共查询到20条相似文献,搜索用时 31 毫秒
1.
D. Schürmann A. Di Leva L. Gialanella D. Rogalla F. Strieder N. De Cesare A. D'Onofrio G. Imbriani R. Kunz C. Lubritto A. Ordine V. Roca C. Rolfs M. Romano F. Schümann F. Terrasi H. -P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》2005,26(2):301-305
The total cross-section of 12C(α,γ)16O was measured for the first time by a direct and ungated detection of the 16O recoils. This measurement in inverse kinematics using the recoil mass separator ERNA in combination with a windowless He
gas target allowed to collect data with high precision in the energy range E = 1.9 to 4.9 MeV. The data represent new information for the determination of the astrophysical S(E) factor. 相似文献
2.
Multi-nucleon transfer reactions56Fe(12C, X) have been studied at an incident12C energy of 60 MeV. Angular distributions of10Be and9Be corresponding to 2p and 2p 1n transfer reactions in transition to low-lying states in the residual nuclei have been measured. The angular distribution
data for 2p transfer have been analysed in terms of finite range DWBA calculations assuming a one-step transfer of two protons. The spectroscopic
factors for three low-lying transitions observed in56Fe(12C,10Be)58Ni have been extracted. Transfer probabilities for the ground state transition in two- and three-nucleon stripping channels
have been obtained and compared with the corresponding sequential transfer probabilities in order to emphasise the role of
direct transfer of nucleons vis-a-vis sequential transfer. 相似文献
3.
用熔融淬冷法制备了系列掺杂浓度的Dy3+:Ge-Ga-S-CsI硫卤玻璃样品,测试了样品拉曼光谱、折射率、吸收光谱、近红外及中红外荧光谱.应用Judd-Ofelt理论计算了Dy3+离子的强度参数 (Ωi, i=2,4,6)、自发辐射跃迁概率(A)、荧光分支比(β)、以及辐射寿命(τrad)等光谱参数.研究了810 nm激光抽运下样品中红
关键词:
硫系玻璃
中红外发光
3+掺杂')" href="#">Dy3+掺杂
多声子弛豫 相似文献
4.
Abstract Three new bands of the B 2Σ+–X 2Σ+ system of 12C17O+ have been investigated using conventional spectroscopic techniques. The spectra were observed in a graphite hollow‐cathode lamp by discharging molecular oxygen (enriched in about 45% of the 17O2 isotope) under 1.0 Torr pressure. The rotational analysis of the 2–4, 2–5, and 2–6 bands was performed with the effective Hamiltonian of Brown (Brown et al., J. Mol. Spectrosc. 1979; 74: 294–318). Molecular constants were derived from a merge calculation, including both the current wavenumbers and the spectroscopic data published by the authors previously. The principal equilibrium constants for the ground state of 12C17O+ are ωe=2185.9658(84), ωe x e = 14.7674(11), B e=1.927001(38), αe=1.8236(22)×10?2, γe=?0.331(28)×10?4, D e=6.041(12)×10?6, βe=0.100(31)×10?7 cm?1, and the equilibrium constants for the excited state are σe=45876.499(15), ωe=1712.201(12), ωe x e=27.3528(39), B e=1.754109(35), αe=2.8706(57)×10?2, γe = ?1.15(19)×10?4, D e=7.491(20)×10?6, βe=2.13(12)×10?7, γe = 2.0953(97)×10?2, and αγe=?9.46(59)×10?4 cm?1, respectively. Rydberg–Klein–Rees potential energy curves were constructed for the B 2Σ+ and X 2Σ+ states of this molecule, and Franck–Condon factors were calculated for the vibrational bands of the B–X system. 相似文献
5.
