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Paramagnetic properties of the RCo_2 compounds (R = rare earth)

The e.p.r. spectra of the Fe-proteins of nitrogenase from all sources studied have unusual features in that they have very anisotropic linewidths and low integrated intensities. These characteristics...Full Text Available

1978-12-01

2

Quantitative electron-paramagnetic-resonance measurements of the electron-transfer components of the photosystem-I reaction centre. The reaction-centre chlorophyll (P700), the primary electron acceptor X and bound iron-sulphur centre A.

The paramagnetic susceptibilities of all the RCo_2 compounds for which measurements are available are found to obey a Curie-Weiss law consistent with the modified indirect exchange model. The rare-earth ions are in a well defined tripositive valence state. Paramagnetic moments and paramagnetic Curie temperatures are obtained for these materials for the first time. The paramagnetic moments of these materials are changed from their free-ion values by the effects of itinerant electron polarisation, an effect which is particularly large for SmCo_2 whose paramagnetic moment is almost three times greater than the free-ion value. The modified indirect exchange model is found to be able to give a full description of the magnitude of the rare-earth, cobalt and diffuse moments in polarised neutron experiments. The band structures of the light RCo_2 compounds are found to ...

1984-03-01

3

Comparison between internal microviscosity of low-density erythrocytes and the microviscosity of hemoglobin solutions: an electron paramagnetic resonance study.

An e.p.r. spectrum of the reduced form of the electron-transport component (X), thought to be the primary electron acceptor of Photosystem I, was obtained. By using line-shape simulations of this component...Full Text Available

1978-02-15

4

Electron paramagnetic resonance of nitroxide-doped magnetic fluids

The hypothesis that the internal viscosity of erythrocytes is governed by the intracellular hemoglobin (Hb) concentration is examined. Here viscosity is determined by labeling of the cytoplasmic reduced...Full Text Available

1996-07-01

5

Magnetic resonance studies of photosynthetic reaction centers and porphyrins

Electron paramagnetic resonance was used to investigate surface-coated magnetite-based magnetic fluids doped with TEMPOL. Two magnetic fluid samples, having magnetite nanoparticles with average diameter of 94 A and coated with different coating layers (lauric acid plus ethoxylated polyalcohol in one case and oleoylsarcosine in the other case), were doped with TEMPOL (6 mM and pH 7.4) and investigated as a function of the nanoparticle concentration. The resonance field and the resonance linewidth both scale linearly with the nanoparticle concentration.

2002-11-01

6

Radiation yield of oxygen-based radicals in hyperquenched glassy water gamma-irradiated at 77 K

During the period covered by this report research has been concerned with the study of photo-induced electron transfer reactions from porphyrins to acceptor molecules with time-resolved Electron Paramagnetic Resonance (EPR) methods. Excited-state electron transfer reactions are of importance from a fundamental point of view and in connection with applications in homogeneous and heterogeneous photosensitization, photopolymerization, and solar energy conversions. For this reason, the study of photo-induced electron transfer reactions is of considerable interest.

1989-11-01

7

High temperature susceptibilities of actinide monopnictides and monochalcogenides

Hyperquenching of liquid water with cooling rates of 10{sup 6}-10{sup 7} K s{sup -1} yields glassy water. Upon {gamma}-irradiation at 77 K, the only paramagnetic species accumulating in hyperquenched glassy water are the hydroxyl and hydroperoxyl radicals. There are no hydrogen atoms or electrons seen by the ESR technique. For irradiation doses up to about 70 kGy, the relative contributions of hydroxyl and hydroperoxyl radicals to the total amount of paramagnetic species remain virtually constant. The total amount of paramagnetic species, n, is sublinear in dose, d, well approximated by n=8.55x10{sup 16}d{sup 0.8} for n in spin g{sup -1} and d in kGy.

1998-12-01

8

Structural characterization of liposomes made of diether archaeal lipids and dipalmitoyl-L-a-phosphatidylcholine

The inverse susceptibilities of the monopnictides and monochalcogenides of the light rare earths plotted vs. temperature flatten off at high temperatures. This behaviour is well explained by van Vleck paramagnetism of the excited states of the multiplet. For almost all actinide pnictides and chalcogenides a similar flattening-off is observed. Since spin orbit coupling is much stronger than in the light rare earth compounds an analogous interpretation is not possible. Susceptibility curves for uranium compounds can be fitted by adding a temperature dependent enhanced Pauli paramagnetism to the Curie-Weiss term (modified Curie-Weiss law). The high temperature susceptibility behaviour of neptunium compounds is very similar to uranium compounds i.e. an appreciable deviation from the Curie-Weiss law is only visible for the chalcogenides. The plutonium chalcogenides show a temperature independent paramagnetism, which can be ...

1998-06-12

9

British Library Electronic Table of Contents (United Kingdom)

The physicochemical properties of binary lipid mixtures of diether C25,25 lipids and dipalmitoyl-L-a-phosphatidylcholine (DPPC) were studied using photon correlation, fluorescence and electron paramagnetic resonance spectroscopy, and transmission electron microscopy. These two types of lipids can be mixed at all molar ratios to form unilamellar and multilamellar liposomes. Fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatrien in mixed liposomes indicates that the abrupt changes in order parameter in the hydrophobic part of bilayer membranes made of DPPC lipids disappears with increasing mol%C25,25 lipids. Electron paramagnetic resonance spectroscopy shows that at temperatures below 50^oC, the interfacial regions of membrane bilayer of mixed liposomes is more fluid than for pure DPPC lipo...

2011-01-01

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Organic electronic conductors and precursors. Pt. 15. Novel dithiolene-nickel complexes based on benzenehexathiolate derivatives

Moxel: A molar tooth voxel model for dosimetric studies

Dithiolato-nickel complexes with multisulfur ligands derived from benzenehexathiolate have been synthesized. The properties of the monomeric and polymeric complexes have been characterized by ESR spectroscopic and magnetochemical data and by electrical conductivity measurements. The prepared complexes are paramagnetic and have characteristic absorptions between 800 and 1000 nm. (orig.).

1992-04-01

11

Free radicals and their transformations in irradiated proteins

Stylized numerical models of the tooth are usually employed in qualification procedure related to Electronic Paramagnetic Resonance in long-term accidental contamination dose reconstruction. In this work a voxel model was developed from the microCT image data set of a human non contaminated molar tooth. A stylized model, reproducing the characteristics of the voxel model, was also created in order to investigate the level of accuracy that can be obtained in this kind of study.

2010-02-15

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Evaluation of paramagnetic species in coals with iodine doping technique; Yoso tenkaho wo mochiita sekitanchu no jojiseishu no hyoka

Experimental investigation data are systematized of free radical states and processes in irradiated proteins. The investigation is performed by the radiospectral methods. Results are discussed in detail of the study of free radicals electronic structure of amino acids, peptides and proteins formed by the action of ionizing radiation. The specificity is stressed of the study of monocrystalls of these compounds by the method of electronic paramagnetic resonance. The nature is also studied of primary centres formed under the effect of radiation on biologically important compounds and their subsequent reactions in solid and liquid solutions. Ion-radical states of different functional groups of the protein molecule are studied. Prospects of the study and the role of anion-radicals in biological processes are discusses.

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Effect of dysprosium doping on the optical properties of SrS:Dy,Cl phosphor

Electron paramagnetic resonance (EPR) of coals was considered by using iodine doping technique. Sub-bituminous coal (WA) and bituminous coal (UF) were used to observe EPR spectra using microwaves. With the UF coal, strength of the narrow component of the spectra was found constant regardless of amount of the doped iodine, wherein radicals without interaction with iodine were detected. Strength of the broad component increased with the iodine doping amount, where in deviation of {pi} electrons was detected, which have been generated as a result of interaction between aromatic rings and iodine in the coals. Spin concentration of the WA coal with low coalification degree is constant regardless of the iodine doping amount, and the interaction of the iodine with the aromatic rings was found small. The higher the coalification degree, the more the aromatic ring structure grows, and electron donor capability ...

1996-10-28

14

On the magnetic behaviour of REBa_2F_7 compounds (RE=Eu, Dy, Ho, Er, Tm and Yb)

The fundamental optical properties of dysprosium (Dy) doped strontium sulfide bulk samples for various dopant concentrations from 0.1 to 1.0 at.% were investigated by X-ray diffraction (XRD), electron paramagnetic resonance spectroscopy (EPR), room temperature photoluminescence (PL), photoluminescence excitation (PLE) and diffuse reflectance spectroscopy (DRS). Investigations by electron paramagnetic resonance yielded the state of Dy in the sample as Dy3+. An additional ESR line due to F+ center was observed. The PL emission spectrum consisted of several intense lines and a number of weaker ones which were identified as transitions between energy levels of Dy3+. The optimum doping concentration for maximum intensity was found to be 0.25 at.%. Blue shift of the absorption edge energy and red shift of the PLE spectrum were observed with increasing doping concentration. The former is due to Burstein-Moss ...

2010-08-13

15

EPR power pattern analysis for cubic sites of Fe"3"+ in MgO

The DC magnetic susceptibility of the REBa_2F_7 compounds was measured by a SQUID magnetometer in the temperature range 5-300 K. Except for Eu, the other compounds show either Curie law or Curie-Weiss law with relatively small values of paramagnetic Curie temperature, #theta#_p, with effective magnetic moments in the range expected of electronic ground state of the trivalent rare earth ion with appropriate J value. The behaviour of Eu is complex. (orig.).

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Visible light photocatalytic activity and Photoelectrochemical property of Fe-doped TiO2 hollow spheres by sol?gel method

A complete electron paramagnetic resonance power pattern characterization of Fe"3"+ in cubic sites in presented. A one-to-one correspondence among the peaks appearing in the powder pattern and the outer fine-structure transitions (Mnot = 1/2 ) observed in the single crystal along the , , and directions is shown. It is shown that the process of mechanically grinding the single crystal to a powder (particle size approx.1--10 #mu#) does not remove the cubic symmetry sites. No axial or lower symmetry sites which may be induced by lattice distortion of the crystallites due to strain have been observed.

1984-01-01

17

British Library Electronic Table of Contents (United Kingdom)

Fe-doped TiO2 hollow spheres (Fe-THs) were synthesized by sol?gel process using carbon spheres as templates. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV?vis diffuse reflectance spectrum (DRS), N2 adsorption?desorption isotherms, Electron paramagnetic resonance (EPR) spectroscopy and Photoluminescence emission spectroscopy (PL). UV?vis spectra showed that Fe3+ doping could extend the absorption edge to the visible region. EPR spectra showed that Fe3+ was incorporated into the crystal lattice of TiO2, which could inhibit the recombination of photo-induced electron?hole pairs and improve the photocatalytic activity. The photocatalytic activities of the prepared samples were evaluated for the degradation of dye Reactive Brillia...

2011-01-01

18

Submegahertz linewidth at 240 GHz from an injection-locked free-electron laser

EPR investigation of some irradiated traditional oriental spices

Radiation from an ultrastable 240 GHz solid state source has been injected, through an isolator, into the cavity of the University of California, Santa Barbara millimeter-wave free-electron laser (FEL). High-power FEL emission, normally distributed among many of the cavity's longitudinal modes, is concentrated into the single mode to which the solid state source has been tuned. The linewidth of the FEL emission is 0.5 MHz, consistent with the Fourier transform limit for the 2 #mu#s pulses. This demonstration of frequency-stable, ultranarrow-band FEL emission is a critical milestone on the road to FEL-based pulsed electron paramagnetic resonance spectroscopy.

2007-10-22

19

Microstructure and atomic effects on the electroluminescent efficiency of SrS:Ce thin film devices

The X-band EPR spectra of unirradiated and "6"0 Co gamma ray irradiated cardamom (Elettaria cardamomum L. Maton, Zingiberaceae), ginger ((Zingiber officinale Rosc., Zingiberaceae), saffron (Crocus sativus L., Iridaceae), and curry have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones, most probably due to the presence of semiquinones, previously reported to have paramagnetic properties. After gamma ray irradiation at absorbed dose up to 11.3 kGy we have noticed in all spices the presence of complex EPR spectra consisting of a superposition of at last two different paramagnetic species whose amplitude increase monotonously with the absorbed dose. A 100 deg. C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that form the initial spectra, but even after 5 h of thermal ...

2005-09-13

20

Magnetic behavior and crystal field of Pr"3"+ in praseodymium selenate octahydrate

Transmission electron microscopy and x-ray diffraction data show that rapid thermal anneals of SrS:Ce thin films enhance grain size and reduce crystalline defects. Electron paramagnetic resonance results suggest that these anneals lead to less variance in the crystal field environments at the nearly cubic Ce"3"+ sites along with the formation of another type of Ce"3"+ site believed to involve a nearby Sr vacancy. We suggest that the association of Ce"3"+ sites with V_S_r shifts the electroluminescence towards larger wavelengths as the symmetry of the activator site is lowered. copyright 1997 American Institute of Physics.

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Investigation of the electronic structure of base adducts derived from tris(#eta#"5-cyclopentadienyl)-lanthanide(III) and related compound types

Measurements are made on the principal magnetic susceptibilities and anisotropies of praseodymium selenate octahydrate single crystals in the temperature range 90 to 300 K. Although the effective magnetic moment is close to the free ion value, the anisotropy is quite high at room temperature. A least sequares fit of the Curie-Weiss law to the observed average susceptibility yields -36.5 K as the paramagnetic Curie temperature. An analysis of the results with a crystal field (CF) of D_4 symmetry, explains the observed results quite well. The CF and the spin-orbit interaction matrix is block diagonalized in the complete 33 dimensional basis of the "3H term in order to obtain the Stark energies and their eigenstates. Intermediate coupling effects are also considered. The ground state being a singlet, the g-factors are absent. Some predictions on the electronic heat capacity and the electronic quadrupole splitting are made in ...

1988-09-01

22

Damage process and luminescent characteristics in silica glasses under ion irradiation

The purpose of this work is the elucidation of the f"n electronic structure of neutral mono base adducts derived from tris(#eta#"5-cyclopentadienyl)-lanthanide(III) (Cp_2Ln). The available data on related compounds like bis adducts and anionic mono adducts of the same moiety was also analyzed. The first aim was to derive the experimental crystal field splitting pattern from optical, magnetooptical and magnetochemical measurements and to reproduce it using an empirical Hamiltonian operator. The eigenvalues and eigenvectors obtained in this manner were used for a quantitative interpretation of the magnetochemical, EPR- and NMR-spectroscopic properties. For the latter subject it was necessary to develop an own procedure for the NMR analysis of paramagnetic compounds. This method is based on factor analysis and as demonstrated in the second part of this work, is clearly superior to all previous procedures. (orig.).

