Gas-Phase Generation and Photoelectron Spectra of Reactive Unsubstituted Cycloalkenethiones

The flash vacuum thermolysis of cycloalkenyl allyl sulfides, potential precursors of unsubstituted cycloalkenethiones, has been investigated by photoelectron spectroscopy. This technique allowed us to characterize in the gas phase very reactive species of this series, the conjugated and nonconjugated cyclopentene and cyclohexenethiones, and to compare the reactivity of these compounds. The assignment of the PE spectra is supported by electronic structure calculations, particularly by the HF method at the MP2 level and the density functional theory (DFT) using the B3LYP and BP86 functionals with the 6-311G(d, p) basis set. Copyright 2001 Academic Press.     

Surface States and Spectra

Let ℤ₊ ^{d +1}= ℤ⁺×ℤ₊, let H ₀ be the discrete Laplacian on the Hilbert space l ²(ℤ₊ ^{d +1}) with a Dirichlet boundary condition, and let V be a potential supported on the boundary ∂ℤ₊ ^{d +1}. We introduce the notions of surface states and surface spectrum of the operator H=H ₀+V and explore their properties. Our main result is that if the potential V is random and if the disorder is either large or small enough, then in dimension two H has no surface spectrum on σ(H ₀) with probability one. To prove this result we combine Aizenman–Molchanov theory with techniques of scattering theory. Received: 18 September 2000 / Accepted: 21 November 2000     

Pondermotive Shift of Photoelectron Spectra in Intense Laser Field

In a recent experimental work on the excess photon detachment （EPD） of H^- ions [Phys. Rev. Lett. 87 （2001） 243001] it has been found that the ponderomotive shift of each EPD peak increases with the order of the EPD channel. By using a nonperturbative quantum scattering theory, we obtain the kinetic energy spectra for the differential detachment rate Mong the laser polarization for several laser intensities. It is demonstrated that higher order EPD peaks are produced mainly at relatively higher laser intensities. By calculating the overall EPD spectra with varying laser intensities, it is found that the ponderomotive shift of each EPD peak increases with the order of the EPD channel Our calculations are in good agreement with the experimental observation. It is found that different EPD channels occur mainly when the laser field reaches some values, thus the intensity distribution of the laser field is responsible for the varying ponderomotive shifts.     

Multiphoton Spectra and States of Halogens

Abstract

Although the diatomic halogens are endowed with a wide range of intravalence-shell electronic states, the number and variety of these states is far from obvious in one-photon absorption from the ground state where only a few regions of structured absorption are present at visible and UV wavelengths. Selection rules on angular momentum and parity are key players in enforcing this sparse structure, but Franck- Condon effects also exercise considerable influence by directing transitions into regions where the transition dipole is small o r into a continuum where much of the detail is lost: further, a simultaneous excitation of two o r more electrons is formally forbidden in single-photon transitions. Some of the obstacles to one-photon absorption are avoided in the sequential absorption of two o r three photons using the conveniently placed, low-lying excited sQtes in the visible region for the initial step, in effect broadening the perspective from the ground state to include that from the lower excited states. This article summarizes progress realized by classical and nonclassical (multiphoton) methods of spectroscopy which, over the last 10–12 years, has led to the identification of many new states of halogens and materially improved the definition of several known ones. The advances are timely in that the same period has witnessed a renewal of interest in halogen spectra, largely because of their use in rare-gas halide lasers but also because the homonuclear halogens and certain interhalogens have potential value as laser systems in their own right [1, 2].     

X-Ray Spectra of Iron Phosphonates

The reaction of dialkyl alkylphosphonates with trivalent metal chlorides has recently been reported (1,2). The typical products of these reactions is a solid which is insoluble in most organic solvents and water. A monomeric structure was postulated for the iron phosphonates(1), while polynuclear structure was proposed for titanium, vanadium, and chromium phosphonates(2). Infrared(1) and Mossbauer-effect(3) studies were unable to differentiate between the monomeric or polynuclear structure for the iron phosphonates, In an attempt to further characterize the iron phosphonates, an x-ray diffration study was undertaken. The results of these studies are reported herein.     

