高谱分辨X光能谱诊断技术

采用国内首次研制出的2000线/mm的自支撑透射光栅配上背照射软X光CCD(charge coupleddevice)组成了高谱分辨透射光栅谱仪。通过实验标定和理论模型计算相结合得到了高线对透射光栅的绝对衍射效率;同时建立了透射光栅谱仪测谱解谱方法,编制了相应的解谱程序。在"神光"激光装置上利用该谱仪通过激光打靶实验获得了金腔靶注入口发射的X光能谱定量实验结果,实验结果表明,该谱仪测谱范围在高能区达到6000eV,谱分辨达到0.1nm,能够清晰地分辨金等离子体M带三峰分布X光谱结构。

X光弯晶成像金属薄膜面密度测量技术

针对靶用高Z金属薄膜的无损检测需求,提出了一种通过超环面弯晶聚焦型X光单能成像器件,实现金属薄膜均匀性及面密度等参数精确标定的测量技术。该技术即通过高通量、高单能性成像,定量获取薄膜X光透过率及其空间分布,有效提升了面密度测量的精度,同时实现了对其均匀性的高空间分辨评估。从总体方案设计、元器件制备和测试实验等方面开展了深入研究,并评估了各种可能因素对测量不确定度的影响。所发展的超环面弯晶成像系统针对20 keV级的高能X射线在mm尺度内实现了优于5μm的微区分辨,能谱分辨达到几eV。通过泡沫金样品面密度测量实验证明了技术可行性,相对不确定度优于2%。研究结果为激光惯性约束聚变高Z靶材料的精密无损检测提供了一种新的测量技术,并有望应用于其他需要大视场、高空谱分辨成像的需求领域。

Classification of Chinese Traditional Drug-"Beimu" (Bulbus Fritillariae) by Pyrolysis High Resolution Gas Chromatography-Pattern Recognition

The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.

Comparative Investigation of Mo（CO）6 Adsorption on Clean and OxidiZed Si（111） Surfaces

Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift of the C-O stretching mode in adsorbed Mo（CO）6 illustrates that different interactions of adsorbed Mo（CO）6 occur on clean Si（111） and SiO2/Si（111） surfaces, weak on the former and strong on the latter. The strong interaction on SiO2/Si（111） might lead to the partial dissociation of Mo（CO）6, consequently the formation of molybdenum subcarbonyls. Therefore, employing Mo（CO）6 as the precursor, metallic molybdenum could be successfully deposited on the SiO2/Si（111） surface but not on the clean Si（111） surface. A portion of the deposited metallic molybdenum is transformed into the MoOa on the SiO2/Si（111） surface upon heating, and the evolved MoO3 finally desorbs from the substrate upon annealing at elevated temperatures.

High-resolution Infrared Spectroscopy of ^15N2^16O in 1650-3450 cm-1

High-resolution ro-vibrational spectroscopy of ^15N2^16O in 1650-3450 cm-1 region is studied using highly enriched isotopologue sample. The positions of more than 7300 lines of ^15N2^16O isotopologue were measured with a typical accuracy of 5.0×10-4 cm-1. The transitions were rovibrationally assigned on the basis of the global effective Hamiltonian model. The band by band analysis allowed for the determination of the rovibrational parameters of a total of 73 bands. 29 of them are newly reported and more rotational transitions have been observed for the others. The maximum deviation of the preidictions of the effective Hamiltonian model is up to 0.70 cm-1 for the ^15N2^16O species.

Determination of trace elements in high purity nickel by high resolution inductively coupled plasma mass spectrometry

The contents ofMg, Al, Si, Ti, Cr, Mn, Fe, Co, Cu, Ga, As, Se, Cd, Sb, Pb and Bi in high purity nickel were determined by high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS）. The sample was dissolved in HNO3 and HCI by microwave digestion. Most of the spectral interferences could be avoided by measuring in the high resolution mode. The matrix effects because of the presence of excess HC1 and nickel were evaluated. Correction for matrix effects was made using Sc, Rh and T1 as internal standards. The optimum conditions for the determination were tested and discussed. The detection limits range from 0.012 to 1.76 ~tg/g depending on the type of elements. The applicability of the proposed method is also validated by the analysis of high purity nickel reference material （NIST SRM 671）. The relative standard deviation （RSD） is less than 3.3%. Results for determination of trace elements in high purity nickel were presented.