23

Local Ce environments and their effects on optical properties of SrS phosphors

Full text of publication follows: Understanding the dynamic irradiation effects on silica glasses is important for developing the diagnostic systems used in fusion and fission environments. While fundamental defects having an un-pared electron such as the E' center have been extensively studied, the neutral oxygen deficiency defects have been insufficiently clarified for lack of the detection methods. The ion induced luminescence is one of the probes that can be used to detect non-paramagnetic defects, and to observe creation and annihilation behavior dynamically. In the present study, we examined the characteristics of the ion induced luminescence such as energy, fluence flux and temperature dependence of the luminescence efficiency to analyze damage process quantitatively. Samples of SiO2 glasses were commercially available fused and synthesized silica glasses, produced by Toshiba Ceramics, Co. Ltd.. A thin films of SiO2 deposited on a Si ...

2007-12-10

24

Chemical transformations of organic matter during the composting of wood industry wastes (residues); Transformacoes quimicas da materia organica durante a compostagem de residuos da industria madeireira

In this study, we use electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopies to determine the various Ce environments in SrS phosphor materials and how these affect absorption and emission properties. As the Ce concentration is increased from 450 to 7500 ppm, the total EPR-active Ce"3"+ and optical absorption signals increase linearly with Ce concentration; by contrast, the PL intensity saturates at fairly low Ce concentrations (1000 ppm Ce). We suggest that the nonlinear behavior of the PL arises from the presence of nonradiative deexcitation pathways such as defects associated with Ce sites, or Ce endash Ce pairs. copyright 1996 American Institute of Physics.

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Analysis of the optical spectra and paramagnetic susceptibility of DyOF

Composting of sawdust and paper mill sludge, using a 'Kneer' process reactor, was studied in an attempt to elaborate upon organic matter transformation during the process and to define parameters to measure the compost maturity level. Temperature, electron paramagnetic resonance data, ash and C, H, N and S contents, and a spectroscopic method using ultraviolet-visible (UV-VIS) for alkaline (pH = 8.5) and solid samples was used to study the maturity of the compost samples. These parameters were measured in 6 humic acids extracted from the compost samples during 29 days. The results of this work show that the 'Kneer' process is efficient in transforming ligno-celulitic residues in a short time (29 days), into an organic fertilizer material with application perspectives (author)

2004-06-01

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Nature of the magnetic susceptibility of dysprosium. Paramagnetic susceptibility of dysprosium - yttrium alloys

The optical absorption spectra of the rhombohedral DyOF were measured at selected temperatures between 9 and 300 K. The emission spectra of the Dy{sup 3+} ion in the LaOF and GdOF matrices were obtained at 77 K and room temperature. The energy level scheme of Dy{sup 3+} (4f{sup 9} electron configuration) was simulated with a Hamiltonian of 20 parameters. The diagonalization of the energy matrices including simultaneously the free ion and crystal field (c.f.) interactions was carried out for the C{sub 3{upsilon}} point symmetry of the RE{sup 3+} site. Good correlation with an rms deviation of 17 cm{sup -1} was obtained between the experimental and calculated energy level schemes of 153 Kramers doublets. The c.f. parameters show only slight distortion from O{sub h} symmetry. A comparison to Pr{sup 3+} (4f{sup 2}), Nd{sup 3+} (4f{sup 3}), Sm{sup 3+} (4f{sup 5}), Eu{sup 3+} (4f{sup 6}), and Tb{sup 3+} (4f{sup 8} electron configuration) in other ...

1996-03-04

27

Skeletal remodeling dynamics: New approaches with imaging instrumentation

The paramagnetic susceptibility of single crystals of dysprosium-yttirum alloys is measured in the basal plane and along the hexagonal axis. It is shown that the susceptibility of the alloys obeys the Curie-Weiss law, the effective magnetic moments allong the different directions being the same and the paramagnetic Curie temperatures being different. The difference between the paramagnetic Curie temperatures in the basal plane and along the hexagonal axis is independent of the dysprosium concentration in the alloy. As a comparison with the theoretical models of magnetic anisotropy shows, this is an indication that the magnetic anisotropy of dysprosium - yttrium alloys is of a single-ion nature.

1976-01-01

28

EPR investigation of some traditional oriental irradiated spices

This report of progress and future objectives timetable is based on an included schematic of goals and objectives and the project abstract which is included as Appendix 1. Five matters are summarized in the order of (1) novel methods of calcified bone confocal microscopy and reconstruction image analysis of decalcified beagle and human cortical bone serial sections, (2) macroscopic cross-correlation of beagle and human cortical and cancellous bone fractions with CT analysis, (3) guidance to the most radiobiologically important skeletal regions of interest with the just completed {sup 90}Sr bone tumor map from life time beagle studies, (4) deposition patterns of radioactive agents that participate in apatite crystal nucleation processes in bone and leave radiation-excited electrons trapped in bone mineral, and (5) the budget period timetable. The discovery that beta particles from {sup 166}Ho (T{sub {1/2}} =26 hr, {beta}{sub max} = 1.8 MeV) phosphonic acid bone ...

1991-12-01

29

Anisotropy in Magnetic Properties and Electronic Structure of Single Crystal LiFePO4

The 9.50 GHz electron paramagnetic resonance (EPR) spectra of unirradiated and "6"0Co #gamma#-ray irradiated cardamom (Elettaria cardamomum L. Maton, Zingiberaceae), ginger ((Zingiber officinale Rosc., Zingiberaceae), and saffron (Crocus sativus L., Iridaceae) have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones. After #gamma#-ray irradiation at an absorbed dose of up to 11.3 kGy, the presence of EPR spectra whose amplitude increase monotonously with the absorbed dose has been noticed with all spices. A 100 "oC isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that compose initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after 83 days storage ...

2007-06-01

30

Study of the electron paramagnetic resonance spectra of Zn(antipyrine)_2(NO_3)_2:VO"2"+

We report the experimental and theoretical results on the anisotropies in the magnetic properties and x-ray absorption spectra of single-crystal LiFePO4. A mean-field theory is developed to explain the observed strong anisotropies in Lande g-factor, paramagnetic Curie temperature, and effective moment for LiFePO4 single crystals. The values of the in-plane nearest- and next-nearest-neighbor spin exchange (J1 and J2), interplane spin exchange (J{perpendicular}), and single-ion anisotropy (D), obtained recently from neutron scattering measurements, are used for calculating the Curie temperatures with the formulas derived from the mean-field Hamiltonian. It is found that the calculated Curie temperatures match well with that obtained by fitting the magnetic susceptibility curves to the modified Curie-Weiss law. For the polarized Fe K-edge x-ray absorption spectra of single-crystal LiFePO4, a different feature assignment for the 1s4p transition features is proposed and ...

2008-01-01

31

EPR, optical, infrared and Raman studies of VO"2"+ ions in polyvinylalcohol films

In this work, a full ligand-field energy matrix (10x10) diagonalization treatment for 3d"1 ions in tetragonal symmetry is developed on the basis of the two-s.o.-coupling-parameter model. Spin Hamiltonian parameters (g factors g_|_|, g_p_e_r_p_e_n_d_i_c_u_l_a_r and hyperfine structure constants A_|_|, A_p_e_r_p_e_n_d_i_c_u_l_a_r) of the tetragonal V"4"+ center in Zn(antipyrine)_2(NO_3)_2 are calculated from the complete energy matrix diagonalization method and the perturbation theory method. The calculated results from both methods are not only close to each other but also in good agreement with the experimental values. Furthermore, the compressed defect structure of V"4"+ center is discussed.

2010-08-01

32

DNA alterations photosensitized by tetracycline and some of its derivatives

Electron paramagnetic resonance (EPR), optical, infrared and Raman spectral studies have been carried out on vanadyl ions doped in polyvinylalcohol (PVA) films. The spin-Hamiltonian parameters (g and A) and the molecular orbital coefficients (#beta#_2"*"2 and k) have been evaluated. The values of spin-Hamiltonian parameters confirm that the vanadyl ions are present in PVA films as VO"2"+ molecular ions in an octahedral site with a tetragonal compression (C_4_v). The temperature variation EPR studies reveal that the variation of number of spins with temperature is in accordance with Boltzmann law. It is interesting to observe that the variation of susceptibility with temperature obeys Curie-Weiss law. The FT-IR and FT-Raman spectrum exhibits few bands, which are attributed to O-H, C-H, C-C and C-O groups of stretching and bending vibrations. The optical absorption spectrum exhibits two bands, which are assigned to "2B_2_g->"2B_1_g and ...

2007-01-15

33

Crystal field and EPR studies of Nd{sup 3+}:YMO{sub 4}(M=V,AS,P)

Bacteriophage M13 mp10 DNA were irradiated with near-UV light in the presence of tetracycline derivatives and primed with synthetic oligonucleotide to be used for DNA synthesis using Escherichia coli DNA polymerase. Chain terminations were observed by denaturing polyacrylamide gel electrophoresis and mapped precisely. All the synthesis stops occurred before or at the level of guanine residues, showing that the photoreaction mediated by tetracycline derivatives led to a preferential alteration of guanine residues. These lesions were demonstrated to be induced in DNA through a pathway involving singlet oxygen. Tetracycline derivatives also photoinduced the breakage of the DNA sugar-phosphate backbone monitored by the conversion of supercoiled phi X174 DNA to a relaxed form. This lesion was shown to be initiated by hydroxyl radicals. The production of this free radical has been confirmed by electron paramagnetic resonance (EPR) spin trapping ...

1986-06-01

34

Crystal field and EPR studies of Nd"3"+:YMO_4(M=V,AS,P)

Crystal field calculation and electron paramagnetic resonance (EPR) have been performed on zircon-type materials Nd:YMO{sub 4} (M=V, As, P). Simulation of the energy level schemes has been carried out and the wave functions composition and g tensor principal values associated to the first sub-level of the {sup 4}I{sub 9/2} manifold were calculated. A rather good correlation is obtained between crystal field calculations and the EPR measurements. Furthermore, some extra lines observed by optical spectroscopy (absorption and emission) also appear on the EPR spectra and a correlation between the two spectroscopies indicates that Nd{sup 3+}-Nd{sup 3+} exchange and dipolar interactions occur in the zircon family, even at very low doping content (less than 8 x 10{sup 19} Nd{sup 3+} ions cm{sup -3}). Nd{sup 3+}-Nd{sup 3+} pairs at distances 3.9, 5.9 and 6.3 A have been identified. (orig.) 13 refs.

1998-07-24

35

Chemical behavior of europium oxides in- LiCI-KCI eutectic melt

Crystal field calculation and electron paramagnetic resonance (EPR) have been performed on zircon-type materials Nd:YMO_4 (M=V, As, P). Simulation of the energy level schemes has been carried out and the wave functions composition and g tensor principal values associated to the first sub-level of the "4I_9_/_2 manifold were calculated. A rather good correlation is obtained between crystal field calculations and the EPR measurements. Furthermore, some extra lines observed by optical spectroscopy (absorption and emission) also appear on the EPR spectra and a correlation between the two spectroscopies indicates that Nd"3"+-Nd"3"+ exchange and dipolar interactions occur in the zircon family, even at very low doping content (less than 8 x 10"1"9 Nd"3"+ ions cm"-"3). Nd"3"+-Nd"3"+ pairs at distances 3.9, 5.9 and 6.3 A have been identified. (orig.)

1998-07-24

36

A dinuclear Ni(I) system having a diradical Ni2N2 diamond core resting state: synthetic, structural, spectroscopic elucidation, and reductive bond splitting reactions.

The electrochemical behavior of lanthanide oxides in molten alkaline chloride media is of great concern in pyrochemical processes for advanced nuclear fuel cycle. We have studied the solubilities of various lanthanide oxides in LiCl-KCl eutectic melt. In general, lanthanide oxides appeared to be insoluble/sparingly soluble in LiCl-KCl eutectic at 723 K. However, europium oxide exhibited an abnormal behavior in solubility and redox chemistry. The solubility of europium oxide was measured to be 1-2 order of magnitude higher than those of other lanthanide oxides. This abnormal solubility may be attributable to different electrochemical behavior of europium in the same experimental conditions. Most lanthanides ion exists as trivalent oxidation states. However, we observed divalent europium dissolved in LiCl-KCl molten salt by applying electron paramagnetic resonance(EPR) spectroscopy. (Figure 1) With the aid of this spectroscopic tool, it was found ...

2005-06-15

37

The anisotropy of the Curie-Weiss law in dysprosium

One-electron reduction of the square-planar nickel precursor (PNP)NiCl ( 1) (PNP (-) = N[2-P(CHMe 2) 2-4-methylphenyl] 2) with KC 8 effects ligand reorganization of the pincer ligand to assemble a Ni(I) dimer, [Ni(mu 2-PNP)] 2 ( 2), containing a Ni 2N 2 core structure, as inferred by its solid-state X-ray structure. Solution magnetization measurements are consistent with a paramagnetic Ni(I) system likely undergoing a monomer dimer equilibrium. The room-temperature and 4 K solid-state X-band electron paramagnetic resonance (EPR) spectra display anisotropic signals. Low-temperature solid-state X-band EPR data at 4 K reveal rhombic values g z = 1.980(4), g x = 2. 380(4), and g y = 2.225(4), as well as a forbidden signal at g = 4.24 for the Delta M S = 2 half field transition, in accord with 2 having two weakly interacting metal centers. Utilizing an S = 1 model, full spin Hamiltonian simulation of the ...

2008-10-15

38

The rare earth antimonates: spectroscopic properties, crystal field and paramagnetic susceptibility simulations

In the paramagnetic region T > 178 K the paramagnetic susceptibility, chi, of Dy was measured as a function of temperature and orientation of the applied magnetic field with respect to the c-axis. For magnetic fields parallel and perpendicular to the c-axis the temperature dependence of chi can be represented by Curie-Weiss laws whereas for arbitrary orientations significant deviations from a Curie-Weiss behaviour were found. The measured anisotropy of the paramagnetic Curie temperatures and of the Curie-Weiss constants is shown to depend mainly on the magnetocrystalline energy and an anisotropic g-factor. (Auth.).

