TD-DFT Study on the Electronic Spectrum Properties of 2,7′-(Ethylene)-bis-8-hydroxyquinoline and Its Derivatives

The structures of 2,7＇-（ethylene）-bis-8-hydroxyquinoline and its derivatives were optimized at the ground states using ab initio HF and B3LYP methods. At the same time, the molecular structures of the first singlet excited state for 2,7＇-（ethylene）-bis-8-hydroxyqulnoline and its derivatives were optimized by CIS/6-31G（d）. The absorption and emission spectra based on the above structures were obtained by the time-dependent density functional theory （TD-DFT） by the B3LYP method with the 6-31G（d） basis set. The calculated results of luminescence originate from the electronic transition from the hydroxphenol ring of 8-hydroxyquinoline A to the pyridine ring of 8-hydroxyquinoline B. Their luminescence wave bands can be tuned by different substituents on the ligand of 8-hydroxyquinoline.

Theoretical Studies on Geometry, Stability and Electronic Spectra of DATB and TATB

The geometries of DATB( 1,3-diamino-2,4 ,6-trinitrobenzene) and TATB( 1,3,5-tri-amino-2,4,6-trinitrobenzene) have been optimized by M1NDO/3 method. It is found that the total energy of the molecule is rather low at the plane configuration. It is also found that the orbitals between the amino-N and its adjacent nitro-N as well as the amino-N and its adjacent nitro-N on the ring are rather close and matched in symmetry and have high orbital interaction through space, which are evidently seen from the computed results of the atomic bond index. The electronic spectra of DATB have been computed by using INDO/2-CI method, and the results are well conformed with the experimental facts. For instance, the transition from 'A' (ground state' ) to 'A' (the 7th exciled state) corresponds to the computed spectrum line(2. 48×104 cm-1) which is close to the experimental value (2. 43×104 cm-1). From a similar computation, we may predict that the major spectrum line of TATB will be 2. 75, 2. 77, 3. 28 and 3. 32×104 cm-1.

Theoretical Studies on Electronic Spectrum Property of 2-(2-Hydroxyphenyl)pyridine Via Time-dependence Density Functional Theory Method

The geometrical structures of 2 (2 hydroxyphenyl) pyridine(PP) and its protonation states were optimized by means of the B3LYP/6 31G(d) method. For all the selected systems, the existence of H bond is in favor of the stability of the systems. On the basis of the optimized geometrical structures, their electronic spectrum properties were studied by time dependent density functional theory(TD DFT) methosd via a hybrid function of B3LYP and 6 31G(d) basis set. The TD DFT calculation result predicts the absorption spectrum of PP at 324 nm(3.82 eV), which is in very good agreement with the experimental value of 322 nm( 3.85 eV ) determined in solvent chloroform. The absorption spectra of the two protonation states both exert a red shift in various pH media.

Size Dependence of Electronic Excitation Energy in Linear C_(2n)H and C_(2n-1)N

The geometries, bondings, and vibrational frequencies of C 2n H ( n =3-9) and C 2n -1 N( n =3-9) were investigated by means of density functional theory(DFT). The vertical excitation energies for the X 2Π→ 2Π transitions of C 2n H( n =3-9) and for the X 2Σ→ 2Π and the X 2Π→ 2Π transitions of C 2n -1 N( n =3-9) have been calculated by the time-dependent density functional theory(TD-DFT) approach. On the basis of present calculations, the explicit expression for the wavelengths of the excitation energies in linear carbon chains is suggested, namely, λ 0=[1240 6A/(2+[KF(]3n+6-3n+3)](1-B e -Cn ), where A=3 24463, B=0 90742 , and C = 0 07862 for C 2n H, and A=2 94714, B=0 83929 , and C =0 08539 for C 2n -1 N. In consideration of a comparison of the theory with the experiment, both the expressions are modified as λ 1=0 92( λ 0+100) and λ 1= 0 95( λ 0+90) for C 2n H and C 2n -1 N, respectively. (1-B e -Cn ), where A=3 24463, B=0 90742 , and C = 0 07862 for C 2n H, and A=2 94714, B=0 83929 , and C =0 08539 for C 2n -1 N. In consideration of a comparison of the theory with the experiment, both the expressions are modified as λ 1=0 92( λ 0+100) and λ 1= 0 95( λ 0+90) for C 2n H and C 2n -1 N, respectively.