Method for obtaining high-resolution velocity spectrum based on weighted similarity

Seismic wave velocity is one of the most important processing parameters of seismic data,which also determines the accuracy of imaging.The conventional method of velocity analysis involves scanning through a series of equal intervals of velocity,producing the velocity spectrum by superposing energy or similarity coefficients.In this method,however,the sensitivity of the semblance spectrum to change of velocity is weak,so the resolution is poor.In this paper,to solve the above deficiencies of conventional velocity analysis,a method for obtaining a high-resolution velocity spectrum based on weighted similarity is proposed.By introducing two weighting functions,the resolution of the similarity spectrum in time and velocity is improved.Numerical examples and real seismic data indicate that the proposed method provides a velocity spectrum with higher resolution than conventional methods and can separate cross reflectors which are aliased in conventional semblance spectrums;at the same time,the method shows good noise-resistibility.

Improving the resolution of seismic traces based on the secondary time-frequency spectrum

The resolution of seismic data is critical to seismic data processing and the subsequent interpretation of fine structures. In conventional resolution improvement methods, the seismic data is assumed stationary and the noise level not changes with space, whereas the actual situation does not satisfy this assumption, so that results after resolution improvement processing is not up to the expected effect. To solve these problems, we propose a seismic resolution improvement method based on the secondary time-frequency spectrum. First, we propose the secondary time-frequency spectrum based on S transform （ST） and discuss the reflection coefficient sequence and time-dependent wavelet in the secondary time frequency spectrum. Second, using the secondary time frequency spectrum, we design a two- dimensional filter to extract the amplitude spectrum of the time-dependent wavelet. Then, we discuss the improvement of the resolution operator in noisy environments and propose a novel approach for determining the broad frequency range of the resolution operator in the time- fi＇equency-space domain. Finally, we apply the proposed method to synthetic and real data and compare the results of the traditional spectrum-modeling deconvolution and Q compensation method. The results suggest that the proposed method does not need to estimate the Q value and the resolution is not limited by the bandwidth of the source. Thus, the resolution of the seismic data is improved sufficiently based on the signal-to-noise ratio （SNR）.

Adaptive Antenna-Activation Based Beamforming for Large-Scale MIMO Communication Systems of High Speed Railway

Large-scale array aided beamforming improves the spectral efficiency(SE) as a benefit of high angular resolution.When dual-beam downlink beamforming is applied to the train moving towards cell edge,the inter-beam ambiguity(IBA) increases as the directional difference between beams becomes smaller.An adaptive antenna activation based beamforming scheme was proposed to mitigate IBA.In the district near the base station(BS),all antenna elements(AEs) were activated to generate two beams.As the distance from the train to the BS increased,only the minimum number of AEs satisfying the resolution criterion would be activated.At the cell edge,one beam was switched off due to intolerable IBA.The proposed scheme can achieve SE gain to the non-adaptive scheme and show more robustness against the direction-of-arrival(DOA) estimation error.

Validation of IASI-Retrieved Atmospheric Water Vapor Data over the Tibetan Plateau Region

The Infrared Atmospheric Sounding Interferometer (IASI) is a new-generation ultraspectral atmospheric sounding instrument mounted on the MetOp-A, the first operational polar-orbiting satellite developed by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). It is an ultrahigh spectral-resolution atmospheric detector which can detect atmospheric chemical composition, temperature, and humidity profiles with high accuracy and resolution. In the present study, through comparative analyses of the similarities and differences between the IASI and the radiosonde observation (RAOB) water vapor data, and between the IASI and the Aqua-AIRS water vapor retrievals, a detailed and systematic assessment of the credibility of the IASI water vapor retrievals over the plateau region was made. A comparison of the IASI retrievals with the AIRS retrievals and the RAOB measurements over the Tibetan Plateau revealed that the IASI retrieval data are reliable and can be used for conducting further studies.