The cross-sections for formation of isomeric pair, 75Gem(σm) and 75Geg(σg), through 76Ge(n, 2n), 75As(n, p) and 78Se(n, α) reactions were measured at 13.73 MeV, 14.42 MeV and 14.77 MeV neutrons and also estimated using EMPIRE-II and TALYS codes over neutron energies from near threshold to 20 MeV. For each (n, 2n), (n, p) and (n, α) reaction, the cross-section initially increases with neutron energy, but starts decreasing as the neutron energy exceeds the respective threshold of (n, 3n), (n, pn) and (n, αn) reactions. The higher values of σm relative to σg reveal that the transitions of the excited 75Ge from higher energy levels to metastable state (7+/2) are favored as compared to unstable ground state (1−/2). The present values of cross sections for formation of 75Gem,g through (n, 2n) and (n, α) reactions are lower, and that of (n, p) reaction are higher compared to most of the corresponding literature cross-sections. 相似文献
6.
ABSTRACT High-resolution emission spectrum of the 1–4 band of the B 2Σ+–X 2Σ+ transition of 14C16O+ was observed for the first time by conventional emission spectroscopy. The band spectrum was excited in a water-cooled Geissler lamp filled with commercial gaseous carbon monoxide enriched in about 80% of the radiocarbon 14C. A rotational analysis has been carried out and obtained molecular constants have been merged with previously published data for the B 2Σ+–A 2Πi and A 2Πi–X 2Σ+ transitions. The principal equilibrium constants for the ground X 2Σ+ state obtained from this work are ωe = 2121.7726(98), ωe x e = 13.9055(27), B e = 1.815290(30), αe = 1.6594(33) × 10?2, and γe = ? 0.377(73) × 10?4 cm?1. Also, presently known experimental equilibrium molecular constants of the X 2Σ+ states of the CO+ isotopic molecules are summarized and isotopic dependence of the B e and ω e constants is discussed. 相似文献
7.
8.
Theoretical calculation of of B-like ions: photoionization cross sections N^2+, O^3+ and F^4+ 下载免费PDF全文
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. 相似文献
9.
研究了808 nm和977 nm激光二极管抽运下铥/镱共掺TeO2-Ga2O3-R2O(R=Li,Na,K)玻璃光谱特性.利用Judd-Ofelt 理论计算了Tm3+离子在碲镓酸盐玻璃中自发辐射跃迁概率、荧光分支比和辐射寿命等光谱参数.在977 nm激光二极管抽运下,观测到Tm3+/Yb3+共掺碲镓酸盐玻璃很强的476 nm上转换蓝光(1G4→3H6)和较弱的650 nm上转换红光(1G4→3H4和3F2,3→3H6).分析表明476 nm蓝光发射为三光子吸收过程,650 nm红光发射为双光子和三光子混合吸收过程;而在808 nm激光二极管抽运下,玻璃上转换蓝色荧光为双光子吸收过程.实验发现,随着碱金属离子半径的增大,977 nm激光二极管抽运下蓝光上转换发光强度增强,而用808 nm激光二极管抽运蓝光上转换发光无明显的变化.
关键词:
碲镓酸盐玻璃
铥镱共掺
Judd-Ofelt 理论
上转换 相似文献
10.
Basically the aim of this work is to define the accurate configuration of the exocyclic double bond of substituted 5-methylenehydantoins and thiohydantoins which have been conceived as potential Aldose Reductase inhibitors. A previsional survey based upon the chemical shifts analysis from 1H and decoupled 13C NMR spectra discloses, for a part of the family of compounds, the assignment of the Zconfiguration for unsubstituted (2,3) and N-3 substituted (6,7,9) derivatives, and the E-configuration for the N-1 substituted (8,11) ones. The qualitative study with Homonuclear NOE (8,11) and the coupling constant measuring 3 JC4-C=C-H6 from coupled 13C NMR (1–11), lead to the assignment of the accurate configuration of the whole family's compounds in agreement with the previsional study. 相似文献
11.