1979-10-01

39

Intrinsic magnetism in Fe doped SnO2 nanoparticles

The rare earth antimonates RE_3Sb_5O_1_2 constitute an isostructural series, where the rare earth site symmetry is S_4. The spectroscopic properties of pure or doped compounds of this family are studied in order to derive their energy level schemes and to simulate them through the crystal field theory, by using the approximated D_2_d potential. The paramagnetic susceptibilities are calculated with the derived wavefunctions and compared to experiment.

1990-09-01

40

Effects of inorganic cation templates on octahedral molecular sieves of manganese oxide

Iron doped semiconducting nanoparticles Sn1-xFexO2 with x=0, 0.001, 0.002, 0.003, 0.004, 0.01 and 0.03 were prepared by a sol-gel method. The X-ray diffraction, Transmission Electron Microscopy measurements confirm the rutile structure with no impurity phase. The three characteristic lines of electron spin resonance (ESR) are observed in the doped samples for all compositions, which is a clear evidence for rhombic Fe3+ in rutile phase. The line width of ESR increases with increase in Fe concentration due to induced disorder. The spin-pumping effect is observed at temperatures below 250 K for the samples with x=0.01 and 0.03. However, based on the Curie-Weiss susceptibility, iron is in paramagnetic state and is subject to weak antiferromagnetic interaction. Blue shift in the optical band gap is observed with increase in the Fe content. -- Graphical abstract: The ESR spectra reveal that the nature of Fe in Sn1-xFexO2 samples ...

2011-01-01

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41

Optically stimulated luminescence (OSL) study of synthetic stishovite

Five hydrated inorganic divalent cations, Mg[sup 2+], Co[sup 2+], Ni[sup 2+], Cu[sup 2+], and Zn[sup 2+], have successfully been used as templates for the synthesis of manganese oxide octahedral molecular sieves (OMS-1) having the todorokite structure. The OMS-1 samples have been well characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy dispersive X-ray studies, inductively coupled plasma analysis, electron paramagnetic resonance, Fourier transform infrared spectroscopy, thiosulfate titration, and cyclohexane sorption. Catalytic CO oxidation and 2-propanol decomposition were carried out. Results show that these OMS-1 samples with a tunnel size of about 6.9 angstroms are crystalline and chemically pure. They have the following formulas: Mg[sub 3.17]Mn[sub 5.05]O[sub 12] [center dot] 4.52H[sub 2]O, Co[sub 1.84]Mn[sub 5.59]O[sub 12] [center dot] ...

1994-11-30

42

Low-temperature behavior of two ternary lanthanide nickel carbides: Superconducting LaNiC_2 and magnetic CeNiC_2

Optically stimulated luminescence (OSL) of synthetic stishovite was investigated for a future dating technique of meteor impact craters. Luminescence around 330 nm was measured on the #gamma#-ray irradiated stishovite under two stimulating light sources of infrared laser (830 nm) and blue light emitting diode set (470 nm). Thermoluminescence (TL) studies before and after the OSL measurements showed the intensities around 100-200 deg. C and 220-350 deg. C to increase and those around 350-450 deg. C to decrease. This indicates that a part of deep-trapped charges excited during the OSL measurements were retrapped by shallower traps. The infrared stimulated luminescence (IRSL) after the TL measurement up to 450 deg. C could not be detected, while the blue light stimulated luminescence (BLSL) after TL had about one-tenth of the intensity before TL. This indicates that a part of the charges in shallower traps were detrapped thermally and returned to the deeper traps which were related to ...

2000-12-15

43

Intrinsic Dosimetry Of Glass Containers Used To Transport Nuclear Materials: Potential Implications to the Field of Nuclear Forensics

A study of the magnetic properties and the heat capacity as functions of temperature and magnetic field of two ternary carbides RNiC_2, where R=La and Ce, confirms that LaNiC_2 becomes superconducting at T_c=2.7thinspK, and that CeNiC_2 orders antiferromagnetically below 18thinspK. LaNiC_2 is a conventional superconductor with a critical field of 900 Oe at T=2thinspK. CeNiC_2 obeys the Curie-Weiss law between 50 and 300thinspK showing the nearly full Ce"3"+ magnetic moment, p_e_f_f=2.47(1)#mu#_B, and has a negative paramagnetic Weiss temperature #THETA#_p=-18.3(8)thinspK. A low net magnetic moment in the ordered state, which is far from saturation in a magnetic field of 5thinspT, is consistent with an antiferromagnetic ground state. Below 20thinspK CeNiC_2 shows multiple-step magnetic transitions at 18, 10, and 2.4thinspK. Both LaNiC_2 (in the normal state) and CeNiC_2 have the same electronic heat capacity, #gamma#=6.5(2)thinspmJ/molthinspK"2, ...

1998-07-01

44

Enhanced Activity of Nanocrystalline Zeolites for Selective Catalytic Reduction of NOx

Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) dosimetry were used to measure dose effects in borosilicate glass with time, from 10 minutes to #approx#60 days following exposure to a dose of up to 10,000 Rad. TL and EPR results were consistent and performed similarly, with both techniques capable of achieving an estimated limit of detection of between 50-100 Rad. Three peaks were identified in the TL glow curve at roughly 110 C, 205 C, and 225 C. The intensity of the 205 C peak was the dominant peak over the time period of this study. The stability of all of the peaks with time since irradiation increased with their corresponding temperature and little or no variation was observed in the glow curve response to a specified total dose attained at different dose rates. The intensity of the 205 C peak decreased logarithmically with time regardless of total dose. Based upon a conservative limit of detection of 330 Rad, a 10,000 ...

45

Dynamic NMR effects in breast cancer dynamic-contrast-enhanced MRI

Nanocrystalline zeolites with discrete crystal sizes of less than 100 nm have different properties relative to zeolites with larger crystal sizes. Nanocrystalline zeolites have improved mass transfer properties and very large internal and external surface areas that can be exploited for many different applications. The additional external surface active sites and the improved mass transfer properties of nanocrystalline zeolites offer significant advantages for selective catalytic reduction (SCR) catalysis with ammonia as a reductant in coal-fired power plants relative to current zeolite based SCR catalysts. Nanocrystalline NaY was synthesized with a crystal size of 15-20 nm and was thoroughly characterized using x-ray diffraction, electron paramagnetic resonance spectroscopy, nitrogen adsorption isotherms and Fourier Transform Infrared (FT-IR) spectroscopy. Copper ions were exchanged into nanocrystalline NaY to increase the catalytic activity. ...

2006-12-31

46

The rare earth antimonates: spectroscopic properties, crystal field and paramagnetic susceptibility simulations

The passage of a vascular-injected paramagnetic contrast reagent (CR) bolus through a region-of-interest affects tissue ¹H₂O relaxation and thus MR image intensity. For longitudinal...Full Text Available

2008-11-18

47

Magnetic fluctuations in paramagnetic Mn{sub 0.81}Ni{sub 0.19}

The rare earth antimonates RE{sub 3}Sb{sub 5}O{sub 12} constitute an isostructural series, where the rare earth site symmetry is S{sub 4}. The spectroscopic properties of pure or doped compounds of this family are studied in order to derive their energy level schemes and to simulate them through the crystal field theory, by using the approximated D{sub 2d} potential. The paramagnetic susceptibilities are calculated with the derived wavefunctions and compared to experiment.

1991-01-01

48

Supramolecular selectivity of [60]-fullerene among equivalently photoactive porphyrins

Magnetic fluctuations present in the paramagnetic Mn{sub 0.81}Ni{sub 0.19} system have been investigated by measuring inelastic magnetic neutron scattering from a single crystal at temperatures of 450, 585 and 700 K. Antiferromagnetic correlations are observed to be present at all the temperatures studied. The spectral width of the magnetic scattering has been observed to increase with temperature, while the spatial range of the magnetic correlations is seen to decrease as the temperature is raised. The wave-vector-dependent susceptibility is found to follow a Curie-Weiss law near the (1 0 0) position, in agreement with theoretical predictions.

2006-11-15

49

Paramagnetic susceptibility of nonstoichiometric fluorides with the fluorite-type structure

The photophysical investigation of different para-substituted tetraphenylporphyrins (TP), viz., meso-tetra(4'-hydroxyphenyl)-21H-23H-porphyrin(1),meso-tetrakis (4'-hex-5-enyloxyphenyl)-21H-23H-porphyrin(2), meso-tetrakis(4'-oct-7-enyloxyphenyl)-21H-23H-porphyrin(3) and meso-tetrakis(4'-undecyloxyphenyl)-21H-23H-porphyrin (4) revealed that except for quantum yield (#phi#) the para-substitution has little effect on any other photophysical properties like lifetime, excitation, emission wavelength, etc. The host-guest type interactions of these tetraarylporphyrins (TP 1-4), with [60]-fullerene (F) have been studied with "1H NMR and fluorescence spectrometric techniques in carbon tetrachloride medium. Fluorescence studies revealed that the Q band of the TPs was sufficiently quenched upon addition of F. All the fullerene/porphyrin systems were found to produce stable complexes with 1:1 stoichiometry. Binding constants (K) of all the ...

2010-10-01

50

Magnetic susceptibility of La_xNd_1_-_xF_3 single crystals

Magnetic properties of single crystals of nonstoichiometric fluorides M[sub 1-x]R[sub x]F[sub 2+x] (M = Ca, Sr, Ba; R = Ce, Pr, Nd, Gd, Ho, Er, Tm, Yb; with 0.05 [le] x [le] 0.28) with the fluorite-type structure have been studied for the first time. The magnetic susceptibility was measured using a Faraday balance in the 15-300 K temperature range. The samples are paramagnetic following the Curie-Weiss law. The values of paramagnetic Curie temperatures and effective magnetic moments of rare-earth ions have been found. Deviations of the temperature dependence of magnetic susceptibility from the Curie-Weiss law are observed for some nonstoichiometric fluorides at temperatures ranging from 60 to 85 K. Possible reaons for these deviations are discussed. Measurements of magnetic susceptibility provide an effective technique for a rapid and accurate determination of the concentration of rare-earth ions in nonstoichiometric fluorides.

1993-01-01

51

EPR and luminescence studies of Eu(II) magnetically diluted in LiCl-KCl salt

The AC susceptibility of La_xNd_1_-_xF_3 single crystals, for 0#<=#x#<=#0.1, has been measured from 1.5 up to 40 K and their DC susceptibility for 0#<=#x#<=#1 has been measured from 3 up to 300 K in magnetic fields up to 0.2 T. In both susceptibilities the magnetic fields were applied parallel to the crystallographic a-axis (perpendicular to the c-axis). The effective Bohr magneton number p_e_f_f and paramagnetic Curie temperature #theta#_p have been obtained, using the Curie-Weiss law in the temperature range 100-300 K. Also the g-values corresponding to the five Kramers doublets in the "4I_9_/_2 ground multiplet of Nd"3"+ ion in La_xNd_1_-_xF_3 have been determined in the direction perpendicular to the c-axis, using the Van Vleck theory of paramagnetic susceptibility. The effect of the dilution of the paramagnetic Nd"3"+ ions with diamagnetic La"3"+ ions is also discussed. (orig.).

52

EPR and luminescence studies of Eu(II) magnetically diluted in LiCl-KCl salt

High-temperature LiCl-KCl molten salt medium provides an efficient way to produce the paramagnetic Eu(II) ion to be magnetically diluted into a diamagnetic host medium. Eu(II) was formed by a dissolution and an auto-reduction processes in a high-temperature LiCl-KCl eutectic melt at 723 K by using Eu{sub 2}O{sub 3} as a starting material. By using EPR and luminescence spectroscopic method, we studied the nature of the magnetically isolated paramagnetic Eu(II) ion diluted in a LiCl-KCl medium. With the aid of these spectroscopic tools, it was found that stable Eu(II) species was formed spontaneously at 723 K under anaerobic conditions. EPR and luminescence spectroscopy provided detailed information regarding the nature of the europium ion in a molten salt.

2007-12-15

53

EPR and luminescence studies of Eu(II) magnetically diluted in LiCl-KCl salt

High-temperature LiCl-KCl molten salt medium provides an efficient way to produce the paramagnetic Eu(II) ion to be magnetically diluted into a diamagnetic host medium. Eu(II) was formed by a dissolution and an auto-reduction processes in a high-temperature LiCl-KCl eutectic melt at 723 K by using Eu_2O_3 as a starting material. By using EPR and luminescence spectroscopic method, we studied the nature of the magnetically isolated paramagnetic Eu(II) ion diluted in a LiCl-KCl medium. With the aid of these spectroscopic tools, it was found that stable Eu(II) species was formed spontaneously at 723 K under anaerobic conditions. EPR and luminescence spectroscopy provided detailed information regarding the nature of the europium ion in a molten salt.

2007-12-01

54

British Library Electronic Table of Contents (United Kingdom)

High-temperature LiCl-KCl molten salt medium provides an efficient way to produce the paramagnetic Eu(II) ion to be magnetically diluted into a diamagnetic host medium. Eu(II) was formed by a dissolution and an auto-reduction processes in a high-temperature LiCl-KCl eutectic melt at 723K by using Eu2O3 as a starting material. By using EPR and luminescence spectroscopic method, we studied the nature of the magnetically isolated paramagnetic Eu(II) ion diluted in a LiCl-KCl medium. With the aid of these spectroscopic tools, it was found that stable Eu(II) species was formed spontaneously at 723K under anaerobic conditions. EPR and luminescence spectroscopy provided detailed information regarding the nature of the europium ion in a molten salt.

2007-01-01

55

Mo"5 and W"5 complexing with tri-tret-butyl phenyl ether of 1.2-naphthoquinonediazide-(2)-5-sulfochloride

Mean magnetic moments of polycrystalline Ce compounds in a tetragonal crystal field

The complexing of paramagnetic salts of molybdenum and tungsten with tri-tert-butylphenyl ester of 1,2-naphthoquinone-diazide-(2)-5-sulfochloride is studied by PMR and EPR methods. From the changes of half-widths of lines in PMR spectra and analysis of g-factor in EPR spectra, the kinetic and thermodynamic parameters of the complexing are determined, and the composition of the complexes formed is established, and the schemes of their formation are suggested.

