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We present an angle-resolved photoelectron spectroscopy study of YBa2Cu3O7-delta films in situ grown by pulsed laser deposition. We have successfully produced underdoped surfaces with ordered oxygen vacancies within the CuO chains resulting in a clear ortho-II band folding of the Fermi surface. This indicates that order within the CuO chains affects the electronic properties of the CuO2 planes. Our results highlight the importance of having not only the correct surface carrier concentration, but also a very well ordered and clean surface in order that photoemission data on this compound be representative of the bulk.

The surfaces and interfaces spectroscopy (SIS) beamline at the Swiss Light Source (SLS) covers the photon energy range from 10 to 800 eV . The beamline will start operation in summer 2001. The optical design is based on a SX-700 type plane grating monochromator extended by a normal incidence light path to provide high resolving power and harmonic rejection also at low photon energies.

Operation of an X-ray spectrometer based on a spherical variable-line-spacing grating is analyzed using dedicated ray-tracing software allowing fast optimization of the grating parameters and spectrometer geometry., Operation of an X-ray spectrometer based on a spherical variable-line-spacing (VLS) grating is analyzed using dedicated ray-tracing software allowing fast optimization of the grating parameters and spectrometer geometry. The analysis is illustrated with optical design of a model spectrometer to deliver a resolving power above 20400 at a photon energy of 930 eV (Cu L-edge). With this energy taken as reference, the VLS coefficients are optimized to cancel the lineshape asymmetry (mostly from the coma aberrations) as well as minimize the symmetric aberration broadening at large grating illuminations, dramatically increasing the aberration-limited vertical acceptance of the spectrometer. For any energy away from the reference, corrections to the entrance arm and light incidence angle on the grating are evaluated to maintain the exactly symmetric lineshape. Furthermore, operational modes when these corrections are coordinated are evaluated to maintain either energy-independent focal curve inclination or maximal aberration-limited spectrometer acceptance. The results are supported by analytical evaluation of the coma term of the optical path function. This analysis thus gives a recipe for designing a high-resolution spherical VLS grating spectrometer operating with negligible aberrations at large acceptance and over an extended energy range.

The occupation, energy separation, and order of the crystal-field-split 4f states are crucial for the understanding of the magnetic properties of rare-earth systems. We provide the experimental evidence that crystal-field-split 4f states exhibit energy dispersion in momentum space leading to variations of energy spacings between them and even of their energy sequence across the Brillouin zone. These observations were made by performing angle-resolved photoemission experiments on YbRh(2)Si(2) and properly simulated within a simple model based on results obtained by inelastic neutron scattering experiments and band structure calculations. Our findings should be generally applicable to rare-earth systems and have considerable impact on the understanding of magnetism and related phenomena.

Angle-resolved photoemission with polarized synchrotron radiation is measured from a ferromagnetic single-crystal Ni(110) surface. Polarization dependence and dispersion with ${\mathbf{k}}_{\ensuremath{\parallel}}$ of spectral structures along the high-symmetry lines $\ensuremath{\Gamma}\text{-K-X}$ of the bulk Brillouin zone is discussed. An ab initio calculation within the one-step theory of photoemission reveals the relation of the observed structures to initial and final states. The energy-momentum distribution of photoemission intensity depending on the light polarization and experimental geometry is explained in terms of even and odd symmetry of the valence-band states with respect to the crystal mirror plane.

Epitaxial graphene on SiC(0001) suffers from strong intrinsic $n$-type doping. We demonstrate that the excess negative charge can be fully compensated by noncovalently functionalizing graphene with the strong electron-acceptor tetrafluorotetracyanoquinodimethane (F4-TCNQ). Charge neutrality can be reached in monolayer graphene as shown in electron-dispersion spectra from angular-resolved photoemission spectroscopy. In bilayer graphene the band-gap that originates from the SiC/graphene interface dipole increases with increasing F4-TCNQ deposition and, as a consequence of the molecular doping, the Fermi level is shifted into the band-gap. The reduction in the charge-carrier density upon molecular deposition is quantified using electronic Fermi surfaces and Raman spectroscopy. The structural and electronic characteristics of the graphene/F4-TCNQ charge-transfer complex are investigated by x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The doping effect on graphene is preserved in air and is temperature resistant up to $200\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$. Furthermore, graphene noncovalent functionalization with F4-TCNQ can be implemented not only via evaporation in ultrahigh vacuum but also by wet chemistry.

