Core level excitation spectra of La and Mn ions in LaMnO3

Manganese-based perovskite is popular for research on ferromagnetic materials,and its spectroscopic studies are essential for understanding its electronic structure,dielectric,electrical,and magnetic properties.In this paper,the M-edge spectra of La ions and the M-edge,L-edge,and K-edge spectra of Mn ions in LaMnO3 are calculated by considering both the free-ion multiplet calculation and the crystal field effects.We analyze spectral shapes,identify peak origins,and estimate the oxidation states of La and Mn ions in LaMnO3 theoretically.It is concluded that La ions in LaMnO3 predominantly exist in the trivalent state,while Mn ions exist primarily in the trivalent state with a minor presence of tetravalent ions.Furthermore,the calculated spectra are in better conformity with the experimental spectra when the proportion of Mn3+is 90%and Mn4+is 10%.This article enhances our comprehension of the oxidation states of La and Mn within the crystal and also provides a valuable guidance for spectroscopic investigations of other manganates.

A novel way to study the nuclear collective excitations

Typically, the unambiguous determination of the quantum numbers of nuclear states is a challenging task. Recently, it has been proposed to utilize to this aim vortex photons in the MeV energy region and, potentially, this could revolutionize nuclear spectroscopy because of the new and enhanced selectivity of this probe. Moreover, nuclei may become diagnostic tools for vortex photons. Still, some open questions have to be dealt with.Nuclei exhibit intricate excitation spectra. Indeed, not all states within these spectra are equally significant. Some are not sensitive to specific terms in the nuclear Hamiltonian or do not display novel features, so that investigating them is not helpful to enhance our overall understanding of nuclear structure. On the other hand, there are states that manifest themselves as prominent peaks, e.g., in the inelastic scattering spectra. Among the best examples are the so-called Giant Resonances that lie at energies of the order of tens of MeV [1].

Theoretical Analyses of 4f^11→4f^105d Excitation Spectra of Er^3＋ Doped in LiYF4

Spectral terms and J-spectral multiplet of low-spin 4f105d configuration of Er3+ were obtained with the method of ligand field theory. According to the selection rules for dipole transitions, the excitation spectra of Er3+ doped in LiYF4 in vacuum ultraviolet region (120～160 nm) of the spectrum were theoretically interpreted by applying the crystal field model, and the six bands were assigned to the spin-allowed transitions from the ground state (4I15/2) to J-spectral multiplet of low-spin 4f105d configuration of Er3+ion.

Microscopic sdgIBM-2 description of low-lying excitation spectra of ^(48,52,56)Cr

Starting from the shell model configurations,valence nucleon effctive interactions and fermion E2 transition operator,a microscopic approach of sdgIBM-2 is used to calculate the energy spectra,E2 transitions,and binding energies for 48,52,56Cr.The results fit the experimental data quite well.

Investigation of autoionization spectra of Sm atoms using an isolated-core excitation method

Using the isolated-core-excitation scheme and three-step laser resonance ionization spectroscopy approach, this paper, for the first time, has systematically investigated the autoionization spectra of atomic Sm, belonging to the 4f^6 6pn/ and 4f^5 5d6sn/ （l = 0,2） configurations. In the experiment, the first two tunable dye lasers are employed to excite the Sm atom from its initial state to the different 4f^6 6sn/ bound Rydberg states, then the third dye laser is scanned to drive the atom to the doubly-excited autoionizing states. With the above excitation scheme, the measured transition profiles of the autoionizing states are nearly symmetric, from which the level energies and widths can be easily obtained.

On the Temperature Dependent Excitation and Reflection Spectra of Ln₃Al₅O₁₂:Ce³⁺Ceramics (Ln = Y, Lu) for White LEDs

Yttrium aluminum garnet (YAG) and Lutetium aluminum garnet (LuAG) doped with Ce3+ are widely applied phosphor powders or ceramics for the conversion of blue into green to yellow light in the rapidly expanding market of white light emitting high power LEDs. Surprisingly, the temperature dependent reflection and excitation spectra of these well-established materials have not been investigated until today. In this work, we report the temperature dependence of the reflection and excitation spectra of Ce3+ doped YAG and LuAG in the temperature range from 300 to 800 K.

