Deflection gating for time-resolved x-ray magnetic circular dichroism-photoemission electron microscopy using synchrotron radiation

In this paper, we present a newly developed gating technique for a time-resolving photoemission microscope. The technique makes use of an electrostatic deflector within the microscope's electron optical system for fast switching between two electron-optical paths, one of which is used for imaging, while the other is blocked by an aperture stop. The system can be operated with a switching time of 20 ns and shows superior dark current rejection. We report on the application of this new gating technique to exploit the time structure in the injection bunch pattern of the synchrotron radiation source BESSY II at Helmholtz-Zentrum Berlin for time-resolved measurements in the picosecond regime.     

High-resolution confocal microscopy using synchrotron radiation

A confocal scanning light microscope coupled to the Daresbury Synchrotron Radiation Source is described. The broad spectrum of synchrotron radiation and the application of achromatic quartz/CaF₂ optics allows for confocal imaging over the wavelength range 200–700 nm. This includes UV light, which is particularly suitable for high-resolution imaging. The results of test measurements using 290-nm light indicate that a lateral resolution better than 100 nm is obtained. An additional advantage of the white synchrotron radiation is that the excitation wavelength can be chosen to match the absorption band of any fluorescent dye. The availability of UV light for confocal microscopy enables studies of naturally occurring fluorophores. The potential applications of the microscope are illustrated by the real-time imaging of hormone traffic using the naturally occurring oestrogen coumestrol. (The IUPAC name for coumestrol is 3,9-dihydroxy-6H-benzofuro[3,2-c][1]benzopyran-6-one ( Chem. Abstr. Reg. No . 479-13-0). The trivial name will be used throughout this paper.)     

Time-of-flight photoelectron spectroscopy of gases using synchrotron radiation

A gas-phase time-of-flight (TOF) photoelectron spectrometer has been developed for use with synchrotron radiation. The excellent time structure of the synchrotron radiation at the Stanford Positron Electron Accelerator Ring (SPEAR) has been used as the time base for the TOF measurements. The TOF analyzer employs two multichannel plates (MCPs) in tandem as a fast electron multiplier with a matched 50-Omega anode to form an electron detector with a timing resolution of 相似文献   

On the implementation of computed laminography using synchrotron radiation

Hard x rays from a synchrotron source are used in this implementation of computed laminography for three-dimensional (3D) imaging of flat, laterally extended objects. Due to outstanding properties of synchrotron light, high spatial resolution down to the micrometer scale can be attained, even for specimens having lateral dimensions of several decimeters. Operating either with a monochromatic or with a white synchrotron beam, the method can be optimized to attain high sensitivity or considerable inspection throughput in synchrotron user and small-batch industrial experiments. The article describes the details of experimental setups, alignment procedures, and the underlying reconstruction principles. Imaging of interconnections in flip-chip and wire-bonded devices illustrates the peculiarities of the method compared to its alternatives and demonstrates the wide application potential for the 3D inspection and quality assessment in microsystem technology.     

Apparatus for time-resolved and energy-resolved measurement of internal conversion electron emission induced by nuclear resonant excitation with synchrotron radiation

A high-energy and large-object-spot type cylindrical mirror analyzer (CMA) was constructed with the aid of electron trajectory simulations. By adopting a particular shape for the outer cylinder, an energy resolution of 7% was achieved without guide rings as used in conventional CMAs. Combined with an avalanche photodiode as an electron detector, the K-shell internal conversion electrons were successfully measured under irradiation of synchrotron radiation at 14.4 keV in an energy-resolved and time-resolved manner.     

利用晶体多重衍射进行同步辐射光子能量标定

介绍了多重衍射的基本原理,包括多重衍射的指标化、衍射光强度的计算和入射光方向的确定,并根据晶体多重衍射现象提出了入射X光能量的标定方法.从理论上讲,使用该标定方法在角度扫描精度为1"时,光子能量标定精度可达到1 eV.在上海光源14B衍射光束线上对提出的标定方法进行了实验验证,在10 keV处用Si(111)为主衍射收...     

Biological calcium absorption edge imaging using monochromatic synchrotron radiation.