An improved secondary electrons energy spectrum model and its application in multipactor discharge

Secondary electron emission （SEE） of metal and dielectric materials plays a key role in multipactor discharge, which is a bottle neck problem for high-power satelliate components. Measurements of both the secondary electron yield （SEY） and the secondary electron energy spectrum （SES） are performed on metal samples for an accurate description of the real SEE phenomenon. In order to simplify the fitting process and improve the simulation efficiency, an improved model is proposed for the description of secondary electrons （SE） emitted from the material surface, including true, elastic, and inelastic SE. Embedding the novel SES model into the electromagnetic particle-in-cell method, the electronic resonant multipactor in microwave components is simulated successfully and hence the discharge threshold is predicted. Simulation results of the SES variation in the improved model demonstrate that the multipactor threshold is strongly dependent on SES. In addition, the mutipactor simulation results agree quite well with the experiment for the practical microwave component, while the numerical model of SEY and SES fits well with the sample data taken from the microwave component.

TD-DFT Study on Pyrazoline Derivatives

The molecular structures of ground state and first single excited state for pyrazoline derivatives are optimized with DFT B3LYP method and ab initio “configuration interaction with single excitations”（CIS） method, respectively. The frontier molecular orbital characteristics have been analyzed systematically, and the electronic transition mechanism has been discussed. Electronic spectra are calculated by using TD-DFT method. These results are consistent with those from the experiment.

Chemical and physical characteristics of quartz from gold deposits in the North China platform: relationship to gold mineralization

This paper seeks to identify macroscopic metallogenic mechanisms of various mineral deposits by studying microscopic typomorphic characteristics of typical minerals associated with the deposits and to reveal the mechanism of lattice gold in detail by studying both physical and chemical characteristics of quartz from representative gold deposits in the North China Platform.As part of their extensive research,the authors examine the relationship between trace elements with wall rock,the ore-forming media,and gold immigration of various types of gold deposits,including their salinity,type,temperature.These are key factors to revealing the mineralization mechanism,and indicators for mineral prospecting,exploration,mining,and metallurgical technology.In order to address the questions posed,the following methods were used:field investigations of geology and sampling of the representative gold deposits,physical study and chemical analysis of quartz including,but not limited to,fluid inclusions as well as their compositions and trace elements in quartz,the unit cell parameters,electron paramagnetic resonance spectrum(EPR),and infrared spectroscopic analysis(ISA).As a result of this study,the authors observe the following key findings:unit cell parameters of quartz vary with their contents of foreign elements including gold,paragenetic stage,wall rock type,and other factors;the higher the forming temperature and the lower the gold content in quartz,the smaller the unit cell parameters,and vice versa.Additionally,the EPR absorption lines resulted from the O–Al defect center.The density of these types of hole centers increases and the EPR signal strengthens when the temperature decreases.Based on the findings,the authors conclude that lattice gold exists in quartz.Gold,in the form of Au^(+)and/or Au^(3+),entering quartz and producing an electron–hole center,namely,the O-Au hole center,makes the center produce spin resonance absorption and results in the EPR absorption peak#I.Both unit cell parameters and EPR of quartz can potentially be used in mineral prospecting,relative ore-forming temperature determination,and grade control during mining.