Theoretical Analysis of 4f and 5p Inner-Shell Excitations of W-W^(3+) Ions

Detailed theoretical calculations are performed for the 4f and 5p inner-shell excitations of W-W^(3+) ions using the multiconfiguration Hartree–Fock method in order to better understand the origin of the XUV photoabsorption spectra of W atoms from the dual laser-produced plasma experiment(Costello et al.J.Phys.B 24(1991)5063 and the spectra of photon-induced single ionization of W^(q+) ions(q=1,2,3)(Müller et al.Phys.Scr.T1441(2011)014052)from photon-ions merged beam experiments,respectively.Two broad and strong resonances in the experimental spectra have also been theoretically identified mainly from 5p–5d resonance.The 4f–5d,6d and 5p–6d transitions also make a small contribution to each spectrum,which are superimposed on the 5p–5d transition arrays.Based on the assumption of a normalized Boltzmann distribution among the excited states,we succeed in reproducing spectra which are in good agreement with experiments.

On Excited Meson Spectra in the Scalar Strong Interaction Hadron Theory

Meson spectra have been treated earlier in the scalar strong interaction hadron theory, choosing the Coulomb and linear type of potentials, neglecting the quadratic one. The spectra of ground state pseudoscalar and vector mesons were adequately accounted for but not that of the excited mesons. Here, the quadratic potential replaces the Coulomb one and the same ground state meson spectra were recovered. Also, the masses of low-lying radially excited pseudoscalar and vector mesons were found to be 4% - 18% smaller than the measured ones. Here, the linear type of potential, by itself of nonlinear nature, has been neglected. For some orbitally excited pseudoscalar mesons, the difference is 14% - 38%. The discrepancies are tentatively attributed to the neglected nonlinear potential, which is expected to increase with meson mass, as can be seen in the tables below.

Blue-shift of Nano-Y_2O_3 : Eu^(3+) Emission Spectra Excited by X-ray

Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomena exist in the nano-Y2O3:Eu3+ emission spectra excited by X-ray. The wave lengths of the peak (5D0→7F2) are related with the grain size of the powder

Redshift of Excitation Wavelength Caused by the Concentration of L-Tryptophan in Water: A Theoretical and Experimental Study

A redshift in the wavelength of excitation spectra is experimentally measured as a function of the concentration parameter for tryptophan solutions in water. To understand the microscopic causes of this behavior, theoretical calculations obtained from four model clusters are carried out: (Trp)1 - (H2O)9, (Trp)2 - (H2O)18, (Trp)3 - (H2O)27 and (Trp)4 - (H2O)36, where there are interactions among 1, 2, 3 and 4 molecules of tryptophan. According to the literature, each interaction occurred with nine molecules of water to stabilize its expected zwitterionic form. In these models, the molecules of tryptophan appear at an adjacent distance among them to generate an analogous behavior when there is an experimental increase in the concentration. It is evident that the distance between adjacent molecules of tryptophan decreases as their concentration increases. The optical properties of these clusters are obtained by studying the corresponding excited states and the molecular orbitals involved, showing charge transfers by using time-dependent density functional theory (TD-DFT) methods. The experimental spectroscopic data are obtained by using the clusters proposed, and good agreement is found by drawing a comparison with the theoretical data.

Diagnostics of laser-induced plasma on carbon-based polymer material using atomic and molecular emission spectra

Time-integrated optical emission analysis of laser-induced plasma on Teflon is presented.Plasma was induced under atmospheric pressure air using transversely excited atmospheric CO_(2) laser pulses.Teflon is a C-based polymer that is,among other things,interesting as a substrate for laser-induced breakdown spectroscopy analysis of liquid samples.This study aimed to determine the optimal experimental conditions for obtaining neutral and ionized C spectral lines and C2 and CN molecular band emission suitable for spectrochemical purposes.Evaluation of plasma parameters was done using several spectroscopic techniques.Stark profiles of appropriate C ionic lines were used to determine electron number density.The ratio of the integral intensity of ionic-to-atomic C spectral lines was used to determine the ionization temperature.A spectral emission of C2 Swan and CN violet bands system was used to determine the temperature of the colder,peripheral parts of plasma.We critically analyzed the use of molecular emission bands as a tool for plasma diagnostics and suggested methods for possible improvements.