56

Magnetic properties of heavy rare-earth tungstates

An alternative and graphical representation of the magnetic moment and the effective paramagnetic moment for polycrystalline Ce compounds with tetragonal site symmetry is described. The reduced moments can be calculated by means of standard perturbation theory. The calculated values deduced from the ground states of CeCu_2Si_2, CeRu_2Si_2, and CePd_2Si_2 polycrystals are compared with experimental magnetic moments.

57

Magnetic behavior in the U/sub 1-x/Th/sub x/Cu_2Si_2 system

Measurement of the magnetic susceptibility of powder samples of heavy rare-earth (Tb, Dy, Ho, Er, Tm and Yb) tungstates have been reported in the temperature range 300 to 900 K. Curie-Weiss law behaviour has been observed for all samples. The Curie constant, paramagnetic Curie temperature and magneton number for the magnetic ions have also been evaluated for each material. (author).

1978-12-01

58

Dynamics of itinerant ferromagnets above T/sub c/

The compound UC_2Si_2 has been found to be ferromagnetic at low temperatures with a Curie temperature of 101"0K. The magnetization follows a Curie-Weiss law in the paramagnetic region with an effective magneton number of 2.12 Bohr magnetons per uranium atom. Partial substitution of Th atoms for the U atoms results in an expansion of the lattice, a rapid drop in the Curie temperature, and a sizable increase in the coercive field.

1986-06-23

59

Electronic Health Records An Audit and Internal Control Guide

The existence of propagating spin waves above T/sub c/ in Ni and Fe has been widely accepted since this picture was first advocated in 1973. In this brief review of our current neutron scattering experiments on Fe and Ni we will present convincing evidence showing that this picture is incorrect. In addition, we will demonstrate that over wide ranges of ..omega.., q and temperature, both Fe and Ni follow a simple paramagnetic scattering function of the spin diffusion type. 19 references.

1984-04-01

60

Retrospective individual dosimetry using luminescence and EPR after radiation accidents

Electronic Health Records

2008-01-01

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61

The effects of applied magnetic fields on the {alpha}/{gamma} phase boundary in the Fe-Si system

In areas where radiation dose monitoring has not been performed, it is essential to use material available in the environment be able to rapidly assess doses to individuals for immediate emergency medical care or for general estimation of the radiological consequences. It was shown that certain types of telephone cards containing microchips have the potential to be used as individual radiation dosimeters in emergency situations to detect doses over 250 mGy by luminescence measurements. In order to understand the dosimetric properties of chip cards, the components obtained from INFINIEON Company at various stages of production were used for luminescence measurements. It is found that the protecting layer used above the chips so called 'globe top' is the main source of radiation induced signal in chip cards. The globe top produced by INFINIEON at that stage is found to contain SiO2 and Epoxy. In order to improve the dosimetric properties of the chip cards, the raw material of the globe ...

62

Magnetic properties of the Mn{sub 1-x}Fe{sub x}In{sub 2}S{sub 4} spinel compounds

The CALPHAD (calculations of phase diagrams) method is used to examine the effects of applied magnetic fields on the {alpha}/{gamma} phase boundary in the Fe-Si system in the paramagnetic state. The reported susceptibility data for pure Fe is first re-evaluated. The contributions to the total Gibbs energy of the ferrite ({alpha}) and austenite ({gamma}) from the external fields are calculated based on the Curie-Weiss law and the re-evaluated susceptibility data. The Fe-Si phase diagram on the Fe-rich side as a function of applied field is calculated using the Thermo-Calc(TM) package. With increasing field strength, the {gamma} loop shrinks monotonically; that is, the {alpha}/{gamma}-Fe transition temperature increases while that for {gamma}/{delta}-Fe transition decreases, albeit more slowly. Finally, in conformance with the existing CALPHAD databank, Redlich-Kister polynomials are proposed to account for the compositional and temperature dependence of the ...

2006-07-21

63

Magnetic properties of Y_2Cu_2O_5, Y_2BaCuO_5, and Y_2Ba_2O_5 compounds

Mn{sub 1-x}Fe{sub x}In{sub 2}S{sub 4} spinel compounds (x=0.3, 0.8) were grown by the chemical vapor transport method. The analysis of the X-ray diffraction data suggest that both the compounds crystallize in a cubic structure under the space group Fd3m. The magnetic study done between 300 and 2 K showed a paramagnetic behavior for the intermediate concentration sample x=0.3. A good fitting to the Curie-Weiss law allows us to calculate the paramagnetic Curie temperature. They are negative indicating predominant antiferromagnetic interactions. However, in sample with high Fe concentration, x=0.8, it was possible to observe a peak at around T{sub sg} congruent with 10 K. From ac magnetic susceptibility data at different driving frequencies f, it is found that the peak at T{sub sg} shifts to lower temperatures with decreasing frequency suggesting an spin-glass behavior.

2004-04-28

64

Magnetic and Moessbauer study of some transition metal based nitroprussides

The magnetic susceptibility of Y_2Cu_2O_5, Y_2BaCuO_5, and Y_2Ba_2O_5 single-phase compounds in weak magnetic fields (H_0=0.1--20 Oe) and moderate magnetic fields (H_0#=#0.2 Oe it converts into a paramagnetic maximum #chi#(T) which corresponds to an antiferromagnetic transition. In a moderate magnetic field H=500 Oe a normal Curie-Weiss law, #chi##approx##mu#"2_e_f_f (T-#theta#) is observed. At temperatures T=150--300 K, #theta#=38 K and #mu#_e_f_f#approx#2.2 #mu#_B/at. Cu. At T<150 k the temperature dependence of #chi# is described by a simple Curie law with #theta##approx#0. Although the paramagnetic signal is extremely weak, in the Y_2Ba_2O_5 compound the curve of #chi#(T, H_0=100 Oe) for a Y_2ba_2O_5 sample exhibits a slightly smeared maximum at a temperature T#approx#13 K.

1989-01-01

65

Ferroelectric and magnetic properties of Ho{sub 2}CuTiO{sub 6} double perovskite

Susceptibility data of freshly precipitated nitroprussides TM[Fe(CN){sub 5}NO] n H{sub 2}O (TM=Mn, Fe, Co, Ni, Cu) follow very well modified Curie-Weiss law down to T=5 K indicating paramagnetic state; nitroprusside (NP) containing Zn is diamagnetic with a sign of paramagnetic contribution. Deviation from Curie-Weiss law and magnetization measurements on MnNP, FeNP and CoNP below T=5 K can indicate ferrimagnetic ordering at low temperatures. A hysteresis behaviour in ZFC and FC magnetisation with the temperature of bifurcation T{sub b}=6 K was found for CoNP and FeNP. Moessbauer spectra taken at room temperature (besides FeNP) consist of a single symmetric quadrupole-split doublet with parameters {delta} and {delta} typical for Fe{sup II} ions in octahedral sites. A more complicated spectrum of FeNP is a consequence of different Fe environments.

2004-05-01

66

Characterization of iron nitrides prepared by spark erosion, plasma nitriding, and plasma immersion ion implantation

Ho{sub 2}CuTiO{sub 6} double pervoskite is synthesized by solid state reaction method and the phase formation was confirmed by X-ray diffraction. Ho{sub 2}CuTiO{sub 6} crystallizes in space group P63 cm and are isostructural in AMnO{sub 3} structure. We have investigated the effect of the presence of a magnetic ion (Ho{sup 3+}{approx}10.4{mu}{sub B}) in Ho{sub 2}CuTiO{sub 6}, on the magnetic properties, compared to that of an isostructural double perovskite containing Y-ion (non-magnetic), i.e., Y{sub 2}CuTiO{sub 6}. Magnetization measurements on Ho{sub 2}CuTiO{sub 6} showed paramagnetic moment of 0.026{mu}{sub B}/Ho at room temperature in an applied field of 7 T although no saturation is observed at room temperature, whereas, at 5 K, the paramagnetic moment was 0.3{mu}{sub B}/Ho in the same field. Since this compound is non-centrosymmetric, it is of interest to look into the possibility of realizing multiferroicity (coexistence of magnetic and ...

2006-08-15

67

Characterization of iron nitrides prepared by spark erosion, plasma nitriding, and plasma immersion ion implantation

The effect of the nitrogen uptake in {alpha}-iron upon spark erosion in gaseous and liquid ammonia, plasma nitriding, and plasma immersion ion implantation is studied. The resulting phases and hyperfine parameters, measured by the Moessbauer spectroscopy, are discussed from the point of view of initial conditions of their preparation and subsequent heat and/or mechanical treatment. Spark erosion in the ammonia gas produces fine particles with the dominating ferromagnetic {alpha}-Fe phase (50%). The 20% of specimen volume form {alpha}'-Fe and {alpha}''-Fe{sub 16}N{sub 2} phases. The last 30% occupy the {gamma}'-Fe{sub 4}N, ferro- and paramagnetic {epsilon} phases, and {gamma}-Fe(N). Nitriding in the liquid ammonia allows to incorporate the higher content of nitrogen into {alpha}-iron particles which results in the formation of paramagnetic {epsilon}({zeta})-Fe{sub 2}N phase. This phase also dominates the ...

2001-09-01

68

Magnetic properties of glasses from geothite industrial wastes recycling (FeOOH)

The effect of the nitrogen uptake in #alpha#-iron upon spark erosion in gaseous and liquid ammonia, plasma nitriding, and plasma immersion ion implantation is studied. The resulting phases and hyperfine parameters, measured by the Moessbauer spectroscopy, are discussed from the point of view of initial conditions of their preparation and subsequent heat and/or mechanical treatment. Spark erosion in the ammonia gas produces fine particles with the dominating ferromagnetic #alpha#-Fe phase (50%). The 20% of specimen volume form #alpha#'-Fe and #alpha#''-Fe_1_6N_2 phases. The last 30% occupy the #gamma#'-Fe_4N, ferro- and paramagnetic #epsilon# phases, and #gamma#-Fe(N). Nitriding in the liquid ammonia allows to incorporate the higher content of nitrogen into #alpha#-iron particles which results in the formation of paramagnetic #epsilon#(#zeta#)-Fe_2N phase. This phase also dominates the surface of #alpha#-iron specimen implanted by nitrogen using ...

2001-09-01

69

Magnetic behavior in defect-perovskites RTa{sub 3}O{sub 9} (R=Nd,Eu and Ho)

It has been carried out the magnetic properties determination for high iron oxide content glasses series obtained from a geothite red mud waste from the zinc hydrometallurgy and dolomite and glass cullet as main raw materials. It has been determined the magnetic susceptibility and magnetization values for the glasses here investigated. The results suggest that the magnetic behaviour are depending on the glass chemical composition, so that glasses can be differently classified like ferrimagnetic, ferromagnetic, superparamagnetic and paramagnetic. (Author) 6 refs.

70

First experiences with application of gadolinium-DTPA in infants and small children under two years of age

Magnetic behavior in three compounds RTa{sub 3}O{sub 9} (R = Nd, Eu and Ho) with defect-perovskite structures has been investigated by DC magnetic susceptibility. The susceptibility of NdTa{sub 3}O{sub 9} shows strong influence of crystal field. For EuTa{sub 3}O{sub 9} a typical Van Vleck paramagnetism has been observed. HoTa{sub 3}O{sub 9} obeys a Curie-Weiss law above 20 K. (orig.) 8 refs.

1998-01-01

71

Scanning Electron Microscope Examination of Cotton Linters ...

The use of Gadolinium-DTPA as a paramagnetic contrast agent in MRI with adults and juveniles concerning brain and spinal cord pathology is well proven since years. In the FRG it is only introduced for children over two years of age. Therefore this report deales with the experience in four infants and small children under the age of two. They all were suffering from neurological tumors and got additional diagnostic information in three cases. Clinical side-effects like urticaria, vomiting or convulsions had not been observed nor had pathologic changes of the biochemical parameters been noticed. (orig./GDG).

72

ELECTRONIC COMPONENT FOR WIRING, ITS MANUFACTURING METHOD, ELECTRONIC DEVICE PACKAGE IN WHICH THE ELECTRONIC COMPONENT IS INCORPORATED FOR USE, AND ITS MANUFACTURING METHOD

... TECHNICAL REPORT ARBRL-TR-02476 SCANNING ELECTRON MICROSCOPE ... SCANNING ELECTRON MICROSCOPE EXAMINATION OF ...

1983-03-01

73

J-STORE (Japan)

Full Text Available

2011-04-07

74

The European XFEL Free Electron Laser at DESY

ScienceCinema

...english ...

75

Nuclear physics with a free electron laser

Measurement of longitudinal distribution of electron beam

No abstract prepared.

2002-07-01

76

Irradiation effects on electronic functional materials

No abstract prepared.

2001-07-01

77

THE INTERPRETATION OF ELECTRON MICROSCOPE ...

No abstract prepared

1998-01-01

78

Energy Dispersive X-ray Analysis in the Electron Microscope

... Accession Number : AD0633770. Title : THE INTERPRETATION OF ELECTRON MICROSCOPE FRACTOGRAPHS. Descriptive Note : Final rept.,. ...

1966-01-21

79

ELECTRON MICROSCOPE STUDIES INTO THE ...

Energy Dispersive X-ray Analysis in the Electron Microscope

2003-01-01

80

The lost heat capacity and entropy in the helical magnet MnSi

ELECTRON MICROSCOPE STUDIES INTO THE MORPHOLOGY AND LOCALIZATION OF OMSK HEMORRHAGIC FEVER VIRUS IN INFECTED ...

1966-08-01

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81

Superconducting A-15 compounds

We report results of measurements and analysis of the heat capacity of MnSi. The measurements included data collection at a magnetic field of 4T, which suppresses strongly the longitudinal spin fluctuations and the phase transition. To analyze the experimental data, calculations of the phonon spectrum and phonon density of states in MnSi were performed. Inelastic neutron scattering with a polycrystalline sample of MnSi was used to validate the computational results. The combination of the experimental and theoretical data turned out to be decisive in revealing some hidden features of the thermal excitations in MnSi. In particular, the analysis of the available data led conclusively to the existence of a negative contribution to the heat capacity and entropy in MnSi at T>Tc, implying that a specific spin ordering process did occur in the paramagnet phase of MnSi.

