Influence Of Collision Energy Research Articles

The influence of collision energy on magnetically tuned 6Li-6Li Feshbach resonance

The effect of collision energy on the magnetically tuned 6Li–6Li Feshbach resonance (FR) is investigated theoretically by using the coupled-channel (CC) method for the collision energy ranging from 1 μK ⋅ k B to 100 μK ⋅ k B. At the collision energy of 1 μK ⋅ k B, the resonance positions calculated are 543.152 Gs (s wave, the unit 1 Gs = 10−4 T), 185.109 Gs (p wave |ml | = 0), and 185.113 Gs (p wave |ml | = 1), respectively. The p-wave FR near 185 Gs exibits a doublet structure of 4 mGs, associated with dipole–dipole interaction. With the increase of the collision energy, it is found that the splitting width remains the same (4 mGs), and that the resonance positions of s and p waves are shifted to higher magnetic fields with the increase of collision energy. The variations of the other quantities including the resonance width and the amplitude of the total scattering section are also discussed in detail. The thermally averaged elastic rate coefficients at T = 10, 15, 20, 25 K are calculated and compared.

碰撞能和反应物激发态对H(D) + LiH(D)反应动力学的影响

碰撞能和反应物激发态对H(D) + LiH(D)反应动力学的影响

Influence of collision energy on the stereodynamics of the H+CH+→C++H2 reaction

The reactive cross section and stereodynamics at selected collision energies for the H(2S)+CH+(X1Σ+)→C+(2P)+H2(X1Σg+) reaction on a globally smooth ab initio potential surface of the 2A' state are calculated in detail by the quasi-classical trajectory(QCT) method. The calculated cross section decreases with the increase of the collision energy, which is found to be in overall good agreement with the previous time-dependent quantum results in the high collision energy regime (Ec>20 meV). The discrepancy between the QCT and previous quantum cross section below 20 meV can be attributed to the limitations of the classical trajectory method, because the QCT method cannot handle the effect of zero point energy. In general, QCT results show qualitative agreement with the quantum results, which confirmsthe validity of the QCT method. The research shows that the product rotational angular momentum vector is aligned and oriented. The alignment of the product rotational angular momentum vector j' depends very sensitively on the collision energy. With the increase of the collision energy, the alignment effect recedesin the low collision energy region (1500 meV), while it is enhanced in the high collision energy region (500-1000 meV). Moreover, the k-k'-j' distributions tend to be asymmetric with respect to the k-k' scattering plane (or about φr=180°), with two peaks appearing at φr=90° and φr=270°, respectively. This indicates that the product rotational angular momentum is not only in the Y-axis direction but also along the positive Y-axis direction. The peak intensity decreases with the collision energy increasing from 1 meV to 100 meV, while it increases with collision energy increasing from 100 meV to 1000 meV. Therefore the Y-axis orientation effect turns weak with the enhancement of the collision energy in the low energy region, while it becomes strong in the high energy region. In addition, the polarization dependent differential cross sections (PDDCSs) (2π/σ)(dσ00/dωt) and (2π/σ)(dσ20/dωt) are calculated. PDDCS (2π/σ)(dσ00/dωt) results indicate that the products have almost symmetrically scattered forward and backward, and the intensity of the scattering increases with the increase of the collision energy. The PDDCS (2π/σ)(dσ20/dωt) shows that the alignment effect of the rotational angular momentum of the products is stronger at the terminal of the scattering angle than at the other directions.

Energy and rotation-dependent stereodynamics of reaction**Project supported by the National Natural Science Foundation of China (Grant Nos. 11474141and 11274149), the Program for Liaoning Excellent Talents in University, China (Grant No. LJQ2015040), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China (Grant No. 2014-1685), and the Special Fund Based Research New Technology of Methanol Conversion and

Quasi-classical trajectory calculations are performed to study the stereodynamics of the reaction based on the first excited state NH2(12A′) potential energy surface reported by Li et al. [Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k–k′ distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k–k′ distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j′ of the product H2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment.

Influence of collision energy and vibrational excitation on the dynamics for the H+HBr→H2+Br reaction

Quasi-classical trajectory (QCT) calculations of H + HBr → H2+Br reaction have been performed on a recently proposed ab initio potential energy surface. The reaction probability and integral cross section are found to be in fairly good agreement with the available quantum mechanical (QM) results on this surface. The behavior of reactivity is well consistent with properties of exothermic reaction. Once the energy of vibrational excited HBr is larger than the barrier height, the integral cross sections for the reaction diverge at very low collision energies close to the threshold, similarly to capture reaction. In addition, differential cross sections show that scattering of the product H2 shift from backward to forward directions as the collision energy and vibrational quantum number increase. All the theoretical findings are reasonably explained by the properties of the surface, as well as reactive mechanisms. A detailed dynamical study of reaction, H+HBr (v=0-3,j=0) → H2+Br, with QCT method has been performed. Both present QCT and available QM results for the HBr (v=0, j=0) have been found to be fairly consistent with each other. The reaction switches from activated to capture-type with increase of the quantum number v.