Soft X-ray contact absorption edge images of unfixed, unstained biological specimens were made using monochromatic synchrotron radiation. X-ray contact replicas of unfixed, hydrated biological specimens at the nitrogen absorption edge and above and below the CaLIII absorption edge were compared to comparative conventional morphological and elemental high-resolution imaging methods (scanning and transmission electron microscopy, TEM-histochemistry and TEM-X-ray microanalysis). Soft X-ray absorption edge images made above the calcium absorption edge clearly revealed morphological detail and identified regions ladened with calcium as verified by TEM histochemistry of identical spores. Similarly, nitrogen absorption edge images identified residual nitrogenous material in the spore resuspension medium, and non-viable spores with nitrogen loss due to protoplast disaggregation.     

X-ray fluorescence with synchrotron radiation

The use of synchrotron radiation for X-ray fluorescence has several advantages over the use of other conventional X-ray sources. The principles of synchrotron radiation and methods for applying synchrotron radiation to the X-ray fluorescence measurements of trace elements are discussed. The Brookhaven National Laboratory X-ray microprobe, facilities dedicated to X-ray fluorescence, and related analytical techniques are discussed. Some examples of trace element analyses in biological materials with synchrotron radiation are presented.     

Vacuum-ultraviolet Gabor holography with synchrotron radiation

We present the realization of high-resolution holographic microscopy using the original Gabor geometry and imaging with radiation in the vacuum-ultraviolet (VUV) spectral region. Synchrotron VUV radiation with a wavelength of 13.8 nm was focused on a small pinhole generating a highly divergent light cone suitable for digital in-line holography. Objects of different thickness and materials have been used to test the imaging properties of holographic microscopy in the VUV wavelength range. The effective numerical aperture was limited by the illuminated area of the detector, yielding a theoretical resolution below 1 microm and an experimental one of approximately 1 microm.     

Excitation energy transfer of porphyrin in polymer thin films by time-resolved scanning near-field optical microspectroscopy

Thin films of water-soluble free-base porphyrin, 5,10,15,20-tetraphenyl-21H, 23H-porphinetetrasulphonic acid (TPPS) mixed with poly(diallyldimethyl ammonium chloride) (PDDA) have been prepared by a spin-coating method, in which the monomeric species were observed in the spin-coat film, whereas dimer was formed in the cast film prepared from TPPS/PDDA solution. Mesoscopic structures and dynamics of excitation energy migration and trapping of TPPS/PDDA spin-coat film have been analysed by time-resolved scanning near-field optical microspectroscopy (SNOM) and atomic force microscope. The observed film structure can be classified roughly into two parts: one is a large, flocculated polymer part, and the other is a smooth part widely spread around the flocculated polymers. In the smooth part, the observed spindle-like structure and circular hills and dips are essentially due to PDDA. The ellipsoidal small structures with ∼2µm length and <1 µm width in the flocculated polymer part show non-exponential fluorescence decays. The non-exponential dynamics originates from the excitation energy migration among TPPS monomers and energy trapping to dimers. From the analysis of fluorescence decay curves based on the equation developed by Klafter and Blumen, the spectral dimension has been estimated to be ∼1.46 for ellipsoidal structures. These results indicate that the distribution of the chromophore is inhomogeneous and a fractal-like structure exists even in the small domains determined by the resolution of the SNOM tip.     

A detector for imaging of explosions on a synchrotron radiation beam

Synchrotron radiation (SR) offers a unique chance to study the structure of a substance in fast processes. Since SR is emitted by electron bunches in a storage ring, the SR burst corresponding to a single bunch may be very short. Should a detector capable of detecting SR from a single bunch without mixing signals from different bunches be available, it is possible to obtain information on changes in the state of the material in a sample under investigation with a very high time resolution. A detector for imaging of explosions on an SR beam—DIMEX—has been developed by the Budker Institute of Nuclear Physics (Siberian Division of the Russian Academy of Sciences, Novosibirsk). This detector is a high-pressure ion-ization chamber with a strip readout at a pitch of 0.1 mm. The electron component of primary ionization is collected within 50 ns, which is substantially shorter than the orbital period of a bunch in the VEPP-3 storage ring (250 ns). The DIMEX is filled with a Xe—CO₂ mixture (3: 1) at an absolute pressure of 7 atm. The spatial resolution of the detector is ∼210 μm, and its efficiency for radiation with an energy of 20 keV is ≥50%. The dynamic range of the detector is ∼100, which allows one to measure the signal with an accuracy of ∼1%. In this case, the maximum flux of X-ray photons, at which the DIMEX operates in a linear region, is ∼10¹⁰ photons/(channel s). Today, the detector has been used in experiments aimed at studying evolution of the density in detonation waves and processes of nanoparticle production at the VEPP-3 storage ring by employing the small-angle X-ray scattering technique.     

