Calculations of inelastic cross sections for rotational excitation

Cross sections for scattering of N₂ (j=0) molecules on He atoms are calculated for relative energies below the excitation threshold for the N₂ (j=2) rotational state. The close coupling method is used and the coupled differential equations are solved numerically. Very sharp resonances (corresponding to a lifetime of 10^?10 sec) caused by quasistable states of the N₂He system are found in the calculated cross section, when the closed channels corresponding to the N₂ (j=2) states were included in the coupled equations. The position of the resonances is compared with the calculated energy eigenvalues of the corresponding two body potential. Furthermore the equilibrium concentration of the N₂He quasistable and orbiting states is calculated at 80 °K andp _{N 2}=1 Atm. Both concentrations are found to be 1%.     

He-HI碰撞的转动激发分波截面

基于作者所发展的分子间相互作用势,采用密耦方法计算了入射He原子能量分别为40,75和100　meV时与HI分子碰撞的弹性和非弹性分波截面.研究表明：激发分波截面比弹性分波截面收敛得快;激发态越高,激发分波截面收敛得越快;能量越高,激发分波截面收敛得越慢. 关键词： 分波截面 密耦方法 He-HI复合物     

Scaling of inelastic differential cross sections

Scaling (in the average sense) of differential cross sections is generalised to include inelastic (non-diffractive) reactions. The “derivation” uses, as in earlier work, the Ascoli-Arzelà theorem. Data on π^?p→π⁰n, ηn, over large s and t ranges, are seen to scale very well.     

Electron-impact excitation cross sections for neon

An analytic atomic independent particle model adjusted to experimental single-particle energy levels is used to generate wavefunctions for the excited states of neon. Using these wavefunctions in conjunction with the Born approximation and the Russell-Saunders LS-coupling scheme, we calculate generalized oscillator strengths and cross sections for electron-impact excitation of neon from the 2p⁶(¹ S ₀) ground state.     

Electron-exciton inelastic collision cross sections for different semiconductors

The electron-exciton inelastic collision cross sections for the different semiconductors CdS, ZnO, CdSe, Si, Cu₂O, CuCl, CuBr and CuI have been calculated in the Glauber approximation. The transitions 1s–2s, 1s–3s, 1s–2p and 1s–3p have been considered. The calculations are carried out as function of the different available values of $\text{σ =}\text{m}{}^1{}_{\mathrm{e}}\text{m}{}^1{}_{\mathrm{h}}$ where m¹_e and m¹_h are, respectively, the electron a corresponding semiconductors.     

Electron impact excitation cross sections for phosphorus

An analytic atomic independent-particle-model is used to generate wave functions for the valence and excited states of the neutral phosphorus atom. These wave functions are used to calculate generalized oscillator strengths, and from these quantities the cross sections are obtained in Born approximation. Various excitations from the ground state are considered, and results are presented for electron impact energies up to 5 keV. Received: 6 May 1997 / Revised: 21 October 1997 / Accepted: 5 December 1997     

On the energy dependence of inelastic cross sections

The new accurate two-state quantum calculations of the inelastic cross sections in H + Li, Na collisions for energies from the thresholds and till 100 eV or 600 eV are performed, and the results are compared with the Landau-Zener model cross sections in both the diabatic and the adiabatic representations. It is found that the low-energy inelastic cross section is very sensitive to nonadiabatic coupling and, hence, the new NaH coupling is computed. The numerical solutions of the coupled channel equations are checked by independent calculations indicating that the quantum results are accurate. These checks are done by means of the analytic formula for a nonadiabatic transition probability derived within the perturbation approach. Both the Landau-Zener-like and the non-Landau-Zener-like behaviour of the excitation cross sections are found. 34.70.+e Charge transfer     

Electron-impact excitation cross sections of atomic silver

The method of extended crossed beams is used to measure excitation cross sections of atomic silver. The results, together with theoretical data on the transition probabilities of AgI, are used to calculate the excitation cross sections of the energy levels of the silver atom and the contribution of cascade population of states. It is found that the dependence of the cross sections on the principal quantum number of the upper level for five spectral series can be expressed as a power law. Zh. Tekh. Fiz. 69, 6–10 (February 1999)     

Electron-impact excitation cross sections of gallium atom

Excitation of gallium atom in collisions with slow electrons is studied using the method of extended crossing beams with recording of the optical signal of excited atoms. At an electron energy of 30 eV, 66 excitation cross sections are measured. In the electron energy range of 0–200 eV, 24 excitation optical functions are recorded. The dependence of the cross sections on the principal quantum number of an upper level is obtained for eight spectral series of Ga I. The results obtained are compared with the data of the previous experiment.     