6 páginas, 4 figuras.-- PACS number(s): 71.20.Tx, 71.38.-k, 79.60.-i, 31.70.-f.-- et al., The low-energy single-particle excitations of highly ordered C60 chains adsorbed on a vicinal copper substrate are investigated by angle-resolved photoemission spectroscopy. The interface state previously identified on C60/Cu(111) shows a one-dimensional dispersion on Cu(553). In contrast, no significant momentum dependence is detected for emission from the lowest unoccupied molecular orbital (LUMO). The LUMO displays similar phonon features as in C60/Cu(111) but it does not peak toward the Fermi level for all considered potassium dopings and its photoemission lineshape is broader than in any other monolayer system investigated so far. This behavior is not easily reconciled with existing theory and indicates that the one-dimensional character of the chains affects the electronic structure of the monolayer in an intricate way., The project was supported by the Swiss National Science Foundation.

Photoelectron diffraction of the bulk and surface components of the Ge 3d core-level has been measured from the Ge(111)- c (2 × 8) reconstructed surface at room temperature and on the Ge(111)-(1 × 1) surface at 400°C. Calculations show good agreement with the results of recent X-ray diffraction work on the c(2 × 8) surface. Results for the (1 × 1) surface show no change in the short-range structure at the surface across the phase transition suggesting that the adatom-restatom building block structure accepted for the c(2 × 8) surface remains intact after the phase transition. This method of measuring the photoelectron diffraction from resolved surface core-levels provides a direct method for assigning these levels to specific species at the surface. In addition, significant variations in the branching ratios as a function of azimuthal angle have been found which are due to differences in the final state for the two spin-orbit components of the Ge 3d photoemission peak.

Using angle resolved photoemission it is shown that the low lying electronic states of the iron pnictide parent compound EuFe$_2$As$_2$ are strongly modified in the magnetically ordered, low temperature, orthorhombic state compared to the tetragonal, paramagnetic case above the spin density wave transition temperature. Back-folded bands, reflected in the orthorhombic/ anti-ferromagnetic Brillouin zone boundary hybridize strongly with the non-folded states, leading to the opening of energy gaps. As a direct consequence, the large Fermi surfaces of the tetragonal phase fragment, the low temperature Fermi surface being comprised of small droplets, built up of electron and hole-like sections. These high resolution ARPES data are therefore in keeping with quantum oscillation and optical data from other undoped pnictide parent compounds., 4 figures, 6 pages

Concepts and technical realization of the high-resolution soft X-ray beamline ADRESS at the Swiss Light Source are described. Optimization of the optical scheme for high resolution and photon flux as well as diagnostics tools and alignment strategies are discussed., The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for resonant inelastic X-ray scattering (RIXS) and angle-resolved photoelectron spectroscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0–180° rotatable linear polarizations) but also the energy without changing the gap. The beamline optics is based on the well established scheme of plane-grating monochromator operating in collimated light. The ultimate resolving power E/ΔE is above 33000 at 1 keV photon energy. The choice of blazed versus lamellar gratings and optimization of their profile parameters is described. Owing to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, the beamline is capable of delivering high photon flux up to 1 × 1013 photons s−1 (0.01% BW)−1 at 1 keV. Ellipsoidal refocusing optics used for the RIXS endstation demagnifies the vertical spot size down to 4 µm, which allows slitless operation and thus maximal transmission of the high-resolution RIXS spectrometer delivering E/ΔE > 11000 at 1 keV photon energy. Apart from the beamline optics, an overview of the control system is given, the diagnostics and software tools are described, and strategies used for the optical alignment are discussed. An introduction to the concepts and instrumental realisation of the ARPES and RIXS endstations is given.

We show that the strongly spin-orbit coupled materials Bi2Te3 and Sb2Te3 and their derivatives belong to the Z2 topological-insulator class. Using a combination of first-principles theoretical calculations and photoemission spectroscopy, we directly show that Bi2Te3 is a large spin-orbit-induced indirect bulk band gap (delta approximately 150 meV) semiconductor whose surface is characterized by a single topological spin-Dirac cone. The electronic structure of self-doped Sb2Te3 exhibits similar Z2 topological properties. We demonstrate that the dynamics of spin-Dirac fermions can be controlled through systematic Mn doping, making these materials classes potentially suitable for topological device applications.