2011-03-01

82

Spin dynamics in Ho{sub 2}Ru{sub 2}O{sub 7}

The critical superconducting paramters of A-15 compounds are reviewed, and the trends analysed in order to predict maximum values. Experimental data on critical temperature is summarized and compared with theory. The ability to form the stoichiometric, well-ordered materials required for maximum Tsub(c) is discussed in terms of the thermodynamic stability of the A-15 phase. It is concluded that critical temperatures in excess of 25 K, in the A-15 structure, are unlikely. The upper critical field data show that, whereas the vanadium-based compounds are paramagnetically limited, the niobium-based compounds are not. The relation between critical current and microstructure is explored. Best data on critical current densities and ac losses is presented. Finally an account is given of the various methods by which actual conductors, both tapes and multifilamentary wires, are made. (author).

83

Spin dynamics in Ho_2Ru_2O_7

The spin relaxation processes within the pyrochlore Ho{sub 2}Ru{sub 2}O{sub 7} have been investigated by neutron scattering and bulk property techniques. A single-ion process, that is thermally activated, dominates the spin-spin relaxation spectrum above 2 K. Assuming Arrhenius behaviour, we found an activation energy {delta} = (329 {+-} 6) K and characteristic relaxation time {tau}{sub 0} (5.2 {+-} 0.3) x 10{sup -12} s in the paramagnetic state, akin to those found in the spin ice, Ho{sub 2}Ti{sub 2}O{sub 7}. Atlow temperature (T<95 K) the activation energy lowers and below 20 K the entropy and ac susceptibility are similar to that observed in other spin ice compounds within a 10 kOe field.

2005-11-09

84

Progress on polarized target materials with pure carbon background

The spin relaxation processes within the pyrochlore Ho_2Ru_2O_7 have been investigated by neutron scattering and bulk property techniques. A single-ion process, that is thermally activated, dominates the spin-spin relaxation spectrum above 2 K. Assuming Arrhenius behaviour, we found an activation energy #DELTA# = (329 #+-# 6) K and characteristic relaxation time #tau#_0 (5.2 #+-# 0.3) x 10"-"1"2 s in the paramagnetic state, akin to those found in the spin ice, Ho_2Ti_2O_7. Atlow temperature (T<95 K) the activation energy lowers and below 20 K the entropy and ac susceptibility are similar to that observed in other spin ice compounds within a 10 kOe field.

2005-11-09

85

Progress on polarized target materials with pure carbon background

A previous note reviewed methods for the paramagnetic doping of materials for spin-polarized solid targets and some of the history of attempts to apply those methods to hydrocarbons. Since the earlier work on hydrocarbons had yielded, at best, rather mediocre results, that note also speculated on some ways to extend and, possibly, to improve upon the earlier work. The sharpest focus was on the light (number of carbons less than six) alkanes, since these are the hydrocarbons that have the highest hydrogen contents ([approx gt] 17wt %) and therefore require the least degree of polarization to be interesting. This present note summarizes the subsequent work done, to date, exploring some of the issues related to the chemical doping method. The main areas of progress have been in the literature search, experimental results on glass formation by alkanes, and a polarizing test of a prototype'' hydrocarbon.

1993-03-24

86

Progress on polarized target materials with pure carbon background

A previous note reviewed methods for the paramagnetic doping of materials for spin-polarized solid targets and some of the history of attempts to apply those methods to hydrocarbons. Since the earlier work on hydrocarbons had yielded, at best, rather mediocre results, that note also speculated on some ways to extend and, possibly, to improve upon the earlier work. The sharpest focus was on the light (number of carbons less than six) alkanes, since these are the hydrocarbons that have the highest hydrogen contents ([approx gt] 17wt %) and therefore require the least degree of polarization to be interesting. This present note summarizes the subsequent work done, to date, exploring some of the issues related to the chemical doping method. The main areas of progress have been in the literature search, experimental results on glass formation by alkanes, and a polarizing test of a prototype'' hydrocarbon.

1993-03-24

87

Phase diagram and low temperature magnetization of Gdsub(x)Ysub(1-x)Rh_4B_4

A previous note reviewed methods for the paramagnetic doping of materials for spin-polarized solid targets and some of the history of attempts to apply those methods to hydrocarbons. Since the earlier work on hydrocarbons had yielded, at best, rather mediocre results, that note also speculated on some ways to extend and, possibly, to improve upon the earlier work. The sharpest focus was on the light (number of carbons less than six) alkanes, since these are the hydrocarbons that have the highest hydrogen contents ({approx_gt} 17wt %) and therefore require the least degree of polarization to be interesting. This present note summarizes the subsequent work done, to date, exploring some of the issues related to the chemical doping method. The main areas of progress have been in the literature search, experimental results on glass formation by alkanes, and a polarizing test of a ``prototype`` hydrocarbon.

1993-03-24

88

Moessbauer study of the firing process of the imitative ancient sky-blue Jun porcelain

The phase diagram of Gdsub(x)Ysub(1-x)Th_4B_4 between the paramagnetic, superconducting and ferromagnetic state is reported. Low temperature dc-magnetization measurements reveal that macroscopic electro-magnetic effects are of minor importance for the suppression of Hsub(2c), which shows a smooth bell-shaped behavior for x >= 0.15 with no indication of an anomaly near Tsub(c2). At low temperature in samples with x >= 0.20 a transition from type II to type I superconductivity seems to occur. The low temperature normal state susceptibility follows a Curie-Weiss law indicating reentrant behavior for x >= 0.10. (orig.).

1981-09-01

89

Moessbauer spectroscopic determination of chemical state of iron in bauxite

Moessbauer spectra of the imitative ancient Jun porcelain indicate that the glaze and body materials contain Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4} and structural iron. It is clear that during the firing process, the glaze undergoes dehydration, dehydroxylation, vitrification and recrystallization. The Fe{sup 2+} quadrupole splitting value of the paramagnetic peak of the body material is high even at low firing temperatures. For the body material, the distinction between dehydration and dehydroxylation is not clear. The changes of magnetism of the glaze and body materials in the firing process and the coloring mechanism of the sky-blue Jun porcelain are analyzed in the present paper. (orig.)

1994-11-01

90

Magnetic resonance imaging in joint diseases

The chemical state of iron contained in several kinds of bauxite, which are utilized as a raw material in the aluminum industry in Japan, were investigated by Moessbauer spectroscopy. The main compounds of iron were identified from the results, which showed variations of the Moessbauer absorption spectra with calcination and measuring temperature. Although the absorption intensities of the spectra differed significantly, major species identified were paramagnetic or superparamagnetic #alpha#-Fe_2O_3 in all of these bauxite samples. The superparamagnetic #alpha#-Fe_2O_3 was found mainly in the gibbsite-type bauxite, but not in the boehmite/gibbsite-type or the boehmite-type bauxite. The Moessbauer absorption spectra of red mud and its calcined products were also given. (author).

91

Magnetic properties of some Au_3R compounds

Magnetic resonance imaging has proven an invaluable method in the diagnosis of joint diseases associated with osteonecrotic, inflammatory, traumatic and degenerative processes. At the clinical level, it has an important role in decisions about the method of treatment and evaluations of the therapeutic success. When the merits of MRT are balanced against those of conventional radiography including tomography and CT, which both ensure better spatial resolution in the visualisation of cortical and spongy bone structures, it becomes quite evident that MRT must not be regarded as an alternative method of imaging but as one that can be used additionally to obtain the most information for the diagnosis of arthropathy. The question as to whether new pulse sequences (snap shots) or invasive techniques like intra-articular injection of paramagnetic substances (MR arthrography) are likely to become routine procedures in the detection of joint diseases using MRT remains to be ...

92

Magnetic properties of ErPd_2Si_2 from magnetization Moessbauer and neutron diffraction measurements

The magnetization of a series of intermetallic compounds Au_3R, where R is Gd through Yb, was investigated at 2.5 to 300"0K in applied fields up to 26 kOe. All the compounds studied exhibited the orthorhombic TiCu_3--Do/sub a/ type structure. For high temperatures, the temperature dependence of the inverse susceptibility followed a Curie--Weiss law, yielding effective paramagnetic moments in good agreement with the values calculated for free tripositive rare earth ions. At low temperatures, deviations from Curie--Weiss behavior were observed in all cases. These deviations are ascribed to the influence of crystal-field and exchange interactions. (auth).

1974-12-03

93

Magnetic characteristic of some TCu_2Si_2 ternary alloys (T = Nd, Dy, Ho, Er, Tm, Y, and La)

Magnetization, neutron diffraction and "1"6"6Er Moessbauer measurements on ErPd_2Si_2 are reported. Below 4.8 K ErPd_2Si_2 orders AF with complex modulated magnetic structures, where the Er moments are aligned along the c-axis. At 1.5 K a squared structure with #mu#_E_r #approx# 7.8(1)#mu#_B is found while a saturation Er moment of 8.2(2)#mu#_B is inferred from the hyperfine field data. The temperature dependence of the Moessbauer spectra in the paramagnetic region is explained in the framework of a relaxation model implying excited crystal field levels. Its analysis is used to estimate the B"m_n CEF parameters. (orig.).

94

Itinerant magnetism of Gd_xLa_1_-_xMSi (M=Fe, Co) compounds

Magnetic characteristics of the ternary alloys TCu_2Si_2 (T = Nd, Dy, Ho, Er, and Tm) have been investigated. Magnetic susceptibility measurements were carried out between 4.2 and 150 K and in magnetic fields of 1 to 18 kOe, using a vibrating sample magnetometer. The Curie-Weiss law is followed by NdCu_2Si_2 above 30 K, by DyCu_2Si_2 and HoCu_2Si_2 above 50 K, and by ErCu_2Si_2 and TmCu_2Si_2 above 9 K. Furthermore, the Curie paramagnetic temperatures are given.

1981-12-01

95

Independent superconductivity and paramagnetism in HoBa/sub 2/Cu/sub 3/O/sub z/

The magnetic properties of polycrystalline and single crystalline rare earth transition metal silicides Gd_xLa_1_-_xMSi (M =Fe, Co) were investigated. Magnetic measurements have been made in static magnetic fields up to 13 kOe and in pulsed magnetic fields up to 250 kOe in the temperature range from 4.2 to 350 K. The magnetic susceptibility in the paramagnetic state of all the investigated compounds obeys the Curie-Weiss law except for LaFeSi and LaCoSi. Increase of the La content in Gd_xLa_1_-_xFeSi compounds leads to a decrease of the Curie and Neel temperatures, which can be explained by a decrease of positive exchange interactions. (orig.).

1995-09-01

96

Heat capacity and magnetic ordering of two cerium sulfides, CeS/sub 1. 393/ and CeS/sub 1. 457/

The magnetic properties of the superconductive materials HoBa/sub 2/Cu/sub 3/O/sub z/ and YBa/sub 2/Cu/sub 3/O/sub z/ have been measured and compared. Both had superconductive transition temperatures T/sub c/ in low magnetic fields near 90 K and exhibited nearly complete magnetic-flux exclusion. The susceptibility of the Ho-based materials followed a Curie-Weiss law both above and below T/sub c/. These results give clear experimental evidence for a nearly complete decoupling of the magnetic and superconductive layers, demonstrating that the superconductivity is highly anisotropic.

1987-07-01

97

Density of states model for the lattice transformation in A-15 compounds

Heat-capacity (0.5--20 K) and magnetic-susceptibility (4--300 K) measurements have been made on two cerium sulfide samples having compositions as CeS/sub 1.393/ and CeS/sub 1.457/. These materials follow the Curie-Weiss law above 100 K, and become ferromagnetically ordered near 6 and 3 K, respectively. Shift of the ordering to higher temperatures under applied magnetic fields is also observed in CeS/sub 1.457/. The estimated effective magnetic moment and entropy associated with the ordering are consistent with the paramagnetic nature of Ce/sup 3 +/ (4f/sup 1/) in a crystalline environment.

1982-08-01

98

Characteristic features of intracranial meningiomas on magnetic resonance tomography

The cubic-tetragonal lattice transformation in A-15 compounds is described by an empirical model in which the density of states function near the Fermi energy is characterized by a two-parametric peak in addition to the constant part. Two types of peak splitting under tetragonal deformation are considered, leading to qualitatively different results about the phase transition. Results are given for the order parameter, the phase stability, the soft elastic modulus, and the paramagnetic spin susceptibility. Comparing with measurements of the magnetic susceptibility of V_3Si single crystals near the phase transition a better agreement is obtained for a twofold degenerate density of states peak than for a threefold degenerate one. (author).

99

Antiferromagnetic Kondo lattice: CePdSi_2

Twenty-three patients with intracranial meningiomas were examined by means of magnetic resonance tomography (MRT). In 13 patients the paramagnetic contrast medium gadolinium DTPA was used. Meningiomas show only slight changes in signal intensity compared with brain in the spin-echo mode, the greatest contrast being found on photon density images (TR 1600 ms, TE 35 ms). In T1 images more than 50% of the patients showed a low signal margin between tumour and brain. Hyperostosis of the calvarium is easily recognised, but MRT is unreliable for showing tumour calcification. After intravenous injection of gadolinium DTPA, there was marked homogeneous uptake in the meningiomas. These signs are useful for the diagnosis of a meningioma by MRT. (orig.).

100

Anisotropic exchange in frustrated pyrochlore Yb2Ti2O7

The compounds CePdSi_2, CeIrSi_2 and CeRhSn_2 have been synthesized and studied by X-ray diffraction, electrical resistivity and magnetic susceptibility. The magnetic susceptibility of CePdSi_2 exhibits two peaks at 6.8 K and 2.5 K, respectively, indicating two antiferromagnetic phase transitions, while that of CeIrSi_2 shows a broad maximum at 150 K, characteristic of valence fluctuating Ce-compounds. CeRhSn_2 remains paramagnetic down to 5 K. The resistivity of CeIrSi_2 exhibits a T"2 dependence at low temperatures, indicating a Fermi-liquid ground state, while those of CePdSi_2 and CeRhSn_2 shows the presence of Kondo and crystal field effects. (orig.).

