共查询到20条相似文献,搜索用时 93 毫秒
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采用全相对论扭曲波方法,系统地计算了类铍N3+和 O4+离子从基态到2s2p和2p2 的各激发态以及从亚稳态到2p2各激发态的电子碰撞激发截面,详细地讨论了靶态的关联效应对激发截面的影响.结果表明:对于2s-2p的单电子激发,在低能碰撞时,靶态的电子关联效应起非常重要的作用,且使得激发截面降低;而高能碰撞时,靶态波函数的描述对连续态波函数的影响比较小,对激发截面影响也比较小.对于2s2-2p2的双电子激发,其中基态2s21S0到J=0的2p23P0,1S0的激发截面较大,其主要原因是末离子态波函数与基组态波函数的混合,但是其他几个激发的激发截面较小.
关键词:
全相对论扭曲波方法
电子碰撞激发
电子关联效应 相似文献
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实验测量了1.7v0—4.2v0(v0为玻尔速度,v0=2.19×108cm/s)的C3+与He,Ne,Ar原子碰撞过程中单电子转移绝对截面.将实验结果与多体经典轨道蒙特卡罗模拟计算结果做了比较,发现测量结果与多体经典轨道蒙特卡罗模拟计算结果在趋势上相符.当入射离子速度在1.7v0—2
关键词:
离子-原子碰撞
单电子转移
绝对截面 相似文献
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利用新近发展的基于全相对论扭曲波方法研究电子-离子碰撞激发过程的计算程序,通过对Breit相互作用的考虑,计算了类氦等电子序列离子从亚稳态1s2s3S1激发2s电子到n=2,3壳层的电子碰撞激发截面;研究了不同入射电子能量时Breit相互作用对碰撞激发截面的影响,进一步总结了沿等电子序列变化时,Breit相互作用对截面影响的一般规律.部分计算结果与实验结果进行了比较,得到了很好的一致性.
关键词:
全相对论扭曲波方法
Breit相互作用
电子碰撞激发截面 相似文献
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用电子冷却储存环提供的C6+脉冲高能离子束轰击Au靶, 测量到Au的Lα和Lβ X射线辐射谱, 分析结果表明, 在高能离子束的轰击下, Au原子的Lα的X射线产生截面大于Lβ的, 两个X射线产生截面随炮弹的动能增加而增加. 本文分别用PWBA理论和ECPSSR理论计算了此实验条件下的X射线产生截面, 结果比实验获得的结果大, 初步分析了其中的原因.
关键词:
脉冲离子束
截面
X射线
内壳层 相似文献
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本文采用全相对论扭曲波方法计算了Cd+离子5s2S1/2 → 5p2P3/2电子碰撞激发总截面、磁能级的激发截面以及退激辐射光子极化度. 详细讨论了电子关联效应对激发截面以及退激辐射光子极化度的影响. 我们发现, 在低能碰撞部分(<10 eV), Core-价关联对电子碰撞激发截面的贡献非常重要, 与不考虑Core-价关联的结果相比, Core-价关联的计算结果使得激发截面降低了1/2到2/3; 在高能碰撞部分(>80 eV), Core-价关联的贡献不是非常明显, 但与不考虑Core-价关联的结果相比, 其激发截面也降低了15%. 然而, 对于退激辐射光子极化度, Core-价关联的贡献非常小, 其影响是可以忽略的. 相似文献
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The total cross section for photoproduction of hadrons on the deutron, σTd, has been measured for photon energies in the range 0.265–40215 GeV. From this, using results for the photon total cross section, obtained previously with the same apparatus, the neutron total cross section has been determined in the resonance region. The resonant structure is found to be quite different from that for the proton. Thereafter the neutron cross section falls off steadily with energy, and the values obtained are consistently lower than those for the proton. Forward scattering amplitudes have been evaluated for the deuteron. 相似文献
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A fitting formula based on the Born approximation is used to fit the total cross sections for electron scattering by diatomic molecules (CO, N2, NO, O2 and HCl) in the intermediate- and high-energy range. By analyzing the fitted parameters and the total cross sections, we found that the internuclear distance of the constituent atoms plays an important role in the e-diatomic molecule collision process. Thus a new semi-empirical formula has been obtained. There is no free parameter in the formula, and the dependence of the total cross sections on the internuclear distance has been reflected clearly. The total cross sections for electron scattering by CO, N2, NO, O2 and HCl have been calculated over an incident energy range of 10–4000 eV. The results agree well with other available experimental and calculation data. 相似文献
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The modified Jain–Khare semi-empirical formalism for the evaluation of differential and integral electron impact ionization cross sections for molecules has been extended to the evaluation of cross sections for the electron ionization of CO2 clusters: (CO2)240 and (CO2)1700. The energy dependent differential cross sections are evaluated at the incident electron energies of 50, 100 and 200 eV. The integral total ionization cross sections have been calculated in the energy range varying from ionization thresholds to 1000 eV which revealed a good agreement with the available experimental and the theoretical data. The ionization rate coefficients have also been evaluated using the presently calculated ionization cross sections and Maxwell–Boltzmann energy distributions. 相似文献
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Chetan Limbachiya Minaxi Vinodkumar Mohit Swadia K.N. Joshipura Nigel Mason 《Molecular physics》2013,111(1):55-62
We report total inelastic, total ionisation and summed total excitation cross sections for electron scattering on furan, tetrahydrofuran (THF) and 2,5-dimethylfuran at energies between the ionisation threshold and 5 keV. We have employed the spherical complex optical potential formalism (SCOP) to calculate the total inelastic cross sections (Qinel) and have used complex scattering potential-ionisation contribution (CSP-ic) method to derive total ionisation cross sections (Qion) and summed total excitation cross sections (∑Qexc) from the calculated Qinel. We have also computed Qion for these molecules using binary-encounter-Bethe (BEB) approach. We have compared our total cross sections (TCS) with available experimental as well as previous theoretical results and have found good agreement. The results are presented graphically as well as numerically. 相似文献
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B. Blank S. Andriamonje R. Del Moral J. P. Dufour A. Fleury T. Josso M. S. Pravikoff S. Czajkowski Z. Janas A. Piechaczek E. Roeckl K. -H. Schmidt K. Sümmerer W. Trinder M. Weber T. Brohm H. -G. Clerc A. Grewe E. Hanelt A. Heinz A. Junghans C. Röhl S. Steinhäuser B. Voss M. Pfützner 《Zeitschrift für Physik A Hadrons and Nuclei》1995,352(1):69-75
