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Purpose Long non-coding RNAs (lncRNAs) may act as oncogenes in several cancers, including endometrial carcinoma (EC). The purpose of the current study is to investigate the regulatory mechanism of exosomal-lncRNA deleted in lymphocytic leukemia1 (DLEU1) on EC. Methods The expression levels of lncRNA DLEU1, microRNA-381-3p and E2F Transcription Factor 3 (E2F3) in EC tissues or cells were detected using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). We then analysed the proliferation, migration, and invasion of EC cells by performing the MTT assay, wound healing assay, and transwell invasion assay, respectively. Identification of exosomes was detected using Western blot assay. The uptake of exosomes was detected by a confocal microscope. The effects of exosomes on EC cells were investigated by construction of cell co-culture system. The interactions among DLEU1, miR-381-3p and E2F3 were confirmed using the dual-luciferase reporter (DLR) assay. Results LncRNA DLEU1 expression was highly up-regulated in EC tissues and cells. Knockdown of DLEU1 inhibited the proliferation, migration, and invasion of EC cells. Exosomes could be uptaken by the ambient EC cells. MiR-381-3p was a target of DLEU1 and was negatively modulated by DLEU1. Overexpression of miR-381-3p suppressed the proliferation, migration, and invasion of EC cells. Additionally, E2F3 was the target gene of miR-381-3p and was negatively modulated by miR-381-3p. Upregulation of miR-381-3p and down-regulation of E2F3 reversed the promoting effect of exosomal DLEU1 on EC cells. Conclusion Exosomal DLEU1 accelerates the development of EC by regulating the miR-381-3p/E2F3 axis, thus DLEU1 may act as a possible therapeutic target for treating EC.

Mars surface composition detector (MarSCoDe) is a scientific instrument suite onboard the Mars rover of the “Tianwen-1” mission, which uses laser-induced breakdown spectroscopy and shortwave infrared spectroscopy to detect the composition of soils and rocks at the surface of Mars. The optical head unit (OHU) is the core hardware of MarSCoDe, containing a Cassegrain telescope and other optical modules for lasers generation and signals transmission. The unit lacks thermal control resources and is located outside the rover’s cabin, which will directly face the Martian surface drastic temperature changes. We introduce the optomechanical designs that realize the lightweight and high thermal stability of the OHU optical system, especially the designs and implementations of the semiopen primary mirror based on silicon carbide and the fully closed optical bench based on carbon fiber-reinforced polymer. Meanwhile, the advantages and difficulties of silicon carbide, long carbon fiber-reinforced silicon carbide composites, and carbon fiber-reinforced polymer materials used for small and compact optomechanical systems are discussed. Subsequently, the environmental adaptability of the telescope system of OHU was studied through analytical and experimental methods, which show that it can achieve the required optical performance over a temperature range of approximately 100°C.

China's Tianwen-1 Mars rover carries a laser-induced breakdown spectroscopy (LIBS) payload named MarSCoDe to analyze the mineral and rock composition on Mars. MarSCoDe is expected to experience a wide working temperature range of about 100 °C, which will lead to a spectral shift of up to ∼40 pixels (∼8.13 nm). Even worse, drastic changes in temperature and environment may cause a loss or increase of some spectral lines of an on-board calibration Ti target. An elastic particle swarm optimization (PSO) approach is proposed to fulfill the on-board spectral calibration of MarSCoDe under this harsh condition. Through establishing a standard wavelength set (SWS) and an individual particle wavelength set (PWS), and further elastically selecting a part of PWS to compare with SWS, the problem of spectral shift and number mismatch can be solved gradually with the evolution of the particle swarm. Some tests of standard lamps and Ti with MarSCoDe, placed in a Mars simulation environment chamber (MSEC) in a temperature range of 70 °C, were completed. Compared with the standard spectrum of the Ti target (obtained at 20 °C), the spectral shifts of the first, second, and third channels are approximately 0.33 nm (5 pixels), 0.85 nm (6.4 pixels), and 8.09 nm (39.8 pixels), respectively, at -40 °C before correction; after PSO correction, the spectral shifts are greatly reduced to up to 0.015 nm, and specially for the 626.28 nm line, the spectral shift is reduced from 8.09 nm to about 0 nm. Experimental results demonstrate that the PSO-based approach can not only correct the on-board spectral shift but also solve the number mismatch of spectral lines of MarSCoDe in the harsh working environment of Mars. Further, it can be extended to the on-board calibration of other spectral payloads for deep space exploration.