The Micro-structural Studies of Ni-BaTiO_3 Nanocomposite Films by TEM and EELS

Epitaxial BaTiO3 films with embedded metallic Ni nanocrystal （Ni-BaTiO3） were successfully fabricated on SrTiO3 （001） single-crystalline substrate through the laser molecular beam epitaxial （L-MBE） technique.High resolution transmission electron microscopy （HRTEM） and electron energy loss spectrum （EELS） with Kramers-Kronig analysis methods were employed to characterize the microstructures,elementary distribution and the electron structure of these films.HRTEM results suggested that the structure of BaTiO3 was tetragonal with lattice parameters of a=0.399 nm and c=0.403 nm.Energy dispersive X-Ray spectroscopy （EDX） confirmed metallic Ni nanocrystal embedded successfully in BaTiO3 epitaxial films.The Ni-BaTiO3 composite films were compound of the epitaxial BaTiO3 （110） layers alternating with Ni NCs array （111） layers.Furthermore,the existence of the misfit dislocations induced by the embedding of Ni nanoparticles was also clearly demonstrated by the HRTEM images.The Ni L2,3 edges of EELS revealed that Ni NCs in their metallic state were embedded uniformly in the BaTiO3 matrix.A chemical shift of about 7 eV regarding L3 edges in the Ni EELS was also observed.The optical band gap of BaTiO3 in these films was about 3.84 eV,higher than 3.55 eV for pure BaTiO3 films at room temperature.

Forming of Space Charge Wave with Broad Frequency Spectrum in Helical Relativistic Two-Stream Electron Beams

We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.

Calculating the electron temperature in the lightning channel by continuous spectrum

Based on the theory of plasma continuous radiation, the relationship between the emission intensity of bremsstrahlung and recombination radiation and the plasma electron temperature is obtained. During the development process of a return stroke of ground flash, the intensity of continuous radiation spectrum is separated on the basis of the spectrums with obviously different luminous intensity at two moments. The electron temperature of the lightning discharge channel is obtained through the curve fitting of the continuous spectrum intensity. It is found that electron temperature increases with the increase of wavelength and begins to reduce after the peak. The peak temperature of the two spectra is close to 25 000 K. To be compared with the result of discrete spectrum, the electron temperature is fitted by the O I line and N II line of the spectrum respectively. The comparison shows that the high temperature value is in good agreement with the temperature of the lightning core current channel obtained from the ion line information, and the low temperature at the high band closes to the calculation result of the atomic line, at a low band is lower than the calculation of the atomic line, which reflects the temperature of the luminous channel of the outer corona.

Measurment of the energy spectrum of an electron beam extracted from an accelerator

The electron energy spectrum is one of the most important characteristics of an electron beam that is extracted from a linear accelerator. The most direct way to determine an electron spectrum would be to use a magnetic spectrometer and this method could also give results with high precision and effectiveness. In this article we describe our design of a new multi-layer absorption method, which is based on the depth-dose curves method that can be used in most irradiation accelerators, and adds the Monte Carlo simulation and iterative algorithm in order to reconstruct the electron energy spectrum. In this article the energy spectrum was measured using these two methods, and good results were acquired. These results could be crosschecked, which made the results more reliable.

Electron acceleration by tightly focused radially polarized few-cycle laser pulses

Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters. We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution.

Studies on the Synthesis and Electron Spectra of 2,6-Bis(p-Aminophenyl)Benzo[1,2-d;5,4-d']Bisoxazole

A novel method to synthesize 2,6-bis(p-aminophenyl)benzo\[1,2-d;5,4-d'\]bisoxazole using 1,2,3-trichlorobenzene as the starting material through nitration, substitution, hydrogenation, and condensation was reported. During the condensation, the influence of the amount of SnCl_2 on the yield of the product was studied. The electron spectra of the compound were discussed, the results showed that it is a fluorescence material with large Stokes shift.

THE SECONDARY ELECTRONS SPECTRUM OF POLYANILINE IN XPS

The secondary electrons spectrum in XPS can be used to determine the work function of polyaniline (PANI). It is shown that the work function of PANI depends on the protonation state and the polymerization method used.

Studies on Electron Impact Mass Spectra of Some Anhydro-sugars

The fragmentation patterns of anhydro sugars 1-6 in electron impact mass spectrometry have been proposed, and verified by means of metastable ions scanning method.

