Thermally stimulated depolarization measurements on NaF:02-, NaCI:S2-.and KC1:S2-

In NaCl:S^2-, KC1:S² and NaF:0^2-(i) optical absorption and emission spectra and (ii) electric conductivity measurements show that after suitable heat treatment the bivalent anion impurities are paired with anion vacancies. Conventional dielectric absorption measurements and sensitive measurements of thermally stimulated depolarizing (t. s. d.) currents (ionic thermocurrent) have failed to detect the presence of bivalent anion-anion vacancy dipoles in these crystals. We suggest that derealization or sharing of the electron of the bivalent impurity ion, possibly with the vacancy, considerably reduces the dipole moment.     

Rotation-vibration spectrum of HT: Line position measurements of the 1-0, 4-0, and 5-0 bands

Optoacoustic techniques have been used to determine the line positions of the 1-0 fundamental and 4-0 and 5-0 overtones of the HT (¹H³H) molecule with an accuracy of better than 0.01 cm⁻¹. Comparison with line positions predicted from ab initio calculations that include adiabatic, relativistic, radiative, and nonadiabatic corrections shows disagreement outside of the experimental uncertainties.     

Geometry, Electronic Structure, and Related Properties of Dye Sensitizer:3,4-bis[1-(carboxymethyl)-3-indolyl]-1H-pyrrole-2,5-dione

运用密度泛函理论中的杂化泛函B3LYP研究了太阳能电池染料敏化剂3,4-二-[1-(羧甲基)-3-吲哚]-1H-吡咯-2,5-二酮(BIMCOOH)的几何结构、电子结构、极化率和超极化率,并用半经验量子化学方法ZINDO-l和含时密度泛函理论(TDDFT)研究了电子吸收谱．自然键轨道方法的研究结果表明,布居于二酮、吲哚和乙酸基团的自然电荷分别为-0.15e、-0.29e、0.44e．计算的各向同性极化率、极化率各向异性不变量和平均超极化率分别是305.4、188.3、1155.4 a.u.．基于TDDFT的计算结果和实验结果的定性符合指认了在可见和近紫外区的吸收属于∏→∏*跃迁,并且TDDFT的计算结果显示,第9～11个激发态的跃迁与光诱导分子内电荷转移过程有关．对电子结构和紫外-可见吸收谱的分析表明,吲哚基团对光电转换过程的敏化起主要作用,发生于染料敏化剂BIMCOOH和TiO2电极界面之间的电荷转移是由染料分子激发态向半导体导带的电子注入过程．     

Fluorescent aggregates of 1-(p-butyloxyphenyl)-4-(p-cyanophenyl)buta-1E,3E-diene: temperature sensing and photoimaging applications

The use of fluorescent solid films of a 1-(p-butyloxyphenyl)-4-(p-cyanophenyl)buta-1E, 3E-diene as an efficient temperature sensor is described. The fluorescence changes in these films are proposed to occur due to a reversible temperature-dependent variation in its monomer-aggregate ratio. Photoisomerization of the butadiene chromophore in solid films was observed to occur only at elevated temperatures (> 120^∘C), making the material also useful for reversible photochemical generation of fluorescence patterns with nondestructive readout properties.     

A Quantum Monte Carlo Study on Mixed-Spin Chains of 1/2-1/2-1-1 and 3/2-3/2 -1-1

The ground-state and thermodynamic properties of quantum mixed-spin chains of1/2-1/2-1-1and 3/2-3/2-1-1are investigated by a quantum Monte Carlo simulation with the loop-cluster algorithm. For 1/2-1/2-1-1 chain, we find it has two phases separated by an energy-gap vanishing point in the ground-state. For 3/2-3/2-1-1 chain, the numerical results show two energy-gap vanishing points isolated by different phases in its ground-state. Our calculations indicate that all these ground state phases can be understood by means of valence-bond-solid picture, and the thermodynamic behavior at finite temperatures is continuous as a function of parameterα=J2/J1.     

A Quantum Monte Carlo Study on Mixed-Spin Chains of 1／2-1／2-1-1 and 3／2-3／2-1-1

The ground-state and thermodynamic properties of quantum mixed-spin chains of 1/2-1/2-1-1 and 3/2-3/2-1-1 are investigated by a quantum Monte Carlo simulation with the loop-cluster algorithm. For 1/2-1/2-1-1 chain, we find it hastwo phases separated by an energy-gap vanishing point in the ground-state. For 3/2-3/2-1-1 chain,the numerical results show two energy-gap vanishing points isolated by different phases in its ground-state. Our calculations indicate that all these ground state phases can be understood by means of valence-bond-solid picture, and the thermodynamic behavior at finite temperatures is continuous as a function of parameter α=J2/J1.     

Author Index,Volume 43, Numbers 1-12, 2000

Radiophysics and Quantum Electronics -     

439-1439-1439-1transitions: model-independent bounds on invariant form factors

In this note we report on some model-independent bounds involving the transition form factors for Ω_b → Ω_c and Ω_b → Ω _c ^* transitions and the nonperturbative matrix elements of the Ω_b system. The bounds are derived by using operator product expansion (OPE) methods in heavy quark effective theory.     

Tables of Contents,Volume 43, Numbers 1-12, 2000

Radiophysics and Quantum Electronics -     

Hidden 467-1467-1467-1

Letn be an integer. Denote byA _n one of the following two graded vector spaces: (a) the space of all multilinear Poisson polynomials of degreen (with a grading described below), or (b) the cohomology of the space of alln-uples of complex numbersz ₁,..., z_n withz _iz_j forij. We prove that the natural action of _n on each homogeneous component ofA _n can be extented to an hidden _n+1 -action and we compute the corresponding character (the _n -character being already given by Klyaschko and Lehrer-Solomon formulas).