We investigate magnetic excitations in the spin-ladder compound Sr_{14}Cu_{24}O_{41} using high-resolution Cu L_{3} edge resonant inelastic x-ray scattering (RIXS). Our findings demonstrate that RIXS couples to two-triplon collective excitations. In contrast to inelastic neutron scattering, the RIXS cross section changes only moderately over the entire Brillouin zone, revealing high sensitivity also at small momentum transfers, allowing determination of the two-triplon energy gap as 100 +/- 30 meV. Our results are backed by calculations within an effective Hubbard model for a finite-size cluster, and confirm that optical selection rules are obeyed for excitations from this spherically symmetric quantum spin-liquid ground state.

The electronic structure of hydrogen adsorbed on Ni(110) at 150 K has been studied using angle-resolved photoelectron spectroscopy with monochromatized He Iα radiation. At a saturation coverage of 1.5 monolayers, we observe a general shift of the spectral weight away from the Fermi level to higher binding energies indicating the hybridization of hydrogen levels with metal d states. Along selected Ni 3d bands the intensity shift is obvious whereas other bands remain unchanged. In addition, contrary to previous observations, a hydrogen induced state is visible at a binding energy of roughly 1.2 eV.

After years of research into colossal magnetoresistant (CMR) manganites using bulk techniques, there has been a recent upsurge in experiments directly probing the electronic states at or near the surface of the bilayer CMR materials ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ using angle-resolved photoemission or scanning probe microscopy. Here, we report temperature-dependent, angle-resolved photoemission data from single crystals with a doping level of $x=0.36$. The first important result is that there is no sign of a pseudogap in the charge channel of this material for temperatures below the Curie temperature ${T}_{C}$. The data show unprecedented sharp spectral features, enabling the unambiguous identification of clear, resolution-limited quasiparticle features from the bilayer split $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-derived Fermi surfaces both at the zone-face and zone diagonal ${k}_{F}$ locations. The data show that these low temperature Fermi surfaces describe closed shapes in ${k}_{\ensuremath{\parallel}}$, centered at the $(\ensuremath{\pi}∕a,\ensuremath{\pi}∕a)$ points in the two dimensional Brillouin zone, and are not open and arclike in nature. The second important result concerns the temperature dependence of the electronic states. The spectra display strong incoherent intensity at high binding energies and a very strong temperature dependence, both characteristics reminiscent of polaronic systems. However, the clear and strong quasiparticle peaks at low temperatures are difficult to place within a polaronic scenario. A careful analysis of the temperature-dependent changes in the Fermi surface spectra both at the zone face and zone diagonal regions in $k$ space indicates that the coherent quasiparticle weight disappears for temperatures significantly above ${T}_{C}$ and that the $k$ dependence of the $T$-induced changes in the spectra invalidates an interpretation of these data in terms of the superposition of a ``universal'' metallic spectrum and an insulating spectrum whose relative weight changes with temperature. In this sense, our data are not compatible with a phase separation scenario.

Experimental studies of the electronic structure remain the basic means for understanding the nature of high-temperature superconductivity (HTSC) and testing relevant theoretical models. Appreciable contributions to establish the overall picture in HTSC have recently been made by investigations on the charge dynamics in BSCCO (ref. 1) and the spin dynamics in YBCO, using Angle Resolved Photoemission Spectroscopy (ARPES) and Inelastic Neutron Scattering (INS), respectively. Concentration of each of these techniques on a "suitable" compound turns out to be a barrier on the way to a crucial quantitative test allowing to support or discard spin fluctuations (interaction between the charge and spin degrees of freedom) as a possible origin for the pairing in doped cuprates. Here we solve the long-standing puzzle of ARPES on YBCO by showing that the photoelectron spectrum of YBCO generally includes two components: One from the topmost anomalously overdoped metallic CuO2 bilayer and the other from the next superconducting bilayer that retains the bulk properties. Our findings clearly show the opening of a large superconducting gap and, for the first time, demonstrate the anisotropic renormalization in the bulk component of YBCO, supporting the universality of these effects for different cuprate families. With our study we re-open this cuprate family for new systematic ARPES investigations.

We present angle-resolved photoemission spectroscopy data on moderately underdoped La1.855Sr0.145CuO4 at temperatures below and above the superconducting transition temperature. Unlike previous studies of this material, we observe sharp spectral peaks along the entire underlying Fermi surface in the superconducting state. These peaks trace out an energy gap that follows a simple d-wave form, with a maximum superconducting gap of 14 meV. Our results are consistent with a single gap picture for the cuprates. Furthermore our data on the even more underdoped sample La1.895Sr0.105CuO4 also show sharp spectral peaks, even at the antinode, with a maximum superconducting gap of 26 meV.