Background Mesenchymal stem cells (MSCs)-derived extracellular vesicles (EVs) have been reported to exhibit therapeutic effects in various animal models of neurological diseases, such as stroke and hypoxic-ischemic brain injury. Objective The present study investigated the potential beneficial effect of MSC-derived EVs in an animal model of Alzheimer's disease (AD). Methods APP/PS1 mice and their non-transgenic littermates (WT) received intracerebroventricle injection of MSC-derived EVs once per two days for two weeks. Then novel object recognition and water maze tasks were carried out to measure the cognitive behaviors. Electrophysiological tests were carried out to measure hippocampal synaptic plasticity. Inducible nitric oxide synthase (iNOS) mRNA and protein levels were measured by qRT-PCR and western blotting in primary cultured neurons treated with amyloid-β peptide (Aβ) or prepared from APP/PS1 mice. Results Treatment with MSC-derived EVs alleviates exogenous Aβ-induced iNOS mRNA and protein expression. In cultured primary neurons prepared from APP/PS1 pups, iNOS mRNA and protein levels were significantly reduced when treated with MSC-derived EVs. MSC-derived EVs improved cognitive behavior, rescued impairment of CA1 synaptic transmission, and long-term potentiation in APP/PS1 mice. Conclusion MSC-derived EVs possessed beneficial effects in a mouse model of AD, probably by suppressing Aβ induced iNOS expression.

Peony seed oil (PSO) is a new woody nut oil which is unique to China. Its unsaturated fatty acids are over 90% and are rich in α - linolenic acid. Although the PSO industry is in its infancy, it is bound to become a top vegetable oil food material because of its own advantages. The potential high commercial profit of its adulteration with cheap vegetable oil will be an important factor hindering the healthy development of PSO industry. It is of great significance to study the adulteration of PSO for preventing large-scale adulteration. In this study, the qualitative and quantitative analysis of PSO was realised based on Raman spectroscopy combined with chemometrics analysis, and the fatty acid composition of PSO was analysed according to Raman characteristic peaks. The technology can be applied to routine analysis and quality control of PSO.

How to quickly and safely identify blood species has always been an urgent problem for scientists. Smear test method has the risk of blood contamination, and the blood itself may carry some unknown viruses or pathogens, which will bring health risks to the testing personnel. Therefore, in order to meet the urgent needs of rapid and safe detection of blood, a technology which can detect dynamic confocal Raman spectroscopy of flowing blood in bionic blood vessel was proposed. The blood, which was sealed in the bionic blood vessel, flowed through the focus gaze area of laser by the microfluidic pump, to detect the dynamic blood Raman spectrum. Human blood and cattle blood were selected as experimental objects, and the experiments were carried out under the same parameters. Combined with PCA-LDA (principal component analysis and linear discriminate analysis) classification model, the predictive classification of the two species without error recognition was realized. The hidden weak Raman signals were mined by derivative spectra, and the fundamental differences of Raman spectra of two species were compared. Then the biochemical information that caused the differences was also analyzed. The results show the method can meet the detection requirements of sealed blood, and the Raman spectra of flowing blood is more representative than those of static blood.

The sources and burial patterns of organic matter in Shamei Lagoon, Hainan, China, were investigated by analyzing the collected sediment cores, in terms of the variations in total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition (δ13C and δ15N), and the ratio of total organic carbon to total nitrogen (TOC/TN). On such a basis, the environmental evolution and primary productivity changes of the lagoon were revealed, and the impacts of both natural environmental changes and human activities were identified. Downcore variation patterns of the parameters representing sources and burial flux of organic matter were predominantly related to natural evolution of the lagoon from 1800 to 1950 and they were increasingly affected by human activities afterwards. In the period 1800–1900, the water exchange capacity of the lagoon declined substantially, but it was still suitable for the growth of marine phytoplankton, as is indicated by relatively high proportion and burial flux of organic matter originated from marine sources. During 1900–1950, the lagoon was transformed into a freshwater environment. After 1950, due to strong influence by human activities, the local freshwater phytoplankton became the major source of buried organic matter; at the same time, marine lost its niche and its burial flux was much lower than that of its freshwater counterpart. The large increment of buried freshwater organic matter also indirectly reflects the eutrophication trend since 1950.

