The influence of electric field on the photodetachment of H^- near a metal surface

The influence of electric field on the photodetachment of H- near a metal surface is investigated based on the closed-orbit theory. It is found that the photodetachment of H- near a metal surface is not only related to the electric field strength but also to the electric field direction. If the electric field is along the ＋z axis, it can strengthen the oscillation in the photodetachment cross section. However, if the electric field is along the -z axis, since the direction of electric field force is opposite to that of static-image force caused by the metal surface, the situation becomes much more complicated. When the electric field is very weak, its influence can be neglected. The photodetachment cross section is nearly the same as that when a single metal surface exists. When the electric field strength is strong enough, the electric field force is able to counteract the metallic attraction, therefore no closed orbit is formed. If the electric field continues to increase until its influence becomes dominant, the photodetachment cross section approaches the case of the photodetachment of H^- in an electric field. Our results may be useful for guiding future experimental studies on the photodetachment of negative ions near surfaces.

Influence of rotational excitation and collision energy on the stereo dynamics of the reaction:N(~4S)+H_2 (v=0,j=0,2,5,10)→NH(X^3Σ^-)+H

The N＋H2 reaction has attracted a great deal of attention from both the experimental and the theoretical community, and most of the attention has been paid to the first excited state N （2 D） atoms in collisions with hydrogen molecules and the scalar properties of the reaction. In this paper, we study the stereo dynamical properties and calculate the reaction cross sections of the N（4S） ＋ H2 （v=0, j=0, 2, 5, 10） → NH（X3∑-） ＋ H using the quasi-classical trajectory （QCT） method on an accurate NH2 potential energy surface （PES） reported by Poveda and Varandas [Poveda L A and Varandas A J C 2005 Phys. Chem. Chem. Phys. 7 28671, in a collision energy range of 25 kcal.mol-1 -140 kcal.mol-1. Results indicate that the reactant rotational excitation and initial collision energy both have a considerable influence on the distributions of the k-j＇ correlation, the k-k＇-j＇ correlation and k-k＇ correlation. The differential cross section is found to be sensitive to collision energy.

Effects of N-doping concentration on the electronic structure and optical properties of N-doped β-Ga_2O_3

The electronic structures and the optical properties of N-doped β-Ga2O3 with different N-doping concentrations are studied using the first-principles method.We find that the N substituting O（1） atom is the most stable structure for the smallest formation energy.After N-doping,the charge density distribution significantly changes,and the acceptor impurity level is introduced above the valence band and intersects with the Fermi level.The impurity absorption edges appear to shift toward longer wavelengths with an increase in N-doping concentration.The complex refractive index shows metallic characteristics in the N-doped β-Ga2O3.

Ab initio investigations of the charge transport properties of endohedral M@C_(20)(M=Na and K)metallofullerenes

Using density functional theory and quantum transport calculations based on nonequilibum Green＇s function formalism, we investigate the charge transport properties of endohedral M@C20（M = Na and K） metallofullerenes. Our results show that the conductance of C20 fullerene can be obviously improved by insertion of alkali atom at its centre. Both linear and nonlinear sections are found on the Ⅰ-Ⅴ curves of the Au-M@C20-Au two-probe systems. The novel negative differential resistance behaviour is also observed in Na@C20 molecule but not in K@C20.

Photodetachment of negative ion in a gradient electric field near a metal surface

Based on closed-orbit theory, the photodetachment of H- in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H- near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps.

Adsorption-controlled transition of the electrical properties realized in Hematite(alpha-Fe_2O_3) nanorods ethanol sensing

Alpha-Fe203 nanorods are synthesized through a hydrotherrnal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods. The device can respond to ethanol vapour in a concentration range from 1 to 1500 parts per million and shows both p-type and n-type responding characteristics during the investigation of the ethanol sensing. The sensor displays a p-type characteristic when the ethanol concentration is low and converted into an n-type characteristic as the concentration exceeds a certain value. Such a phenomenon is attributed to the chemisorbed oxygen, which leads to different modifications of the energy band at the surface, namely, depletion layer or inversion layer.

