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Here we report on the structural and electronic phase diagram of lithium and ethylenediamine intercalated FeSe in a wide range of dopant concentration $(x=0\ensuremath{\sim}0.8)$. Undoped ${({\mathrm{C}}_{2}{\mathrm{H}}_{8}{\mathrm{N}}_{2})}_{y}\mathrm{F}{\mathrm{e}}_{2}\mathrm{S}{\mathrm{e}}_{2}$ crystallizes in an orthorhombic phase. With increasing lithium doping, an orthorhombic to tetragonal phase transition occurs at $x=0.35$, and the superconducting tetragonal phase persists until $x=0.5$. Meanwhile, the ${T}_{c}$ is found dependent strongly on dopant concentration, raising rapidly from 30 K at $x=0.35$ to 45 K at $x=0.5$. The crystal structures of $\mathrm{L}{\mathrm{i}}_{0.31(3)}{({\mathrm{C}}_{2}{\mathrm{H}}_{8}{\mathrm{N}}_{2})}_{0.52(7)}\mathrm{F}{\mathrm{e}}_{2.03(2)}\mathrm{S}{\mathrm{e}}_{2}$ are determined by using high-resolution neutron diffraction data at 5, 60, 150, and 295 K, respectively. The distortion of the FeSe tetrahedron is enhanced significantly from 150 to 295 K, meanwhile, the normal-state Hall resistivity changes sign from negative to positive in the same temperature range. The dominant hole carrier in electron-doped $\mathrm{L}{\mathrm{i}}_{0.5}{({\mathrm{C}}_{2}{\mathrm{H}}_{8}{\mathrm{N}}_{2})}_{y}\mathrm{F}{\mathrm{e}}_{2}\mathrm{S}{\mathrm{e}}_{2}$ above 230 K suggests that the temperature-induced structure distortion may lead to a reconstruction of the Fermi surface topology and the appearance of hole pockets.

The experiment was carried out to study the low frequency surface waves due to the horizontal high frequency excitation. The feature of the phenomenon was that the big amplitude axisymmetric surface wave frequency was typically about 1/50 of the excitation frequency. The viscous effect of water was neglected as a first approximation in the earlier papers on this subject. In contrast, we found the viscosity was important to achieve the low frequency water wave with the cooperation of hundreds of "finger" waves. Photographs were taken with stroboscopic lighting and thereafter relevant quantitative results were obtained based on the measurements with Polytec Scanning Vibrometer PSV 400.

1) The storage ring operation energy was raised to 1.5 GeV, the maximum value limited by dipole magnets, to improve electron beam lifetime and to extend its spectrum to higher energies in 1996. 2) Five permanent-magnet insertion devices have been constructed and installed, as listed in Table I, by the end of 1999 to provide synchrotron radiation with higher brightness and energies. In 2003, the U10 undulator was removed and loaned to ANKA, Germany. 3) The booster energy was increased from 1.3 to 1.5 GeV. With this accomplishment, the facility can perform full energy injection and reduces the transient behavior between shifts, opening the possibility of top-up injection mode. 4) The stability of electron beam has been improved. With the raise of electron beam position monitors (EBPM) resolution to better than 1μm, the reduction of both air and cooling water temperature fluctuations to less than ±0.1 , and the °C implementation of the global feedback system, the beam orbit stability of ~ 1μm with a drift of ~ 5μm in a single shift is routinely achievable now.

On June 14, 1998, a Pi 2 pulsation of unusually large amplitude was observed simultaneously by ground stations located in both of dayside and nightside local time sectors and with 145-degree latitude span (from 70.6°N to 74.7° S). The geomagnetic field observed by stations in nightside clearly showed substrom signatures at the event time and it appeared that the dayside Pi 2 signature is also associated with the substorm. We analyzed the polarization of the dayside Pi 2 wave in the horizontal plane and found that the longitudinal variation of the polarization agreed with that generated by a current wedge. This has previously been reported for nighttime Pi 2 but is unexpected for daytime events.

A Kirkpatrick–Baez (K–B) mirror system is designed while considering gain, efficiency, and focal spot size to theoretically achieve a spot size of 6.7×2.9 μm2 and a gain of 6.2×103 in the elliptical polarization undulator (EPU) soft X-ray beamline. This mirror system, which contains two high order polynomial corrected cylindrical mirrors (i.e., horizontal microfocusing mirror, HMFM, and vertical microfocusing mirror, VMFM) with a monolithic flexure-hinge design, can collect and microfocus the undulator source into a nearly perfect point image. To ensure that the mirrors are easily mounted and adjusted, a modular system on a rotatable CF flange is designed to independently motorize each mirror with four degrees of freedom.