A 3D Supramolecular Pd(Ⅱ) Complex via Hydrogen-bonding and Weak M…M Interactions

The reaction of 2,4,6-tris（2-pyridyl）-1,3,5-triazine （tptz） and K2PdCl4 in THF/H2O （10：1） results in the hydrolysis of tptz to bis（2-pyridylcarbonyl）amide anion （bpca）, and affords complex Pd（bpca）Cl 1, which is the first example of Pd（Ⅱ）-promoted hydrolysis of ligands. Crystal data for 1： orthorhombic, space group Pbcn, a = 12.0136（17）, b = 14.180（2）, c = 6.9747（11）A, V= 1188.2（3） A3, Z = 4, Mr = 368.06, Dc = 2.058 g/cm3, F（000） = 720,μ = 1.786 mm^-1, λ（MoKα） = 0.71073 A, T= 293（2） K, 2θmax = 54.9°, GOOF = 1.085, the final R= 0.0647 and wR = 0.1051 for 1234 observed reflections with I 〉 2σ（I） （refinement on F2）. Complex 1 is connected through hydrogen bonding to give a 2D network. And weak Pd...Pd interactions are also found between adjacent molecules with the distance of 3.6074（5） A, so the complex is further extended into a 3D supramolecular structure. Thermal gravity analysis （TGA） shows that 1 exhibits high thermal stability below 310℃. X-ray powder diffraction （XRD） and UV/Vis spectrum of 1 are also discussed.

Real-Time Dynamic Spectrum Analysis for Plasma Electron Density and Faraday Rotation Angle Measurement on HL-2A

Electron density and Faraday rotation angle are important physical parameters in nuclear fusion research.To measure them simultaneously,the three-wave polarimeter/interferometer diagnostic system is applied.Both the final probe output signal and the reference signal contain three frequency components.The time-varying phase difference curve of each frequency component can be measured by the Real-time Dynamic Spectrum Analysis（RDSA）method based on Field-Programmable Gate Array（FPGA）.The phase difference precision is better than 0.1° and the real-time feedback delay is less than 1 ms,which satisfy the requirements of HL-2A.

Fast-electron-impact study on excitations of 4d electron of xenon

The electron energy loss spectrum of the 4d excitations of xenon was measured at an incident electron energy of1500 eV and a scattering angle of 6°. Besides the optically allowed transitions of 4d5/2^-1np and 4d3/2^-1np, the optically forbidden transitions of 4d5/2^-1ns, 4d5/2^-1nd, 4d3/2^-1ns, and 4d3/2^-1nd were observed. The measured features are assigned with the help of the calculation by the Cowan Code. The line profile parameters of both optically allowed transitions and optically forbidden ones were determined and compared with the previous available data. It is found that the natural widths of both dipole-allowed and dipole-forbidden excitations are approximately identical, which means the spectator transitions dominate the resonant Auger effect for both dipole-allowed and dipole-forbidden transitions.

Pulsating aurora - a review

In this review, the observational facts about pulsating aurorae are summarized and discussed in the frame of the recent develpment of the theories which intend to explain the mechanism of auroral pulsations. Although new data are available some key observations in the magnetosphere are still missing in order to identify the wave mode to precipitate electrons into the atmosphere and in order to understand the role of magnetospheric plasma in producing pulsating aurora. It apters that the Coroniti-Kennel or micropulsation theory needs to be re-visited although the so-called flow cyclotron maser model seems to explain many of the characteristics of auroral pulsations.

Research on the detuning system of a cooling electron beam for the dielectronic recombination experiment at CSRm

The storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination （DR） experiments. In order to fulfill the requirement of DR measurements at the main Cooler Storage Ring, a detuning system for the precision control of the relative energy between the ion beam and the electron beam has been installed on the electron cooler device. The test run using 7.0 MeV/u C6＋ beam was performed with recording the Schottky spectra and the ion beam currents. The influence of pulse heights and widths of the detuning voltage on the ion beam was analyzed. For the small pulse height, the experimental results from the Schottky spectra were in good agreement with the theoretical results. The frequency shift in the Schottky spectra was significantly reduced for the short pulse width. For the large pulse height, an oscillation phenomenon was observed and some effective ways to reduce the oscillation were pointed out. The detailed description of the phenomenon and the theoretical model based on the plasma oscillation was discussed in this paper. The overall results show that the new detuning system works properly, and could fulfill the requirements of future DR experiment.