${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{Si}$ single crystals with different Co concentrations were grown using the tri-arc Czochralski technique. Samples with 0, 5, and $20\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%$ of Co were studied with photon energies of 21.2 and $40.8\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ with spectral resolutions as high as $8\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ at the Fermi level. For FeSi, a full gap of $28\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ has been found, which closes with 5% of Co. In the range between 20 and $150\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, energy dependent angle-resolved measurements in the [111] direction were made for FeSi. Through a comparison with theoretical calculations, the states at the Fermi energy can be directly assigned to $\mathrm{Fe}\phantom{\rule{0.2em}{0ex}}3d$ states. No sign of Kondo resonance is found.

We show that in the angle resolved photoemission spectroscopy (ARPES) near-surface induced fields can be useful for disentangling the surface and bulk related emission. The jump of the dielectric function at the interface results in a nonzero term $\operatorname{div}\textbf{A}$ in the photoemission matrix element. The term happens to be significant approximately within the first unit cell and leads to the circular dichroism for the states localized therein. As an example we use ARPES spectra of an YBa$_2$Cu$_3$O$_{7-\delta}$ crystal to distinguish between the overdoped surface related component and its bulk counterparts., Comment: 4 pages, 2 figures

We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy of >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of E/δE>3×104. The device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.

We performed ultrafast time resolved near infrared pump resonant soft x ray diffraction probe measurements to investigate the coupling between the photoexcited electronic system and the spin cycloid magnetic order in multiferroic TbMnO3 at low temperatures. We observe melting of the long range antiferromagnetic order at low excitation fluences with a decay time constant of 22.3 ± 1.1 ps which is much slower than the ~1 ps melting times previously observed in other systems. To explain the data we propose a simple model of the melting process where the pump laser pulse directly excites the electronic system which then leads to an increase in the effective temperature of the spin system via a slower relaxation mechanism. Despite this apparent increase in the effective spin temperature we do not observe changes in the wave vector q of the antiferromagnetic spin order that would typically correlate with an increase in temperature under equilibrium conditions.We suggest that this behavior results from the extremely low magnon group velocity that hinders a change in the spin spiral wave vector on these time scales. DOI: 10.1103/PhysRevB.92.184429

By combining surprising new results from a full polarization analysis of nodal angle-resolved photoemission data from pristine and modulation-free ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ with structural information from LEED and ab initio one-step photoemission simulations, we prove that the shadow Fermi surface in these systems is of structural origin, being due to orthorhombic distortions from tetragonal symmetry present both in surface and bulk. Consequently, one of the longest standing open issues in the investigation of the Fermi surface of these widely studied systems finally meets its resolution.

We present a 5 m long spectrometer for soft x rays to be used at a synchrotron radiation beamline for resonant x-ray emission spectroscopy and resonant inelastic x-ray scattering in the 400-1600 eV energy range. It is based on a variable line spacing spherical grating (average groove density of 3200 mm(-1), R=58.55 m) and a charge coupled device two dimensional detector. With an x-ray spot on the sample of 10 mu m, the targeted resolving power is higher than 10 000 at all energies below 1100 eV and better than 7000 at 1500 eV. The off-line tests made with Al and Mg K alpha(1,2) fluorescence emissions indicate that the spectrometer can actually work at 12 000 and 17 000 resolving power at the L-3 edges of Cu (930 eV) and of Ti (470 eV), respectively. SAXES (superadvanced x-ray emission spectrometer) is mounted on a rotating platform allowing to vary the scattering angle from 25 degrees to 130 degrees. The spectrometer will be operational at the ADRESS (advanced resonant spectroscopies) beamline of the Swiss Light Source from 2007.

We apply the new-generation angle-resolved photoemission spectroscopy methodology to the most widely studied cuprate superconductor YBa2Cu3O(6+x). Considering the nodal direction, we found noticeable renormalization effects known as kinks both in the quasiparticle dispersion and scattering rate, the bilayer splitting, and evidence for strong interband scattering--all the characteristic features of the nodal quasiparticles detected earlier in Bi2Sr2CaCu2O(8+delta). The typical energy scale and the doping dependence of the kinks clearly point to their intimate relation with the spin-1 resonance seen in the neutron scattering experiments. Our findings strongly suggest a universality of the electron dynamics in the bilayer superconducting cuprates and a dominating role of the spin fluctuations in the formation of the quasiparticles along the nodal direction.