转动喇曼散射截面的群论计算

本文利用群链U(4)U(3)O(3)描述双原子分子N_2和O_2振转谱的对称性质,并利用群论方法计算了N_2和O_2分子转动喇曼散射的跃迁矩阵元,给出了它们的转动喇曼散射的截面。结果与实验较好地符合。     

Magnetic sub-state population cross sections in inelastic alpha-nucleus scattering

Properties of the sub-state population cross sections σ_M for inelastic α-nucleus scattering are explored within the deformed collective nuclear model. The interference between the nuclear and Coulomb parts of the inelastic transition potential is calculated with the DWBA. The effect on the M = ?2 sub-state cross section is substantially more pronounced than that for the usual inelastic differential cross section Σ_mσ_m. The effect of re-orientation terms is calculated by means of a coupled channel formalism for small values of the quadrupole deformation parameter β₂. It is found to shift the angular position of the minima of the σ_M relative to the DWBA result, in a way which depends on the sign of β₂. A spin orbit potential has only a small effect on the σ_M. The calculations refer to 15 MeV α-particles incident on a nucleus of the size and charge of Ca.     

Differential cross sections for excitation of atomic hydrogen by protons

Calculations are presented for the differential cross section for the excitation of atomic hydrogen to the (2s + 2p) level by protons at 50, 100 and 150 keV, employing a close-coupling pseudo-state model. Good agreement is obtained with the recently published data.     

Ne原子与HF分子碰撞振转激发分波截面的研究

采用单双取代并加入三重激发项校正的二次组态相互作用QCISD(T)方法, 以及aug-cc-pVTZ基组对Ne-HF分子间相互作用势进行了计算, 并考虑了Boys和Bernardi提出的均衡法, 在计算的基础上消除基组重叠误差. 计算得到了11个方向的Ne-HF碰撞系统的相互作用势能点数据, 使用Huxley势函数对数据点进行非线性最小二乘法拟合, 计算了各向异性势的径向系数V₀, V₁, V₂, V₃等, 其函数形式能够很好地描述Ne原子与HF分子碰撞系统的势能面; 采用密耦近似计算得到了Ne原子与HF分子碰撞系统不同能量下的总截面、 弹性分波截面和非弹性分波截面. 关键词： He-HF 碰撞 相互作用势 密耦近似     

氦同位素原子与钠分子碰撞转动激发积分散射截面的理论计算

多体刚性椭球模型是一种比较精确的描述氦原子与钠分子碰撞的理论模型.本文用多体刚性椭球模型计算了不同能量下He的同位素原子3He,4He,7He,10He与Na2分子碰撞的转动激发积分散射截面,表明增加椭球等势面个数可以得到更准确的转动激发积分散射截面;总结出3He,4He,7He,10He-Na2碰撞体系转动激发积分散射截面随相对入射能量和体系约化质量变化的规律;讨论了相对入射能量为100meV时,相互作用势的不同区域对4He-Na2碰撞体系转动激发积分散射截面的影响情况.     

Electron impact excitation cross sections for N(V)

Generalized oscillator strengths and integrated cross sections from threshold to 1 keV are calculated in the Born approximation for the electron impact excitation of N(V).     

Differential cross sections for elastic and inelastic positron scattering from alkali atoms

We have investigated positron scattering from the alkali atoms lithium, sodium, potassium and rubidium, focusing on the calculation of differential cross sections for elastic scattering and impact excitation. The results obtained with the two-state and five-state close-coupling method as well as the first-order distorted wave Born approximation are compared with each other and with some selected results for electron scattering. Numerical problems due to lack of, or numerically inaccurate, calculation of partial waves with large angular momenta are solved through semi-empirical fitting/extrapolation procedures.