Influence of collision energy on the dynamics of the reaction H (2S) + NH (X3Σ−) → N (4S) + H2 (X1Σ g + ) by the state-to-state quantum mechanical study

State-to-state time-dependent quantum dynamics calculations have been carried out to study the abstraction processes in the title reaction for the first time. The ab initio potential energy surface of the lowest quartet electronic state of the system recently reported by Zhai et al. (J Chem Phys 135:104314/1–104314/7, 2011) is employed in this investigation. Influences of the collision energy on the product state-resolved differential cross sections (DCSs) are calculated and discussed. For low collision energies, we find that reactive collisions along the collinear pathway result in the H2 product backward scattering. In the case of high collision energy, the stripping collisions with larger impact parameters tend to produce sideways scattering and furnish a high internal excitation of the H2. The product H2 is found to have an inverted rotational distribution and no inversion in vibrational distributions. Moreover, the state-to-state DCSs provide a global perspective of the reaction mechanisms and their contribution to the final H2 internal energy states. A reaction model is built and works well for our calculated results.

Influence of collision energy and reagent vibrational excitation on the stereodynamics of reaction Ar+H2+→ArH++H

The quasi-classical trajectory is calculated for the reaction Ar+H2+→ArH++H (12A’) on the latest potential surface. The correlated integral reaction cross section, P(θr), P(φr) distribution and the polarization dependent differential cross sections polariztion dependent differential cross sections (PDDCSs) are discussed in detail. The results show that the integral reaction cross sections are well consistent with the experimental values at different collision energies and reagent vibrational excitations which indicates that our potential energy surface is accurate. The results indicate that the vibration excitation has less influence on the P(θr) distribution than the collision energy. The P(φr) distribution, and PDDCS are quite sensitive to collision energy and reagent vibrational excitation.

The Influence of Collision Energy on the Reaction H+HS→H2+S

Quasi-classical trajectory calculations have been carried out for the reaction H+HS by using the newest triplet 3A potential energy surface (PES). The effects of the collision energy and reagent initial rotational excitation are studied. The cross sections and thermal rate constants for the title reaction are calculated. The results indicate that the integral cross sections (ICSs) are sensitive to the collision energy and almost independent to the initial rotational states. The ro-vibrational distributions for the product at different collision energies are presented. The investigations on the vector correlations are also performed. It is found that the collision energies play a postive role on the forward scatter of the product molecules. There is a negative influence on both the alignment and orientation of the product angular momentum for low collision energy at low energy region. Whereas the influence of collision energy is not obvious at high energy region.

Influence of collision energy and reagent vibrational excitation on the dynamics of the reaction H + LiH

We present a detailed quasiclassical trajectory (QCT) study of the dynamics corresponding to the reaction H + LiH proceeding via depletion and H‐exchange paths on a new potential energy surface of the electronic ground state. The effects of collision energy and reagent initial vibrational excitation on the reaction probability and cross sections are studied over a wide range of collision energies. The QCT‐calculated reaction probability and cross sections are in good agreement with previous time‐dependent wave packet results. More importantly, we found that the vibrational excitation of LiH molecule inhibits the LiH depletion reaction, whereas it promotes the H‐exchange reaction. In addition, the differential cross sections calculated for the depletion reaction at different collision energies and excitation states indicate a strong forward scattering of the product molecule H2. © 2013 Wiley Periodicals, Inc.

Influence of collision energy and reagent vibrational excitation on the stereodynamics of the reaction H + LiH → H2 + Li

Quasi-classical trajectory calculations have been carried out to investigate the stereodynamics of the reaction H+LiH→H2+Li which proceeds on the ground electronic state of LiH2 system, using a recent potential energy surface of Prudente et al. The effects of collision energy and reagent vibrational excitation on the product polarization are studied for the ν=0–3, j=0 states of LiH over a wide collision energy range. It has been found that the collision energy and the vibrational excitation of the reagent remarkably influence the four generalized polarization-dependent differential cross-sections, the distributions of P(θr), P(ϕr), and P(θr,ϕr). The calculated results show that the rotational angular momentum j′ of the product H2 is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The orientation of j′ depends very sensitively on the collision energy and the vibrational excitation of the reagent.