1996-08-19

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101

Magnetic electronic lenses, quadrupole and octupole for microsystem electron beam techniques

The local Yb3+ magnetic susceptibility tensor was recently measured in the frustrated pyrochlore compound Yb2Ti2O7 by means of in-field polarized neutron scattering in a single crystal. A very anisotropic effective exchange tensor was derived for the Yb3+ ion. Using this result, we reinterpret here the data for the powder susceptibility in Yb2Ti2O7. We show that, in the case of a well-isolated Kramers doublet with anisotropic g and exchange tensors, the inverse susceptibility for a powder sample does not strictly obey a Curie-Weiss law at low temperature. We discuss the consequences regarding the paramagnetic Curie temperature, usually taken as a measure of the exchange/dipolar interaction, and the exotic 'slow fluctuation' ground state of Yb2Ti2O7. (fast track communication)

2009-12-09

102

Study of the Electron Beam Dynamics in the Fermi @ Elettra Linac

The MOS-technology allows to make tiny electronic lenses for multibeam electron systems. In the paper results of research and principles of designing of tiny magnetic electron lenses are submitted. Electronic lenses with a nonconventional configuration of tiny magnetic circuit and electronic lenses with coincident electric and magnetic fields in nonconventional tiny performance are considered

2006-09-01

103

Study of the Electron Beam Dynamics in the FERMI @ ELETTRALinac

A study of the electron beam dynamics in the linac is conducted for the FERMI free electron laser (FEL) founded for construction at the Sincrotrone Trieste.

2006-07-19

104

Photon statistics of the free-electron--laser startup

A study of the electron beam dynamics in the linac is conducted for the FERMI free electron laser (FEL) founded for construction at the Sincrotrone Trieste

2006-06-17

105

Mathematical Analysis of Three Free-Electron-Laser Issues

We show that, for the high electron currents used in present-day free-electron lasers, spontaneous radiation is distributed according to thermal statistics.

1983-09-01

106

Electron Microscope Database - GCMD - NASA

... iFfficiency-en- enhanced spontaneous radiation at the free-electron- ... as enhanced spontaneous radiation at the free-electron-laser wavelength. ...

1990-09-30

107

Synthesis, structure and characterisation of the n=4 Aurivillius phase Bi5Ti3CrO15

Electron Microscope Database. Entry ID: em_database ... Ancillary Keywords. electron microscope. Data Set Progress. IN WORK. Originating Center ...

108

Structure properties and magnetic susceptibility of diluted magnetic semiconductor Y_2_-_xHo_xO_3

The n=4 Aurivillius phase, Bi5Ti3CrO15, was synthesised by solid state reaction. Rietveld analysis of high resolution neutron diffraction data demonstrated this material to adopt the polar space group A21am at room temperature, transforming to the aristotype I4/mmm structure above 650 oC. This phase transition is coincident with an anomaly in DSC signal and relative permittivity, which are characteristic of a ferroelectric-paraelectric phase transition. Bi5Ti3CrO15 exhibits paramagnetic behaviour at low temperature, with short range antiferromagnetic interactions, but no evidence for long range magnetic ordering. This is considered a consequence of significant disorder of Ti and Cr over the available octahedral sites, as demonstrated by analysis of neutron diffraction data. -- Graphical abstract: We report here the synthesis, structure and characterisation of the n=4 Aurivillius phase Bi5Ti3CrO15. Analysis of neutron powder diffraction and XANES data, supported by ...

2011-02-01

109

Positioning of the Alzheimer A{beta}(1-40) peptide in SDS micelles using NMR and paramagnetic probes

The polycrystalline samples of Y_2_-_xHo_xO_3 (0.10#<=#x#<=#1.80) were synthesized by ceramic technology. The X-ray powder diffraction data were collected and the crystal structures were refined by the Rietveld method for the samples Y_2_-_xHo_xO_3 (x=0.00, 0.20, 0.40, 1.20, 1.80, 2.00). Holmium ions Ho"3"+ were randomly distributed over two cationic sites 8b and 24d in the space group Ia3 in all refined structures. Cation-anion-cation bonds important for superexchange interaction were determined. Magnetic susceptibility measurements were done by the Faraday method in the temperature range 290 to 620 K and a behaviour in accordance with the Curie-Weiss law was obtained. The molar Curie's constants linearly depend on concentration. The effective magnetic moments of Ho"3"+ ions were smaller than the free ion value. The Curie-Weiss paramagnetic temperatures indicated antiferromagnetic interaction. The gram ion susceptibilities confirmed the random distribution ...

1995-01-01

110

Paramagnetic susceptibility simulations from crystal field effects on Nd{sup 3+} in magnesium borate MgNd(BO{sub 2}){sub 5}

NMR spectroscopy combined with paramagnetic relaxation agents was used to study the positioning of the 40-residue Alzheimer Amyloid {beta}-peptide A{beta}(1-40) in SDS micelles. 5-Doxyl stearic acid incorporated into the micelle or Mn{sup 2+} ions in the aqueous solvent were used to determine the position of the peptide relative to the micelle geometry. In SDS solvent, the two {alpha}-helices induced in A{beta}(1-40), comprising residues 15-24, and 29-35, respectively, are surrounded by flexible unstructured regions. NMR signals from these unstructured regions are strongly attenuated in the presence of Mn{sup 2+} showing that these regions are positioned mostly outside the micelle. The central helix (residues 15-24) is significantly affected by 5-doxyl stearic acid however somewhat less for residues 16, 20, 22 and 23. This {alpha}-helix therefore resides in the SDS headgroup region with the face with residues 16, 20, 22 and 23 directed away from the hydrophobic ...

2007-09-15

111

The European XFEL Free Electron Laser at DESY

From the crystal field analysis of optical absorption spectra on monoclinic S.G. P2{sub 1}/c MgNd(BO{sub 2}){sub 5}, where Nd{sup 3+} occupies a single crystallographic position with no symmetry elements, energy level schemes and an expression of the associated wavefunctions for the 4f{sup 3} configuration of Nd{sup 3+} have been derived, considering approximate C{sub 2v} and C{sub s} (C{sub 2}) symmetries. Despite of the low symmetry of Nd{sup 3+}, resulting rms deviations between calculated and experimental levels are very satisfactory. The composition of the crystal field wavefunctions from both sets of phenomenological free-ion and crystal field parameters has been checked through a calculation of the thermal evolution of the paramagnetic susceptibility {chi}, according to the Van Vleck formula. The same simulation was performed with crystal field parameters (CFPs) resulting from the ab initio simple overlap model (SOM), considering the Nd{sup 3+} real point ...

1999-01-01

112

ScienceCinema

...spontaneous radiation ...

113

Influence of cosmic rays and the runaway-electron breakdowns on thunderstorm processes in the atmosphere

Free electron lasers for gamma-gamma colliders - a summary

Not Available

2009-09-01

114

Free electron lasers for gamma-gamma colliders - a summary

Short communication.

1995-02-01

115

Dirac-Coulomb Hamiltonian in N-Electron Model Spaces.

Short communication.

116

Czech Academy of Sciences Repository

Full Text Available

2003-01-01

117

Dead-time calibrator

Scratch and Corrosion Resistance of an Aluminum Flange with an Electron Beam Modified Seal Edge

... interval analyzers counting techniques discriminators electronic circuits

118

Role of the #DELTA#(1232)-resonance at the systematic reduction of magnetic isovector transitions

Scratch and Corrosion Resistance of an Aluminum Flange with an Electron Beam Modified Seal Edge

2011-01-01

119

Request for an Analytical Transmission Electron Microscope.

... electron reactions electrons excitation inelastic scattering m1-transitions proton

120

Particle-Sizing System for Scanning Electron Microscope ...

... Accession Number : ADA189111. Title : Request for an Analytical Transmission Electron Microscope. Descriptive Note : Final rept. ...

1987-10-16

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121

Full-Potential Electronic Structure Method Energy and Force Calculations with Density Functional and Dynamical Mean Field Theory

... THESIS PARTICLE-SIZING SYSTEM FOR SCANNING ELECTRON MICROSCOPE IMAGES OF SOLID-PROPELLANT COMBUSTION EXHAUST ...

1991-03-01

122

ELECTRON ATTACHMENT OF SEF6

Full-Potential Electronic Structure Method

2010-01-01

123

A bright field scanning transmission electron microscope (STEM ...

... attachment tube which is sketched in Fig. 1. It is mounted inside a cylindrical evacuated tube. A beam of thermal electrons ...

1961-06-20

124

Studies of electron-molecule scattering at microelectronvolt energies using very-high-n Rydberg atoms

A bright field scanning transmission electron microscope (STEM) micrograph showing a Wassonite grain in dark contrast. ...

125

Polaron model of electron spectra and superconductivity of A-15 compounds

Atoms in very high Rydberg states, 100 approx-lt n approx-lt 1100, are used to investigate electron-molecule interactions at electron energies extending down to a few microelectronvolts. At such energies the cross section for electron capture by CCl_4 is observed to vary inversely with electron velocity, indicative of an s-wave process. Studies with the polar target CH_3Cl suggest that dipole-supported states may be important in inelastic electron-polar molecule scattering at very low electron energies.

126

Polaron model of electron spectra and superconductivity of A-15 compounds

The existence of a narrow peak of electron state density in A-15 is explained by a strong electron-phonon interaction that brings about the polaron narrowing of zone. In the supposition of weak and intermediate bond, the analytical expression for the critical transition temperature is found that corre lates Tsub(c) with phonon spectrum. The model permits to explain Tsub(c) correlation with the number of electrons per atom, temperature direction of resistance, value and temperature dependence of magnetic susceptibility and electron thermal capacity.

1983-02-01

127

Pair formation in two-electron correlated chains

The existence of a narrow peak of electron state density in A-15 is explained by a strong electron-phonon interaction that brings about the polaron narrowing of zone. In the supposition of weak and intermediate bond, the analytical expression for the critical transition temperature is found that corre lates Tsub(c) with phonon spectrum. The model permits to explain Tsub(c) correlation with the number of electrons per atom, temperature direction of resistance, value and temperature dependence of magnetic susceptibility and electron tehrmal capacity.

128

MAGNETIC ELECTRON MICROSCOPE UEMB-100

We study two correlated electrons in a nearest-neighbour tight-binding chain, with both on-site and nearest-neighbour interaction. Both the cases of parallel and antiparallel spin are considered. In addition to the free electron band for two electrons, there are correlated bands with positive or negative energy, depending on whether the interaction parameters are repulsive or attractive. Electrons form bound states, with amplitudes that decay exponentially with separation. Conditions for such states to be filled at low temperatures are discussed.

2003-05-21

129

In-beam conversion electron spectroscopy using the SACRED array

A new magnetic electron microscope, UEMB-100, was designed with an increased electron-optical parameter. The electron-optical system consists of an electron canon (the high voltage is supplied by armored lead) and condensed, objective, intermediate, and projection lenses. In contrast to other native apparatuses, the microscope has a high resolving property (up to 20A) snnd great universality. (tr-auth)

1958-07-01

130

Electron accelerator unit for electron beam therapy

Conversion electron studies of medium-heavy to heavy nuclear mass systems are important where the internal conversion process begins to dominate over gamma-ray emission. The use of a segmented detector array sensitive to conversion electrons has been used to study multiple conversion electron cascades from nuclear transitions. The application of the silicon array for conversion electron detection (SACRED) for in-beam measurements has successfully been implemented. (orig.). With 2 figs.

131

Electron accelerator unit for electron beam therapy

An electron accelerator unit is described for electron beam therapy, comprising: a source of an electron beam; means for finally directing at least a portion of the beam to a therapy site, the directing means being mechanically independent of, and electrically isolated from, the source, and having a target area; and means for aligning the source with the directing means, the aligning means comprising means for projecting at least one beam of light from the source toward the target area.

1987-01-27

132

Current results from the Texas A and M electron beam ion source

An electron accelerator unit is described for electron beam therapy, comprising: a source of an electron beam; means for finally directing at least a portion of the beam to a therapy site, the directing means being mechanically independent of, and electrically isolated from, the source, and having a target area; and means for aligning the source with the directing means, the aligning means comprising means for projecting at least one beam of light from the source toward the target area.

133

A novel application of the multi-group method: Coupled neutron-gamma-electron cross-section library

The electron beam ion source (EBIS) at Texas A and M University was constructed and is currently undergoing tests on the injection and transmission of the electron beam through the solenoid. Results of computer simulation of the electron beam are presented, as well as measurements of electron beam profiles using a pinhole beam analyzer.

134

A novel application of the multi-group method: Coupled neutron-gamma-electron cross-section library

A multi-group neutron-gamma cross-section library in DTF-IV format is supplemented with electron production matrix to generate a coupled neutron-gamma-electron library. This is realized by estimating the contributions from Compton scattering, pair production and photoelectric effect to the electron production cross-sections. A novel application of this new library, which involves transport of neutrons, gammas and electrons, for estimating the Compton current due to a pulse of radiation in air is discussed.

2006-02-15

135

Weak ferromagnets with integer and half-integer spin quantum numbers

A multi-group neutron-gamma cross-section library in DTF-IV format is supplemented with electron production matrix to generate a coupled neutron-gamma-electron library. This is realized by estimating the contributions from Compton scattering, pair production and photoelectric effect to the electron production cross-sections. A novel application of this new library, which involves transport of neutrons, gammas and electrons, for estimating the Compton current due to a pulse of radiation in air is discussed.

2006-02-01

136

Thermodynamic properties of dicarbonyl rhodium o-semiquinonate complex whose crystals display photomechanical properties

Experimental investigations are presented which demonstrate that the weak ferromagnets are special materials of a larger group of magnets which exhibit two magnetic ordering structures. In weak ferromagnets the main order is antiferromagnetic with a small ferromagnetic component existing in addition. On the other hand, materials in which other combinations of the two basic ordering structures coexist are also known. Common to all these non-collinear spin structures is that the moment components of the two magnetic structures are orthogonal. In the weak ferromagnets this orthogonality manifests already in the paramagnetic phase as a crossover from an isotropic to an anisotropic susceptibility with respect to the applied magnetic field: at high temperatures the antiferromagnetic Curie-Weiss law of the total moment is observed while for T->Tc crossover to a second Curie-Weiss law due to the weak ferromagnetic component occurs. For T->Tc the ferromagnetic ...

2005-01-31

137

The models of experimental magnetic measurements of various biological samples

In an adiabatic low-pressure calorimeter, the temperature dependence of the standard molar heat capacity of paramagnetic dicarbonyl rhodium complex with o-semiquinone (CO){sub 2}Rh(SQ) has been determined in the range from T=(6 to 355)K mainly with an accuracy of about 0.3%. Over the ranges from T=(205 to 234) K, T=(266 to 315)K and T=(316 to 345)K physical transformations have been revealed and their enthalpies and entropies have been estimated. The experimental data were used to calculate the thermodynamic functions C{sub p,m}{sup o}/R,{delta}{sub 0}{sup T}H{sub m}{sup o}/(R.K),{delta}{sub 0}{sup T}S{sub m}{sup o}/R and {phi}{sub m}{sup o}={delta}{sub 0}{sup T}S{sub m}{sup o}-{delta}{sub 0}{sup T}H{sub m}{sup o}/T (where R is the universal gas constant) between T=(0 and 355)K. The fractal dimension D in the heat capacity function of the fractal variant of Debye heat capacity theory has been evaluated.