Effect of Carried-Envelope Phase on Transient Process in a Cascade-Type System

这份报纸调查带信封的阶段的效果在上短暂在一种串联类型处理原子系统，它被二超短波的激光脉搏(探查和信号激光) 驾驶。这被发现一个光子和相应于小径 | 的二光子的过程 0 >| 1 > 并且 | 0 >| 1 >| 2 > 能被 modulating 提高或压制探查的带信封的阶段激光脉搏。我们的数字结果也证明二个激动的状态的短暂人口能被探查激光脉搏的带信封的阶段周期性地影响。与某些时间，在二个退出的状态之间的部分人口转移能就被调整探查激光脉搏的带信封的阶段认识到。

Geometrical,energetic and electronic properties of Au_n-(C_3H_6O)_m complexes(n = 3,5,m≤n):A density functional theory study

The interactions of acetone molecules with clusters of Au3 and Au5 are investigated by using a density functional theory （DFT） within a generalized gradient approximation （GGA）. The geometries, adsorption energies and deformation electron density distributions are used to analyse these interactions. The present calculations show that more than one acetone molecules can be adsorbed onto small gold clusters, and this adsorption is different from that of single molecule absorption. The coordination number of the adsorption site on the gold cluster is the dominant factor responsible for the strength of the interactions. The effects of the Au O bond lengths in the complexes on adsorption energies between Au clusters and acetone molecules are also examined.

Theoretical Study of the Influence of Femtosecond Laser Wavelength on the Evolution of a Double-Minimum Electronic Excited State Wave Packet for NaRb

Employing the two-state model and the time-dependent wave packet method, the influence of femtosecond laser wavelength on the evolution of the double-minimum electronic excited state wave packet is numerically investigated. For different laser wavelengths, evolutions of the double-minimum electronic excited state wave packet with time and internuclear distance are different. One can control the evolution of the wave packet by varying the laser wavelength appropriately, which will benefit the light manipulation of atomic and molecular processes. Furthermore, study of the dynamics of the NaRb molecule may yield clues to creating an ultracold molecule.

The polarization dependent differential cross sections of the reactions:H+LiH^+(v=0,j=0)→H_2+Li^+ and H^++ LiH(v=0,j=0)→H_2^++Li

Quasi-classical trajectory(QCT) calculations have been carried out to study the generalized polarization dependent differentialcross sections(PDDCSs) for the reactions H + LiH^+(v = 0,j = 0)→H_2 + Li^+ and H^+ + LiH(v = 0,j = 0)→H_2^+ + Li occurring onthe two lowest-lying electronic states of the LiH_2^+ system,using the ab initio potential energy surfaces(PESs) of Martinazzo et al.[3].Four PDDCSs,i.e.,(2π/σ)(dσ_(00)/dω_t),(2π/σ)(dσ_(20)/dω_t),(2π/σ)(dσ_(22+)/dω_t),(2π/σ)(dσ_(21-)/dω_t) have been discussed ...

Stereodynamics of the reactions Ne+H_2^+/Ne+D_2^+/Ne+T_2

The vector correlations between products and reagents for the reactions Ne＋H2＋, Ne＋D2＋, and Ne＋T2＋ are calculated by means of the quasi-classical trajectory method on a new potential energy surface constructed by Lfi et al, [J. Chem. Phys. 2010 132, 014303]. The polarization-dependent differential cross-sections （27π/σ）（dσ00/dωt）, （2π/σ）（dσ20/dwt）, （27π/σ）（dσ22＋/dwt）, and （2π/σ）（dσ21-/dwt）, and the distributions of P（θr）, P（φ）, and P（θr, Cr） are calculated. The isotopic effect, which is associated with the difference in mass factor among the three reactions, is revealed.

Theoretical study on the complexes of He,Ne and Ar

This paper investigates the effect of basis sets through the potential energy curves （PECs） of six rare gas complexes He2, Ne2, Ar2, HeiNe, He-Ar, and Ne-Ar. The coupled cluster singles and doubles method with perturbative treatment of triple excitations, doubly augmented basis sets of d-aug-cc-pVQZ, bond functions, and basis set superposition errors are employed. The diffuse function is more effective than the polarization function on describing the dissociation energy. The PECs are fitted into analytical potential energy functions （APEFs） using three expressions. It is found that all the expressions are suitable for describing the complexes of rare gases. Based on these APEFs, the spectroscopic parameters are calculated and the results are compared with the theoretical and experimental data available in the literature.

The influence of interface modifier on photodetachment of negative ions in an electric field near a metal surface

Based on closed-orbit theory, the influence of an interface modifier on the photodetachment of H^- in an electric field near a metal surface is studied. It is demonstrated that the interface strengthens the oscillations in the photodetachment cross section. However, when the electric field environments are different, the strengthening oscillations are caused by different sources. When the electric field direction is upward, the interface enhances the oscillations by shortening the period and the action of the closed orbit. When the electric field direction is downward, the interface strengthens the oscillations either by extending the coherent energy range or by increasing the total number of the closed orbits. We hope that our results will be conducive to the understanding of the photodetachment process of negative ions near interfaces, cavities and ion traps.

