共查询到20条相似文献,搜索用时 31 毫秒
1.
A novel finite basis set method is used to calculate the Bethe logarithm for the ground 2 (2)S(1/2) and excited 3 (2)S(1/2) states of lithium. The basis sets are constructed to span a huge range of distance scales within a single calculation, leading to well-converged values for the Bethe logarithm. The results are used to calculate an accurate value for the complete quantum electrodynamic energy shift up to order alpha(3) Ry. The calculated 3 (2)S(1/2)-2 (2)S(1/2) transition frequency for 7Li is 27 206.092 6(9) cm(-1), and the ionization potential for the 2 (2)S(1/2) state is 43 487.158 3(6) cm(-1). The 7Li-6Li isotope shift is also considered, and all the results compared with experiment. 相似文献
2.
First measurement of the partial widths of 209Bi decay to the ground and to the first excited states
Beeman JW Biassoni M Brofferio C Bucci C Capelli S Cardani L Carrettoni M Clemenza M Cremonesi O Ferri E Giachero A Gironi L Gorla P Gotti C Nucciotti A Maiano C Pattavina L Pavan M Pessina G Pirro S Previtali E Sisti M Zanotti L 《Physical review letters》2012,108(6):062501
209Bi alpha decay to the ground and to the first excited state have been recently observed for the first time with a large BGO scintillating bolometer. The half-life of 209Bi is determined to be τ(1/2)=(2.01±0.08)×10(19) yr while the branching ratio for the ground-state to ground-state transition is (98.8±0.3)%. 相似文献
3.
The coupled equation method (CEM) has been applied to investigating the resonance structures for the ground state 1s22s 2S of the neutral lithium from the first threshold up to 64.5 eV. Resonance structures of atomic lithium due to single excitations of the 1s and 2s electrons are studied by infinite-order calculations in detail. The effect of spin-orbit splitting is also included for some of the low-lying 1s2snp(↑↓) resonance,and the influence of the interference between 1s2s 3Snp ↓ and 1s2s 1Snp ↑ states on the resonance structure has been confirmed theoretically. The results show that the presented technique can give the reasonable resonance structures very well in photoionization processes. 相似文献
4.
High-order harmonic generation spectrum of an excited one-dimensional Coulomb atom in an intense laser field
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Response of the wave packet of a one-dimensional Coulomb atom
to an intense laser field is calculated using the symmetrized
split operator fast Fourier method. The high-order harmonic
generation (HHG) of the initial state separately being the ground and excited states
is presented. When the hardness parameter \alpha in the soft
Coulomb potential V(x)=-1/\sqrt{x^2+\alpha} is chosen to be small
enough, the so-called hard Coulomb potential
V(x)=-1/|x| can be obtained. It is well known that the hard one-dimensional Coulomb atom
has an unstable ground
state with an energy eigenvalue of $\sim0.5$ and it
has no states corresponding to physical states in the true atoms, and
has the first and second excited states being degenerate. The parity effects on the HHG
can be seen from the first and second excited states of the hard
one-dimensional Coulomb atom. The HHG spectra of the excited states
from both the soft and hard Coulomb atom models are shown to have more
complex structures and to be much stronger than the corresponding
HHG spectrum of the ground state of the soft Coulomb model with
$\alpha=2$ in the same laser field. Laser-induced non-resonant
one-photon emission is also observed. 相似文献
5.
6.
Optics and Spectroscopy - Spin-exchange cross sections and the magnetic-resonance frequency shift in collision of lithium and potassium atoms in the ground state have been calculated for the first... 相似文献
7.
Saturated three-step resonance ionization of ground state lithium was demonstrated and the first measurement of the photoionization cross section from the excited n = 3 manifold of lithium was made. This demonstration of saturation shows the feasibility of detecting single atoms of lithium using sensitive charge detection methods. 相似文献
8.
V. A. Kartoshkin 《Technical Physics》2009,54(5):737-739
The cross sections of magnetic resonance frequency shifts are calculated for the first time in the system formed by a metastable
helium atom and a lithium atom in the ground state. The results are compared with the results of calculations for He-K systems.
It is shown that the shift cross section increases upon heating from 50 to 550 K, changing its sign near T = 80 K. 相似文献
9.