In order to evaluate the role of positron emission tomography (PET) with N-methyl-[(11)C]-2-(4'-methylaminophenyl)-6-hydroxybenzothiazole, also known as Pittsburgh compound B (PIB), in the early diagnosis of Alzheimer's disease (AD). Clinical data were collected, and PIB PET cerebral imaging was performed in patients with AD (n = 6), mild cognitive impairment (MCI) (n = 7), and elderly, mentally normal controls (NCs) (n = 7). PET images of the subjects were then analyzed. Visual analysis showed that the radioactivity clearance rate in AD patients was significantly different from that found in the NC group. Furthermore, the radioactivity clearance rate 45 min after PIB injection was significantly lower than the NC group. Images from the MCI group presented heterogeneous results, overlapping with those from both the AD and NC groups. Statistical analysis showed that the radioactivity clearance rate during 5-45 min post-injection was significantly lower in the AD group (41-77%) than the control group (75-81%) (P > 0.05) and the MCI group (59-77%). The radioactivity clearance rate in the bilateral parietal lobes, frontal, temporal, and right occipital lobes, and the bilateral corpora striata in MCI group were lower than that in control group (P < 0.05). PIB PET brain imaging can differentiate early AD patients from NCs and may have certain value in identifying patients progressing to MCI.

A small sedimentary basin (the Yuehu lagoon), located at the eastern tip of Shandong Peninsula, China, was selected to study its filling by sediment and the vertical flux of particulate organic carbon in response to natural/anthropogenic processes. Surficial and short core sediment samples were collected and analyzed to obtain data sets of grain size, organic carbon content, deposition rates and vertical fluxes of sediment and organic carbon. The analytical results show that the lagoon is covered mainly with fine-grained sediments with high deposition rate and particulate organic carbon content being found from the central part of the mud deposit. The sediment balance of the lagoon indicates high denudation rates of the catchment basin, which may be related to soil erosion in response to farming and land use pattern changes. Furthermore, preliminary analysis of the organic carbon fluxes of the Yuehu lagoon and other embayments of the region shows that these coastal systems make an important contribution to the regional shallow sea carbon burial.

Soft x-ray fluorescence spectroscopy has been used to examine the electronic structure of deeply buried silicide thin films that arise in Fe/Si multilayers. These systems exhibit antiferromagnetic (AF) coupling of the Fe layers, despite their lack of a noble metal spacer layer found in most GMR materials. Also, the degree of coupling is very dependent on preparation conditions, especially spacer layer thickness and growth temperature. The valence band spectra are quite different for films with different spacerlayer thickness yet are very similar for films grown at different growth temperatures. The latter result is surprising since AF coupling is strongly dependent on growth temperature. Combining near-edge x-ray absorption with the fluorescence data demonstrates that the local bonding structure in the silicide spacer layer in epitaxial films which exhibit AF coupling are metallic. These results indicate the equal roles of crystalline coherence and electronic structure in determining the magnetic properties of these systems.

The advent of third-generation synchrotron radiation sources has stimulated interest in the study of X-ray emission using photon excitation. Soft X-ray fluorescence (SXF) provides a means of measuring the element and angular momentum selective valence band density of states in complex materials. Tenability of the excitation source allows a detailed investigation of the dynamical behavior of the relaxation channels and the coupling between the excitation and emission process that occurs near a resonance or an absorption edge. As an example of resonant inelastic scattering studies in solid systems by SXF spectroscopy at the insertion device beam line BL 8.0 at ALS, results from CaF 2 will be presented. When the energy of exciting photons is tuned to the Ca 2p–3d threshold absorption peak in CaF 2 , the SXF produced by recombination of the excited electrons with core holes exhibits remarkable resonances for both the 2p 3/2 and 2p 1/2 levels. When the resonant 2p–3d SXF peaks are excited, additional broad peaks appear in the spectra below the normal valence band spectrum, which are displaced from the resonant peaks by about 17 eV and track the changes in excitation energy. We identify this as evidence of a coherent, inelastic scattering process, analogous to resonant Raman scattering, in which incident photons excite a localized electronic transition and are re-radiated at an energy reduced by the energy of the excitation. Evidence is also presented which indicates that the 2p–3d absorption transitions lie about 1 eV above a weak Ca 4s absorption threshold.