Theoretical Study of the Stereodynamics of the Reaction C(^(3)P)+CH(X^(2)Π) and Its Isotopic Variants

Vector correlations between products and reagents of the reaction C+CH and the isotopic variant reactions are calculated by employing the quasi-classical trajectory method based on the adiabatically 1^(2)A" double−many-body-expansion potential-energy surface computed and numerically fitted by Boggio-Pasqua et al.The normalized polarization-dependent differential cross-sections and the distributions of P(θr),P(φr)and P(θr,φr)at the selected collision energy are discussed in detail.The values of the product rotational alignment parameter{P_(2)(j'⋅k)}are also calculated and plotted as functions of the collision energy in the range 0.005–0.5 eV.The computed results show that the rotational polarizations of the product present pronounced different characters as the mass substituted atom increasing.

Tight focus of a radially polarized and amplitudemodulated annular multi-Gaussian beam

The focusing of a radially polarized beam without annular apodization ora phase filter at the entrance pupil of the objective results in a wide focus and low purity of the longitudinally polarized component. However, the presence of a physical annular apodization or phase filter makes some applications more difficult or even impossible. We propose a radially polarized and amplitude-modulated annular multi-Gaussian beam mode. Numerical simulation shows that it can be focused into a sharper focal spot of 0.125λ2 without additional apodizations or filters. The beam quality describing the purity of longitudinally polarized component is up to 86%.

Deterministic generation of Greenberger-Horne-Zeilinger and W states for three distant atoms via adiabatic passage

We propose two schemes for generating Greenberger-Horne-Zeilinger and W states of three distant atoms. In the present schemes, the atoms are individually trapped in three spatially separated optical cavities coupled by two optical fibres. Performing an adiabatic passage along dark states, the population of cavities and fibres excited is negligible under certain conditions. In addition, the spontaneous decay of atoms is also efficiently suppressed based on our proposals. Furthermore, the discussion about the entanglement fidelity is given and we point out that our schemes work robustly with small fluctuations of experimental parameters.

Total cross sections for electron scattering from fluoromethanes:A revised additivity rule method

The additivity rule for electron-molecule scattering is revised by considering the difference between the free atom and the bound atom in the molecule. The total cross sections for electron scattering from fluoromethanes （CF4, CF3H, CF2H2, and CFH3） are calculated in an energy range from 100 eV to 1500 eV by the revised additivity rule. The present calculations are compared with the original additivity rule results and the available experimental data. Better agreement with each other is obtained.

First-principles study on electronic structure and optical properties of N-doped P-type β-Ga_2O_3

The band structure, density of states, electron density difference and optical properties of intrinsic β-Ga2O3 and N-doped β-Ga2O3 were calculated using first-principles based on density functional theory. After N doping, the band gap decreases, shallow acceptor impurity levels are introduced over the top of the valence band and the absorption band edge is slightly red-shifted compared to that of the intrinsic one. The anisotropic optical properties are investigated by means of the complex dielectric function, which are explained by the selection rule of the band-to-band transitions. All calculation results indicate that N-doping is a very promising method to get P-type β-Ga2O3.

Electronic structure and optical properties of N-Zn co-doped-Ga_2O_3

The electronic structure and optical properties of N-doped-Ga2O3 and N-Zn co-doped-Ga2O3 are investigated by the first-principles calculation.In the N-Zn co-doped-Ga2O3 system,the lattice parameters of a,b,c,V decrease and the total energy E total increases in comparison with N-doped-Ga2O3.The calculated ionization energy of N-Zn co-doped-Ga2O3 is smaller than that of N-doped-Ga2O3.Two shallower acceptor impurity levels are introduced in N-Zn co-doped-Ga 2O3.Compared with N-doped-Ga2O3,the major absorption peak is red-shifted and the impurity absorption edge is blue-shifted for N-Zn co-doped-Ga2O3.The results show that the N-Zn co-doped-Ga2O3 is found to be a better method to push p-type conductivity in-Ga 2O3.

Electrical and optical properties of deep ultraviolet transparent conductive Ga_2O_3/ITO films by magnetron sputtering

Ga2O3/ITO films were prepared by magnetron sputtering on quartz glass substrates. The transmittance and sheet resistance of ITO films and Ga2O3/ITO films were measured by using a double beam spectrophotometer and four point probes. The effect of the ITO layer and Ga2O3 layer thickness on the electrical and optical properties of Ga2O3/ITO hi-layer films were investigated in detail. Ga2O3 （50 nm）/ITO （23 nm） films exhibited a low sheet resistance of 323 Ω/□ and high deep ultraviolet transmittance of 77.6% at a wavelength of 280 nm. The ITO layer controls the ultraviolet transmittance and sheet resistance of Ga2O3/ITO films. The Ga2O3 layer thickness has a marked effect on the transmission spectral shape of Ga2O3/ITO films in the violet spectral region.