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 electromigration failure distribution for fine-line interconnects is unknown, but expected to be strongly affected by microstructure. Results from tests on lines with controlled grain sizes and distributions of grain sizes argue for a series model of failure elements in fine lines. A new statistical model of elect…
A single-band model and a three-band model which consists of one σ→σ* and two major π→π* electronic transitions were developed for understanding the refractive index dispersions of uniaxial liquid crystals. This information is particularly important for liquid-crystal-display applications. By comparing the three-band…
Relaxation dynamics of the n=1 and 2 image-potential states on Ag(100) and Ag(111) are investigated using femtosecond pump-probe techniques. Transient two-photon photoemission measurements are performed using femtosecond pulses with photon energies of 2.00 and 4.00 to 4.35 eV, generated via self-phase modulation and f…
The Adam–Gibbs theory of relaxation for glass-forming liquids is based on an ensemble of independent and equivalent cooperatively rearranging regions (CRR’s). In this work we extend the Adam–Gibbs theory by incorporating the mutual interactions between the CRR’s. This is done by the method of the coupling scheme in wh…
Absolute photoabsorption cross sections of free neutral sodium clusters containing from N=3 to 40 atoms are presented. Investigation of a wide continuous range of cluster sizes reveals the size development of the photoabsorption behavior. In the smallest clusters the absorption is moleculelike. A transition to collect…
Graphitization of amorphous carbon has been studied at high static pressures up to 15 GPa and high temperatures up to 1300 °C, primarily under diamond-stable conditions. Upon heating at 2 GPa, amorphous carbon turns into graphite at ∼900 °C. The temperature for the graphitization decreases with increasing pressure and…
We have carried out a realistic ab initio calculation of the contribution of cubic anharmonicity to the inverse lifetime \ensuremath{\Gamma} and the frequency shift \ensuremath{\Delta} of phonons in silicon. The cubic coupling constants for phonons throughout the Brillouin zone are obtained from an anharmonic Keating-…
Space-charge-limited-current conduction is the dominant charge transport mechanism in electrodeposited films of cuprous oxide; the measurement of current-voltage characteristic and temperature dependence of conductivity, while charge transport is space-charge limited, is used to evaluate the electrical parameters of t…
The total measured ac conductivity σ(ω)m of lightly doped polypyrrole films has been measured in the frequency range 100 Hz–10 MHz and in the temperature range 77–350 K. In the low-temperature region the measured ac conductivity is almost independent of temperature but shows a strong dependence on frequency and can be…
A generalized Brownian motion simulation technique developed by Kim and Torquato [J. Appl. Phys. 68, 3892 (1990)] is applied to compute ‘‘exactly’’ the effective conductivity σe of heterogeneous media composed of regular and random distributions of hard spheres of conductivity σ2 in a matrix of conductivity σ1 for vir…
We have studied the vibrational and electronic structure and the elementary charged excitations of poly(1,4-phenylene-vinylene) and a series of its (2,5-alkoxy) derivatives including poly(2,5-methoxy-PV), poly(2,5-hexoxy-PV), poly(2,5-octoxy-PV), and poly[2-methoxy,5-(2'ethyl-hexoxy)-PV] by absorption, photoinduced (P…
ZnO:Al films were deposited on (12̄10) oriented sapphire substrates heated up to 400 °C by rf magnetron sputtering from a ZnO target mixed with Al2O3 of 2 wt%. Films deposited on a substrate heated to a temperature in the range 50–350 °C were (0001) oriented single crystals but those grown at 400 °C consisted of cryst…
Molecular dynamics calculations are performed that simulate the diffusion of penetrant molecules through an amorphous polymer. For the polymer and the penetrant molecules, model potentials are chosen that approximate polyethylene and methane, respectively. The simulations extend over several hundred picoseconds. The r…
Phonon-dispersion curves, lattice mode Gr\"uneisen parameters, and the coefficients of thermal expansion are calculated for Si and C within a tight-binding model. The results are in good agreement with experimental data. The origin of the negative thermal expansion in Si is examined, and we find that the different the…
A molecular-dynamics simulation has been carried out for liquid and amorphous selenium in the temperature range 350--720 K. The simulation used 64 atoms in a constant-volume simple cubic cell, and the energy surfaces and forces were calculated using the density-functional formalism, with a local-density approximation…
Pseudomonas aeruginosa elastase (PAE) is a zinc metalloprotease with 301 amino acids. We have crystallized and solved the three-dimensional structure of PAE, using data to 1.5-A resolution, and have refined the native molecular structure to R = 0.188. The overall tertiary structure of the PAE molecule is similar to th…
First direct experimental evidence for clathrate structures of (H2O)nH+ (n=20,21) is reported based on a technique allowing the number of nonhydrogen-bonded surface hydrogens to be counted. Neutral clusters (H2O)n⋅((CH3)3N)m, prepared in a pulsed nozzle supersonic expansion, are ionized by multiphoton ionization and i…
The stress in diamond films prepared by microwave plasma CVD was investigated as a function of methane concentration (0.2%–3.0%) and deposition temperature (600–900 °C). Tensile and compressive total (thermal and intrinsic) stress were observed, depending on the deposition conditions. The thermal stress is compressive…
The electron localization is increased with increasing one dimensionality of a quasi-one-dimensional disordered system (quasi-1D-DS). This concept is tested by studying the electron localization in the methyl ring-substituted derivative of polyaniline (PAN), poly(o-toluidine) (POT). The studies include the measurement…
[Fe(ptz)6](BF4)2 (ptz=1-propyltetrazole) is an Fe(II) spin crossover system, which shows a light-induced low-spin (1A1)→high-spin (5T2) conversion below ∼50 K by irradiating into the spin allowed 1A1→1T1 d–d absorption band. This phenomenon, known as light-induced excited spin state trapping (LIESST), is reversible, a…