Chain length dependence of high magnetic field effects on lifetimes of radical ion pairs linked by a methylene chain: interpretation by both spin—lattice and spin—spin relaxations

High magnetic field dependence of lifetimes of methylene-chain-linked radical ion pairs (RIPs) generated by photo-induced electron transfer from zinc(II) porphyrin to viologen has been confirmed in aqueous acetonitrile using a pulse magnet-laser flash photolysis apparatus. In the case of a short methylene chain it was first revealed that the dependence was definitely different from that for a long one, and was characterized by a reversal in the dependence. In addition to a long lifetime independent of the magnetic field, RIP in fields above 7T exhibited short lifetimes that depended on the field. These results were interpreted not only by spin-lattice (longitudinal) relaxation but also by spin-spin (transverse) relaxation in RIPs.     

Ce填充分数对p型CeyFe1.5Co2.5Sb12化合 物热电传输特性的影响

研究了Ce填充分数对富Co组成的填充式skutterudite化合物：Ce_yFe_{1.5Co2.5Sb12(y=0—0.46)的热电传输特性的影响.CeyFe1.5Co2.5Sb12有现为p型传导.霍尔系数ＲH随Ce填充分数的增加而增加,空穴浓度p和电导率σ随Ce填充分数的增加而减少.泽贝克 系数α随Ce填 关键词： 填充分数 载流子浓度 电导率 泽贝克系数 晶格热导率}     

Instability of a system and its estimation in terms of the hybrid density functional theory method: a magnetic effective density functional (MEDF) approach

Potential curves and high and low spin energy gaps for radical clusters were calculated by spin polarized molecular orbital methods. Through-space effective exchange integrals (J _ab) and relative energies of spin projected low spin states by post-Hartree-Fock (HF) calculation were reproduced by the hybrid density functional theory (DFT) method. The hybrid parameters that could reproduce post-HF values such as UCCSD(T)'s for each model had close relations with the instabilities of those systems. Information entropy and related chemical indices were used to estimate the magnitude of the instabilities. A magnetic effective density functional (MEDF) scheme for spin clusters was proposed for practical computation of J _ab values in molecular magnetic materials.     

Skutterudite化合物FexCo4-xSb12的固相反应合成及热电特性

用固相反应法在900—1000K温度范围和x＝0—10的组成范围内合成了单相Co基Skutterudite化合物Fe_xCo_4-xSb₁₂,并对化合物的结构和热电特性影响进行了研究.结果表明：化合物的晶格常数随Fe置换量的增加线性增加,载流子浓度和电导率随Fe置换量的增加而增加,Seebeck系数随Fe置换量的增加而减少,Seebeck系数的峰值温度随Fe置换量的增加向高温方向移动,晶格热导率由于Fe的置换而大幅度下降,并随Fe的置换量的增 关键词：     

Fe对CeyFexCo4-xSb12化合物结 构和热电传输性质的影响

用熔融法合成了单相填充式skutterudite化合物Ce_yFe_xCo_4-x Sb₁₂(x=0—3.0,y=0—0.74).对Ce的填充范围,置换Fe原子对化合物的结 构及热电传输特性的影响进行了研究,Ce的填充分数随Fe含量的增加而线性增加,当Fe含量 大约为3时,Ce的填充分数达到0.74.晶格常量a随Fe含量的增加而增加,Ce的填充使晶格常 量进一步增加.当Ce填充分数达到饱和状态时,Ce_y 关键词： 填充式skutterudite化合物 晶体结构 热电传输性质     

Fe对CeyFexCo4-xSb12化合物结构和热电传输性质的影响

用熔融法合成了单相填充式skutterudite化合物CeyFexCo4 -xSb12 (x =0— 3 0 ,y =0— 0 74) .对Ce的填充范围 ,置换Fe原子对化合物的结构及热电传输特性的影响进行了研究 ,Ce的填充分数随Fe含量的增加而线性增加 ,当Fe含量大约为 3时 ,Ce的填充分数达到 0 74.晶格常量a随Fe含量的增加而增加 ,Ce的填充使晶格常量进一步增加 .当Ce填充分数达到饱和状态时 ,CeyFexCo4 -xSb12 化合物表现为 p型传导 ,霍尔系数RH 随Fe含量的增加而降低 ,空穴浓度 p和电导率σ随Fe含量的增加而增加 ,泽贝克系数α随Fe含量的增加而降低 .当Fe/Co比大约为 1 5 / 2 5时 ,CeyFexCo4 -xSb12 的晶格热导率 (κl)达到最小值 .     

Detection of highly oriented aggregation of L-glutamic acid-derived lipids in dilute organic solution

Aggregation structures in organic gels and xerogels formed from L-glutamic acid-derived lipids were investigated by scanning and transmission electron microscopies, X-ray analyses, and 1H NMR and IR spectroscopic methods. These analyses showed that the gels were produced through the formation of highly oriented aggregates based on a single layer and a remarkable development of their fibrous morphology. We also describe how the critical aggregation concentration can be observed at a concentration below the critical gel concentration by using a dye-complexation method with a cyanine dye, NK-77.     

Theoretical investigation of magnetic parameters in two-dimensional sheets of pure organic BEDT-TTF and BETS molecules by using ab initio MO and DFT methods

The effective exchange integrals (J _ab(M)) between two cation radicals of title compounds in the Heisenberg model were calculated by ab initio molecular orbital (MO) and density functional theory (DFT) methods, together with hybrid DFT methods. The J _ab(D) values between two dimer mono-cation radicals were also estimated assuming J _ab(D) = J _ab(M)/2. It is found that the spin lattice obtained by the ab initio method is square planar and linear in BEDT-TTF and BETS planes, respectively, although other previous calculations show that spin lattice in the BEDT-TTF plane is a triangular one. The J _ab and overlap integrals (s_ab ) values by the ab initio methods were used to determine transfer integral (t_ab ) and Coulomb repulsion (U_cff ) parameters of the Hubbard model, which were compared with those of the previous results. Implications of the calculated results are discussed in relation to the spin-mediated mechanism for superconductivity.     

Solvent effects on the intrinsic enhancement factors of the triplet exciplex generated by photoinduced electron transfer reaction between eosin Y and duroquinone

The spin dynamics of the duroquinone anion radical (DQ^?-) generated by photoinduced electron transfer reactions from triplet eosin Y (³EY^2-) to DQ have been studied by using transient absorption and pulsed EPR spectroscopy. Unusual net-absorptive electron spin polarization plus net-emissive polarization were observed, suggesting the production of the triplet exciplex or contact radical pair as the reaction intermediate. The kinetic parameters and intrinsic enhancement factors of the electron spin polarization were determined in various alcoholic solvents. The net-absorptive electron spin polarization was also observed in ethanol-water mixed solvents. The solvent effects on the radical yield are analysed on the basis of a stochastic Liouville equation established for the magnetic field effects on the radical yield. The zero-field splitting constants of the triplet exciplex are estimated from the solvent viscosity dependence of the enhancement factors due to spin-orbit coupling induced depopulation of the reaction intermediate.