BaZnOS:Bi^(3+)荧光粉的制备及光学性能研究

以碳酸钡、硫化锌和氧化铋为原料,采用高温固相法合成了一系列铋(Bi)掺杂BaZnOS的蓝绿色荧光粉。研究了BaZnOS中Bi的位点占据、晶胞变化及其发光特性之间的相关性。在BaZnOS中,根据离子配位相同及半径相似原理,Ba位点是Bi最适合和稳定占据的位点。由于Bi^(3+)的半径略小于Ba^(2+)的半径,导致掺杂过后的晶胞参数有所缩小。在波长为372 nm的紫外光激发下,BaZnOS和BaZnOS:Bi^(3+)在400~600 nm处都显示出非常宽的发射带。其中未掺杂的BaZnOS发光归因于合成过程中的氧空位缺陷,掺杂Bi^(3+)后,Bi^(3+)结合到BaZnOS的晶格中,由于Bi^(3+)的^(3)P_(1,0)→^(1)S_(0)跃迁,最终使位于400~600 nm处的光致发光进一步增强2~3倍。通过色坐标计算,所制备的BaZnOS:Bi^(3+)荧光粉色坐标均位于蓝绿色区域,可作为与红光协调发射白光的潜力荧光粉,用于白光发光二极管领域。

基于生物滤池的炼化企业反渗透浓水处理研究

在炼化企业进行侧线试验考察反硝化生物滤池和碳基曝气生物滤池(CBAF)组合工艺对炼化企业污水回用过程中产生的反渗透浓水中总氮和有机物的去除效果,并分析处理过程中的有机物变化情况。结果表明:组合工艺可以有效去除反渗透浓水中的总氮(平均去除率为51.25%),降低化学需氧量(降低幅度为59.44%);反渗透浓水中主要污染物为腐殖酸类物质和溶解性微生物代谢产物,通过CBAF工艺处理后的污水中主要污染物的荧光强度显著降低;经过CBAF处理后,小分子酸类物质、构造块、小分子中性类物质、腐殖酸类物质和生物聚合物等亲水性有机碳的浓度分别可以降低81.65%,68.58%,63.85%,60.83%,49.30%;同时,由于载体的吸附作用,CBAF反应器对亲水性、疏水性有机碳都有较高的去除率(分别为64.20%和74.58%)。

激发态分子内质子转移金属-有机光学材料的构建及发光调控策略——论结构化学中原子光谱项

激发态分子内质子转移(ESIPT)的过程包括独特的四能级能态循环和伴随的多重发射,在ESIPT激发态的调控下,通过表现各种光物理过程(非辐射跃迁、辐射跃迁、能量转移、电荷转移等)的平衡和转换关系,ESIPT金属-有机超分子光学材料显示丰富的发光机制和多领域应用。鉴于对ESIPT金属-有机超分子材料性质的认识处于起步阶段,迫切需要建立新的调控发光机制策略,综述了ESIPT金属-有机超分子材料的构建及发光调控,对未来新型光功能材料的构建具有指导意义,同时加强认识原子光谱项在超分子材料领域的理论价值。

Co-Precipitation Synthesis and Spectral Characteristics of Long Afterglow Phosphor Y_2O_2S:Sm^(3+), Mg^(2+), Ti^(4+)

Y2O2S：Sm^3＋, Mg^2＋, Ti^4＋ phosphor was synthesized by co-precipitation method. The crystalline structure of all synthesized phosphors was investigated by XRD. The result showed that all synthesized phosphors had a hexagonal crystal structure, which was the same as Y2O2S. The emission spectrum and excitation spectrum were measured, and the effect of Sm^3 ＋ molar ratio on the spectra was discussed. The emission spectra of the phosphors showed three emission peaks due to typical transitions of Sm^3 ＋ （4G5/2→6HJ ,J = 5/2, 7/2, 9/2）, and the emission peaks at 606 nm was stronger than others. With the increase of Sm^3 ＋ molar ratio, the emission intensity was strengthened. The excitation peaks were ascribed to the representative energy transition 4f→4f of Ti^4＋ phosphor prepared by co-precipitation method was Sm^3＋ ions. The results indicated that the Y2O2S ： Sm^3＋ , Mg^2＋ , an efficient long afterglow phosphor.