Mikhail G. Brik Nicolae M. Avram Calin N. Avram 《Central European Journal of Physics》2005,3(4):508-524
The exchange charge model of crystal field theory has been used to analyze the ground and excited state absorption of tetrahedrally coordinated Cr4+ ion in lithium aluminum oxide LiAlO2 (γ-phase) and lithium dioxogallate LiGaO2. The parameters of the crystal field acting on the Cr4+ ion are calculated from the crystal structure data, taking into account the crystal lattice ions located at distances up to 12.744 Å in LiGaO2 and 13. 180 Å in LiAlO2. The obtained energy level schemes were compared with experimental ground and excited state absorption spectra and literature data on the application of other crystal field models (the angular overlap model and Racah theory) to the considered crystals; a good agreement with experimental data is demonstrated. 相似文献
10.
向根祥 《原子与分子物理学报》2011,28(5)
本文运用密度泛函B3LYP/6-311+G(3df,2p)方法研究了联氨分子的电子结构和能量,并系统分析了联氨分子的分解反应,计算绘制了单分子联氨在基态和单态第一激发态下沿N-N分解反应的势能曲线。本文计算发现联氨分子在这两种电子态下的离解能分别是:基态58.8 kcal/mol,单态第一激发态495.5 kcal/mol。基态分子分解反应是吸热反应,而单态第一激发态分解反应是放热反应。计算发现单态第一激发态的激发能是554.2 kcal/mol。结合这两种电子态下联氨分子的红外振动频率分析,本文认为,在非强制断键的情况下,联氨分子沿N-N键均裂而生成两个NH2自由基的可能性很小。 相似文献
11.
本文运用密度泛函B3LYP/6-311+G(3df,2p)方法研究了联氨分子的电子结构和能量,并系统分析了联氨分子的分解反应,计算绘制了单分子联氨在基态和单态第一激发态下沿N-N分解反应的势能曲线。本文计算发现联氨分子在这两种电子态下的离解能分别是:基态58.8 kcal/mol,单态第一激发态495.5 kcal/mol。基态分子分解反应是吸热反应,而单态第一激发态分解反应是放热反应。计算发现单态第一激发态的激发能是554.2 kcal/mol。结合这两种电子态下联氨分子的红外振动频率分析,本文认为,在非强制断键的情况下,联氨分子沿N-N键均裂而生成两个NH2自由基的可能性很小。 相似文献
12.
We present an ab initio calculation of the Li+ photoion yield in the presence of laser coupling between the triply excited 2s(2)2p(2)P(o) and 2s2p(2) (2)D(e) resonances in lithium, the first of which is assumed excited by synchrotron radiation from the ground state. The laser coupling between the triply excited states is shown to lead to a significant and readily measurable modification of the line profile which provides a unique probe of the dipole strength between highly correlated triply excited states. 相似文献
13.
<正>The static electric dipole polarizabilities of the ground state and n≤3 excited states of a lithium atom embedded in a weekly coupled plasma environment are investigated as a function of the plasma screening radium.The plasma screening of the Coulomb interaction is described by the Debye-H(u|¨)ckel potential and the interaction between the valence electron and the atomic core is described by a model potential.The electron energies and wave functions for both the bound and continuum states are calculated by solving the Schrodinger equation numerically using the symplectic integrator.The oscillator strengths,partial-wave,and total static dipole polarizabilities of the ground state and n≤3 excited states of the lithium atom are calculated.Comparison of present results with those of other authors, when available,is made.The results for the 2s ground state demonstrated that the oscillator strengths and the static dipole polarizabilities from np orbitals do not always increase or decrease with the plasma screening effect increasing, unlike that for hydrogen-like ions,especially for 2s→3p transition there is a zero value for both the oscillator strength and the static dipole polarizability for screening length D = 10.3106a0,which is associated with the Cooper minima. 相似文献
14.
V.M. Shabaev A.N. Artemyev O.M. Zherebtsov V.A. Yerokhin G. Plunien G. Soff 《Hyperfine Interactions》2000,127(1-4):279-286
The present status of calculations of the hyperfine splitting and the transition probability between the hyperfine splitting
components in hydrogen and lithium like ions is discussed. The results of the calculations are compared with recent experimental
data. A special attention is focused on the hyperfine splitting in hydrogen like lead and lithium like bismuth. It is shown
that the theoretical prediction for the ground state hyperfine splitting in lead based on the single particle nuclear model
for the Bohr-Weisskopf effect is in fair agreement with experiment. The theoretical prediction for the ground state hyperfine
splitting in lithium like bismuth is improved due to more accurate calculations of the interelectronic interaction, QED, and
nuclear corrections.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
The infrared vibration-rotation bands of SeH have been measured in the X(2)Pi ground state using a Fourier transform spectrometer. The bands were observed in a microwave discharge of a mixture of H(2) and Se in the presence of He. The rotational structure of the 1-0, 2-1, 3-2 bands of the X(2)Pi(3/2) spin component and the 1-0 band of X(2)Pi(1/2) spin component has been observed in the 1800-2600 cm(-1) region. The principal ground state molecular constants obtained are omega(e) = 2421.7153(234) cm(-1), omega(e)x(e) = 44.6012(110) cm(-1), omega(e)y(e) = 0.20697(236) cm(-1), B(e) = 7.899187(696) cm(-1), alpha(e) = 0.220749(399) cm(-1), and r(e) = 1.464319(64) ?. This work is the first determination of the equilibrium molecular constants of the X(2)Pi state of SeH. Copyright 2000 Academic Press. 相似文献
16.