Influence of collision energy on cross section and stereodynamical properties for the reaction H + OCl → OH + Cl

The quasi-classical trajectory calculations are carried out for the reaction H+OCl→OH+Cl on the singlet ground state potential energy surface. The reaction probability for total angular momentum J=0 and the integral cross section as a function of collision energy are presented. Furthermore, the product rotational alignment <P2(j′·k)> has been obtained, and the value tends to decrease with the increasing of collision energy with fluctuations. To investigate the collision-energy-dependent effects on chemical stereodynamics, the four generalized polarization-dependent differential cross sections (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt) and (2π/σ)(dσ21−/dωt), the distribution P(θr) of the angle between j′–k and the angle distribution P(ϕr) in terms of k–k′–j′ correlation have also been calculated.

Influence of collision energy and reagent rotation on the cross sections and product polarizations of the reaction F+ HCl

Quasiclassical trajectory calculations have been carried out for the F+HCl reaction in three dimensions on a recent DHSN PES of the ground 1(2)A' electronic state [M. P. Deskevich, M. Y. Hayes, K. Takahashi, R. T. Skodje, and D. J. Nesbitt, J. Chem. Phys. 124, 224303 (2006)]. The effects of the collision energy and the reagent initial rotational excitation on the cross sections and product polarization are studied for the v = 0 and j ≤ 10 states of HCl over a wide collision energy range. It has been found that either the collision energy or the HCl rotational excitation increase remarkably reaction cross sections. The QCT-calculated integral cross sections are in good agreement with previous QM results. A detailed study on product polarization for the title reaction is also performed. The calculated results show that the product rotational angular momentum j' is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The orientation of the HF product rotational angular momentum vector j' depends very sensitively on the collision energy and also affected by the reagent rotation. The theoretical findings and especially the roles of the collision energy and initial rotational momentum on the product polarization are discussed and reasonably explained by the HLH mass combination, the property of the PES, as well as the reactive mechanism.

Quasi-classical trajectory studies of the stereodynamics of the reaction O + HCl → ClO + H

The stereodynamics of the O + HCl → ClO + H reaction are investigated by quasi-classical trajectory (QCT) method. The calculations are carried out on the ground 1 1A′ potential energy surface (PES). The orientation and alignments of the product rotational angular momentum for the title reaction are reported. The influence of collision energy on the product vector properties is also studied in the present work. Four (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt), and (2π / σ)(dσ21−/dωt), and have been calculated in the center of mass frame.

Characterization of AMPylation on Threonine, Serine, and Tyrosine Using Mass Spectrometry

Recent studies have suggested that adenosine 5'-monophosphate (AMP) post-translational modification of proteins could represent a novel molecular signaling pathway. Mass spectrometric fragmentation characteristics of this modification have not previously been described and studied systematically. In this work, we therefore examined the fragmentation pattern of chemically synthesized peptides containing AMPylated Thr, Ser, and Tyr. The formation of characteristic ions and the influence of collision energy (CE) on the detection of characteristic ions and their relative peak intensity are reported. When peptide with AMPylated Ser/Thr underwent collision induced dissociation (CID), peaks at m/z 348.1, 136.1, and 250.1, fragments with AMP group attached, and fragments consistent with neutral loss of 347 Da were major characteristic ions; fragments consistent with neutral loss of 135 Da or 249 Da were weaker and not always detectable. The observations for Tyr AMPylation followed the same general patterns as those for Ser/Thr modification, with the exception that the ions detected for Tyr AMPylation did not include either the peak at m/z 348.1, or fragments with a mass shift of -347 Da. The results described in this paper highlight a series of diagnostic ions, which can be used not only to confidently identify the AMPylation site based on MS and MS/MS data, but also to selectively scan AMPylated peptides in complex protein mixtures.

THEORETICAL STUDY OF THE STEREO-DYNAMICS OF THE REACTION O + HCl → ClO + H

Quasi-classical trajectory (QCT) method is used to study the stereo-dynamics of the title reaction on the ground 1 1A′ potential energy surface (PES). Differential cross-sections (DCSs) and alignments of the product rotational angular momentum for the reaction are reported. The influence of collision energy on the product vector properties is also studied in the present work. The distribution of angle between k and j′, P(θr), the distribution of dihedral angle denoting k-k′-j′ correlation, P(ϕr) ⋅ (2π/σ)( d σ00/ d ωt), (2π/σ)( d σ20/ d ωt), (2π/σ)( d σ22+/ d ωt) and (2π/σ)(dσ21-/dωt) have been calculated in the center of mass frame, respectively.

THE STEREODYNAMICS STUDY OF THEC(3P) +OH(X2Π) →CO(X1Σ+) +H(2S) REACTION

The stereodynamics of the title reaction on the ground electronic state X2A' potential energy surface (PES)1has been studied using the quasiclassical trajectory (QCT) method. The commonly used polarization-dependent differential cross-sections (PDDCSs) of the product and the angular momentum alignment distribution, P(θr) and P(Φr), are generated in the center-of-mass frame using QCT method to gain insight of the alignment and orientation of the product molecules. Influence of collision energy on the stereodynamics is shown and discussed. The results reveal that the distribution of P(θr) and P(Φr) is sensitive to collision energy. The PDDCSs exhibit different collision energy dependency relationship at low and high collision energy ranges.