Bimorph piezoelectric optics with a third-order-polynomial surface is designed and a prototype is fabricated as active optics. Two pairs of silicon (Si) and lead zirconate titanate (PZT) piezoelectric ceramic are bonded as Si–PZT–PZT-Si together with a multi-electrode or thin film resistor coating used as the control electrode between Si and PZT and metallic films as grounding between the interface of PZT ceramics. A linear voltage is applied to the bimorph PZT optics by probing the control electrodes from a two-channel controllable power supplier. In doing so, the optics surface can achieve a desired third-order-polynomial surface. Reducing hysteresis and creep in bimorph PZT X-ray optics is the only feasible way by inserting an appropriate capacitor in series with bimorph PZT optics to significantly reduce both effects.

A novel high resolution, high flux bending magnet beamline with an energy range from 5to 40eV has beenconstructed at SRRC. This Dragon-like beamline, which horizontally collects 50mrad of synchrotron radiationfrom a bending magnet source, uses four cylindrical gratings with an included angle of 1408 and a movablecurved exit slit. The average photon flux with an energy resolving power of 1000 is about 2 1210 photons/s,which is among the highest of all existing VUV bending magnet beamlines. An energy resolving power of24000 at 6.8eV has been obtained from the Schumann–Runge bands (B 3 P u 3XP g ) absorption spectra ofO 2 gas. A photon flux of 3 10 9 photons/s is measured at the energy resolving power of 24000. This high fluxbending magnet beamline offers excellent opportunities for VUV experiments with a wide range spectrum. # 2001ElsevierScienceB.V.Allrightsreserved. PACS: 33.80. b;39.30.+w;42.79.Dj;51.50.+vKeywords: Beamline;Highflux;Highresolution 1.IntroductionAhighfluxandhighresolutionbendingmagnetbeamlinewithanenergyrangefrom5to40eVhasbeenconstructedatSRRC[1]fortheexperimentsofdilutesystems,oflowsignal-to-noiseratio,andexperimentswhichrequirelowenergyphotonsandverygoodenergyresolution.Theopticallayoutofthis beamline is shown in Fig.1. This beamlinecollects 50mrad of horizontal radiation from abending magnet source. Similar to the Dragon-type beamline, a 6m-CGM is arranged betweenpre-andpost-focusingmirrors.Wehaveadoptedseveralspecialfeaturesincludingamodifiedplane-elliptical horizontal pre-focusing mirror (HFM),one movable entrance slit, and one curvedmovableexitslittooptimizethebeamlineperfor-mance.Fourcylindricalgratingswithanincludedangle of 1408 are used to cover the entire energyrange interested. Two horizontal refocusing mir-rors(HRFM1andHRFM2)areusedtodeliverthe photon beam to two separate experimentalstationsthroughthehigh-andlow-energybranch,respectively. The beamline is expected to deliverphoton fluxes of 1 10

An active polynomial grating has been designed for use in synchrotron radiation soft-X-ray monochromators and spectrometers. The grating can be dynamically adjusted to obtain the third-order-polynomial surface needed to eliminate the defocus and coma aberrations at any photon energy. Ray-tracing results confirm that a monochromator or spectrometer based on this active grating has nearly no aberration limit to the overall spectral resolution in the entire soft-X-ray region. The grating substrate is made of a precisely milled 17-4 PH stainless steel parallel plate, which is joined to a flexure-hinge bender shaped by wire electrical discharge machining. The substrate is grounded into a concave cylindrical shape with a nominal radius and then polished to achieve a roughness of 0.45 nm and a slope error of 1.2 μrad rms. The long trace profiler measurements show that the active grating can reach the desired third-order polynomial with a high degree of figure accuracy.

The plasma maser effect in the existence of enhanced kinetic Alfven wave turbulence is investigated as the generation mechanism of the whistler turbulence at the magnetopause. The numerical results of the growth rate show that on the scale of neither the ion inertial length nor the electron inertial length, the whistler waves can be excited, and the peak of the maximum growth rate occurs on the scale of the effective ion Larmor radius. The kinetic Alfven wave dynamics associated with the scale length of the effective ion Larmor radius is intrinsically important in the magnetic reconnection and leads to the generation of whistler turbulence. The theoretical model of the generation of whistler turbulence is useful for explaining the observations of intense electromagnetic fluctuations at the magnetopause.

