Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
The electrical properties of the charge-density-wave compound blue bronze (${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$) have been investigated at several temperatures around T=4.2 K. A nonlinear current-voltage relationship was observed with an increase of the conductance by six orders of magnitude above a well-defined t…
A surface-potential stabilization technique is described which permits one to take vibrational spectra of excellent quality with high-resolution electron-energy-loss spectroscopy on insulating samples of very different types, such as ionic insulators and polymers. Induced surface conductivity and enhanced secondary-el…
We have measured the temperature dependence of the low-field, linear conductivity and the high-field, nonlinear conductivity resulting from charge-density-wave (CDW) motion in ${\mathrm{K}}_{0.30}$${\mathrm{MoO}}_{3}$, ${\mathrm{TaS}}_{3}$, and (${\mathrm{TaSe}}_{4}$${)}_{2}$I at zero frequency. In ${\mathrm{K}}_{0.30…
We compute the dynamic resistivity ρ≡ρ1+iρ2 for a model of heavily n-doped semiconductors with special regard to transparent and heat-reflecting In2O3:Sn films. The Sn impurities are ionized and the ensuing electrons occupy part of the In2O3 conduction band as a free-electron gas (with plasma energy ℏωp). We use pseud…
The relationship between high order J-multiplet splitting moments and crystal field invariants is investigated. Expressions for corrections due to crystal field intermultiplet coupling are obtained. The formalism is applied to determine the crystal field parameters of lanthanide ions in cubic sites from ground multipl…
A theoretical model, based on the bond-polarizability concept, is presented for the calculation of the Raman scattering intensities for crystals. The bonds in a unit cell are classified into groups in which the individual bond Raman polarizabilities are equivalent. The Raman polarizability of the crystals is expressed…
Homogeneous melt-quenched (${\mathrm{Ge}}_{0.99}$${\mathrm{Sn}}_{0.01}$${)}_{\mathrm{x}}$S $_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ glasses in the glass-forming range 0<x<0.43 have been studied by scanning calorimetry, Raman, and M\"ossbauer spectroscopy. At the stoichiometric composition x=(1/3), two well-define…
Microcrystallites of the layered semiconductor ${\mathrm{PbI}}_{2}$ were prepared in colloidal form and examined by transmission electron microscopy and optical absorption. The crystallites have lateral dimensions grouped around 12, 18, and 29 A\r{} corresponding to close-packed clusters with bulk ${\mathrm{PbI}}_{2}$…
The static properties of spin density waves (SDW) in (TMTSF) 2 PF 6 were determined by a precise analysis of 1 H-NMR lineshape in the low temperature SDW state. The observed angular dependence of lineshape was well reproduced by a picture of incommensurate sinusoidal SDW's. The wave number was found to be (0.5, 0.24±0…
Calculation of the lattice dynamical properties of black phosphorus, which is a narrow-gap covalent semiconductor with a layered structure, based on the valence force field model is presented. The results obtained are in good agreement with the experiments, except for infrared active optical modes. The results are dis…
A fundamental aspect in the study of the charge–transfer (CT) organic crystals with ionic or partially ionic ground states is the investigation of the spectroscopic effect of the electron–molecular vibration coupling. 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (TCNQF4), an electron acceptor much stronger tha…
A new model is presented that makes it possible to determine the degree of electron transfer in alloys from measurements of the Auger parameter. This approach is superior to the use of core-ionization-energy shifts in conjunction with a potential model. The Auger parameter does not depend on any reference level, where…
In this paper we examine the following problem: Given a band of localized states randomly distributed in space and obeying a distribution function for energies, how does an excitation diffuse as a function of time and initial energy? This question is encountered in luminescence, photoconductivity, and transport work i…
The macroscopic polarizability of silicon is calculated from first principles as a function of the lattice distortion induced by a zone-center optical phonon. The electronic response to the electric field is dealt with by dielectric matrices, and the lattice distortion is treated by frozen-phonon techniques. Our resul…
A comprehensive development of the charge-transfer theory of surface enhanced Raman scattering (SERS) is presented. We incorporate the Herzberg–Teller mixing of zero-order Born–Oppenheimer electronic states by means of vibronic interaction terms in the Hamiltonian. This is similar to the theory of Tang and Albrecht12…
The dispersion relations are solved for waves guided by a thin, lossy metal film surrounded by media of dielectric constant ${\ensuremath{\epsilon}}_{1}$ and ${\ensuremath{\epsilon}}_{3}$. For symmetric structures (${\ensuremath{\epsilon}}_{1}$=${\ensuremath{\epsilon}}_{3}$), there are the usual two Fano modes whose v…
The recombination kinetics of charged carriers in GaAs have been investigated on a picosecond time scale. A pump-probe technique was used to measure reflectivity changes as a function of time up to 900 ps. Initially, (1.2±0.2)×1020 carriers/cm3 were excited into the conduction band. The decay curve indicated dominance…
The authors prove a theorem that relates the energies of unit transmission through a finite, repeated one-dimensional structure to the band structure of the associated infinite lattice formed by periodic repetition of the one-dimensional structure.
We have experimentally discovered that in a nematic liquid crystal subjected to an ac electric field, the first convective structure at low frequencies is in fact a set of oblique rolls, contrary to the accepted picture. We show that it is a new structure with a helical flow motion, and thus lower in symmetry than the…
The origins and development of the concept of carbonaceous mesophase, as derived from discotic aromatic nematic liquid crystals, enable applications to be made to industrial processes. The world availability of pitch materials is such that there is an abundance of pitch which produces cokes of little commercial value.…