the reaction S-(^(2)P)+H_(2)(^(1)∑_(g)^(+))→SH-(^(1)∑)+H(^(2)S)based on the electronic ground state(^(2)A′)potential energy surface of the SH_(2)-ionic molecule.The collision energy dependent reaction probabilities and integral cross sections are obtained.The numerical results suggest that there are significant oscillation structures over all the studied range of the collision energies.The vibrational excitation and rotational excitation of the diatomic reagent H_(2) promote the reactivity significantly as suggested by the numerical total reaction probabilities with the initial rotational quantum number of j=0,2,4,6,8,10,and the vibrational quantum number v=0,1,2,3,4.The numerical integral cross sections are quite consistent with the experimental data reported in previous work.

REACTION PROBABILITIES OF ENERGETIC SPECIES AT GROWING DIAMOND FILM SURFACES BY MOLECULAR DYNAMICS SIMULATION

A Molecular Dynamics (MD) simulation with Tersoff empirical many-bodypotential has been employed to investigate the growth processes of diamond film with energeticspecies deposition. In the present study, we have studied the reaction probabilities of energeticspecies with energies of 0.1 e V to 10eV at the substrate temperature of 1100K. In the cases of thediamond growth on the surface with H passivation, the reaction probability of hydrocarbon speciesconsiderably increases when the species energy is higher than 2eV. This means that the diamond filmcan grow in the case of high incident species energy without the process of hydrogen abstraction,which is needed in the case of incident species with low energy. The reaction mechanism of energeticspecies on hydrogen passivated diamond surface is also discussed.

A quantum scattering study of collinear state-to-state reaction probabilities for the F+H_2(ν)→-HF(v')+H system

A new quantum scattering approach (linear combination of arrangement channels-scattering wavefunction,LCAC-SW) proposed by Deng and his co-workers is used to calculate collinear state-to-state reaction probabilities for the F + H-2(v)→HF(v')+H system.Several interesting problems such as threshold energy,compound states and enhance by translational energy of the reactants and the vibration excitation of products are discussed and they are compared with other theoretical investigations reported in the literature.It is shown that the LCAC-SW approach is the successful one of quantum scattering methods.

Exact quantum calculations on the collinear hydrogen atom transfer reaction——I. Study on oscillations of the reaction probabilities of Cl+HCl

1-D quantum calculations of reaction probabilities have been carried out for the col- linear reaction Cl+HCl (v≤3)→ClH (v＇≤3)+Cl using hyperspherical coordinates. An LEPS po- tential energy surface with a shallow well depth of -3.22 KJ/mol has been used in the calculations. The state-to-state reaction probabilities have been calculated. According to the results obtained we found that the diagonal (v=v＇) reaction probabilities dominate over the off-diagonal (vv＇) reaction probabilities and the largest off-diagonal reaction probabilities are smaller than 0.1. The reaction probabilities show oscillation as a function of energy. Dynamic resonances strengthen for the potential energy surface with a well.

LCAC-SW quantum scattering dynamic study on the ion-pair formation process

LCAC-SW method has been extended to study the reaction dynamics for ion-pair formation processes. M+ X2→Mt + X2 reaction system involves two potential energy surfaces, i.e., the covalence state (M + X2) and the ionic state (M + X2) and their crossing effect. The working equations for calculating state-to-state probability have been derived based on the above two-state model, Satisfied results d collinear state-to-state probabilities for K+ I2 → K+ + I2 ion-pair formation system have been obtained.