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1.
铜原子能级结构的理论计算具有非常大的挑战性。本文基于多组态Dirac-Hartree-Fock(MCDHF)方法和相对论组态相互作用(RCI)方法,通过三个大规模的关联模型计算了单激发态3d104p 2P1/2、双激发态3d94s(3D)5s4D3/2,1/2,3d94s(3D)5s 2D3/2,3d94s(1D)5s 2D3/2以及离子态3d10 1S0能级和波函数。结果表明,铜原子能级结构对有限组态空间的选择极其敏感,双激发态3d94s(3D)5s 4D3/2,1/2,3d94s(3D)5s 2D3/2,3d94s(1D)5s 2D3/2和离子态3d10 1S0与单激发态之间的能量差相对于已有实验结果均存在大约-0.4 eV的偏差,而计算得到的共振电子能量与实验结果符合得较好。此外,根据辐射跃迁矩阵元和非辐射跃迁矩阵元计算了双激发态的Fano参数q,并基于Fano理论得到了铜单激发态3d104p 2P1/2的总光电离截面,该理论考虑了直接光电离与光激发自电离之间的干涉效应,即共振3d94s(3D)5s 4D3/2,1/2、3d94s(3D)5s 2D3/2和3d94s(1D)5s 2D3/2具有明显的非对称的Fano轮廓,表明光电离过程与光激发自电离过程之间的干涉对双激发态共振附近的光电离截面轮廓有着极其重要的影响。 相似文献
2.
The photoionization cross-section of Be2+ has been measured in the range from threshold at 154 eV up to 420 eV. The value at threshold of [1.4 ± 0.2] × 10?18 cm2 is in good agreement with theoretical predictions. The method used was that of absorption using two laser produced plasmas. The doubly excited resonance 2s2p 1p0 at 281.25 ± 0.07 eV has been observed and its Fano profile measured. 相似文献
3.
S.-U. Haq S. Mahmood M. A. Kalyar M. Rafiq R. Ali M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):439-447
We present experimentally measured absolute values of the photoionization
cross sections from the 5s5p 1P1 and 5s5p 3P1 excited
states of strontium at the first ionization threshold as 11.4±1.8 Mb
and 10.7±1.7 Mb respectively using saturated absorption technique
along with a thermionic diode ion detector in conjunction with a Nd:YAG
pumped dye laser system. These threshold photoionization cross sections
values have been utilized to determine the oscillator strengths of the
5s5p 1P1↦5snd 1D2 and 5s5p 3P1↦5snd 3D2 Rydberg transitions. The oscillator strength densities in the
continuum corresponding to the 5s5p 3P1 excited state have also
been determined by measuring the photoionization cross sections at five
ionizing wavelengths above the first ionization threshold. Smooth merging of
the discrete f-values into the oscillator strength densities has been
observed for the 5s5p 3P1↦5snd 3D2 series across the
ionization threshold. 相似文献
4.
Separation of lithium isotopes has been achieved using two-step laser photoionization in conjunction with an atomic beam and
in-house built time of flight (TOF) mass spectrometer. We present an efficient pathway for the enrichment of Li6 isotope by tuning the exciter laser to the 3p 2
P
1/2, 3/2 excited state of Li6. A concentration of up to 60% is demonstrated from a natural isotopic abundant lithium sample. In addition, the first measurement
of the absolute photoionization cross-section of the 3p excited state of Li6 and Li7 are reported as 26.8±4 Mb and 25.5±3.8 Mb, respectively.
PACS 32.10.Bi; 32.80.t; 32.80.Fb 相似文献
5.
6.
N. Amin S. Mahmood M. Saleem M. A. Kalyar M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):331-337
The photoionization cross-sections from the 2p2P1/2, 3/2, 3d2D3/2, 5/2 and 3s2S1/2 excited states of lithium have
been measured at different ionizing laser wavelengths, above the first
ionization threshold. The experiments are performed by using a thermionic
diode working in the space charge limited mode and the cross-sections are
measured by employing the saturation technique. By changing the ionization
photon energy, a smooth frequency dependence of the cross-sections has been
observed for the 2p and 3d states. The cross-section from the 3s excited
state has been measured at a single photon energy. The measured values of
the photoionization cross are compared with the available data. 相似文献
7.