卤化银微晶中光电子衰减谱的特性

光电子在卤化银材料潜影形成过程中发挥着重要的作用 ,光电子衰减行为在很大程度上决定于卤化银的晶体结构。采用光学与微波双共振技术 ,测量了自由光电子和浅俘获光电子的衰减谱 ,得到了卤化银中电子陷阱的密度和深度分布。以自由光电子寿命为纽带 ,通过分析掺杂卤化银晶体中电子陷阱的分布情况 ,可以确定浅电子陷阱掺杂剂的最佳掺杂浓度。     

掺有K4Fe(CN)6/K3IrCl6/K4Ru(CN)6的AgClBr微晶的光电子时间分辨谱

微波吸收介电谱检测技术具有很高的时间分辨率 ,可用于固体中电子输运特性的无接触测量 ,是研究晶体中光生载流子寿命及其迁移行为的有效方法。本文利用高时间分辨的微波吸收薄膜介电谱检测装置 ,测量了掺杂K4Fe(CN) 6,K3 IrCl6和K4Ru(CN) 6的AgClBr晶体在 35ps超短脉冲激光曝光后的光电子衰减的时间分辨谱。得到了不同的掺杂剂对AgClBr乳剂的自由光电子和浅俘获光电子的时间特性的影响关系。试验结果表明 ,对于所用的 3种乳剂 ,在掺杂量为 1× 10 -6、掺杂位置为 30 %时 ,掺杂K4Fe(CN) 6的AgClBr乳剂的自由光电子衰减时间相对较短 ,感光度相对较高。利用此方法可进一步研究乳剂光电子时间特性与掺杂剂、颗粒形状、颗粒结构、光谱增感和化学增感剂等参数的依赖关系。     

Spin-Dependent Transport and Densities of States in Non-collinear Magnetic Barriers

The spin-dependent transport properties in the non-collinear pattern of series of δ-magnetic barriers are studied by using scattering theory and Green‘s function methods. The Green‘s function is obtained by using distorted wave approach and the scattering matrix is related by Fisher-Lee relationship. In addition to reproducing the results of Papp‘s and Xu‘s in parallel and antiparallel configurations, we also obtain further results, where arbitrary orientations of the magnetic barriers and arbitrary number of barriers are included. The main finding of our results is that the signs of polarizations can be switched around some “geometric unpolarized windows“. The well-known antiparallel configuration has no such characteristics. Furthermore, we discuss spin-related partial densities of states in both polarized and unpolarized structures.     

Many-Electron Effects in Th 5p and 5s X-Ray Photoelectron Spectra of ThO2

JETP Letters - The Th 5p photoelectron spectrum of the ThO2 oxide exhibits an anomalous spin–orbit splitting, intense satellite, and a poorly observable very strongly broadened Th 5s line....     

Dynamic Interference Photoelectron Spectra in Double Ionization:Numerical Simulation of 1D Helium

We report our numerical simulation on the dynamic interference photoelectron spectra for a one-dimensional(1D) He model exposed to intense ultrashort extreme ultraviolet(XUV) laser pulses.The results demonstrate an unambiguous interference feature in the photoelectron spectra,and the interference is unveiled to originate from the dynamic Stark effect.The interference photoelectron spectra are prompted for intense sub-femtosecond XUV laser pulses in double ionization.The stationary phase picture is corroborated qualitatively in the two-electron system.The ability of probing the dynamic Stark effect by the photoelectron spectra in a pragmatic experiment of single-photon double ionization of He may shed light on further investigation on multi-electron atoms and molecules.     

Electronic and Resonance Raman Spectra of a Multibridged Iron Porphyrin

Abstract

Reported are the electronic and resonance Raman (rR) spectra of a multibridged iron porphyrin derived from meso-tetra(4-pyridil)porphynate iron(II) by complexing the pyridine residues with [Ru^II(edta)]^2- ions. The polymetallated system exhibits the characteristic Soret band at 428 nm (log ε = 5.2) and a shoulder around 465 nm (4.6). The rR enhancement of the porphyrin vibrational modes is similar to those previously reported for typical porphyrins; however, an additional feature appears around 465 nm, associated with the selective enhancement of some pyridine vibrational modes. Based on the rR excitation profiles the absorption band at 465 nm was assigned to a Ru^II-to-pyridine dπ→Pπ? charge-transfer transition.     

Inflationary Spectra,Decoherence, and Two-Mode Coherent States

We re-examine the question of the entropy stored in the distribution of primordial density fluctuations. To this end we make use of two-mode coherent states. These states incorporate the isotropy of the distribution as well as the temporal coherence and the semi-classical character of highly amplified modes. They also provide a lower bound for the entropy if, as one expects, decoherence processes erase the quantum squeezing which originally characterized the distribution in inflationary models. This lower bound is one half the maximal (thermal) value. By considering backreaction effects, we also provide an upper bound for this entropy at the onset of the adiabatic era.     