At the projectile-fragment separator FRS of GSI, relativistic secondary beams of about 520 MeV/nucleon were produced by fragmentation of a primary beam of58Ni at 650 MeV/nucleon in a beryllium target. By means of aΔE—Bρ—TOF measurement, the fragments have been identified and their charge-changing probabilities in targets of CH2, C, Al, and Pb have been determined. We describe the results for the total charge-changing cross sections in this first paper, whereas a second article deals with the partial charge-changing cross sections. At the drip line, the measured charge-changing cross sections exhaust close to 100% of the total interaction cross sections as calculated with semiempirical models. The measurements at the proton drip line with low-Z targets indicate that only a very small increase of the cross sections may be observed, whereas the measurements with a lead target show that no significant increase of the total charge-changing cross sections is present which would be a hint for low-lying dipole strength. Our experimental data are compared to Glauber-type calculations. 相似文献
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The total cross sections for positron impact on hydrocarbons have been calculated using the additivity rule in which the total
cross section for a molecule is the sum of the total cross section for the constituent atoms. The energy range considered
is from a few eV to several thousand eV. The total cross sections for positron impact on an atom are calculated by employing
a complex spherical potential which comprises of a static, polarization and an absorption potential. We have good agreement
with the experimental results for hydrocarbons for positron energy ⩾100 eV. Our results also agree with the available calculations
for CH4 and C2H2 which employed full molecular wavefunctions beyond 100 eV. Our absorption cross sections also agree with molecular wave-function
calculations for C2H2 and CH4 beyond 100 eV. We have shown the Bethe plots fore
+−C ande
+−H scattering systems and Bethe parameters have been extracted. We have fitted the cross section for positron impact on hydrocarbons
in the formσ
t(C
n
H
m
)=naE
−
b+mcE
−
d in the energy range 300–5000 eV wherea=195.0543,b=0.7986,c=371.1757 andd=1.1379 withE in eV andσ
t in 10−16 cm2. 相似文献
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The total fast neutron cross section of27Al has been determined by transmission measurements using Si(Li)-solid state detectors for neutron spectroscopy. The energies of the bombarding neutrons have been in the range betweenE n=5,24 andE n=7,26 MeV. A comparision has been made between the total cross sections obtained in this experiment and values obtained via the time-of-flight technique. At most neutron energies the agreement was within experimental errors quoted for the works being compared. 相似文献
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S. Graubmann U. Berghaus H. Brückmann P. Lara H.G. Körber H.P. Meyer-Rassow K. Sinram K. Wick 《Nuclear Physics A》1979,325(1):72-82
Alpha-particle spectra resulting from the bombardment of douterons with α-particles have been measured at energies of 20.4, 24.2 and 28.1 MeV for all kinematically possible scattering angles θ1ab > 5°. Angular distributions for the break-up cross section have been obtained by integration over the α-particle energy. The total reaction cross section is computed by extrapolating the angular distributions to 0°. The results are compared with predictions calculated from α-d phase shifts and Faddeev theory. 相似文献
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We report calculated total elastic cross sections Qel, total ionisation cross sections, Qion, summed total excitation cross sections ∑Qexc and total cross sections QT for CH3SH upon electron impact for energies from ionisation threshold to 5 keV. We have employed Spherical Complex Optical Potential (SCOP) formalism to calculate total elastic cross section Qel, and total inelastic cross section Qinel and used Complex Scattering Potential – the ionisation contribution (CSP-ic) method to extract the ionisation cross sections, Qion, from the calculated Qinel. The calculated total cross sections are examined as functions of incident electron energy and are compared with available data wherever possible and overall good agreement is observed. In this work Qel, Qion, and ∑Qexc are reported for the first time for CH3SH in this energy range. 相似文献
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M. Vinodkumar K. Korot P. C. Vinodkumar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,59(3):379-387
In this article, we report calculations of total
ionization cross sections, Q
ion
, for simple atoms (C, N, O, F) and
molecules (NO and NH3)_{3}) of atmospheric interest on electron impact at
energies from threshold to 2000 eV. We have employed the complex scattering
potential – ionization contribution (CSP-ic) method for the present study.
Attempt has been made to improve the method by computing the parameter that
involves the ratio of sum of the total excitation cross sections
(Σ
Q
exc
) and total inelastic cross section (Q
inel
) at the peak of the
inelastic cross section. The present study not only provided a better
estimation of the parameter involved in the CSP-ic method but also provided
better agreement with the available experimental and theoretical data on the
ionization cross sections of the simple atomic and molecular targets studied
here. 相似文献