A novel Re(I) complex for electroluminescence application: synthesis, theoretical studies, photophysical and electroluminescent properties

In this paper, we report a novel phosphorescent Re(I) complex of Re(CO)₃(ETCP)Br, where ETCP=1-ethyl-2-naphthalen -1-yl-1H-1,3,7,8-tetraaza-cyclopenta[l]phenanthrene, including its photophysical properties, geometric/electronic structures, electrochemical and thermal properties. Experimental data suggest that Re(CO)₃(ETCP)Br is a promising yellow emitter peaking at 540--nm with short excited state lifetime of ∼0.06 μs. Re(I) center localizes in a distorted octahedral field in Re(CO)₃(ETCP)Br and the emissive state of Re(CO)₃(ETCP)Br has metal-to-ligand-charge-transfer character, leading to the room-temperature phosphorescence. Further analysis reveals that Re(CO)₃(ETCP)Br has HOMO and LUMO energy levels at −6.03 V and −3.56 V, respectively, as well as its high thermal decomposition temperature of 377 °C. Using Re(CO)₃(ETCP)Br as a dopant, an electroluminescence peaking at 565-nm is realized, with a maximum luminance of 5900 cd/m² and a maximum current efficiency of 11.3 cd/A.     

New energy levels and transitions for the 4s4p5p configuration in Kr VI

The spectrum of five-time ionized krypton, Kr VI, was recorded in the 240-2600 Å wavelength range, resulting in 61 new classified lines as transitions between levels of configurations 4p³, 4s²5p, 4s4p4d, 4s4p5s and 4s4p5p. All the 18 energy levels belonging to 4s4p5p configuration except one were determined. Eight new energy level values corresponding to configurations 4s4p4f and 4p24d, supported by 26 new classified lines were also determined and used in the interpretation of the observed 4s4p5p configuration. The experimental data were obtained from a capillary-discharge tube and theta pinch light sources. Multiconfiguration Hartree-Fock calculations with relativistic corrections and a least-squares fitted parametric calculation has been carried out.     

Hints of incomplete thermalization in RHIC data

The large elliptic flow observed in Au- Au collisions at RHIC is often put forward as a compelling evidence for the formation of a strongly interacting quark-gluon plasma. The main argument is that the measured elliptic flow is as large as the value given by fluid dynamics models that assume complete thermalization. It is argued that this claim may not be justified, since a detailed examination of experimental data rather suggests that the system created is not fully equilibrated at the time when anisotropic flow develops.     

掺入Ni元素的LiCoO2晶体光谱结构及电子顺磁共振g因子

在弱场图像下，利用Racah不可约张量算符方法得到了三角对称3d⁴/3d^{6电子组态的210阶可完全对角化的微扰哈密顿矩阵、最近邻点电荷模型晶体结构常量公 式和电子顺磁共振g因子公式.研究了LiCoO₂晶体和掺入Ni的LiCoO₂ :Ni晶体中Co3+的基态能级、晶体结构和电子顺磁共振g因子.考虑了LiCoO ₂晶体和LiCoO₂:Ni晶体中自旋单重态和 关键词： 基态能级 掺杂 晶体结构 g因子}     

Zn Ⅰ-BrⅥ离子n=4(Δn=0)跃迁谱线波长和振子强度的理论计算

对类锌ＺｎⅠ－ＢｒⅥ离子４ｓ２、４ｓ４ｐ、４ｓ４ｄ、４ｓ５ｓ组态能级进行了系统的理论拟合计算。发现了文献［１－３］中有个别辨认的错误。给出了４ｓ２—４ｓ４ｐ，４ｓ４ｐ—４ｓ４ｄ跃迁谱线波长值和相应的ＨＸＲ方法计算的振子强度。     

Low-spin states of doubly odd 184Au

Low-spin states of ¹⁸⁴Au have been studied using the β⁺/EC decay of ¹⁸⁴Hg. γ-ray and conversion-electron singles spectra were recorded with ¹⁸⁴Hg mass-separated sources. For γ-γ-t and X-γ-t coincidence measurements, mercury nuclei were produced in the ¹⁴⁸Sm + ⁴⁰Ar reaction and transported by a He-jet system. The electron spectra were recorded from ¹⁸⁴Hg sources produced at ISOLDE. A level scheme of ¹⁸⁴Au including 48 transitions is proposed. The experimental results are interpreted in the frame of a semi-microscopic axial-rotor-plus-two-quasiparticle model developed in the context of the HF+BCS approximation.     

Identification of Hg and shape coexistence in odd-A Hg isotopes

In-beam γ-ray transitions in ¹⁸¹Hg, the lightest odd-A Hg isotope known thus far, have been identified from fragment mass-γ and γ-γ coincidence measurements. Five prolate deformed rotational bands were placed in the level scheme. A decoupled band built on the strongly prolate deformed 1/2⁻[521] ground state was observed up to 29/2⁻. A 5/2⁻[512] configuration is suggested for a pair of strongly coupled bands displaying no signature splitting. The other two bands are also signature partner bands. They are populated with the largest intensity and exhibit splitting. They have been associated with the mixed neutron i_13/2 orbitals and are proposed to decay to an i_13/2 isomeric state associated with an oblate state.     

Relaxation Processes at High Levels of Vibrational Excitation of Polyatomic Molecules in the Ground Electronic State

By the spectral and kinetic characteristics of the luminescence of vapors of polyatomic molecules (anthracene, anthraquinone, fluorenone) initiated by selective IR multiphoton excitation (IR MPE) of molecules in the ground electronic state S ₀ the relaxation processes proceeding under vibrational excitation of molecules to energies exceeding the energies of the lower excited electronic states have been investigated. The changes in the spectral and kinetic characteristics with increasing CO₂ laser energy density and vapor P _v and foreign gas pressure P _FG are analyzed. They are similar to the characteristics obtained for normal fluorescence of these molecules with changing vibrational energy E _vib content. On the basis of experimental data and model calculations it has been concluded that at the laser radiation densities used in the case of IR MPE the molecules reach energies considerably exceeding the energies of the electronic levels. It is shown that a nonadiabatic connection between the electronic states leads to the population of mixed electronic states isoenergetic to the vibrational levels of the ground electronic state and to emission of delayed luminescence spectrally identical to the normal luminescence of these molecules. It has been found that when high vibrational levels are populated, new relaxation channels, such as reverse electron relaxation, emission from high vibrational levels of the ground electronic state, and multiquantum vibrational energy transfer at collisions leading to a rapid establishment of vibrational equilibrium become important.     

Frontiers and challenges of the nuclear shell model

Two recent developments of the nuclear shell model are presented. One is a breakthrough in computational feasibility owing to the Monte Carlo Shell Model (MCSM). By the MCSM, the structure of low-lying states can be studied with realistic interactions for a wide, nearly unlimited basically, variety of nuclei. The magic numbers are the key concept of the shell model, and are shown to be different in exotic nuclei from those of stable nuclei. Its novel origin and robustness will be discussed. Received: 1 May 2001 / Accepted: 4 December 2001