Influence of collision energy on the axial polarization of product molecule for reaction F + HO → HF + O

Quasi-classical trajectory (QCT) calculations are performed for the reaction F + HO(0,0) → HF + O based on the adiabatic potential-energy surface (PES) of the 13A′′ triplet state. The product molecule axial alignment factor &lt;P2 (A · k)&gt; as a function of collision energy, the distribution P(α) of the angle between k and A, the distribution P(β) of the dihedral angle denoting k – k′ – A correlation, and the angular distribution P(α, β) of the product rotational vectors in the form of polar plots have been calculated in the center-of-mass (CM) frame, respectively. The effects of collision energy and PES on the polarization of the product molecule HF axis vectors A are revealed, which provides the theoretical foundation for the relative experiment.

Structural characterization of trace stilbene glycosides in Lysidice brevicalyx Wei using liquid chromatography/diode-array detection/electrospray ionization tandem mass spectrometry

The mass fragmentation patterns of stilbene glycosides isolated from the genus Lysidice were investigated by negative ion electrospray ionization tandem mass spectrometry, and the influence of collision energy on their fragmentation behavior is discussed. It is found that the presence of the Y(0)(-) and B(0)(-) ions in the MS(2) spectra is characteristic for 1-->6 linked diglycosyl stilbenes, while the Y(0)(-), Y(1)(-), and Z(1)(-) ions are representative ions of 1-->2 linked diglycosyl stilbenes. These results indicate that ESI-MS(n) in the negative ion mode can be used to differentiate 1-->6 and 1-->2 linked diglycosyl stilbenes. Based on the fragmentation rules, 9 new trace constituents were identified or tentatively characterized in a fraction of Lysidice brevicalyx by using HPLC/HRMS and HPLC-DAD/ESI-MS(n). The results of the present study can assist in on-line structural identification of analogous constituents and targeted isolation of novel compounds from crude plant extracts.

Influence of collision energy on the N(2D)+O2→O(3P)+NO reaction dynamics: A quasiclassical trajectory study involving four potential energy surfaces

The influence of collision energy (ET) on the dynamics of the N(2D)+O2→O(3P)+NO atmospheric reaction was studied by means of the quasiclassical trajectory method. The four lowest potential energy surfaces (PESs) involved in the process were used in the calculations (2 2A′, 3 2A′, 1 2A″, and 2 2A″ PESs), and the nonadiabatic couplings between them were neglected. The dependence of the scalar and two-vector properties of the reaction with ET was analyzed. Moreover, the different modes of reaction taking place were investigated. Although only one type of microscopic mechanism (abstraction) was found for the 2 2A′, 3 2A′, and 2 2A″ PESs, two different modes of reaction (abstraction and insertion) were observed to coexist for the 1 2A″ PES. For this PES, the abstraction mechanism is the most important one at room temperature, while the insertion mechanism increases its contribution to reactivity with ET (it accounts for about half of the reactivity above 0.5 eV).

Direct dynamics study of N-protonated diglycine surface-induced dissociation. Influence of collision energy

A quantum mechanical and molecular mechanical (QM + MM) direct dynamics classical trajectory simulation is used to study energy transfer and fragmentation in the surface-induced dissociation (SID) of N-protonated diglycine, (gly) 2H +. The peptide ion collides with the hydrogenated diamond {111} surface. The Austin Model 1 (AM1) semiempirical electronic structure theory is used for the (gly) 2H + intramolecular potential and molecular mechanical functions are used for the diamond surface potential and peptide/surface intermolecular potential. The simulations are performed at collision energies E i of 30, 50, 70, and 100 eV and collision angle of 0° (perpendicular to the surface). The percent energy transfer to the peptide ion is nearly independent of E i , while energy transfer to the surface increases with increase in E i . A smaller percent of the energy remains in peptide translation as E i is increased. These trends in energy transfer are consistent with previous trajectory simulations of SID. At each E i the most likely initial pathway leading to fragmentation is rupture of the +H 3NCH 2CONHCH 2COOH bond. Fragmentation occurs by two general mechanisms. One is the traditional Rice-Ramsperger-Kassel-Marcus (RRKM) model in which the peptide ion is activated by its collision with the surface, “bounces off”, and then dissociates after undergoing intramolecular vibrational energy redistribution (IVR). The other mechanism is shattering in which the ion fragments as it collides with the surface. Shattering is the origin of the large increase in number of product channels with increase in E i , i.e., 6 at 30 eV, but 59 at 100 eV. Shattering becomes the dominant dissociation mechanism at high E i .