By employing a two-center model, the total and differential cross sections in the photodetachment of ＂a negative molecular ion＂ are studied theoreticedly and obtained for the case of light polarization paredlel to t...By employing a two-center model, the total and differential cross sections in the photodetachment of ＂a negative molecular ion＂ are studied theoreticedly and obtained for the case of light polarization paredlel to the molecular axis. We find that in contrast to the smooth behavior of the total cross section for perpendicular polarized light, the cross section for parallel polarized light shows an interesting oscillatory structure. The oscillations in the toted cross section may provide a method to determine the distance between the two centers. We explain the oscillation in the toted cross section as an interference effect using closed-orbit theory. We also cedculated the detached-electron flux distributions on a screen placed at a large distance from the negative molecular ion. The distributions display multiple-ring-like interference patterns. Such interference patterns are similar to those in the photodetachment microscopy experiments.展开更多
The electron flux distributions in the photodetachment of HF- near an interface are studied using a two-center model and the theoretical imaging method. An analytical expression for electron flux distributions is deri...The electron flux distributions in the photodetachment of HF- near an interface are studied using a two-center model and the theoretical imaging method. An analytical expression for electron flux distributions is derived, which displays oscillations on an observation plane similar to the recent results published by Wang but in the presence of a static electric field. We also discuss the expressions for soft and hard wall cases in detail. A comparison is made with the previous work. The expression is a more general result, and we can deduce from it the electron flux distributions for the photodetachment of H2 near an interface. Finally, we show that the expression reveals similar results as those in [Chin. Phys. B 19 020306 （2010）] when the wall effect is neglected.展开更多
Density functional theory based calculations have been carried out to study structural, electronic, and magnetic properties of Znl-xCoxO （x = 0, 0.25, 0.50, 0.75） in the zinc-blende phase, and the generalized gradie...Density functional theory based calculations have been carried out to study structural, electronic, and magnetic properties of Znl-xCoxO （x = 0, 0.25, 0.50, 0.75） in the zinc-blende phase, and the generalized gradient approximation proposed by Wu and Cohen has been used. Our calculated lattice constants decrease while the bulk moduli increase with the increase of Co2＋ concentration. The calculated spin polarized band structures show the metallic behavior of Co-doped ZnO for both the up and the down spin cases with various doping concentrations. Moreover, the electron population is found to shift from the Zn-O bond to the Co-O bond with the increase of Co2~ concentration. The total magnetic moment~ the interstitial magnetic moment, the valence and the conduction band edge spin splitting energies, and the exchange constants decrease, while the local magnetic moments of Zn, Co, O, the exchange spin splitting energies, and crystal field splitting energies increase with the increase of dopant concentration.展开更多
Theoretical and interpretative study on the subject of photodetachment of H^- near a partially reflecting surface is presented, and the absorption effect of the surface is investigated on the total and differential cr...Theoretical and interpretative study on the subject of photodetachment of H^- near a partially reflecting surface is presented, and the absorption effect of the surface is investigated on the total and differential cross sections using a theoretical imaging method. To understand the absorption effect, a reflection parameter K is introduced as a multiplicative factor to the outgoing detached-electron wave of H^- propagating towards the wall. The reflection parameter measures, how much electron wave would reflect from the surface; K = 0 corresponds to no reflection and K = 1 corresponds to the total reflection.展开更多
基金National Natural Science Foundation of China under Grant No.90403028
文摘By employing a two-center model, the total and differential cross sections in the photodetachment of ＂a negative molecular ion＂ are studied theoreticedly and obtained for the case of light polarization paredlel to the molecular axis. We find that in contrast to the smooth behavior of the total cross section for perpendicular polarized light, the cross section for parallel polarized light shows an interesting oscillatory structure. The oscillations in the toted cross section may provide a method to determine the distance between the two centers. We explain the oscillation in the toted cross section as an interference effect using closed-orbit theory. We also cedculated the detached-electron flux distributions on a screen placed at a large distance from the negative molecular ion. The distributions display multiple-ring-like interference patterns. Such interference patterns are similar to those in the photodetachment microscopy experiments.
文摘The electron flux distributions in the photodetachment of HF- near an interface are studied using a two-center model and the theoretical imaging method. An analytical expression for electron flux distributions is derived, which displays oscillations on an observation plane similar to the recent results published by Wang but in the presence of a static electric field. We also discuss the expressions for soft and hard wall cases in detail. A comparison is made with the previous work. The expression is a more general result, and we can deduce from it the electron flux distributions for the photodetachment of H2 near an interface. Finally, we show that the expression reveals similar results as those in [Chin. Phys. B 19 020306 （2010）] when the wall effect is neglected.
基金Project supported by the Ministry of Higher Education (MOHE) of Malaysia and the Universiti Teknologi Malaysia (UTM)(Grant Nos. Q.J13000.7126.00J33, R.J130000.7726.4D034, and R.J130000.7826.4F113)
文摘Density functional theory based calculations have been carried out to study structural, electronic, and magnetic properties of Znl-xCoxO （x = 0, 0.25, 0.50, 0.75） in the zinc-blende phase, and the generalized gradient approximation proposed by Wu and Cohen has been used. Our calculated lattice constants decrease while the bulk moduli increase with the increase of Co2＋ concentration. The calculated spin polarized band structures show the metallic behavior of Co-doped ZnO for both the up and the down spin cases with various doping concentrations. Moreover, the electron population is found to shift from the Zn-O bond to the Co-O bond with the increase of Co2~ concentration. The total magnetic moment~ the interstitial magnetic moment, the valence and the conduction band edge spin splitting energies, and the exchange constants decrease, while the local magnetic moments of Zn, Co, O, the exchange spin splitting energies, and crystal field splitting energies increase with the increase of dopant concentration.
文摘Theoretical and interpretative study on the subject of photodetachment of H^- near a partially reflecting surface is presented, and the absorption effect of the surface is investigated on the total and differential cross sections using a theoretical imaging method. To understand the absorption effect, a reflection parameter K is introduced as a multiplicative factor to the outgoing detached-electron wave of H^- propagating towards the wall. The reflection parameter measures, how much electron wave would reflect from the surface; K = 0 corresponds to no reflection and K = 1 corresponds to the total reflection.
