185 resultados para Coccoid-like spheroids
Resumo:
There can be found some notable discrepancies with regard to the resonance structures when R-matrix calculations from the Opacity Project and other sources are compared with recent absolute experimental measurements of Bizau et al [Astron. Astrophts. 439 387 (2005)] for B-like ions N2+, O3+ and F4+. We performed close-coupling calculations based on the R-matrix formalism for the photoionizations of ions mentioned above both for the ground states and first excited states in the near threshold regions. The present results are compared with experimental ones given by Bizau et al and earlier theoretical ones. Excellent agreement is obtained between our theoretical results and the experimental photoionization cross sections. The present calculations show a significant improvement over the previous theoretical results.
Resumo:
The foil-excited the spectrum of highly stripped titanium ions between 12-40 nm has been studied. Titanium ions of 80 and 120 MeV were provided by the HI-13 tandem accelerator at the China Institute of Atomic Energy. GIM-957 XUV-VUV monochromator was refocused to get highly-resolved spectra. Our experimental results and the published spectral data of laser-produced plasma show agreement in nearly all cases within +/- 0.03 nm. The spectra contained some weak or strong lines previously unclassified. These spectral lines mainly belong to 2s2p(2) for TiXVIII, 2p(3) for TiXVIII, 2s2p(3) for TiXVII, 2p(6)4p for Ti XII and 2p(6)3d for Ti XII transitions.
Resumo:
在类氢离子能级相对论修正的基础上,依据屏蔽方法,给出了类氟体系基态电离能的一种表达式.依据原子序数9至20的元素类氟体系基态电离能的实验数据,使用Microcal Origin软件拟合出类氟体系非电离电子平均屏蔽系数与原子序数的函数关系,总结出类氟体系基态电离能遵从的关系式并进行了验证.推算了原子序数21至40的元素类氟离子的基态电离能.
Resumo:
The electron impact excitation (EIE) cross sections from the ground state to all of the 2s(2)2p(5)3l and 2s2p(6)3l(l=s, p, d) states along the Ne-like isoelectronic sequence of ions (Z = 50-57) have been calculated by using the multiconfiguration Dirac-Fock package GRASP92 and the fully relativistic distorted-wave program REIE06. In the calculations, the relativistic effects and electron correlation effects are considered systematically. Based on those calculations, the EIE cross sections along the Ne-like isoelectronic sequence of ions for different incident electron energies are discussed, and some important conclusions are drawn. We also study the influence of the correlation effects on the values of the 3C/3D line-intensity ratio [3C: (2p(1/2)3d(3/2))(1) -> 2s(2)2p(6) S-1(0), 3D: (2p(3/2)3d(5/2))(1) -> 2s(2)2p(6) S-1(0)] along the Ne-like sequence. A comparison is made between the present results and previous theoretical calculations and experimental results for the EIE cross sections in Ba-46 (+) ions, and a good agreement is obtained.
Resumo:
In this paper, we explored the characteristics of the interference effects between perturbative states in hyperfine induced 2s2p P-3(0), P-3(2) -> 2s(2) S-1(0) transitions of Be-like ions. It was found that the interference effects non-monotonically change with increasing atomic number Z in these two transitions. The strongest interference effect is near Z = 9 for 2s2p P-3(0), -> 2s(2) (1)S(0)transition and near Z = 7 for the other.
Resumo:
A detailed investigation of plasma screening effects on atomic structure and transition properties are presented for He-like ions embedded in dense plasma environment. Multi-configuration Dirac-Fock calculations were carried out for these ions by considering a Debye-Huckel potential. A large-scale relativistic configuration-interaction method is adopted to calculate transition energies and transition probabilities and to allow for a systematic improvement of the calculations. Comparison of the presently calculated results with others, when available, is made.
Resumo:
Two-electron-one-photon (TEOP) M1 and E2 transition energies, line strengths and transition probabilities between the states of the 2p(3) and 2s(2)2p odd configurations for B-like ions with 18 <= Z <= 92 have been calculated using the GRASP2K package based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Employing active-space techniques to expand the configuration list, we have systematically considered the valence, core-valence and core-core electron correlation effects. Breit interaction and quantum electrodynamical (QED) effects were also included to correct atomic state wavefunctions and the corresponding energies. Influences of electron correlation, Breit interaction and QED effects on transition energies and line strengths of the TEOP M1 and E2 transitions were analysed in detail. The present results were also compared with other theoretical and experimental values.
Resumo:
The alpha decay constant is the product of the penetrability P and assault frequency nu(0) in the fission-like model. An effective assault frequency P-nu replacing the previous assault frequency nu(0) is introduced for improvement of a fission-like model named the generalized liquid drop model (GLDM) to describe the nuclear alpha decay process more accurately. Two analytical formulae are proposed for the effective assault frequency due to experimental data within the GLDM. The improved model can be used to give accurate calculations for alpha decay half-lives.
Resumo:
On the basis of previous work, the hyperfine-induced 3s3p P-3(2) -> 3s(2) S-1(0) E1 transition probabilities of Mg-like ions were further calculated using the GRASP2K package based on the multiconfiguration Dirac-Hartree-Fock method. The contribution to the lifetime of the P-3(2) level from the 3s3p P-3(2) -> 3s(2) S-1(0) hyperfine-induced E1, 3s3p P-3(2) -> 3s3p P-3(1) M1, 3s3p P-3(2) -> 3s(2) S-1(0) M2 and 3s3p P-3(2) -> 3s3p P-3(0,1) E2 transition was discussed in detail. It was found that hyperfine interaction has an obvious effect on the lifetime at the beginning of the Mg-like isoelectronic sequence.
Resumo:
Hyperbranched poly(amido amine)s containing vinyl and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3-amino-1,2-propanediol (APD) with equal molar ratio in feed. H-1, C-13 and HSQC NMR techniques were used to clarify the structure of hyperbranched polymers and polymerization mechanism.
Resumo:
Novel star-like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3-amino-1,2-propanediol (APD) with feed molar ratio of 1:2. H-1, C-13, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers
Resumo:
In this Letter, we report the morphological transition of dry block copolymer vesicles into onion-like multilamellar micelles induced through heating. When the temperature is higher than the glass transition temperature of block copolymer, the vesicles can collapse, and finally form onion-like multilamellarmicelles via micro phase separation. This phenomenon is observed in both A-B and A-B-A block copolymer vesicles, indicating that the technique used in this study can be an alternative method to synthesize multilamellar micelles.
Resumo:
We first suggested a one-pot method to synthesize monodisperse raspberry-like submicrometer gold spheres (MRSGS) with high yield. The resulting gold spheres were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersed X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and electrochemical technology. It was found that the rough structure provided by raspberry-like gold spheres led to a tremendous electrochemical active area, which was very important because these novel hierarchical gold spheres will probably find important applications in biosensors, electrocatalysis, and others.
Resumo:
A star-like white light-emitting polymer with an orange emissive core and four blue emissive arms is designed and synthesized. White electroluminescence is observed with simultaneous orange emission from the core and blue emission from the arms. A single-layer device based on this polymer emits white light with CIE coordinates of (0.35, 0.39) and a luminous efficiency of 7.06 cd A(-1).