报道了Tm3+/Ho3+共掺的镓铋酸盐玻璃14Ga2O3-25Bi2O3-20GeO2-31PbO-10PbF2玻璃1.47μm(S波段)发光和能量传递特征,应用Judd-Ofelt理论计算了玻璃的强度参数Ωt(t=2,4,6),自发辐射概率A、荧光分支比β,荧光辐射寿命τ等各项光谱参数以及有效荧光线宽Δλeff和峰值发射截面σpeake.通过测量荧光光谱和荧光寿命研究了Ho3+离子掺杂浓度对Tm3+离子1.47μm波段发光性能的影响,分析了Tm3+和Ho3+之间的能量传递过程.结果表明一定浓度内Ho3+的共掺迅速降低了Tm3+:3F4能级的粒子数,而对3H4能级粒子数影响不大,从而降低了3F4和3H4能级间布居数反转的难度,极大地提高了1.47μm发光效率.研究表明镓铋酸盐玻璃是适用于S波段光纤放大器的一种潜在基质材料,而掺杂一定浓度的Ho3+离子有利于提高Tm3+离子在1.47μm波段的发光效率.
关键词:
重金属氧化物玻璃
光谱性质
3+/Ho3+离子')" href="#">Tm3+/Ho3+离子
能量传递 相似文献
12.
13.
基于完全对角化方法(complete diagonalization method, CDM), 研究了6S(3d5)态离子在立方对称晶场中的磁相互作用,分析了自旋哈密顿参量(a, g,Δg)的微观起源.研究中除了考虑研究者通常考虑的SO(spin-orbit)磁相互作用外,同时考虑了SS(spin-spin),SOO(spin-other-orbit),OO(orbit-orbit)磁相互作用.研究表明:6S(3d5)态离子在立方对称晶场中的自旋哈密顿参量起源于五种机理,即SO机理,SS机理,SOO机理,OO机理以及SO-SS-SOO-OO联合作用机理.文中研究了五种机理的相对重要性,结果表明:SO机理与SO-SS-SOO-OO联合作用机理在五种机理中最为重要.尽管SS,SOO,OO磁相互作用单独作用时对自旋哈密顿参量的贡献很小,但它们的联合作用SO-SS-SOO-OO机理对自旋哈密顿参量的贡献非常可观.此外研究表明:零场分裂参量a主要来自纯自旋四重态及自旋二重态与自旋四重态联合作用的贡献,而Zeemang(或者Δg)因子主要来自纯自旋四重态的贡献.纯自旋二重态对自旋哈密顿参量a与g(或者Δg)的贡献为零.在我们所选择的晶场区域,发现下列关系始终成立:a>0,a(-|Dq|)<a(|Dq|),g(-Dq)=g(Dq),a(-Dq,-ξd,B,C)=a(Dq,ξd, B,C),Δg(-Dq,-ξd, B, C)=Δg(Dq,ξd, B, C).作为本文理论的应用,研究了四种典型的Mn2+掺杂晶体材料,即Mn2+:KZnF3,Mn2+: RbCdF3,Mn2+: MgO,Mn2+: CaO,理论与实验测量符合很好.
关键词:
自旋哈密顿参量
6S(3d5)态离子')" href="#">6S(3d5)态离子
磁相互作用
完全对角化方法(CDM) 相似文献
14.
15.
It is found that in light nuclei it is very important to use a relative kinetic energy operator. This kinetic energy is mass
number dependent and contributes in all odd parity (J*,T) channels. In particular it is seen to produce the spurious state exactly at zero energy in the (1−, 0) channel in TDA both in4He and16O. The effect of the relative KE is to decrease the central force attraction and increase the relative importance of the tensor
force. The latter is important in RPA. Sussex matrix elements without the hard core are used. 相似文献
16.
Pablo J. Bruna 《Molecular physics》2013,111(3):429-446
Theoretical calculations on the fine, hyperfine and Zeeman (g-factor) parameters are reported for the X2Π and A2Σ+ states of FH+, ClH+ and BrH+. The fine-structure constants [spin–orbit (A), Λ-doubling (p, q) and spin–rotation constants (γ Π, γ Σ)] are evaluated up to second order (via SO/L couplings with several excited states) using a multireference configuration interaction (MRCI) method, a Breit–Pauli Hamiltonian and 6-311++(2d,2pd) basis sets. Hyperfine constants of magnetic and electric type [Frosch–Foley (a, b, c, d) and nuclear quadrupole (eQq 0, eQq 2)] are studied with density functional methods and various basis sets. Magnetic dipole moments (parameterized via g-factors) are calculated in second order like the fine structure constants. The situation is somewhat complex for X2Π since no less than five different g’s have to be evaluated in second order. In general, our results are in good agreement with those reported in the literature, mostly limited to the ground state. Our calculations confirm that, at equilibrium, all second-order properties are dominated by the couplings between the electronic states X and A. 相似文献
17.