A compact time-resolved system for near infrared spectroscopy based on wavelength space multiplexing

We designed and developed a compact dual-wavelength and dual-channel time-resolved system for near-infrared spectroscopy studies of muscle and brain. The system employs pulsed diode lasers as sources, compact photomultipliers, and time-correlated single photon counting boards for detection. To exploit the full temporal and dynamic range of the acquisition technique, we implemented an approach based on wavelength space multiplexing: laser pulses at the two wavelengths are alternatively injected into the two channels by means of an optical 2×2 switch. In each detection line (i.e., in each temporal window), the distribution of photon time-of-flights at one wavelength is acquired. The proposed approach increases the signal-to-noise ratio and avoids wavelength cross-talk with respect to the typical approach based on time multiplexing. The instrument was characterized on tissue phantoms to assess its properties in terms of linearity, stability, noise, and reproducibility. Finally, it was successfully tested in preliminary in vivo measurements on muscle during standard cuff occlusion and on the brain during a motor cortex response due to hand movements.     

Mythen detector for X-ray diffraction at the Beijing synchrotron radiation facility

Time-resolved X-ray powder diffraction may be used to elucidate the structure of polycrystalline matter, but a fast-response full-profile detector is often necessary. This article describes a Mythen detector incorporated in beamline 4B9A of the Beijing Synchrotron Radiation Facility. Basic parameters of this detector are reported, and flat-field correction, angular calibration, eccentric error, and other data treatment for this detector are discussed. X-ray diffraction measurement of lanthanum boride demonstrates that this detector provides high-quality, time-resolved X-ray powder diffraction measurements.     

同步辐射在生物大分子结构研究中的应用

本文介绍同步辐射X射线衍射技术的特点及其在生物大分子结构研究中的应用     

航空发动机整机红外辐射特性台架试验方案研究

根据航空发动机整机红外辐射特性台架试验要求,给出了发动机整机红外辐射特性试验的测试场地规划,并介绍了红外辐射测量设备的工作原理和技术指标等。重点对红外辐射特性试验测试结果准确性的影响因素进行了分析,并提出了提高红外测试精度的相关措施。根据具体试验场地和环境,规划了开展航空发动机整机红外辐射台架试验的测试场地、现场校准、背景遮挡装置等具体的测试方案,为后续发动机红外辐射特性地面台架试验的开展奠定重要基础。     

Absorption edge imaging of bacterial endospores with synchrotron radiation

This article describes a new method of viewing biological specimens by taking advantage of the absorptive characteristics of monochromatic X-rays above and below the absorption edge of a specific element. Bacterial endospores were imaged before and after treatment with an experimental vanadium-containing sporocide using monochromatic synchrotron radiation at the nitrogen absorption edge, and above and below the vanadium LIII absorption edge. This morphological study demonstrates a rapid, easy-to-use method of soft X-ray absorption edge imaging that can be used by the biologist to obtain morphological and elemental information that is not readily accessible using conventional microscopic and analytic techniques.     

Development of the system for stabilizing the position of a synchrotron radiation beam

The development of the system for stabilizing the vertical position of the “white” synchrotron radiation beam on the 2.5-GeV SIBERIA-2 storage ring at the Kurchatov Center of Synchrotron Radiation is considered. Two versions of the multichannel stabilizing system that are currently in operation are described. In the first, the procedures executed when introducing the first beam-stabilizing feedback loop in one channel are merely replicated for all other beamlines. In this case, an individual computer transmitting information to the control system of the storage ring via the local-area network is used in each beamline to process information from a beam position sensor equipped with a video camera. The other version of the stabilizing system is based on a central computer with a multichannel input card for video images. In this version, beam position sensors are sequentially interrogated by the computer and results of data processing are transmitted to the control system of the storage ring.     

Observation of mass analyzed threshold ionization using synchrotron radiation on a new-style time of flight mass spectrometer

We have developed an efficient and applicable apparatus that combines mass-analyzed threshold ionization (MATI) with continuous molecular-beam mass spectrometry using tunable vacuum ultraviolet synchrotron radiation at National Synchrotron Radiation Laboratory. The new design, in which the spoiling field and the pulsed ionization field are perpendicular to each other, can obtain efficiently the ionic spectra of molecule. The MATI spectra of Ar and N(2) have been recorded in the energy region between 15.5 and 17.5 eV to illustrate the feasibility of this scheme. With its unique features, the important experiment considerations are potentially a powerful tool for study of information of ionization energies and ionic states of complex organic compounds.