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Photon-excited yttrium ${M}_{\mathrm{I}\mathrm{V},\mathrm{V}}$, and electron-excited oxygen $K$ x-ray emission spectra for yttrium oxide are presented. It is shown that, as in the case of yttrium metal, the decay of ${M}_{\mathrm{IV}}$ vacancies does not contribute substantially to the oxide ${M}_{\mathrm{I}\mathrm{V},\mathrm{V}}$ emission. The valence emission is interpreted in a one-electron picture as a measure of the local $p$-type partial density of states. The yttrium and oxygen valence emission bands are very similar and strongly resemble published photoelectron spectra. Using local-density approximation electronic structure calculations, we show that the broadening of the Y-$4p$ signal in yttrium oxide relative to Y metal are due to two inequivalent yttrium sites in ${\mathrm{Y}}_{2}$${\mathrm{O}}_{3}$. Features present in the oxide, but not the metal spectrum, are the result of overlap (hybridization) between the Y-$4p$ wave function and states in the oxygen $2s$ subband.

Synchrotron base O 1s and N 1s photoabsorption spectroscopy have been used to determine the composition and thickness of oxynitride films grown in N 2 O on a Si(100) surface. Core-level photoabsorption spectroscopy is shown to be a very sensitive probe capable of measuring surface coverages lower than 0.1 monolayers of N (6.5×10 13 N atoms/cm 2 ). Film composiion was monitored as a function of growth to demonstrate the stoichiometry reversal from primarily N terminated surfaces in thin films to nearly pure SiO 2 in films thicker than ∼ 20 A. A sample with a 60 A oxynitride film was depth-profiled by etching in HF and was shown, via N 1s absorption spectroscopy, to have N segregation within 10 A above the Si/SiO 2 interface.

This article is a summary of four different aspects of soft x‐ray spectroscopy that are being used or developed by our group to probe the interface. The first is to study the change in valence band fluorescence emission by mimicking a high density of interface atoms through the use of a multilayer. The second method uses an intense localized excited state to characterize the buried interface. The third uses Raman scattering to probe changes in band structure produced by stoichiometric changes in the valence band density of states for atoms at the interface. Finally, a method to study interface atoms by using valence emission from interface atoms that are excited by x‐ray standing waves is being developed.

In a number of solid state systems with localized conduction band states and excitonic states, sharp features in absorption spectra were observed. We have measured the x-ray absorption spectra from borides, nitrides, and some calcium and titanium compounds using BL 6.3.2, an entrance slitless bend magnet beamline operating in the 50–1000 eV region, equipped with a Hettrick-Underwood type varied line space (VLS) grating monochromator. As an example, absorption measurement of selected compounds in B-K (∼190 eV), CaL (∼350 eV), and TiL (∼460 eV) x-ray region will be presented along with their accurate energy positions.

Synchrotron‐based O 1s and N 1s photoabsorption spectroscopy, O 1s, N 1s, Si 2p, and valence‐band photoelectron spectroscopy (PES), and medium energy ion scattering (MEIS) have been used to determine the composition and thickness of oxynitride films grown in N2O on a Si(100) surface. Core‐level photoabsorption spectroscopy is shown to be a very sensitive probe capable of measuring surface coverages lower than 0.1 monolayers of N (6.5×1013 N atoms/cm2). Film composition was monitored as a function of growth to demonstrate the stoichiometry reversal from primarily N‐terminated surfaces in thin films to nearly pure SiO2 in films thicker than ∼20 A. A sample with a 60 A oxynitride film was depth profiled by etching in HF and was shown, via N 1s absorption spectroscopy, to have N segregation within 10 A above the Si/SiO2 interface. Core‐level PES and MEIS were used to study the growth mechanisms of oxynitrides on Si(100) and these data were used to create a schematic phase diagram showing three distinct region...

Soft-x-ray emission spectra for the La {ital N}{sub 4,5}{ital O}{sub 2,3} transitions in lanthanum aluminate LaAlO{sub 3} include contributions from several relatively intense multiplet lines near 80 eV. The appearance of this spectrum contrasts sharply with the three diagram lines observed for the {ital N}{sub 4,5}{ital O}{sub 2,3} emission spectrum of Ba in BaF{sub 2}. An atomic model of the La {ital N}{sub 4,5}{ital O}{sub 2,3} transition, assuming single occupancy of the 4{ital f} shell by a spectator electron, provides a good approximation of the measured spectrum. Emission features due to the low-energy {sup 3}{ital P}{sup {ital o}} and {sup 3}{ital D}{sup {ital o}} terms of the 4{ital d}{sup 9}4{ital f} configuration are also apparent in the LaAlO{sub 3} emission spectra, but not in emission spectra from BaF{sub 2}. Reflection measurements indicate that the 4{ital f} level is not occupied in the ground state in LaAlO{sub 3}. The data suggest that charge transfer from ligand orbitals following creation of a 4{ital d} vacancy prior to the emission process is the predominant mechanism giving rise to the required 4{ital f} occupancy.