采用完全对角化方法,以尖晶石结构的ZnAl2O4:Cr3+,ZnGa2O4:Cr3+和MgAl2O4:Cr3+系列晶体为例,联系晶格局域结构,对三角对称下3d3离子2E态g因子性质进行了研究.研究中考虑了包括自旋与自旋相互作用、自旋与另一轨
关键词:
2E态g因子')" href="#">2E态g因子
3离子')" href="#">3d3离子
尖晶石结构
磁相互作用 相似文献
18.
Tunneling conductance in quantum wire/insulator/dx2 -y2 + idxy mixed wave superconductor junctions 下载免费PDF全文
Using the extended Blonder-Tinkham-Klapwijk (BTK) theory, this paper calculates the tunnelling conductance in quantum wire/insulator/dx2-y2 + idxy mixed wave superconductor (q/I/dx2-y2 + idxy) junctions. That is different from the case in d- and p-wave superconductor junctions. When the angle α between a-axis of the dx2-y2 wave superconductor and the interface normal is π/4, there follows a rather distinctive tunnelling conductance. The zero-bias conductance peak (ZBCP) may or may not appear in the tunnelling conductance. Both the interface potential z and the quasi-particle lifetime factor Γ are smaller, there is no ZBCP. Otherwise, the ZBCP will appear. The position of bias conductance peak (BCP) depends strongly on the amplitude ratio of two components for dx2-y2 + idxy mixed wave. The low and narrow ZBCP may coexist with the BCP in the tunnelling conductance. Using those features in the tunnelling conductance of q/I/dx2-y2 + idxy junctions, it can distinguish dx2-y2 + idxy mixed wave superconductor from d- and p-wave one. 相似文献
19.
《光谱学快报》2013,46(4-5):477-485
Abstract The 1H‐ and 13C‐NMR spectra of some substituted stilbenes and chalcones were assigned unambiguously on the basis of a combination of homo‐ (COSY) and heteronuclear (HETCOR) two‐dimensional methods, the chemical shifts, as well as spin‐coupling constants. The Aik empirical parameters of the –O–C(S)–N(CH3)2, –S–C(O)–N(CH3)2, and –SH group were calculated to help predict the chemical shifts of substituted stilbenes, 4′‐nitrostilbenes, and chalcones. The 1H‐ and 13C‐NMR spectra have been shown to be able to differentiate between the isomers of O‐stilbenyl (4, 5) and S‐stilbenyl N,N‐dimethylthiocarbamates (7, 8) as well as O‐chalconyl (6) and S‐chalconyl N,N‐dimethylthiocarbamates (9). 相似文献
20.
利用直流磁控共溅射方法制备了GaN:Er薄膜.X射线衍射结果显示薄膜为纳米多晶结构,根据谢乐公式,计算得到了GaN薄膜晶粒的平均大小为58nm;透射电子显微镜结果显示为非晶基质中镶嵌了GaN纳米颗粒,尺寸在6—8nm之间;紫外可见谱结果表明在500—700nm的可见光范围内,薄膜的平均透过率大于80%,在紫外可见谱基础上,利用Tauc公式计算得到了纳米晶GaN薄膜的光学带隙为322eV;最后,测量了GaN:Er薄膜的室温光致发光谱,获得了Er3+离子在554nm处的强烈绿光发射.
关键词:
纳米晶GaN薄膜
3+掺杂')" href="#">Er3+掺杂
光学带隙
光致发光 相似文献