2006-06-15

138

Temperature dependence of a twofold magnetic behaviour of a nanoscopic metal/silicon hybrid system - a comparison between Ni/Si and Co/Si

Complete text of publication follows. At the Geomagnetic Institute, in the Laboratory for paleomagnetism and archeomagnetism research and at the Geomagnetic Observatory, Grocka (GCK) during the period from November 2004 to February 2008 the researchers carried out experimental magnetic measurements of the total-intensity gradient of the magnetic field vector (changes in the total magnetisation vector) of various biomaterials. Measurements of the gradient total intensity of the magnetic field vector were carried out by GSM-19 magnetometers of high accuracy and recording resolution (accuracy: #DELTA#F=0.1 nT; sampling rate: 1-5 per second). During these experimental biomagnetic measurements samples of water, tissue, blood, cotton, wool, pitch and magnetite-powder were used. In this study, the part of the biomagnetic measurement results relate to the water, blood and tissue. The results of the measurements of gradient total-intensity of the magnetic field for the biomaterial samples ...

2009-08-23

139

Study of praseodymium complexing with ethylenediaminetetraacetic acid by proton magnetic resonance

The investigated hybrid nanocomposite consists of a porous silicon template with electrochemically embedded Ni or Co nanostructures and offers magnetic characteristics which can be tailored by the electrochemical process parameters during fabrication. A twofold magnetic behaviour can be observed, a first one due to the spinmagnetism at magnetic fields below the saturation magnetization of the deposited metals and a second non-saturating term at higher fields (>1 T up to 7 T) above the saturation magnetization. In case of Ni deposited within the pores this non-saturating term shows a paramagnetic characteristic and follows exactly the Curie-Weiss law, whereas for Co/porous silicon samples the temperature dependent magnetization shows some deviations from the Curie Weiss law. In this high field region a difference in the temperature dependence between Ni and Co is observed whereas the non-saturating term does not depend on the geometry of the embedded ...

2009-10-15

140

Structure and properties of a novel cobaltate La0.30CoO2

The method of proton magnetic resonance (PMR) has been used to study the mechanism of reaction of complexing of paramagnetic Pr/sup 3 +/ ion with ethylenediaminetetra acetic acid (EDTA). The influence of medium acidity (pH5-12), EDTA/Pr ratio varying from 1 to 50, Pr/sup 3 +/ ion concentration (from 5x10/sup -3/ to 3x10/sup -1/ g-ion/l) and temperature (8-98 deg C) on chemical shifts and broadening of signals of EDTA molecule protons is investigated. Data on ratio of components, coordination and stability of forming complexes are obtained. The existence of two types of complexes with the Pr/EDTA ratio equal to 1:1 and 1:2 has been found. Equimolecular complex (1:1) is stable all over the studied temperature interval in contrast to the complex 1:2 for which at 50 deg C fast extrasphere exchange (Pr EDTA)EDTA * + EDTA/sup 0/ reversible (PrEDTA)EDTA/sup 0/ + EDTA * is observed, while at t=98 deg C intrasphere exchange (PrEDTA)EDTA * reversible (PrEDTA *)EDTA occurs in ...

1983-05-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

141

British Library Electronic Table of Contents (United Kingdom)

The layered cobaltate La0.30CoO2 was prepared from NaxCoO2 precursor by a solid-state ionic exchange and was characterized by means of X-ray and neutron diffraction, magnetic, thermal and electric transport measurements. The compound consists of hexagonal sheets of edge-sharing CoO6 octahedra interleaved by lanthanum monolayers. Compared to Na+ in the parent system, the La3+ ions occupy only one-third of available sites, forming a 2-dimensional superstructure. The deviation from the ideal stoichiometry La1/3CoO2 introduces extra hole carriers into the diamagnetic LS Co3+ matrix making the sample Pauli paramagnetic. The temperature dependence of the electrical conductivity in La0.30CoO2 follows Mott's T?1/3 law up to about 400K, which is in contrast w...

2011-01-01

142

Spin correlations in the frustrated square lattice Pb{sub 2}VO(PO{sub 4}){sub 2}

Radiation damage studies on CrO_4"2"- doped alums

The new frustrated square-lattice system, Pb{sub 2}VO(PO{sub 4}){sub 2}, has been investigated using polarised neutron scattering. From these studies, made on powdered samples, we have determined the nature of the exchange interactions and the magnetic ordering for this novel quantum magnet. Quantum order from disorder occurs at low temperature, and the ground state observed below the Neel temperature T {sub N}{approx}3.7 K is a collinear antiferromagnet. At room temperature there are no magnetic correlations and it is possible to model the scattering with the V{sup 4+} magnetic form factor. However, at T{approx}20 K, a temperature well into the paramagnetic phase, magnetic correlations are observed, and these spin correlations have been modelled using a high-temperature series expansion. Ferromagnetic nearest-neighbour exchange J {sub 1}{approx}-2 K and antiferromagnetic next-nearest-neighbour exchange J {sub 2}{approx}6.5 K are obtained, and this is of particular ...

2007-03-15

143

Neutron diffraction study of quasi-one-dimensional spin-chain compounds Ca3Co2-xFexO6

Radiation damage studies have been carried out on undoped and CrO_4"2"- doped potassium and ammonium alums. The optical absorption bands observed around 27100 and 36500 cm"-"1 before irradiation have been attributed to the transitions t_1 #-># e and t_1 #-># t_2, on the basis of Ball-hausen and Liehr scheme. On prolonged X-irradiation, these bands disappear in both the alums and three new bands seem to grow in ammonium alum while only two new bands could be seen in potassium alum. EPR studies at RT reveal that there are two lines at g = 2.004 and g = 2.010 in ammonium alum and only one line at g = 2.004 in potassium alum. Besides these two nearly isotropic lines, there is a set of lines around g = 1.95 in both the alums. Correlating the optical and EPR studies it is concluded that SO_3"- and O_3"- centres have formed on X-irradiation in ammonium alum while only SO_3"- seems to have formed in potassium alum. The most important feature is the formation of a new ...

144

Measurements of K-shell x-ray production cross sections and K to L and M-shell radiative vacancy transfer probabilities for Nd, Eu, Gd, Dy and Ho at excitation with 59.5 keV photons in an external magnetic field

We report the results of the DC magnetization, neutron powder diffraction and neutron depolarization studies on the spin-chain compounds Ca3Co2-xFexO6 (x = 0, 0.1, 0.2 and 0.4). Rietveld refinement of neutron powder diffraction patterns at room temperature confirms the single-phase formation for all the compounds in rhombohedral structure with space group R3-barc. Rietveld refinement also confirms that Fe was doped at the trigonal prism site, 6a (0, 0, 1/4) of Co. The high temperature magnetic susceptibility obeys the Curie-Weiss law; the value of the paramagnetic Curie temperature (?p) decreases as the concentration of iron increases and it becomes negative for x = 0.4. No extra Bragg peak as well as no observable enhancement in the intensity of the fundamental (nuclear) Bragg peaks has been observed in the neutron diffraction patterns down to 30 K. No depolarization of neutron beam has been observed down to 3 K confirming the absence of ferro- or ...

2008-11-01

145

Magnetization and 61Ni Moessbauer effect study of the ternary arsenide CrNiAs

The effect of the #+-# 0.75 T external magnetic field on the K_#alpha#_1, K_#alpha#_2, K_#beta#_'_1 and K_#beta#_'_2 x-ray production cross sections and radiative vacancy transfer probabilities from K-shell to L2 and L3 subshells and M-shell for ferromagnetic Nd, Gd and Dy and paramagnetic Eu and Ho have been investigated, using the 59.5 keV incident photons. K-shell fluorescence yields and K x-ray intensity ratios for these elements have been determined in the external magnetic field also. The K x-rays from different targets were detected using a high-resolution Si(Li) semiconductor detector. For B = 0, the present experimental results were compared with the experimental and theoretical data in the literature. The results show that K-shell fluorescence parameters such as photoionization cross section, fluorescence yield, radiation rates, vacancy transfer probabilities and spectral linewidth can change owing to the applied magnetic field. (authors)

2006-06-19

146

Magnetic susceptibility and "1"5"1Eu Moessbauer studies on cubic ternary compounds: EuPtSi and EuPdSi

The results of x-ray diffraction, dc magnetization, and 61Ni Moessbauer spectroscopy studies of the ternary arsenide CrNiAs are reported. This compound crystallizes in the orthorhombic Fe2P-type structure (space group P6-bar2m) with the lattice parameters a 6.1128(2) A and c = 3.6585(1) A. CrNiAs is a mean-field ferromagnet with Curie temperature TC = 171.9(1) K and the critical exponents ? 0.514(18), ? = 1.010(16), and ? = 2.922(10). The temperature dependence of the magnetic susceptibility above TC follows the modified Curie-Weiss law with a paramagnetic Curie temperature of 176.0(3) K and effective magnetic moment per transition metal atom of 2.42(1) ?B. The magnetic moment per formula unit at 4.2 K is found to be 1.114(33) ?B. The hyperfine magnetic field at 61Ni nuclei at 4.2 K of 41.5(1.0) kOe implies that the Ni atoms carry a magnetic moment of 0.15(3) ?B, and that the moment carried by the Cr atoms is 0.95(6) ?B. The Debye temperature of CrNiAs is 221(1) K.

2008-08-13

147

Magnetic resonance imaging in multiple sclerosis. Imagerie nouvelle par resonance magnetique nucleaire au cours de la sclerose en plaques

Two new equiatomic ternary compounds, EuPtSi and EuPdSi, have been synthesized and are found to crystallize in the cubic LaIrSi type structure. The magnetic susceptibility of both compounds follows Curie-Weiss behavior in the temperature range 10 to 300 K with an effective magnetic moment close to that of Eu"2"+ moment. The paramagnetic Curie temperatures are 5 K for EuPtSi and 9 K for EuPdSi. There is no clear indication of magnetic ordering in the susceptibility of both the compounds down to 4.2 K. However, "1"5"1Eu Moessbauer studies show a hyperfine split pattern in EuPtSi at 4.2 K indicating the onset of magnetic ordering. The "1"5"1Eu isomer shifts are temperature independent and are characteristic of the divalent Eu ion. All these results establish that the Eu ions are in a stable divalent state in these compounds. (orig.).

148

Magnetic properties of a SmNiSn single crystal

Magnetic resonance imaging (MRI) has rapidly attained a major position among the examinations used in the diagnostic approach of multiple sclerosis because it is highly sensitive in demonstrating lesions. However, these lesional images may have several meanings, and there is the problem of distinguishing between oedema, which is said to reflect recent lesions, and gliosis which is thought to betray old lesions. The intrinsic MRI parameters studied (i.e. relaxation times) are unable to make this distinction, whereas it is provided by paramagnetic contrast media such as gadolinium. There is no correlation between the changes observed at MRI and the severity of the disease. Another problem is the accuracy of lesion localization, since visualization is predominantly macroscopic. This raises several questions about the demonstration of correlations between clinical signs and site of the lesion(s). At the moment, several teams of neuroradiologists are trying to find the ...

1991-09-15

149

Magnetic and superconducting quantum critical points of heavy-fermion systems

The magnetic properties of a single crystal of SmNiSn with the orthorhombic {epsilon}-TiNiSi-type crystal structure have been investigated by magnetic susceptibility, magnetization and electrical resistivity measurements from 1.5 K to room temperature. Two anomalies have been found in the magnetic susceptibility, indicating an antiferromagnetic phase transition at T{sub N}=9.4 K and a second transition at 4.4 K. A large magnetic anisotropy has been found at low temperatures in the temperature and field dependencies of magnetic susceptibility and magnetization. Below 80 K, the easy axis of the magnetization is the c-axis. At T=2.0 K, the c-axis magnetization curve exhibits metamagnetic-like behavior at H{sub c}=42 kOe and reaches 0.54 emu/g at H=55 kOe, whereas for the a- and b-axis the magnetization is linear and smaller. The paramagnetic susceptibilities do not follow the Curie-Weiss law suggesting a large van Vleck contribution of the Sm ions.

2003-04-01

150

Exploring the 2D to 3D dimensionality crossover in thin iron films

Two examples of heavy-fermion systems are presented : CePd{sub 2}Si{sub 2}, an antiferromagnet with a quantum critical point at P{sub C}=28 kbar and UGe{sub 2} an itinerant ferromagnet which transits in a paramagnetic phase above P{sub C}=16 kbar. In CePd{sub 2}Si{sub 2} the superconductivity domain is centered on P{sub C}. Special attention was given to the superconducting and magnetic anomalies at their superconducting and Neel temperatures. In UGe{sub 2} superconductivity appears in 9 kbar at a temperature T{sub S}, more than two orders of magnitude lower than the Curie temperature; furthermore, it occurs only on the magnetic border (P<P{sub C}). Another characteristic temperature T{sub X} is detected by resistivity; the zigzag uranium chain of the lattice may favor a supplementary nesting in the majority spin band.

2001-05-01

151

Crystal structure and magnetic properties of Sm{sub 3}ReO{sub 7}

The temperature dependence of the spontaneous magnetization of epitaxial iron films with a thickness ranging from d=20 to 200nm has been measured. The films are grown on GaAs (100) substrates which are covered by a 150nm thick silver (100) buffer layer. For three-dimensional BCC iron it was observed already in 1929 that saturation of the spontaneous magnetization for T->0 is perfectly described by a T{sup 2} power law. On the other hand, for thin two-dimensional (2D) iron films a T{sup 3/2} law has been established in many recent experimental investigations. In our iron films grown on diamagnetic silver, this dimensionality change occurs at a thickness between d=100 and 200nm. Comparison of the here-observed T{sup 3/2} coefficients with those on iron films grown on paramagnetic tungsten (110) shows that the 2D interactions are {approx}20 times larger in the films on tungsten. Recent results on Fe films which are grown directly on GaAs (100) confirm that the ...