Crystal growth and spectral properties of Tb：Lu2O3

The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb：Lu2O3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10（-22）cm2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt（J-O）intensity parameters 2,4,and 6 were computed to be 3.79×10（-20）cm2,1.30×10（-20）cm2,and 1.08×10（-20）cm2,with a spectroscopic quality factor 4/6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10（-22）cm2 and 1.32×10（-22）cm2,respectively.The fluorescence lifetimeτexp of -5D4 was fitted to be 1.13 ms.The data suggest that the Tb：Lu2O3 crystal could be a potential candidate for green and yellow laser operation.

Charge Transfer Spectra (CTS) in CaS:Ce^(3+) Phosphors

This paper describes the excitation spectra nearby 220hm of CaS:Ce^(3+),Na^+ and CaS:Ce^(3+),X^-(X=F,Cl or Br).It is considered that the charge transfer excitation is caused by electron transfer of S^(2-)on 3p^6 to the 4f shell of Ce^(3+).It has been discussed that,when halogen ions act as coactivators,this excitation band shifts to low- er wavenumber.

Ab initio investigation of excited state dual hydrogen bonding interactions and proton transfer mechanism for novel oxazoline compound

Owing to the importance of excited state dynamical relaxation, the excited state intramolecular proton transfer(ESIPT) mechanism for a novel compound containing dual hydrogen bond(abbreviated as "1-enol") is studied in this work.Using density functional theory(DFT) and time-dependent density functional theory(TDDFT) method, the experimental electronic spectra can be reproduced for 1-enol compound. We first verify the formation of dual intramolecular hydrogen bonds, and then confirm that the dual hydrogen bond should be strengthened in the first excited state. The photo-excitation process is analyzed by using frontier molecular orbital(HOMO and LUMO) for 1-enol compound. The obvious intramolecular charge transfer(ICT) provides the driving force to effectively facilitate the ESIPT process in the S1 state. Exploration of the constructed S0-state and S1-state potential energy surface(PES) reveals that only the excited state intramolecular single proton transfer occurs for 1-enol system, which makes up for the deficiencies in previous experiment.

Site Selective Spectra of Eu^(3+)-Doped Y_2SiO_5 Crystal

By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochromator, a phase-lockingamplifier and a computer as the data detecting system, the transmission spectrum, fluorescence spectra, excitation spectrum and siteselective fluorescence spectra ofthe Eu3+: Y2SiO5 crystal were observed. More than thirty out of thetotal fifty spectral lines were observed for 5D0→7F0,1,2,3,4 transitions. The Eu3+ ions occupy twokinds of the Y3+ sites with the lowsymmetry in this crystal. The difference of the wavelengths of thetwo Eu3+ sites for 7F0→5D0 transition is about 0. 2 nm. It was foundthat the two sites were nonequivalent optical ones at room temperature. Crystal lattice constants a,b, c, and β of Eu3+: Y2SiO5 werealso measured by the X-ray diffraction method. The results show thatthe lattice constants a, b, and cof the crystal doped Eu3+ ions isvery close to those of the Y2SiO5crystal undoped Eu3+ ions.

Dynamic NMR and Twisted Intramolecular Charge Transfer Excited States

In this paper the results of dynamic NMR studies on ethylmethylamino-tertiary-butyl-phenylborane (EMABPB) with or without light are reported. The NMR data were recorded on a Bruker 400 MHz NMR equipped with our custom-made optical probe and with our custom-made 450 watts (W) monochromatic light sources. The molecular photochemistry including twisted intramolecular charge-transfer-excited-state (TICT) of the EMABPB in several solvents has been investigated. These results indicate that the aminoborane demonstrates multiple configurations in CD3Cl and CD2Cl2 resulting in the shifts of the signals of the alkyl groups on the nitrogen and boron. This indicates that there are some time-dependent changes at constant temperature over the irradiation interval. At ﹣60°C and the presence of light (λ = 265 nm), we observed a large change in the populations of the two sites, and this by itself indicates a modification in the rotation around the boron nitrogen bond in the excited state. By considering the existence of the TICT state, many important energy technologies may be developed with higher efficiency by controlling the back-electron transfer processes.