Satyabrata Sahoo Y.K. Ho 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(1):52-62
We present theoretical photoionization cross sections for He 1s2s 1S and He 1s2p 1P states in a Debye plasma environment by the complex coordinate rotation method, using a finite L2 basis set constructed from one electron Laguerre orbitals. The plasma environment is found to appreciably influence the photoionization cross sections near the ionization threshold. In this regard, the photoionization cross sections of isolated He are compared with other theoretical and experimental results. Our results are in good agreement with the previous results. A new minimum appears in the photoionization cross section curve for the metastable 1s2s 1S state. Results are given for the S- and D-wave partial photoionization for the excited 1s2p 1P state. 相似文献
8.
N. Amin S. Mahmood M. Anwar-ul-Haq M. Riaz M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(1):23-28
The photoionization cross-section and number density of the 3p 2P1/2,3/2 excited levels of sodium have been measured as a function of the laser energy using two-step laser excitation in conjunction
with a thermionic diode working in the space charge limited mode. Employing
the saturation technique, the cross-sections for the 3p 2P1/2 and
3p 2P3/2 levels are determined as 2.16 (43) Mb and 3.74 (74) Mb respectively. 相似文献
9.
Nasir Amin S. Mahmood S.U. Haq M. Rafiq 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(5):863-872
New measurements of the photoionization cross sections from the 4p 2P1/2,3/2, 5d 2D5/2,3/2 and 7s 2S1/2 excited states of potassium are presented. The cross sections have been measured by two-step excitation and ionization using a Nd:YAG laser in conjunction with a thermionic diode ion detector. By applying the saturation technique, the absolute values of the cross sections from the 4p 2P3/2 and 4p 2P1/2 states at 355 nm are determined as 7.2±1.1 and 5.6±0.8 Mb, respectively. The photoionization cross section from the 5d 2D5/2,3/2 excited state has been measured using two excitation paths, two-step excitation and two-photon excitation from the ground state. The measured values of the cross sections from the 5d 2D5/2 state by two-photon excitation from the ground state is 28.9±4.3 Mb, whereas in the two-step excitation, the cross section from the 5d 2D3/2 state via the 4p 2P1/2 state and from the 5d 2D5/2,3/2 states via the 4p 2P3/2 state are determined as 25.1±3.8 and 30.2±4.5 Mb, respectively. Besides, we have measured the photoionization cross sections from the 7s 2S1/2 excited state using the two-photon excitation from the ground state as 0.61±0.09 Mb. 相似文献
10.
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
11.
Using the configuration interaction Pauli-Fock including core polarization (CIPFCP)
approach we have calculated absolute total and partial cross sections for photoionization
of excited
mp
5(m + 1)p J = 0−3
levels in Ar, Kr and Xe (m = 3−5) near threshold. Particular emphasis is
paid to the lineshapes of the odd mp
1/25
n(s/d)′
autoionizing
resonances and their variation with the character of the intermediate excited
J = 0−3 state. For selected intermediate levels of Ar and Kr the
computed cross sections are compared with laser spectroscopic measurements; good agreement
between the theoretical and experimental lineshapes and branching ratios for different
resonances is observed. 相似文献
12.
Anne-Lise Roche K. Kirby S.L. Guberman A. Dalgarno 《Journal of Electron Spectroscopy and Related Phenomena》1981,22(3):223-235
Calculations are carried out, at similar levels of approximation, of the photoionization cross-sections for the ground X3Σg? and metastable a1Δg states of O2 leading to the X2Πg state of O2+. Estimates, based upon measurements for the X3Σg? state, are made of the photoionization cross-section of the a1Δg state for transitions populating excited states of O2+. 相似文献
13.
The two photon coincidence technique yields an absolute measurement of a cascade decay rate without knowing the detection efficiency of each detector. This method is applied to calcium atoms in an atomic beam excited to the 4p21S0 state, and decaying via the resonant 1P1 state; it yields the excitation rate of the upper 4p21S0 level. Since the excitation process (two photon absorption) is controlled, one can compute the excitation rate of the upper level as a function of the transition probabilities in the cascade. The lower transition is well known and we can therefore deduce the transition probability for the 4p21S0 -4s4p 1P1, transition which previously had not been accurately determined. The preliminary measurements yield a line strength s = 0.98 ± 0.3 au in good agreement with a recent measurement of the lifetime of the 4p21S0 state. 相似文献
14.
C. Gerth B. Kanngießer M. Martins P. Sladeczek K. Tiedtke P. Zimmermann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(1):65-69
The resonances of atomic Lu have been investigated by photoelectron and photoion spectroscopy using monochromatized synchrotron
radiation in the vacuum ultraviolet energy region. The total photoion yield has been compared to calculations in which the
extended Fano theory (Mies formalism) and the Hartree-Fock method were applied. The resonance structure is dominated by the
spin-orbit splitting of the 5p core hole. In the photoion yield spectra of singly and doubly charged ions a high fraction of Lu2+ ions has been found in the region of the 5p
-1
(2
P
1/2
)nd resonances. Photoelectron spectra, recorded in this resonance region, have been investigated with respect to deexcitation
channels connected with Lu2+ ions. The 5p
-1
(2
P
1/2
)nd resonances predominantly autoionize by spin-flip into states, which decay in the second step into Lu2+ final ionic states.