Experimental and Theoretical Study of the Electronic States and Spectra of BiNa

Gas-phase emission spectra of the hitherto unknown free radical BiNa have been measured in the NIR range with a Fourier transform spectrometer. The emissions were observed from a fast-flow system in which bismuth vapor in argon carrier gas was passed through a microwave discharge and mixed with sodium vapor in an observation tube. Two systems of blue-degraded bands observed in the ranges 8900-9800 and 7200-7800 cm(-1) were measured at high spectral resolution and vibrational and rotational analyses were performed. To aid in the analysis of the experimental data, a series of relativistic configuration interaction calculations has been carried out to obtain potential curves for the low-lying states of BiNa and also electric dipole transition moments connecting them. As in the isovalent BiH system, the ground state of BiNa is found to be X(3)Sigma(-) with a spin splitting of about 1769 cm(-1). The first excited state is A(3)Pi, and the observed band systems are assigned to the transitions A(3)Pi(A(2)0(+)) --> X(3)Sigma(-)(X(1)0(+), X(2)1). Comparison with earlier work on the isovalent BiH system emphasizes that the relative weakness of the varsigma MO in BiNa is responsible for qualitative differences in the electronic spectra of these two systems. Copyright 2000 Academic Press.     

三种钢铁材料的光电光谱分析

介绍了铁基线材、高铬铸铁、高锰钢等3种钢铁的光电光谱定量测定方法。该方法是通过选用与分析材质同基体,主成分接近的标准样品绘制校准曲线,采用自编的计算机校正程序,找出试样的光谱分析值和化学分析值之间的关系模型,并将模型通过计算机程序拟合到控制样品中,当进行材质测定时,只需要在日常标准化操作后将拟合好的控制样品对校准曲线进行控样校正,就可以直接进行试样的测定。该测定方法实用,结果可靠,适用于无相同标准样品条件下的试样光谱定量分析。     

CH2NH+2-CHNH++H2反应过渡态振动光谱研究

本文利用Gaussian-03计算程序,分别采用B3LYP／6—31G（d）和MP2／6-311＋G（d,户）对CH2NH2^＋——CHNH^＋H2反应进行了过渡态计算,并用相应的IRC计算进行了确认。对两个过渡态结构及能量大小简单比较后,计算了它们的振动光谱,发现虚频所对应的振动模式有利于过渡态脱氢而生成产物,其他的振动频率和振动模式有一定的差异。     

Many-Electron Effects in Co 3s X-Ray Photoelectron Spectra of Diamagnetic ScCoO3 and Paramagnetic BiCoO3 Cobaltites

JETP Letters - A new method based on the solution of the Dyson equation in the basis of atomic wavefunctions has been developed to quantitatively describe the influence of the dynamic effect on the...     

Derivation of Hamaker Dispersion Energy of Amorphous Carbon Surfaces in Contact with Liquids Using Photoelectron Energy-Loss Spectra

Hamaker interaction energies and cutoff distances have been calculated for disordered carbon films, in contact with purely dispersive (diiodomethane) or polar (water) liquids, using their experimental dielectric functions ε (q, ω) obtained over a broad energy range. In contrast with previous works, a q-averaged <ε (q, ω) >  _q is derived from photoelectron energy-loss spectroscopy (XPS-PEELS) where the energy loss function (ELF) < Im[?1/ε (q, ω)] >  _q is a weighted average over allowed transferred wave vector values, q, given by the physics of bulk plasmon excitation. For microcrystalline diamond and amorphous carbon films with a wide range of (sp³/sp² + sp³) hybridization, non-retarded Hamaker energies, A ₁₃₂ (L < 1 nm), were calculated in several configurations, and distance and wavenumber cutoff values were then calculated based on A ₁₃₂ and the dispersive work of adhesion obtained from contact angles. A geometric average approximation, H _0?CVL ?=?(H _0?CVC H _0?LVL )^1/2, holds for the cutoff separation distances obtained for carbon-vacuum-liquid (CVL), carbon-vacuum-carbon (CVC) and liquid-vacuum-liquid (LVL) equilibrium configurations. The linear dependence found for A _CVL, A _CLC and A _CLV values as a function of A _CVC, for each liquid, allows predictive relationships for Hamaker energies (in any configuration) using experimental determination of the dispersive component of the surface tension, \( {\gamma}_{CV}^d \), and a guess value of the cutoff distance H _0?CVC of the solid.

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