By combining surprising new results from a full polarization analysis of nodal angle-resolved photoemission data from pristine and modulation-free Bi(2)Sr(2)CaCu(2)O(8+delta) with structural information from LEED and ab initio one-step photoemission simulations, we prove that the shadow Fermi surface in these systems is of structural origin, being due to orthorhombic distortions from tetragonal symmetry present both in surface and bulk. Consequently, one of the longest standing open issues in the investigation of the Fermi surface of these widely studied systems finally meets its resolution.

We report the observation of a novel effect in the bilayer Pb-Bi2Sr2CaCu2O8 (Pb-Bi2212) high-T(c) superconductor by means of angle-resolved photoemission with circularly polarized excitation. Different scattering rates, determined as a function of energy separately for the bonding and antibonding copper-oxygen bands, strongly imply that the dominating scattering channel is odd with respect to layer exchange within a bilayer. This is inconsistent with a phonon-mediated scattering and favors the participation of the odd collective spin excitations in the scattering mechanism in near-nodal regions of the k space, suggesting a magnetic nature of the pairing mediator.

We present angle-resolved photoemission spectroscopy results for thin films of the three-dimensional manganese perovskite La$_{1-x}$Sr$_{x}$MnO$_{3}$. We show that the transition temperature ($T_c$) from the paramagnetic insulating to ferromagnetic metallic state is closely related to details of the electronic structure, particularly to the spectral weight at the ${\bf k}$-point, where the sharpest step at the Fermi level was observed. We found that this ${\bf k}$-point is the same for all the samples, despite their different $T_c$. The change of $T_c$ is discussed in terms of kinetic energy optimization. Our ARPES results suggest that the change of the electronic structure for the samples having different transition temperatures is different from the rigid band shift., Accepted by Journal of Physics: Condensed Matter

The high-T(c) superconductor Tl(2)Ba(2)CuO(6 + delta) is studied by angle-resolved photoemission spectroscopy. For a very overdoped T(c) = 30 K sample, the Fermi surface consists of a single large hole pocket centered at (pi, pi) and is approaching a topological transition. Although a superconducting gap with d(x(2)-y(2)) symmetry is tentatively identified, the quasiparticle evolution with momentum and binding energy exhibits a marked departure from the behavior observed in under and optimally doped cuprates. The relevance of these findings to scattering, many-body, and quantum-critical phenomena is discussed.

Applied Physics A, 79 (4-6), ISSN:0947-8396, ISSN:1432-0630, ISSN:0340-3793

The Surfaces and Interfaces Spectroscopy beamline (SIS) started user operation in spring 2002 as one of the first beamlines at SLS. It is optimized for high resolution photo electron spectroscopy. The beamline concept with two helical undulators plus a plane grating monochromator with grazing‐ and normal incidence optics is very flexible and offers a well balanced performance from 10 eV to 800 eV. We report on beamline features and performance measurements. The final characterization is still in progress since not all options have been commissioned so far.

The recent entry of X-ray free electron lasers (FELs) to all fields of physics has created an enormous need, both from scientists and operators, for better characterization of the beam created by these facilities. Of particular interest is the measurement of the arrival time of the FEL pulse relative to a laser pump, for pump-probe experiments, and the measurement of the FEL pulse length. This article describes a scheme that corrects one of the major sources of uncertainty in these types of measurements, namely the jitter in the arrival time of the FEL relative to an experimental laser beam. The setup presented here uses a combination of THz streak cameras and a spectral encoding setup to reduce the effect of an FEL's jitter, leaving the pulse length as the only variable that can affect the accuracy of the pulse length and arrival time measurement. A discussion of underlying principles is also provided.