Received: 2 September 1998 / Accepted: 17 September 1998 相似文献
15.
P.A. Grimm T.A. Whitley P.R. Keller J.W. Taylor 《Journal of Electron Spectroscopy and Related Phenomena》1984,33(4):361-367
Relative partial cross-sections for photoionization to the X2E ground state of the methylacetylene ion over the photon energy range 11–26 e V have been determined using synchrotron radiation. The observed cross-sections show a broad resonance feature similar to the results for photoionization to the X2IIu ground state of the acetylene ion. An explanation involving autoionization from a π* (e) excited state is proposed. 相似文献
16.
A. K.S. Jha P. Jha S. Tyagi M. Mohan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):391-398
We present relativistic close-coupling photoionization calculations of Al IV
using the Breit-Pauli R-matrix method to obtain photoionization cross-section of Al IV from the ground state and the lowest
two J=0 (even) excited
states. A multi-configuration eigenfunctions expansion of the core Al V is
employed with spectroscopic configurations 2s22p5,
2s2p6,
2s22p43s, 2s22p43p, 2s22p43d and
2s22p44s. We have included, for the first time, the lowest 68
level target states of Al V in the photoionization calculations of Al IV.
Extensive configuration interaction wavefunctions are used to describe both
the initial Al IV states and the final Al V states. Cross-sections are
compared from three level calculations including only 2s2 2p5 2Po
3/2, 1/2 and 2s 2p6
2S1/2 levels of Al
V. The present calculation using the lowest 68 target levels of Al V are
presented for the first time and should provide reasonably complete database
for practical application for photoionization cross-section for Al IV, where
high-energy cross-sections along with near-threshold photoionization cross-section is required. 相似文献
17.
We have investigated the doubly excited 1,3
P
e resonance states of positronium negative ion with Coulomb and screened Coulomb potentials using highly accurate correlated
exponential wavefunctions. For Coulomb interaction, the stabilization and the complex-rotation methods are employed to extract
resonance parameters (resonance positions and widths). We have obtained two 1
P
e resonances and three 3
P
e resonances below the n = 3 Ps threshold. In addition to Feshbach resonances lying below n = 3 Ps threshold, we have calculated one 3
P
e shape resonances lying above the Ps (n = 2) threshold. For screened Coulomb (Yukawa) interaction, we employ the stabilization method to extract resonance parameters
as functions screening parameter. The resonance energies and widths for 1,3
P
e resonance states of Ps− below the n = 3 Ps threshold for different screening parameters ranging from infinity (Coulomb case) to small values are reported, along
with the Ps(3S) and Ps(3P) threshold energies. The screened Coulomb results for the 1,3
P
e resonance states are reported for the first time in the literature. 相似文献
18.
S.U. Haq Ali Nadeem M. Nawaz 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(16):2058-2065
The absolute photoionization cross sections from the 6p 2P1/2 excited state of cesium at threshold and above the threshold region have been measured using the saturation absorption technique. The photoionization cross section at the ionization threshold is determined as 22.6±3.6 Mb, whereas in the region above threshold its value ranges from 22 to 20 Mb for photoelectron energies up to 0.1 eV. A comparison of the photoionization cross sections with earlier reported theoretical and experimental data have been presented and are in good agreement within the uncertainty. In addition, the oscillator strengths of the 6p 2P1/2→n d 2D3/2 (21≤n≤60) Rydberg transitions of cesium have been calibrated using the threshold value of the photoionization cross section. A complete picture of the oscillator strengths from the present work and previously reported data from n=5–60 is presented. 相似文献
19.
基于铯原子6S1/2 -6P3/2 -8S1/2的阶梯型能级系统,对室温下铯原子气室中的电磁感应透明(EIT)谱进行了研究.由于探测光的频率锁定于基态6S1/2(F=3)到中间态6P3/2的超精细跃迁线上,耦合光在中间态6P3/2和激发态8S1/2之间扫描,得到的EIT谱具有平坦的背景,提高了光谱的精度.理论上,采用了一个多能级的EIT模型,将其计算结果与所观察的实验现象进行了比较,二者符合得比较好.
关键词:
电磁感应透明
光抽运
超精细结构
阶梯型系统 相似文献