A corrective factor (E,ρ)≤1) dependent on ion energy and mass density of material for energy loss has been introduced into Bethe-Bloch formula, so that the energy deposition process of fast ion penetrating through t...A corrective factor (E,ρ)≤1) dependent on ion energy and mass density of material for energy loss has been introduced into Bethe-Bloch formula, so that the energy deposition process of fast ion penetrating through the allotropic solid films are well discussed with the two-component assumption. An analysis expression of electronic stopping power for different phase structures has been derived from the contribution of "valence" and "core" electrons. The two thirds of inelastic scattering arisen from valence electron was revealed by comparing the theoretical calculation and experimental results on both random and oriented lattice site. The corrective factor representative to the role of inner electrons increases with the projectile energy but decreases with mass density of solids.展开更多
A density functional theory （DFT） investigation has been performed in this work on the cage-like boron-rich boron oxide clus-ters Bn（BO）n^2-,CBn-1（BO）n^-,and C2Bn-2（BO）n （n = 5–12） which are boronyl analogu...A density functional theory （DFT） investigation has been performed in this work on the cage-like boron-rich boron oxide clus-ters Bn（BO）n^2-,CBn-1（BO）n^-,and C2Bn-2（BO）n （n = 5–12） which are boronyl analogues of the closo-boranes BnHn2-,monocarbo-ranes CBn-1H-n,and dicarboranes C2Bn-2Hn. These boron oxide clusters possess similar geometrical and electronic structures with the corresponding boranes and carboranes and prove to be three-dimensional （3D） aromatic compounds,consistent with the previously proposed BO/H isolobal analogy. Neutral C2Bn-2（BO）n species possess considerably high ionization potentials in the range 12.0–12.7 eV and CBn-1H-n monoanions have the vertical electron detachment energies in the range 6.6–9.4 eV at the DFT level. BO terminals singly bonded to the skeletal vertexes through a B atom possess the characteristic stretching vi-brational frequencies at about 2000 cm-1,clearly indicating the existence of B-O triple bonds in these clusters. Experimental syntheses and characterizations of these interesting clusters may expand the structural concepts of boron oxides and bring im-portant applications for boron oxide clusters as molecular devices in chemistry and new materials in boron neutron capture therapy.展开更多
This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitatio...This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitation functions were compared with calculation values of the statistical model. A new formula used to estimate the peak cross section of isobaric analogue resonance was tested and it was found that calculation values agree reasonably well with the present data within experimental error, which confirms that the excitation strength of isobaric analogue state in （p,n） reaction not only depends on its spin, but also proportionally increases with the projectile proton spatial transmission Tp and the spectroscopic factor S for reaction （d,p） on the same target.展开更多
文摘A corrective factor (E,ρ)≤1) dependent on ion energy and mass density of material for energy loss has been introduced into Bethe-Bloch formula, so that the energy deposition process of fast ion penetrating through the allotropic solid films are well discussed with the two-component assumption. An analysis expression of electronic stopping power for different phase structures has been derived from the contribution of "valence" and "core" electrons. The two thirds of inelastic scattering arisen from valence electron was revealed by comparing the theoretical calculation and experimental results on both random and oriented lattice site. The corrective factor representative to the role of inner electrons increases with the projectile energy but decreases with mass density of solids.
文摘(n,a)反应截面对于反应堆,特别是对快堆和聚变堆工程设计是一种很重要的数据。在一些近似条件下,基于核反应蒸发和预平衡激子模型理论研究了入射能量小于 20 MeV的(n,a)激发函数。在靶核30≤A≤209 范围内,基于(n,a)反应的截面实验数据对得到的半经验公式的参数进行了研究,得到了参数对靶核的 N 和 Z 以及中子入射能量的依赖关系。利用普适参数预言(n,a)反应的激发函数,预言值在其误差范围内与实验数据一致。
基金supported by the National Natural Science Founda-tion of China (20873117)the Shanxi Natural Science Foundation (2010011012-3)
文摘A density functional theory （DFT） investigation has been performed in this work on the cage-like boron-rich boron oxide clus-ters Bn（BO）n^2-,CBn-1（BO）n^-,and C2Bn-2（BO）n （n = 5–12） which are boronyl analogues of the closo-boranes BnHn2-,monocarbo-ranes CBn-1H-n,and dicarboranes C2Bn-2Hn. These boron oxide clusters possess similar geometrical and electronic structures with the corresponding boranes and carboranes and prove to be three-dimensional （3D） aromatic compounds,consistent with the previously proposed BO/H isolobal analogy. Neutral C2Bn-2（BO）n species possess considerably high ionization potentials in the range 12.0–12.7 eV and CBn-1H-n monoanions have the vertical electron detachment energies in the range 6.6–9.4 eV at the DFT level. BO terminals singly bonded to the skeletal vertexes through a B atom possess the characteristic stretching vi-brational frequencies at about 2000 cm-1,clearly indicating the existence of B-O triple bonds in these clusters. Experimental syntheses and characterizations of these interesting clusters may expand the structural concepts of boron oxides and bring im-portant applications for boron oxide clusters as molecular devices in chemistry and new materials in boron neutron capture therapy.
文摘This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitation functions were compared with calculation values of the statistical model. A new formula used to estimate the peak cross section of isobaric analogue resonance was tested and it was found that calculation values agree reasonably well with the present data within experimental error, which confirms that the excitation strength of isobaric analogue state in （p,n） reaction not only depends on its spin, but also proportionally increases with the projectile proton spatial transmission Tp and the spectroscopic factor S for reaction （d,p） on the same target.