Monochromatic photon beams were used to excite barium {ital N}{sub IV,V} soft x-ray emission spectra from YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, BaF{sub 2}, and BaTiO{sub 3}. Near threshold excitation was used to demonstrate that small contributions to the barium {ital N}{sub V} and {ital N}{sub IV} emission spectra in the energy region above the 5{ital p}{r_arrow}4{ital d} core-core transitions do not arise as satellite emission from transitions in multiply excited atoms but rather occur as a result of transitions from the valence states. The emission spectrum of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} reveals a contribution to the electronic density of states at the barium site in the region near the Fermi level. The YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} compound is a superconductor and PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} is an insulator. It has been proposed that the difference between them is due to mixing of praseodymium and barium among the sites occupied by yttrium and barium, with an accompanying change in electronic structure. However, our measurements indicate that the barium partial density of states for the two compounds are essentially identical.

A third generation of synchrotron radiation facilities is coming on line worldwide, whose brilliance exceeds previous ultraviolet and x-ray light sources by four orders of magnitude. The capabilities at second and third generation light sources are discussed, using examples in surface and interface chemistry and magnetic nanostructures. The authors' experience at the IBM-Tennessee-Tulane-LLNL-LBL undulator beam line will serve as a hands-on guide for work at one of the new facilities.

The full spectrum of occupied and unoccupied σ and π orbitals is presented for solid C60, C70, and graphite, using Cls emission and absorption spectroscopy. There are significant diffcrences between C60 and C70, and even larger changes relative to their infinite analog graphite (C∝). A comparison is made with photocmission and inverse photoemission results, along with first principles quasiparticle calculations.

Boron carbide thin films of several B/C ratios have been deposited on Si(111) using plasma‐enhanced chemical vapor deposition from nido‐pentaborane(9) (B5H9) and methane (CH4). X‐ray diffraction studies of boron carbide thin films on Si(111) exhibited characteristic microcrystalline diffraction lines. Soft x‐ray emission spectroscopy was used to verify that the local electronic structure and composition of each sample corresponded to a homogeneous solid solution boron carbide phase.

Soft-x-ray emission (SXE) and soft-x-ray absorption (SXA) are used to investigate the electronic structure of \ensuremath{\alpha}-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, anodized ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, MgO, and ${\mathrm{MgAl}}_{2}$${\mathrm{O}}_{4}$. It is found that both SXE and SXA are sensitive to the crystal phase, suggesting their use as a structural probe. Comparison of the Al ${\mathit{L}}_{2,3}$ SXE of \ensuremath{\alpha}-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ and the Mg ${\mathit{L}}_{2,3}$ SXE of MgO with local-density-approximation (LDA) density-of-states calculations shows that the agreement is good, and suggests that the final-state rule is valid for the SXE of these oxides. On the other hand, comparisons show that results of the SXA and LDA calculations are not in good agreement. A model based on atomiclike excitations explains a portion of the MgO SXA spectrum well. Evidence which suggests that the remaining features are due to band structure is given.

Photon-excited soft x-ray emission spectra for CuO, Cu{sub 2}O, and bismuth cuprate in the region of the Cu 3{ital d}{r arrow}3{ital p} transitions were measured to obtain bulk-sensitive electronic partial density-of-states information. For CuO and Cu{sub 2}O transitions from the valence levels into the {ital M}{sub II} and {ital M}{sub III} levels were clearly resolved. The emission features were separated by the 2.3-eV spin-orbit interaction of the copper 3{ital p}{sub 1/2} and 3{ital p}{sub 3/2} states and appeared in the statistical intensity ratio. The copper {ital M}{sub III} emission spectrum of the superconductor is broader than the spectra of CuO and Cu{sub 2}O. For all three compounds the shape of the {ital M}{sub III} emission spectrum extracted from the data is qualitatively similar to calculations of the copper single-particle local density of states. No evidence of multiplet structure was observed in the emission spectrum of CuO in spite of the open {ital d} shell in the ground state. The measurements are compared with published copper {ital L} emission data and photoemission results.