An aluminum alloy vacuum chamber, 4 m in length, for an undulator was installed in the 1.3 GeV electron storage ring of the Synchrotron Radiation Research Center in the spring of 1996. The inner cross section of this vacuum chamber is an elliptical shape, 10 mm in height and 80 mm in width. A beam life time of 7 h at 200 mA beam current was quickly achieved after beam cleaning on the new chamber walls. The impact of this new vacuum chamber, before and after the installation, to the storage ring was compared. The injection rate was reduced. The stronger beam loss during the injection was measured. The effects of a small vertical aperture and the effective pumping to the electron beam lifetime are reported. The planning in upgrading the storage ring vacuum system is also described.

The design, construction and commissioning of a beamline and spectrometer for inelastic soft X-ray scattering at high resolution in a highly efficient system are presented. Based on the energy-compensation principle of grating dispersion, the design of the monochromator–spectrometer system greatly enhances the efficiency of measurement of inelastic soft X-rays scattering. Comprising two bendable gratings, the set-up effectively diminishes the defocus and coma aberrations. At commissioning, this system showed results of spin-flip, d–d and charge-transfer excitations of NiO. These results are consistent with published results but exhibit improved spectral resolution and increased efficiency of measurement. The best energy resolution of the set-up in terms of full width at half-maximum is 108 meV at an incident photon energy tuned about the Ni L3-edge.

An evolution equation in the form of a modified Korteweg-de Vries equation is developed which describes the small-amplitude version of the infinitesimal rotational discontinuity (RD) studied by Wang and Sonnerup (1984). It is shown that the small-amplitude version of the equilibrium pulse solution obtained by Wang and Sonnerup is metastable and thus unlikely to arise spontaneously. When the initial pulse amplitude is smaller than and/or the initial pulse width is greater than the equilibrium value, the pulse decays. When the reverse is the case, the pulse is converted to an infinitesimal intermediate-mode solitary wave having greater pulse amplitude and speed. A simulation experiment is performed in which one of the equilibrium intermediate-mode solitary waves overtakes another, less rapidly moving version of the same wave. The existence of multipeaked intermediate-mode solitary pulses is demonstrated.

Magnetic, electronic, and thermal transport properties of ${\mathrm{Eu}}_{0.55}{\mathrm{Sr}}_{0.45}\mathrm{Mn}{\mathrm{O}}_{3}$ have been experimentally studied. The compound is found to exhibit a complex magnetic behavior with the change of temperature and magnetic field. Without magnetic field, it stays in a Griffiths-like state in a wide temperature range above $\ensuremath{\sim}100\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, characterized by the presence of ferromagnetic (FM) clusters of the size of $\ensuremath{\sim}8$ Mn ions, and an antiferromagnetic (AFM) state below $\ensuremath{\sim}100\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, evidenced by thermopower and heat conductivity. FM phase emerges and grows in the AFM matrix with applied field, resulting in a series of phase transitions from the paramagnetic (PM) state first to the AFM state, then to the FM and the AFM states upon cooling $(\ensuremath{\sim}0.8\phantom{\rule{0.3em}{0ex}}\mathrm{T}lHl\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{T})$, or a simple PM-FM transition $(Hg\ensuremath{\sim}2.3\phantom{\rule{0.3em}{0ex}}\mathrm{T})$. The AFM state is unstable under high fields, and the high- and low-temperature AFM transitions are depressed by the fields above $\ensuremath{\sim}1$ and $\ensuremath{\sim}2.3\phantom{\rule{0.3em}{0ex}}\mathrm{T}$, respectively. The FM transition is incomplete when the field is below $\ensuremath{\sim}1.5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$, leading to a coexistence of the FM and PM (or AFM) phases in the intermediate temperature range. A spin-glass-like behavior is observed in the AFM background below $\ensuremath{\sim}50\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Significant response of resistance, thermopower, and heat conduction to magnetic transition, either FM or AFM transition, has been observed. Unlike the typical AFM manganites, for which usually a depression of thermal conduction occurs at the AFM state, the AFM transition in ${\mathrm{Eu}}_{0.55}{\mathrm{Sr}}_{0.45}\mathrm{Mn}{\mathrm{O}}_{3}$ enhances the thermal conduction. From the PM phase to the AFM phase and to the FM phase, thermal conductivity increases monotonically. A remarkable result of the present work is the different behaviors of thermopower and resistivity. The former displays a metallic behavior below a distinct temperature that is significantly lower than the metal-to-insulator transition temperature determined by resistivity. Furthermore, thermopower remains metallic while the resistivity shows up an upturn due to the AFM transition in the low-temperature range under the field of $1.5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. Based on these data, a magnetic phase diagram is proposed.