High Resolution Electron Momentum Spectroscopy Study on Ethanol： Orbital Electron Momentum Distributions for Individual Conformers

The outer-valence binding energy spectra of ethanol in the energy range of 9-21 eV are mea- sured by a high-resolution electron momentum spectrometer at an impact energy of 2.5 keV plus the binding energy. The electron momentum distributions for the ionization peaks cor- responding to the outer-valence orbitals are obtained by deconvoluting a series of azimuthal angular correlated binding energy spectra. Comparison is made with the theoretical calcu- lations for two conformers, trans and gauche, coexisting in the gas phase of ethanol at the level of B3LYP density functional theory with aug-cc-pVTZ basis sets. It is found that the measured electron momentum distributions for the peaks at 14.5 and 15.2 eV are in good agreement with the theoretical electron momentum distributions for the molecular orbitals of individual conformers （i.e., 8a＇ of trans and 9a of gauche）, but not in accordance with the thermally averaged ones. It demonstrates that the high-resolution electron momentum spectrometer, by inspecting the molecular electronic structure, is a promising technique to identify different conformers in a mixed sample.

Preparation of Carbon Encapsulated Iron Nanoparticles with Very Thin Shells by DC Arc Discharge

Carbon encapsulated iron nanoparticles （CEINPs） with very thin shells and good core-shell structures were prepared by DC arc discharge at argon intake temperature （AIT） of 800 ℃. The results of high resolution transmission electron microscope （HRTEM）, energy dispersive X-ray （EDX） spectroscope, X-ray diffraction （XRD）, and X-ray photoelectron spectroscope （XPS） characterizations on the product B show that the thickness of the carbon shells of CEINPs in the product B is in the range of ca. 0.5-5.3 nm, i. e., which can be as thin as only two layers of graphite. The average diameter of the CEINPs is about 24. 7 nm. The total content of Fe element in the product B is 77.0 wt%. The saturation magnetization （Ms） and coercivity （Hc） of the product B are 107.4 emu/g and 143 Oe. resnectivelv. The formation of the CEINPs in the oroduct B is discussed briefly.

Ultra High Energy Cosmic Rays： Spectral Signatures and Observations

The observations of Ultra High Energy Cosmic Rays （UHECR） are renewed, focusing on the energy spectra as measured by HiRes, Telescope Array （TA） and Auger detectors （PAO）. It is found that highest energy Auger steepening does not agree with GZK cutoff, which is most probably explained by the nuclei mass composition detected by Auger. At present the difference in mass composition in Auger and HiRes/TA data remains the main unsolved problem of UHECR origin.

Alpine grassland fPAR change over the Northern Tibetan Plateau from 2002 to 2011

In this study, two different methods including Digital Camera and Reference Panel （DCRP） and traditional in situ fPAR observation for measuring the in situ point fPAR of very short alpine grass vegetation were compared, and the Moderate Resolution Imaging Spectroradiometer （MODIS） fPAR products were evaluated and validated by in situ point data on the alpine grassland over the Northern Tibetan Plateau, which is sensitive to climate change and vulnerable to anthropogenic activities. Results showed that the MODIS alpine grassland fPAR product, examined by using DCRP, and traditional in situ fPAR observation had a significant relationship at the spatial and temporal scales. The decadal MODIS fPAR trend analysis showed that, average growing season fPAR increased by 1.2 × 10^-4 per year and in total increased 0.86% from 2002 to 2011 in alpine grassland, when most of the fPAR increments occurred in southeast and center of the Northern Tibetan Plateau, the alpine grassland tended to recover from degradation slightly. However, climatic factors have influenced the various alpine grassland vegetation fPAR over a period of 10 years; precipitation significantly affected the alpine meadow fPAR in the eastern region, whereas temperature considerably influenced the alpine desert steppe fPAR in the west region. These findings suggest that the regional heterogeneity in alpine grassland fPAR results from various environmental factors, except for vegetation characteristics, such as canopy structure and leaf area.

^13C NMR and ^1H NMR Spectroscopic Analysis of Adansonia digitata, Albizia lebbeck and Daniellia ofiveri Oils

Oils of AD （Adansonia digitata）, AL （Albizia lebbeck） and DO （Daniellia oliveri） were studied using ^13C NMR （nuclear magnetic resonance） and ^1H NMR. The gated decoupled high resolution ^13C NMR spectra revealed the presence of both saturated and unsaturated triacylglycerides. However, there is a higher percentage of unsaturation in AL seed oil. The peaks at 0.7 ppm to 0.9 ppm which correspond to the terminal methyl groups in the fatty acid and that at 1.2 ppm to 1.3 ppm are more intense and bigger in DO which show that it is more saturated than AD and AL oils. The results obtained by ^13C NMR and ^1H NMR are compared favorably with those obtained by gas chromatographic analysis.