Bulk iron silicides and implanted iron silicides have been studied by soft-x-ray emission (SXE) spectroscopy. The Si {ital L}{sub 2,3} emission spectra of these materials are measured. For bulk silicides, these spectra provide a measure of {ital s}- and {ital d}-type partial density of states (PDOS) localized on the Si sites. We compare them with available band-structure calculations and also with photoemission measurements. For implanted systems, the Si {ital L}{sub 2,3} emission spectra provide useful information about the silicide formation process with the variation of implant doses.

We present temperature-dependent soft-x-ray emission and soft-x-ray absorption measurements on MgO, \ensuremath{\alpha}-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, and \ensuremath{\alpha}-${\mathrm{SiO}}_{2}$. The measurements show in detail the final-state effect on phonon broadening for transitions involving the Mg 2P core state in MgO. In addition, we report the temperature dependence of emission and absorption features for MgO, \ensuremath{\alpha}-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, and \ensuremath{\alpha}-${\mathrm{SiO}}_{2}$. The temperature dependence of the transitions involving the valence- and conduction-band states should be an important check on band-structure calculations. These results are compared to published temperature-dependent optical-reflectivity measurements.

The Al {ital L}{sub 2,3} and O {ital K} thresholds for single-crystal {alpha}-Al{sub 2}O{sub 3} have been studied by photoemission. Energy-distribution curves, constant-initial-state (CIS), and constant-final-state (CFS) spectra are reported and compared to the absorption spectrum reported previously. An exciton appears as a doublet at threshold in the Al {ital L}{sub 2,3} CFS, CIS, and absorption spectra. The details of the Al {ital L}{sub 2,3} CFS spectrum and absorption spectrum are similar, while the exciton is the only feature present in the CIS spectrum. Comparisons of the various Al {ital L}{sub 2,3} spectra allow the probabilities of different exciton decay channels to be determined. The probability for nonradiative direct recombination of the exciton is found to be (8{plus minus}1)% and the probability for Auger decay of the exciton is found to be (72{plus minus}20)%. Comparisons of the O {ital K} CIS and CFS spectra suggest that no O {ital K} exciton is formed.

The Si L2,3 emission spectra of silicon crystals implanted with Co at doses of (1–8) × 1017 Co/cm2 have been examined using soft‐x‐ray‐emission (SXE) spectroscopy. At the lowest dose, the spectra are little modified from that of crystalline Si, indicating that only a small fraction of Si is in the form of silicides within the probe depth of SXE spectroscopy. For higher doses and implant profiles with Co extending to the surface, there is clear evidence for ordered CoSi2 combined with richer Co phases, but little evidence for pure Si or for ordered regions of CoSi.

The Ni and Co monosilicides and disilicides are studied by soft-x-ray-emission spectroscopy. The Si {ital L}{sub 2,3} spectra, which provide a measure of the partial densities of states of {ital s} and {ital d} angular momentum symmetry (({ital s}+{ital d}) PDOS) localized on the Si site, are compared with available theoretical calculations, and discussed in terms of the contribution of {ital s} electrons to the bonding. The Ni and Co {ital M}{sub 2,3} emission spectra are also obtained, and analyzed to provide information about the {ital d} PDOS localized at the metal site. These spectra are discussed in terms of {ital p}-{ital d} bonding in the silicides.

The stability of nitric acid oxidized carbon nanotubes (CNTs) and the precipitation of oxidized CNTs in water by salts were investigated. Stability investigation shows that during an aging time of 30 days, oxidized CNTs dispersion shows characteristic UV-vis absorbance peak of individual CNTs at 252 nm and CNTs concentration in the dispersion after 30d aging is 85% of the initial concentration. The precipitation value of salts were measured and the precipitation value follows the order of NaCl>KCl>1/2(MgCl(2))>1/2(CaCl(2))>1/3(FeCl(3))>1/3(AlCl(3)). The nature of anions investigated has little effect on precipitation values of salts.

The C 1s and O 1s core‐level photoabsorption spectra of poly[2‐methoxy,5‐(2′‐ethyl‐ hexoxy)‐1,4‐phenylene vinylene] (MEH‐PPV) before and after exposure O2 and broadband visible light were recorded to determine the degradation pathway for this polymer. The change in the O 1s spectra as a function of exposure demonstrates that the O adds to the polymer chain to form a carbonyl group. Exposure to only O2 or only light causes no change in the C 1s or O 1s spectra. In the C 1s spectra, the change in the dependence on the photon angle of incidence after exposure demonstrates that O attacks the polymer at the double bond in the vinyl group thereby altering the extended conjugation of the polymer.