Liddick SN Grzywacz R Mazzocchi C Page RD Rykaczewski KP Batchelder JC Bingham CR Darby IG Drafta G Goodin C Gross CJ Hamilton JH Hecht AA Hwang JK Ilyushkin S Joss DT Korgul A Królas W Lagergren K Li K Tantawy MN Thomson J Winger JA 《Physical review letters》2006,97(8):082501
Two new alpha emitters 109Xe and 105Te were identified through the observation of the 109Xe --> 105Te --> 101Sn alpha-decay chain. The 109Xe nuclei were produced in the fusion-evaporation reaction 54Fe(58Ni,3n)109Xe and studied using the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. Two transitions at Ealpha = 4062 +/- 7 keV and Ealpha = 3918 +/- 9 keV were interpreted as the l = 2 and l = 0 transitions from the 7/2+ ground state in 109Xe (T1/2 = 13 +/- 2 ms) to the 5/2+ ground state and a 7/2+ excited state, located at 150 +/- 13 keV in 105Te. The observation of the subsequent decay of 105Te marks the discovery of the lightest known alpha-decaying nucleus. The measured transition energy Ealpha = 4703 +/- 5 keV and half-life T1/2 = 620 +/- 70 ns were used to determine the reduced alpha-decay width delta2. The ratio delta105Te(2)/delta213Po(2) of approximately 3 indicates a superallowed character of the alpha emission from 105Te. 相似文献
17.
Chernykh M Feldmeier H Neff T von Neumann-Cosel P Richter A 《Physical review letters》2007,98(3):032501
The first excited 0(+) state in 12C (Hoyle state) has been predicted to be a dilute self-bound gas of bosonic alpha particles, similar to a Bose-Einstein condensate. To clarify this conjecture, precise electron scattering data on form factors of the ground state and the transition to the Hoyle state are compared with results of the fermionic molecular dynamics model, a microscopic alpha-cluster model, and an alpha-cluster model with reduced degrees of freedom (in the spirit of a Bose-Einstein condensed state). The data indicate clearly a dilute density with a large spatial extension of the Hoyle state. A closer inspection of the model calculations, which reproduce the experimental findings, reveals that the term Bose-Einstein condensation of three alpha particles must not be taken too literally. 相似文献
18.
Hoefman M Aphecetche L Bacelar JC Delagrange H Descouvemont P Diaz J d'Enterria D van Goethem M Holzmann R Huisman H Kalantar-Nayestanaki N Kugler A Lohner H Marques FM Martinez G Messchendorp JG Ostendorf RW Schadmand S Siemssen RH Simon RS Schutz Y Timmermans R Turrisi R Volkerts M Wagner V Weller H 《Physical review letters》2000,85(7):1404-1407
19.
利用单电子近似下锂原子精确的模型势,通过数值求解三维含时薛定谔方程的方法,研究了锂原子在激光场中发射低阶谐波的性质,研究结果表明,对于锂原子电离阈值以下的低阶谐波,除了通常的奇次谐波外,还有侧峰结构出现,运用同步压缩变换技术(SST)分析这些低阶谐波的辐射特性,我们发现这些侧峰是由原子在激光场中的缀饰态之间的跃迁和无场下激发态到基态的跃迁组成的,如果当激光脉冲结束后,仍有发射的侧峰,其位置与主峰之间的能量差可以用来估算原子激发态在激光场中的最大Stark移动. 相似文献
20.
230—245nm范围内Cl原子共振增强多光子电离光谱 总被引:1,自引:0,他引:1
利用共振增强多光子电离--时间飞行质谱技术获得了Cl原子在230-245nm范围内的代振增强多光子电离光谱,共观察到26条谱线,其中5条是作者新观察到的,这些谱线对应从Cl原子基态到激发态的双光子跃迁。从中还观察到Cl原子在强电场中的Stark效应,发现在强场条件下,Cld原子绵基太^2P1/2^0和^2P3/2^0两能级之间的能工位移1.35cm^=1。而各电子激发态的Stark位移则大致相等, 相似文献