Equation of state of boron subarsenide B12As2 to 47 GPa

Compressibility of boron subarsenide B₁₂As₂ has been studied by synchrotron X-ray diffraction up to 47?GPa at room temperature in a diamond anvil cell using Ne pressure transmitting medium. A fit of experimental p–V data by Vinet equation of state yielded the bulk modulus of 150(4) GPa and its first pressure derivative of 6.4(3). No pressure-induced phase transitions have been observed.     

Ionicities of boron-boron bonds in B(12) icosahedra

First-principles calculations are used to investigate ionicities of boron-boron bonds in B(12) icosahedra. It is observed that the geometrical symmetry breaking of B(12) icosahedra results in the spatial asymmetry of charge density on each boron-boron bond, and further in the ionicity of B(12) icosahedra. The results calculated by a new ionicity scale, a population ionicity scale, indicate that the maximum ionicity among those boron-boron bonds is larger than that of boron-nitrogen bonds in the III-V compound cubic BN. It is of great importance that such an ionicity concept can be extended to boron-rich solids and identical atom clusters.     

Photolysis of compounds with P−I and As−I bonds

Detailed experimental investigations are reported of the parameters of lasing on the transition²P_1/2→²P_3/2, λ = 1.3 μm of atomic iodine upon photodissociation of the molecules (CF₃)₂AsI and (CF₃)₂PI. The light source was an IFP-5000 flash lamp. The experimental data are used to determine the sequence of the basic reactions that accompany the photolysis of the molecules (CF₃)₂AsI and (CF₃)₂PI and to determine the energy parameters of the generated radiation.     

Erratum to: Multiple magnetic transitions in single crystals of Ce12Fe57.5As41and La12Fe57.5As41

Commercial computers based on electronic logic devices have brought great changes to the world. However, traditional electronic devices are suffering from numerous technical challenges in their attempts to continue to satisfy Moore's law. Alloptical logic devices, as promising successors to their electronic counterparts, have become a major focus of optics research. In this paper, we provide a review of current all-optical logic devices. The logic gates in these devices, which are described in the first part of the review, are divided into five categories based on the different principles used in their realization. Complex optical devices with various functions and reconfigurable devices are summarized in the next section. In the final part of this paper, we discuss some of the previous works on all-optical integrated chips with specific functions. This review will provide a complete technological roadmap for all-optical devices and aims to be helpful in possible future developments in this growing field.     

B12@B12@B60 and B12@(B12)12 giant clusters with doping atoms observed by high-resolution electron microscopy

B₁₂@B₁₂@B₆₀ and B₁₂@(B₁₂)₁₂ giant clusters consisting of B₁₂-based icosahedral clusters in B₁₀₅Al_2.6Cu_1.8 and B₅₆Y crystals were directly observed by high-resolution electron microscopy, image calculation and crystallographic image processing. Doping atom positions such as Al, Cu, and Y were also detected in the high-resolution images. The present work indicates that the cluster arrangements with light element of boron could be detected by using the crystallographic image processing technique.     

Melting of B12P2 boron subphosphide under pressure

Melting of boron subphosphide (B₁₂P₂) to 26?GPa has been studied by in situ synchrotron X-ray powder diffraction in a laser-heated diamond anvil cell, and by quenching and electrical resistance measurements in a toroid-type high pressure apparatus. B₁₂P₂ melts congruently, and the melting curve has a positive slope of 23(6)?K/GPa. No solid-state phase transition was observed up to the melting in the whole pressure range under study.     

Electronic Structure of InCo2As2 and KInCo4As4: LDA + DMFT

JETP Letters - A comparative analysis of the electronic structure obtained in the DFT/LDA and LDA + DMFT approaches of the possible isostructural analogues of iron superconductors InCo2As2 and...     

Multiphonon absorption in As2S3As2Se3 glasses

Multiphonon absorption in As₂S₃ and As₂Se₃ glasses is well explained by a molecular model in terms of combination bands of high frequency vibrational modes of pyramidal AsY₃ and bent AsYAs groups (Y = SorSe). Multiphonon absorption coefficients in mixed As₂S₃As₂Se₃ glasses are nearly additive in terms of the pure components, suggesting a high degree of non-random mixing.     

Frequency dependent conductivity in As2Se3 and As2Se3 + 15% Sb

Dc and ac measurements were performed on bulk samples of undoped and 15% Sb doped As₂Se₃ as a function of temperature (90–400 K) and frequency (10³–10⁶ Hz). The dc results show an activated conductivity dependence on temperature with an activation energy of 0.8 eV above room temperature. The ac results give a temperature dependent frequency exponent s. The temperature dependence of G _ac is discussed in terms of the mechanisms involved. Results are compared with the predictions of the Quantum Mechanical Tunnelling and Correlated Barrier Hopping models. It is found that doping increases the dc conductivity but has no effect on the ac conductivity.     

