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971.
The antiferromagnetic phenomena of both mixed valent FeIIIFeII spin clusters and homodinuclear FeIIIFeIII clusters in complexes have been studied by means of our covalent magnetic exchange theoretical method. The sensitive relations between the exchange parameter J and the covalent factors NA (for FeIII) and NB (for FeII) and the Fe?Fe separation R have been derived by use of our double-Slater function calculation procedure, the corresponding theoretical curve of J vs. NA,NB and R has been obtained. By taking the typical covalent factors of FeIII and FeII, and using the observed Fe-O bond lengths: for FeIII-O-FeII cluster in model complex {[Fe(acacen)]2ONa}2; for FeIII-O-FeIII cluster in oxyhemerythrin, we obtained the theoretical values: for FeIII-O-FeII cluster and for FeIII-O-FeIII cluster. These are in good agreement with the corresponding experimental findings in {[Fe(acacen)]2ONa}2 and in oxyhemerythrin, respectively. 相似文献
972.
Sinova J Culcer D Niu Q Sinitsyn NA Jungwirth T MacDonald AH 《Physical review letters》2004,92(12):126603
We describe a new effect in semiconductor spintronics that leads to dissipationless spin currents in paramagnetic spin-orbit coupled systems. We argue that in a high-mobility two-dimensional electron system with substantial Rashba spin-orbit coupling, a spin current that flows perpendicular to the charge current is intrinsic. In the usual case where both spin-orbit split bands are occupied, the intrinsic spin-Hall conductivity has a universal value for zero quasiparticle spectral broadening. 相似文献
973.
Culcer D Sinova J Sinitsyn NA Jungwirth T MacDonald AH Niu Q 《Physical review letters》2004,93(4):046602
Motivated by recent interest in novel spintronics effects, we develop a semiclassical theory of spin transport that is valid for spin-orbit coupled bands. Aside from the obvious convective term in which the average spin is transported at the wave packet group velocity, the spin current has additional contributions from the wave packet's spin and torque dipole moments. Electric field corrections to the group velocity and carrier spin contribute to the convective term. Summing all terms we obtain an expression for the intrinsic spin-Hall conductivity of a hole-doped semiconductor, which agrees with the Kubo formula prediction for the same quantity. We discuss the calculation of spin accumulation, which illustrates the importance of the torque dipole near the boundary of the system. 相似文献
974.
Hardy type and Rellich type inequalities on the Heisenberg group 总被引:13,自引:0,他引:13
Pengcheng Niu Huiqing Zhang Yong Wang 《Proceedings of the American Mathematical Society》2001,129(12):3623-3630
This paper contains some interesting Hardy type inequalities and Rellich type inequalities for the left invariant vector fields on the Heisenberg group.
975.
具有三维网络的新型配位聚合物[Nd(C7H6NO2)3.H2O]n的合成、结构和性质 总被引:6,自引:0,他引:6
以Nd(NO3).6H2O和NH2C6H4COOH为原料,经[Nd(C7H6NO2)3.H2O]的自组装,得到了具有三维网络结构的配位聚合物[Nd(C7H6NO2)3.H2O]n。该聚合物晶体属单斜晶系,空间群P2(1)/n,a=0.98069(5)nm,b=2.2736(2)nm,c=0.98254(8)nm,β=100.053(5)°,V=2.1571(3)nm^3,Z=4。最后的一致性因子R=0.038。磁性研究表明,该化合物在低温下表现出反铁磁性质。测定了化合物的UV-vis-NIR和IR光谱,进行了分析和指认。 相似文献
976.
用半微量相平衡方法研究了硫酸锌 -苏氨酸 -水体系在 2 5℃及全浓度范围内的溶度性质 ,绘制了体系的相图和饱和溶液折光率曲线 ,体系中不存在新化合物 .在水 -丙酮混合溶剂中合成了未见文献报道的Zn(Thr)SO4 ·H2 O三元固态化合物 ,通过化学分析、元素分析 ,IR ,XRD ,XPS和TG -DTG等对其组成、结构及热稳定性进行了研究 .用精密转动弹热量计测定了配合物的标准燃烧能 ( - 11848.76± 17.76)J·g-1,求得它的标准燃烧焓 ( - 3 5 3 4.82±5 .3 0 )kJ·mol-1,标准生成焓 ( - 2 5 6.3 7± 5 .69)kJ·mol-1. 相似文献
977.
978.
Search for a TeV Gamma Rays Emission from the Shell-like SNP G40.5-0.5 Using the Yangbajing Extend Air Shower Array 下载免费PDF全文
ZHANG Ji-Long CUI Shu-Wang DING Lin-Kai DING Xiao-Hong FENG Cun-Feng FENG Zhen-Yong GAO Xiao-Yu GENG Qing-Xi GUO Hong-Wei HE Hui-Hai HE Mao 《中国物理C(英文版)》2006,30(1):13-17
Using observation data of the Yangbajing extensive air shower array from October 2000 to September 2001, the TeV gamma rays from the shell-like SNR G40.5-0.5 direction were detected. A region with the highest excess of 4.4σ was found using two dimensional analysis method.The position of EGRET unidentified source GeV J1907+0557 is near the centrer of the region. 相似文献
979.
Zhi-juan Zhang Chun-xia Wang Yong Wang Shu-hua Niu Chang-gui Liu De-gang Fu 《化学物理学报(中文版)》2007,20(6):796-800
"?Fluorescence spectra of naked gold nanoparticles, triphenylphosphine stabled gold nanoparticles, and 3-mercaptopropionic acid substituted gold nanoparticles were studied. It was found that fluorescence intensities of gold nanoparticles were highly sensitive to surface molecules. The fluorescence quenching effect of these gold nanoparticles on CdSe nanoparticles was also investigated. This quenching effect was related to the overlap degree between the absorption spectra of gold nanoparticles and the emission spectrum of CdSe nanoparticles, and was surface-dependent as well. " 相似文献
980.
Enhancement of Kerr nonlinearity with vanishing absorption in a tripod scheme 总被引:1,自引:0,他引:1 下载免费PDF全文
The giant enhancement of Kerr nonlinearity in a four-level tripod
type system is investigated theoretically. By tuning the value of
the Rabi frequency of the coherent control field, owing to the
double dark resonances, the giant-enhanced Kerr nonlinearity can be
achieved within the right transparency window. The influence of
Doppler broadening is also discussed. 相似文献