To accommodate the growing number of users in the soft X‐ray spectroscopy research at NSRRC, we have developed a modified Dragon‐type beamline, namely the active grating monochromator (AGM) beamline. In this beamline, a selected photon beam of 9 mrad radiation fan in the horizontal direction from a bending magnet is focused horizontally by a tangential elliptical mirror to a position 1.7 m after exit slit, and vertically by a cylindrical vertical focusing mirror (VFM) onto the entrance slit. After the entrance slit, the photon beam is energy‐dispersed and vertically focused by an active grating onto the fixed exit slit. During the energy scan, the radius and shape of the active grating are adjusted accordingly, and therefore the defocus and coma aberrations terms can be effectively eliminated, and hence the energy resolution is optimized. Following the exit slit, the dispersed photon beam is refocused by a toroidal mirror onto the sample. Shadow ray‐tracing program is employed to simulate the beamline per...

The Taiwan light source (TLS) uses a photon beam intensity system (Io monitor) to index the electron beam stability. This index combines the information of the fluctuations of electron beam position and size. For understanding the impact of these fluctuations to the electron beam instability, a set of the optical diagnostic system was installed in the TLS BL10 diagnostics beamline. This system includes the photon beam position monitor (PBPM), the beam size monitor (BSM) and the Io monitor. From the result, we concluded that about one‐third impact of beam instability came from the fluctuation of electron beam position and about two‐thirds impact of beam instability came from the fluctuation of electron beam size. The hardware configuration is described in this paper.

The operation of the Synchrotron Radiation Research Center 1.3 GeV synchrotron light source vacuum system shows good features of quick beam self‐cleaning, low carbonaceous gas desorption, and less dust. The phenomenon of the photon induced desorption (PID) has been studied. Recently, a set of new vacuum chambers for wiggler were installed, and the commissioning of the storage ring was restarted. The pressure rise and the PID coefficients during the beam running both in the straight and bending chambers were compared. The performance of the overall vacuum system is to be described.

By using two aspherical variable‐line‐space active gratings and applying the energy compensation principle, we have designed a very efficient active grating monochromator — active grating spectrometer (AGM‐AGS) beamline system for the photon demanding inelastic soft‐x‐ray scattering experiments. During the energy scan, the defocus and coma aberrations of the AGM can be completely eliminated to make the focal point fixed at the sample position and to maintain high spectral resolution for the entire spectral range. The AGS, which has an optical system identical to that of the AGM, but positioned reversely along the optical path, collects the photons emitted from the sample with a nearly identical energy spread as the AGM and focus them onto a position sensitive detector located at the exit slit position. The ray tracing results show that the efficiency of the AGM‐AGS is two orders of magnitudes higher than that of conventional design while maintaining a very high spectral resolution.

Two high‐performance asymmetric‐cut curved crystal monochromator (ACCM) side‐branch x‐ray beamlines have been designed to fully utilize the sideway output of a superconducting multipole wiggler (SMPW) source for protein crystallography research. Each of the two ACCM beamlines collects 1 mrad of radiation in the horizontal direction. One of them is located at 4 mrad and the other at 3 mrad away from the centerline of the radiation fan of the wiggler output. These two beamlines will deliver photon flux, through a 100 μm pinhole, of greater than 1×1011 photons/sec with energies from 12 keV to 14 keV and resolution (ΔE/E) of 1.5×10−3 for standard monochromatic crystallography experiments. A Rh‐coated, water‐cooled vertical focusing mirror is placed upstream of the ACCM to simplify the energy tuning mechanism and to reduce the heat load of the crystal by cutting off the photon beams at energies above 15 keV. Considering that existing ACCM designs with bender either have insufficient cooling efficiency or are difficult to manufacture, we designed a special cost‐effective ACCM that comprises a crystal plate affixed to a water‐cooled, bendable Cu substrate, where heat conducts through a paste‐like alloy. With this design, the monochromator will provide high photon flux and resolution while maintaining excellent stability.

The incompressible MHD equations with nonvanishing viscosity and resistivity are simplified by use of the boundary layer approximation to describe the flow and magnetic field in the exit flow regions of magnetic field reconnection configurations when the reconnection rate is small. The conditions are derived under which self-similar solutions exist of the resulting boundary layer equations. For the case of zero viscosity and resistivity, the equations describing such self-similar layers are then solved in terms of quadratures, and the resulting flow and field configurations are described. Symmetric solutions, relevant, for example, to reconnection in the geomagnetic tail, as well as asymmetric solutions, relevant to reconnection at the earth's magnetopause, are found to exist. The nature of the external solutions to which the boundary layer solutions should be matched is discussed briefly, but the actual matching, which is to occur at Alfven-wave characteristic curves in the boundary layer solutions, is not carried out. Finally, it is argued that the solutions obtained may also be used to describe the structure of the intense vortex layers observed to occur at magnetic separatrices in computer simulations and in certain analytical models of the reconnection process.