稀土区奇奇核πh1／2×vi13／2带B（M1）／B（E2）比值增强特性

在稀土区奇奇核πh1／2×vi13／2转动带中，系统地观测到随转动频率或角动量增加，B(M1)／B(E2)曲线表现出所谓parabola-1ike形状，即在增加到某一转动频率或自旋后，B(M1)／B(E2)比值快速增强。基于推转模型和粒子转子模型关于奇奇核二准粒子转动带磁偶极约化跃迁几率的描述，对稀土区双奇核的这一行为进行了讨论。指出该现象的发生与vi13/2准中子转动顺排特性密切相关。B(M1)／B(E2)比值在接近第二带交叉(即BC准中子对顺排)的较高频率处的增强效果，可以理解为主要来源于带交叉引起的波函数中混合四准粒子成分的结果。通过对B(M1)/B(E2)比值的增强效果发生在较低频率处的分析，对稀土区奇奇核πh1／2×vi13／2带角动量耦合图像有了进一步认识。It is systematically observed that the B(M1)/B(E2) plots with the increasing of rotational frequency, behaves as a so called parabola like shape in the π h11/2 νi13/2 bands of rare earth doubly odd nuclei (i.e., the B(M1)/B(E2) ratios increase rapidly after a certain rotational frequency). Such a phenomenon is discussed based on the formula of magnetic dipole reduced transition probability deduced from the Cranking Shell Model and Particle Rotor Model respectively. It is pointed out that, the occurrence of this behavior is closely related to the alignment nature of the νi 13/2 quasineutron. The increasing of B(M1)/B(E2) occurring at large frequency approaching the second BC crossing can be understood as mainly resulted from the mixing of wave function with the 4 quasiparticle band caused by the band crossing. Insight into the angular momentum coupling scheme between the quasiparticles and collective core in the πh11/2 νi 13/2 structures of rare earth doubly odd nuclei is gained by analyzing the increasing behavior of B(M1)/B(E2) ratios occurring at low rotational frequency.     

Comparative study of electronic structure of new superconductors (Sr, Ca)Pd2As2 and related compound BaPd2As2

This paper presents the comparative study of LDA calculated electronic structure of new isostructural to iron based systems superconductors (Sr, Ca)Pd₂As₂ with T _c about 1 K and similar but structurally different system BaPd₂As₂. Despite chemical formula looks similar to iron superconductors and even main structural motif is the same—layers of Fe square lattices, electronic structure of (Sr, Ca)Pd₂As₂ and BaPd₂As₂ differs from Fe (As, Se)-HTSC completely. All these systems have essentially three dimensional Fermi surfaces in contrast to Fe (As, Se) materials. The Fermi level is crossed by low intensive tails of Pd-4d and As-4p states. However, (Sr, Ca)Pd₂As₂ and BaPd₂As₂ materials have rather well developed peaks of Pd-4d (x ² ? y ²) band. Thus, by doping of about 2 holes per unit cell one can increase density of states at the Fermi level by a factor about 2.5. Since experimentally these compounds were found to be simple BCS superconductors the hole doping may considerably increase T _c . LDA calculated total densities of states at the Fermi level for stoichiometric systems perfectly agree with experimental estimates signifying rather small role of electronic correlations.     

A DFT study on the formaldehyde (H2CO and (H2CO)2) monitoring using pristine B12N12 nanocluster

The interaction between formaldehyde monomer (H₂CO) as well as dimer ((H₂CO)₂) and pristine B₁₂N₁₂ nanocluster is investigated at B3LYP/6-311++G(d,p) level of theory. It is found that in contrary to the pristine boron nitride nanotube and nanosheet, formaldehyde adsorption induce considerable variation in the electronic properties of the B₁₂N₁₂ nanocluster. Also it is shown that the pristine B₁₂N₁₂ cluster could adsorb up to four monomer and three dimer of formaldehyde molecules in which the HOMO–LUMO gap decreased about 38–55%. Since the conductivity of the B₁₂N₁₂ nanocluster changes by the adsorption of formaldehyde molecules, the presence of this toxic gas could be detected. The Bader theory of atoms in molecules (AIM) is also applied to analyze the interaction of formaldehyde with nanocluster. It is suggested pristine B₁₂N₁₂ nanocluster could be a promising candidate for detecting formaldehyde molecule. The results indicate that B₁₂N₁₂ may be a promising chemical sensor for detection of formaldehyde molecule.     

Morse Franck-Condon Factors and R-Centroids for Some Lyman Bands of H2, HD and D2

Using new rotational and vibrational constants, Morse Franck-Condon factors and r-centroids are computed for 108 Lyman bands of astrophysical importance H₂, HD and D₂ molecules. Experimental oscillator strengths conjoint with Morse Franck-Condon Factors for six Lyman bands of molecular hydrogen yield radiative lifetimes for v = 0–5 levels of the B 1σ_u ⁺ state that are inconsistent with the experimental lifetime measurements. The limitation of analytic Morse function in the region of small internuclear separation for the B 1σ_u ⁺ state of H₂ is discussed. The r-centroids (r_v′v″) are found to increase with frequencies of the Lyman bands of H₂, HD and D₂. For a sequence, Δr = r_{v′+1,v″+1} - r_v′v″ is constant. A comparison of r_v′v″ values of the Lyman bands shows that r_v′vv″ of the band (v′v″) increases in going from H₂ to D₂.     

Fourier Transform Spectroscopy of the O(2) Herzberg Bands

From absorption spectra obtained at high resolution by coupling a Fourier transform spectrometer to a long-path multiple reflection cell [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] the intensities of the O(2) Herzberg bands (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), A'( 3)Delta(u)-X(3)Sigma(-)(g)) have been studied at ambient temperature. The integrated cross section values are given for the lines of the (v'-0) bands in the A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A'( 3)Delta(u)-X(3)Sigma(-)(g) transitions with v' = 0-11, v' = 2-19, and v' = 2-12, respectively. The band oscillator strengths have been deduced and transition moments have been calculated. The total absorption values in the region of the Herzberg bands together with the photoabsorption values determined previously above the dissociation limit can be modeled by a single curve, in agreement with the continuity relationship of the cross sections through the dissociation limit. Copyright 2000 Academic Press.