We report on the ultrafast dynamics of magnetic order in a single crystal of CuO at a temperature of 207 K in response to strong optical excitation using femtosecond resonant x-ray diffraction. In the experiment, a femtosecond laser pulse induces a sudden, nonequilibrium increase in magnetic disorder. After a short delay ranging from 400 fs to 2 ps, we observe changes in the relative intensity of the magnetic ordering diffraction peaks that indicate a shift from a collinear commensurate phase to a spiral incommensurate phase. These results indicate that the ultimate speed for this antiferromagnetic re-orientation transition in CuO is limited by the long-wavelength magnetic excitation connecting the two phases., Accepted by Physical Review Letters (Dec. 2, 2011)

The designs of a compact, fast CCD (cFCCD) camera, together with a resonant soft x-ray scattering endstation, are presented. The cFCCD camera consists of a highly parallel, custom, thick, high-resistivity CCD, readout by a custom 16-channel application specific integrated circuit to reach the maximum readout rate of 200 frames per second. The camera is mounted on a virtual-axis flip stage inside the RSXS chamber. When this flip stage is coupled to a differentially pumped rotary seal, the detector assembly can rotate about 100°/360° in the vertical/horizontal scattering planes. With a six-degrees-of-freedom cryogenic sample goniometer, this endstation has the capability to detect the superlattice reflections from the electronic orderings showing up in the lower hemisphere. The complete system has been tested at the Advanced Light Source, Lawrence Berkeley National Laboratory, and has been used in multiple experiments at the Linac Coherent Light Source, SLAC National Accelerator Laboratory.

The administration of aflatoxin B1 to rats on days 17 and 19 of pregnancy caused increased synthesis of the total lipids and the fatty acids, and decreased synthesis of the phosphatidyl choline in 21-day-old fetal lung. Aflatoxin B1 caused toxicity in the fetal lung as evidenced by the excessive accumulation of the lamellar bodies and the osmiophilic spheroids in the type II cells and the alveolar lumen, respectively. The rearrangement of the lamellar form to the continuous sheet-like tubular myelin form was reduced in the alveolar lumen of the treated lung.

The administration of aflatoxin B1 to rats on days 17 and 19 of pregnancy caused increased synthesis of the total lipids and the fatty acids, and decreased synthesis of the phosphatidyl choline in 21-day-old fetal lung. Aflatoxin B1 caused toxicity in the fetal lung as evidenced by the excessive accumulation of the lamellar bodies and the osmiophilic spheroids in the type II cells and the alveolar lumen, respectively. The rearrangement of the lamellar form to the continuous sheet-like tubular myelin form was reduced in the alveolar lumen of the treated lung.

2-(benzoylamino) pyridinium benzoate (BAPB) has exhibited an antisickling effect with homozygous S/S erythrocytes in vitro. This study suggests that BAPB prevents sickling by inhibiting the gelation of hemoglobin S.

We identify dd-excitations in the quasi-one dimensional compound Ca$_2$Y$_2$Cu$_5$O$_{10}$ using resonant inelastic x-ray scattering. By tuning across the Cu L$_3$-edge, we observe abrupt shifts in the dd-peak positions as a function of incident photon energy. This observation demonstrates orbital-specific coupling of the high-energy excited states of the system to the low-energy degrees of freedom. A Franck-Condon treatment of electron-lattice coupling, consistent with other measurements in this compound, reproduces these shifts, explains the Gaussian lineshapes, and highlights charge-orbital-lattice renormalization in the high energy d-manifold., 5 pages, 4 figures

The nature and the role of 1 to 5 nm thick TiO2 seed layers for the growth of textured PbTiO3 and Pb(Zr, Ti)O-3 thin films on textured Pt(111) thin film substrates have been studied. Under otherwise identical in situ sputter deposition process conditions, the PbTiO3 texture could be turned from (100) to (111) orientation by adding the seed layer. This is demonstrated by patterning the TiO2 film. Auger electron spectroscopy and x-ray photoemission spectroscopy showed that the seed layer was a continuous TiO2 film. X-ray photoelectron diffraction measurements revealed epitaxial ordering in the seed layer. As there is no azimutal order among the Pt grains, the reduced information of azimutally averaged polar cuts is obtained. These give strong evidence for a strained rutile (110) structure. Various deposition experiments indicated that the TiO2 is effective only when it is ordered before the PbTiO3 nucleation starts. The epitaxial relationship between PbTiO3(111) and Pt(111) is thus mediated by the intermediate, epitaxial TiO2 film, which is dissolved of transformed to PbTiO3 afterwards. The observed growth behavior is discussed in terms of surface and interface energies. (C) 1998 American Institute of Physics. [S0021-8979(98)03607-X].

We report an angle-resolved photoemission study of the electronic structure of the pseudogap state in La1.48Nd0.4Sr0.12CuO4 (Tc, New Journal of Physics, 10, ISSN:1367-2630