First-principles study on electronic structures and absorption spectra for BaWO4 crystal containing barium vacancy

The electronic structures, dielectric function and absorption spectra for the perfect BaWO₄ (BWO) crystal and the BWO crystal containing barium vacancy () have been studied using density functional theory code CASTEP with the lattice structure optimized. The results indicate that the optical properties of the BWO crystal exhibit anisotropy and its optical symmetry coincide with lattice structure geometry of the BWO crystal. For the BWO crystal containing , there exhibit four absorption bands peaking at 0.71 eV (1751 nm), 1.85 eV (672 nm), 3.43 eV (362 nm) and 3.85 eV (322 nm), respectively. The origins of the 370 nm absorption band should be related to the .     

Photoabsorption cross section of C60 thin films from the visible to vacuum ultraviolet

Absolute photoabsorption cross sections of C₆₀ thin films are determined in the hν range from 1.3 to 42 eV by using photon attenuation method. The spectrum shows a prominent peak of 1180 Mb at 22.1 eV with several fine structures due to single-electron excitation similarly to the case of C₆₀ in the gas phase. The complex refractive index and complex dielectric function are calculated up to 42 eV through the Kramers-Kronig analyses. From the present data of C₆₀ thin films the cross section curve of a molecular C₆₀ is calculated with an assumption that the polarization effect of surrounding C₆₀ molecules can be expressed by the standard Clausius-Mossotti relation. The spectrum thus obtained shows an excellent agreement with that of C₆₀ in the gas phase measured independently.     

论宋代咏物词的两大创作范式

文章把宋代咏物词分为两大创作范式。第一种范式重在摹写物态,具体写法又有状物与体物二种。状物者力求穷形尽相,即尽物之态;体物者力求潜心于物,以穷物之情。第二种范式重在即物言情,具体也可分为两种,一种是托物言志,即借物之特征以寄寓某种人格精神;另一种为因物寄情,即借客观事物作为引发情感的触媒。     

The 3D Amlouk-Boubaker expansivity-energy gap-Vickers hardness abacus: A new tool for optimizing semiconductor thin film materials

In this study, we propose a new abacus based on a synthetic parameter: the Amlouk-Boubaker expansivity ψ_AB. This abacus gathers the band gap energy E_g., Vickers microhardness and ψ_AB. This abacus is presented as a guide to evaluate and optimize photovoltaic-thermal semiconductor thin films thermal and optical performance. The definition of this parameter ψ_AB takes into account the thermal diffusivity and the optical effective absorptivity of the material. As a first approximation, this parameter, could be considered as a 3D velocity of the transmitted heat inside the material.New functional semiconductor materials have been significantly classified using this abacus.     

Determination of optical constants of thin films from transmittance trace

A simple method is depicted in this communication to determine the optical constants of transparent thin films from transmittance versus wavelength traces, showing no fringes, for evaluating thickness. The strength of this technique is apparent when applied to Zn_1 − xMg_xO films.     

Optical constants and band edge of amorphous zinc oxide thin films

The optical characteristics of amorphous zinc oxide (a-ZnO) thin films grown by radio frequency reactive magnetron sputtering on various substrates at temperature < 325 K have been investigated in the spectral range 340-1600 nm. The amorphous nature of the a-ZnO films was verified by X-ray diffraction and the optical constants were obtained by analysis of the measured ellipsometric spectra using the Cauchy-Urbach model. Refractive indices and extinction coefficients of the films were determined to be in the range 1.67-1.93 and 3.9 × 10^− 8-0.32, respectively. The band edge of the films on Si (100) and quartz has been determined by spectroscopic ellipsometry (3.39 ± 0.05 eV) and spectrophotometric (3.35 ± 0.05 eV) methods, respectively. From the angle dependence of the p-polarized reflectivity we deduce a Brewster angle of 60.5°. Measurement of the polarized optical properties shows a high transmissivity (81%-99%) and low absorptivity (< 5%) in the visible and near infrared regions at different angles of incidence. Also, we found that there was a higher absorptivity for wavelength < 370 nm. This wavelength, ∼ 370 nm, therefore indicated that the band edge for a-ZnO thin films is about 3.35 eV.     

二晏研究百年回顾与展望

百年来的二晏研究所取得的成果,不管是从数量上看还是从质量上看都是引人注目的,这些成果主要表现在二晏生平思想的研究和二晏文学作品的研究;然而其依然在六个方面存在着遗憾和不足。为了更好地推动下一步的更深入一层的研究,因此很有必要对二晏研究进行回顾和总结。     

论"温韦"的词风差异及其形成原因

温庭筠、韦庄同属花间词派作家,被人们并称为“温韦”,实际上他们的作品代表着两种不同的风格。论述了两人词风的差异及其形成原因。