The geometric and electronic structure of a buried monolayer of boron nitride (BN) has been probed using resonant soft x‐ray fluorescence (SXF). By using the strong π* resonance feature in the resonant fluorescence spectrum near the B (1s) threshold, we were able to detect the BN thin film and examine changes in its electronic structure when the monolayer is placed between different materials. Our results demonstrate the capability of the resonant SXF technique for probing the element‐specific electronic structure of a buried thin film nondestructively.

Si L 2.3 x-ray emission stimulated with narrow-band synchrotron radiation has been studied as a function of excitation energy. In strong contrast to crystalline silicon, amorphous silicon yields emission spectra that are independent of the excitation energy, thereby demonstrating that long-range order plays a necessary role in the excitation-energy dependence of the crystalline emission

X-ray optical processes in solids—absorption, fluorescence and resonant scattering—are modeled within a band-structure-based approach to describe electron states. The theory goes beyond a simple one-electron treatment by considering self-energy corrections for electron states, the perturbation acting on electron states because of a core hole, and, to a lesser degree, lifetime effects for high-energy electron states in solids. Aspects of the work that suggest extensions to be made in the future are discussed. Theoretical results for all three types of x-ray spectra (absorption, fluorescence and resonant scattering) are presented and compared to experiment. Results are presented for diamond, graphite, NaF and Al.

This paper is a summary of some of the recent activities of our soft x-ray spectroscopy group. We are using soft x-ray emission spectroscopy to probe the electronic properties of matter, emphasizing atoms in the bulk and at interfaces. In particular we have used incoherent photon excitation to obtain a basic understanding of the electronic properties of a wide variety of materials such as yttrium oxide and titanium diboride, we have used the penetrating power of x-rays to study multilayers of silicon and iron and have shown that iron silicide is present in the silicon layer and provides evidence that in the antiferromagnetic Fe/Si multilayer system the FeSi2 layer is conducting rather than insulating. The ubiquitous presence of Raman scattering has been used to elucidate the electronic band structure of materials including graphite and hexagonal boron nitride. Such scattering can produce dramatic changes in the emission spectrum that can further the basic understanding of the electronic band structure. We...

We are using resonant soft x-ray fluorescence at the Advanced Light Source to probe the electronic and geometric structure of novel materials. In the resonant process, a core electron is excited by a photon whose energy is near the core binding energy. In this energy regime the absorption and emission processes are coupled, and this coupling manifests itself in several ways. In boron nitride (BN), the resonant emission spectra reflect the influence of a “spectator” electron in an unoccupied excitonic state. The resonant emission can be used to distinguish between the various bulk phases of BN, and can also be used to probe the electronic structure of a monolayer of BN buried in a bulk environment, where it is inaccessible to electron spectroscopies. For highly-oriented pyrolytic graphite (HOPG) a coherent absorption-emission process takes place in the resonant regime, whereby crystalline momentum is conserved between the core excited electron and the valence hole which remains after emission

Phonon-relaxation effects on the ${\mathit{L}}_{2,3}$ soft-x-ray emission of MgO, ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{SiO}}_{2}$ are measured by comparing soft-x-ray emission spectra to photoelectron spectra. The observed shifts of the soft-x-ray emission spectra relative to the photoelectron spectra are identified as Stokes shifts and are described in terms of partial phonon relaxation. The observed Stokes shifts are 0.5, 0.9, and 1.2 eV for MgO, ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{SiO}}_{2}$, respectively. Similar measurements on Mg, Al, and Si show no detectable Stokes shift within the experimental uncertainty of 0.2 eV. The larger Stokes shifts observed in the oxides are due to the longer core-hole lifetime, the faster phonon relaxation, and larger phonon relaxation energy in the oxides.

We present the first soft x-ray-emission spectra for solid Kr (4{ital p}-3{ital d}) and Xe (5{ital p}-4{ital d}) that are free of complicating satellite spectra. Monochromatic synchrotron-radiation excitation is used to suppress the satellites. The data are analyzed to determine the {ital P}{sub 3/2} bandwidth for both elements; these results are compared with both photoemission data and available theoretical calculations. Bandwidths are found to be larger than those predicted by most electronic structure calculations.