Ultrasonic Resonator Techniques for Broad-band Spectroscopy and for High-resolution Sound Velocity Measurement of Liquids

This review gives a short introduction into the principles of ultrasonic measurement techniques for liquids, using cavity resonators. Guidelines for the resonator design in broad-band ultrasonic stxctroscopy as well as in high-resolution single-frequncy or narrowband applications are presented. Deviations of the field configuration in real cells frtxn that in an ideal resonator are discussed and relations for the mode spectrum of cavity fields are given. Recent resonator measurement procedures and methods of data evaluation are mentioned briefly. Some examples of measurements show the extended usability of ultrasonic resonator techniques in basic science and in a wide range of applications for rrkaterials characterization, in manufacturing processes, as well as in control routines.

Basis Set Extrapolation for the High Resolution Spectroscopy

Valence and all electron correlation energies of a large set of atoms and molecules with structural motifs from amino acids and peptides at their equilibrium as well as non-equilibrium geometries are calculated at the levels of MP2, RI-MP2, and CCSD （T） with Dunnings sequential correlation consistent basis sets. A two point basis set extrapolation scheme for correlation energies to the complete basis set limit based on only DZ （double-zeta） and TZ （triple-zeta） results is presented and analyzed. We show that this basis set extrapolation scheme reduces the computational cost by two to three orders of magnitude to obtain the same accuracy as simpler extrapolations from higher order basis set computations.

Time-resolved two-photon excitation fluorescence spectroscopy and microscopy using a high repetition rate streak camera

We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time- and spectrum- resolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond streak camera for providing time- and spectrum- resolved measurement and imaging in biomedicine. The performance of the system is tested and characterized by the fluorescence spectrum and lifetime analysis of several standard fluorescent dyes and their mixtures. Spectrum-resolved fluorescence lifetime images of fluorescence beads are obtained. Potential applications of the system include clinical diagnostics and cell biology etc.

Investigations of the fragmentation behavior of 11 isoflavones with ESI-IT-TOF-MS^n

The fragmentation behavior of isoflavones was studied using electrospray ionization-ion trap-time of flight mass spectrometry （ESI-IT-TOF-MSn）. It was found that the isoflavone glycoside bond was easily broken. The fragmentation occurred mostly on the C-ring, and the fragment ions of A^1,3＋ produced by the RDA cracking will predict the hydroxylation replacement on A-ring or B-ring. In addition, four carbonyl groups on the C-ring were fragmented through neutral loss of 28 （-CO）. A and B-rings primarily lose substituents which including a neutral losses of 32 （-CH3OH）, 16 （-CH4）, or 16 （-O）, and 18 （-H2O）. A-ring in the presence of adjacent hydroxylation, also easily made to be a neutral losses of 28 （-CO） or 18 （-H20）. It is likewise common to see methoxy replaced with a neutral losses of 16 （-CH4） or 32 （-CHaOH） in B-ring, also the hydroxylation on benzene ring can occasionally results with the neutral loss of 28 （-CO）.

Chemical profiling of Scutellaria barbata by ultra high performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry

An ultra high performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry （UHPLC-quadrupole-orbitrap MS） method was developed to systematically analyze chemical constituents of Scutellaria barbata D. Don. The 70% methanol extract was separated on an Agilent Eclipse Plus Cl8 column （1.8μm, 150 mm×2.1 mm）, and eluted with a gradient of methanol-acetonitrile-water containing 0.1% formic acid at a flow rate of 0.25 mL/min. Constituents were identified by HRMS in the negative ion mode using both full scan and two-stage threshold-triggered mass modes. A total of 56 compounds, including 20 free flavonoids, 20 flavonoid O-glycosides, 2 flavonoid C-glycosides, 4 phenylethanoid glycosides, and 10 phenolic compounds were identified by analyzing their high resolution mass spectral data. Among them, 8 flavonoids and 2 phenylethanoid glycosides were unambiguously identified by comparing with reference standards. This study demonstrates that hybrid quadrupole-orbitrap mass spectrometry is a powerful tool in structural identification of unknown compounds in comolicated herbal extracts.