2006-05-15

152

Crystal electric field excitations in the cerium compound CeRh{sub 3}B{sub 2} studied by inelastic neutron scattering

Crystals of a new ternary samarium rhenium oxide, Sm{sub 3}ReO{sub 7} were obtained by subsolidus reaction of samariumsesquioxide and rheniumdioxide (ratio 1.5:1) in sealed Pt-10Rh-tubes at 1673 K. The structure was determined by single-crystal X-ray diffraction. Sm{sub 3}ReO{sub 7} crystallizes in the orthorohombic system with unit cell dimensions a = 10.736(5), b = 7.392(3), and c = 7.519(3) in space group Cmcm (No. 63) with Z = 4. The structure consists of ReO{sub 6} octahedra, distorted SmO{sub 6} octahedra, and SmO{sub 8} prisms that are interconnected to each other to form a three-dimensional network. Rhenium has the formal oxidation state of +5 but no metal-metal bond is observed in this compound. The observed magnetization in the temperature range 4 K < T < 52 K is explained by a Curie-Weiss law modified by a temperature independent Van Vleck paramagnetism of samarium (3+).

1996-08-01

153

Crystal electric field excitations in the cerium compound CeRh_3B_2 studied by inelastic neutron scattering

We have performed inelastic neutron scattering (INS) experiments on CeRh{sub 3}B{sub 2} at various temperatures to obtain direct information on the crystal electric field (CEF) in this compound, which exhibits some very peculiar magnetic properties for a Ce system: it is ferromagnetic with an unusually high Curie temperature (115 K), which contrasts with a strongly reduced and anisotropic magnetization (0.4 {mu}{sub B}/fu within the c-plane of the hexagonal structure). Measurements with high incident energies show only one well defined magnetic excitation around 150 meV, its exact position varying with the temperature. These results, combined with our previous data of magnetization and magnetic form factor, have permitted us to determine the CEF energy level scheme taking into account the two J multiplets of the Ce{sup 3+} ion. Information on the ground state (quasielastic contribution and ground state moment) has also been obtained by experiments at low incident energies in the ...

2007-12-19

154

Antiferromagnetic Kondo lattice: CePdSi{sub 2}

We have performed inelastic neutron scattering (INS) experiments on CeRh_3B_2 at various temperatures to obtain direct information on the crystal electric field (CEF) in this compound, which exhibits some very peculiar magnetic properties for a Ce system: it is ferromagnetic with an unusually high Curie temperature (115 K), which contrasts with a strongly reduced and anisotropic magnetization (0.4 #mu#_B/fu within the c-plane of the hexagonal structure). Measurements with high incident energies show only one well defined magnetic excitation around 150 meV, its exact position varying with the temperature. These results, combined with our previous data of magnetization and magnetic form factor, have permitted us to determine the CEF energy level scheme taking into account the two J multiplets of the Ce"3"+ ion. Information on the ground state (quasielastic contribution and ground state moment) has also been obtained by experiments at low incident energies in the ...

2007-12-19

155

ESR study of X-ray irradiated rare earth (Ln) ion-doped glaserite and Ln ion-doped langbeinite

The compounds CePdSi{sub 2}, CeIrSi{sub 2} and CeRhSn{sub 2} have been synthesized and studied by X-ray diffraction, electrical resistivity and magnetic susceptibility. The magnetic susceptibility of CePdSi{sub 2} exhibits two peaks at 6.8 K and 2.5 K, respectively, indicating two antiferromagnetic phase transitions, while that of CeIrSi{sub 2} shows a broad maximum at 150 K, characteristic of valence fluctuating Ce-compounds. CeRhSn{sub 2} remains paramagnetic down to 5 K. The resistivity of CeIrSi{sub 2} exhibits a T{sup 2} dependence at low temperatures, indicating a Fermi-liquid ground state, while those of CePdSi{sub 2} and CeRhSn{sub 2} shows the presence of Kondo and crystal field effects. (orig.). 5 refs.

1997-02-01

156

Soluble Variants of Rhodobacter capsulatus Membrane-anchored Cytochrome c_y Are Efficient Photosynthetic Electron Carriers*

X-ray irradiation-induced paramagnetic radicals in rare earth (Ln) ion-doped glaserite and Ln ion-doped langbeinite were studied by means of ESR technique, aiming at developing the highly sensitive sensor for an ESR dosimetry. The samples were prepared by two kinds of procedures as follows. In one process, the glaserite (K{sub 3}Na(SO{sub 4}){sub 2}) matrix or the langbeinite (K{sub 2}Mg{sub 2}(SO{sub 4}){sub 3}) matrix were synthesized by heating the mixture of K{sub 2}SO{sub 4} and Na{sub 2}SO{sub 4} or the mixture of K{sub 2}SO{sub 4} and MgSO{sub 4} at 1023 K for 1 hour in He flow. The matrices obtained were mixed well with a fixed amount of Ln{sub 2}(SO{sub 4}){sub 3} (Ln=La, Eu, Gd, Lu) powder and heated at 1023 K for 1 hour in He flow. In the other process, the homogeneous mixture of a fixed amount of K{sub 2}SO{sub 4}, Na{sub 2}SO{sub 4} and Ln{sub 2}(SO{sub 4}){sub 3} powders or a fixed amount of K{sub 2}SO{sub 4}, MgSO{sub 4} and Ln{sub 2}(S0{sub 4}){sub ...

1992-06-01

157

Investigation of the hadronic final state in electron-proton interactions at HERA

Photosynthetic (Ps) electron transport pathways often contain multiple electron carriers with overlapping functions. Here we focus on two c-type cytochromes (cyt) in facultative phototrophic...Full Text Available

2008-05-16

158

Review of electron beam therapy physics

The main subject of this thesis is the study of the hardronic final state in deep-inelastic electron-proton scattering. Theexperiment described in this thesis is performed with such a high resolution that the substructure of the proton is probed by the electron beam with a resolution of less than 10{sup -15} cm. (orig./HSI).

1995-09-18

159

Quasi-elastic electron scattering by GaAs surface

For over 50 years, electron beams have been an important modality for providing an accurate dose of radiation to superficial cancers and disease and for limiting the dose to underlying normal tissues and structures. This review looks at many of the important contributions of physics and dosimetry to the development and utilization of electron beam therapy, including electron treatment machines, dose specification and calibration, dose measurement, electron transport calculations, treatment and treatment-planning tools, and clinical utilization, including special procedures. Also, future changes in the practice of electron therapy resulting from challenges to its utilization and from potential future technology are discussed. (review)

2006-07-07

160

Polarization of high-energy electrons traversing a laser beam

Using the slow electrons spectrometer one can get information on the surface structure, its element composition, chemical bonds, adsorption phenomena, electron state density and surface oscillation. We have developed the methods and created the apparatus that makes it possible to investigate the electron backscattering by solid surface. We have studied the electron scattering by the polycrystalline and monocrystalline. GaAs surface in the energy range of 0 to 9 eV. The FWHM of electron energy distribution function was 70 meV. (author).

1994-03-20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

161

Polarization of high-energy electrons traversing a laser beam

When polarized electrons traverse a region where the laser light is focused their polarization varies even if their energy and direction of motion are not changed. This effect is due to interference of the incoming electron wave and an electron wave scattered at zero angle. Equations are obtained which determine the variation of the electron-density matrix, and their solutions are given. The change in the electron polarization depends not only on the Compton cross section but on the real part of the forward Compton amplitude as well. It should be taken into account, for example, in simulations of the e{yields}{gamma} conversion for future {gamma}{gamma} colliders. (orig.). 16 refs.

1998-02-21

162

Inelastic electron--dipole-molecule scattering at sub-milli-electron-volt energies: HF and NH_3

When polarized electrons traverse a region where the laser light is focused their polarization varies even if their energy and direction of motion are not changed. This effect is due to interference of the incoming electron wave and an electron wave scattered at zero angle. Equations are obtained which determine the variation of the electron-density matrix, and their solutions are given. The change in the electron polarization depends not only on the Compton cross section but on the real part of the forward Compton amplitude as well. It should be taken into account, for example, in simulations of the e#->##gamma# conversion for future #gamma##gamma# colliders. (orig.).

163

Advanced Power Electronics Interfaces for Distributed Energy Workshop Summary: August 24, 2006, Sacramento, California

Studies of destruction of very-high-n (100electron model suggests that, for ultralow electron energies (#approx#80 #mu#eV--1.4 meV), the cross section #sigma#(var-epsilon) for rotationally inelastic scattering of electrons by a polar target varies approximately as 1/var-epsilon, where var-epsilon is the electron energy.

164

Use of electron backscattering for smoothing the discharge in electron-beam-controlled lasers: computations

The Advanced Power Electronics Interfaces for Distributed Energy Workshop, sponsored by the California Energy Commission Public Interest Energy Research program and organized by the National Renewable Energy Laboratory, was held Aug. 24, 2006, in Sacramento, Calif. The workshop provided a forum for industry stakeholders to share their knowledge and experience about technologies, manufacturing approaches, markets, and issues in power electronics for a range of distributed energy resources. It focused on the development of advanced power electronic interfaces for distributed energy applications and included discussions of modular power electronics, component manufacturing, and power electronic applications.

2006-10-01

165

The Physical Attractiveness of Electronic Physician Notes

... Smith, RC Westinghouse Research Labs., Pittsburgh v. 25(5) p. 292-295.

166

Stabilizing effect of the electron-beam self-fields on the phase-space trajectory in a self-amplified spontaneous emission free-electron laser operating in ultraviolet and x-ray spectral ranges

Though notes in electronic medical record systems (EMRs) have advantages, they are often criticized for their unattractive and unprofessional appearance. We sought to identify notes regarded by physicians...Full Text Available

2010-01-01

167

Secondary electron yield measurements from thin surface coatings for NLC electron cloud reduction

A detailed treatment is introduced to measure the dynamic stability of the relativistic electrons in a self-amplified spontaneous emission free-electron laser (FEL) system, which includes the numerical approach of the Kolmogorov entropy (entropy-like quantity), the general equations of motion for a charged particle and the method of monitoring the simulation accuracy. Numerical experiments reveal a new phenomenon that there exists the possibility of the transition from chaotic to non-chaotic phase-space trajectories of the strongly relativistic electrons due to the effect of their self-fields. The adiabatic magnetic field of a one-dimensional wiggler may have a slight influence on the electron transportation in the absence of the FEL fields, but substantially affects the dynamic stability of the electrons in the process of the FEL interaction. Moreover, the laser fields diminish the ...

2004-02-28

168

Proposal for the award of a blanket purchase contract for the supply of electronics subracks for the CERN accelerator control system

In the beam pipe of the positron damping ring of the Next Linear Collider, electrons will be created by beam interaction with the surrounding vacuum chamber wall and give rise to an electron cloud. Several solutions are possible for avoiding the electron cloud, without changing the bunch structure or the diameter of the vacuum chamber. Some of the currently available solutions for preventing this spurious electron load include reducing residual gas ionization by the beam, minimizing beam photon-induced electron production, and lowering the secondary electron yield (SEY) of the chamber wall. We will report on recent SEY measurements performed at SLAC on TiN coatings and TiZrV non-evaporable getter thin films.

2004-01-01

169

Preparation of covalently modified organic-inorganic composite nanoparticles and their interfacial electron transfer researches

Proposal for the award of a blanket purchase contract for the supply of electronics subracks for the CERN accelerator control system

2010-01-01

170

Multiple glomus tumours: successful treatment with electron beam irradiation

Preparation of covalently modified organic-inorganic composite nanoparticles and their interfacial electron transfer researches

1998-01-01

171

Medium voltage analytical electron microscopy microanalysis versus radiation damage

A case is reported of a 23-year old male with multiple glomus tumours that showed marked involution after he had electron beam therapy. (author).

1990-11-01

172

Inelastic electron scattering, M1 giant resonances and the quest for subnuclear degrees of freedom

The kinetic energy transferred to some elements by an electron of kinetic energy 100 to 400 kV is discussed. The displacement rates are compared to the signal generation. (DCL)

1985-09-01

173

Gadolinium electronic band structure: augmented plane wave calculation

... electrons fine structure giant resonance inelastic scattering iron 54 iron 54

1983-01-17

174

Electronics in mining symposium

Augmented plane wave calculation of gadolinium electronic structure crystallized in a hexagonal close-packed lattice is carried out.

175

Electron capture decay of "2"0"3Bi

The symposium reviewed the use of electronics in mining today. Subjects covered include control systems; remote sensing; telemetry; data transmission; microprocessors and transportation systems. 15 papers have been abstracted separately.

1984-01-01

176

Electron Diffraction Examination of Gun Barrel Coatings.

The electron capture decay scheme of "2"0"3Bi is studied. Energies and relative intensities of gamma rays are given.

177

Dose enhancement in bone in electron beam therapy

... Accession Number : ADA954164. Title : Electron Diffraction Examination of Gun Barrel Coatings. Descriptive Note : Special rept.,. ...

1942-10-20

178

Dose enhancement in bone in electron beam therapy

This study investigated dose to bone tissue in electron beam therapy. Measurements were made using films and thermoluminescent dosimeters in a polystyrene phantom containing bone inhomogeneity for 15-MeV, 12-MeV, and 9-MeV electron beams. An increase in dose of approximately 18%, 12%, and 11%, for the three electron energies respectively, relative to the dose in polystyrene, was found for bone material having an electron density (relative to water) of 1.73. Measurements were also made using films for 15- and 9-Mev electrons in a phantom with a mandibular bone and teeth. A dose enhancement in bone of approximately 10% and 7%, respectively, for the two energies was found in the phantom where the electron density of bone was about 1.60. These results suggest that injury to bone is possible in those clinical situations where high doses of ...

1984-05-01

179

Background information on the high energy physics program and the proposed Stanford linear electron accelerator project

This study investigated dose to bone tissue in electron beam therapy. Measurements were made using films and thermoluminescent dosimeters in a polystyrene phantom containing bone inhomogeneity for 15-MeV, 12-MeV, and 9-MeV electron beams. An increase in dose of approximately 18%, 12%, and 11%, for the three electron energies respectively, relative to the dose in polystyrene, was found for bone material having an electron density (relative to water) of 1.73. Measurements were also made using films for 15- and 9-Mev electrons in a phantom with a mandibular bone and teeth. A dose enhancement in bone of approximately 10% and 7%, respectively, for the two energies was found in the phantom where the electron density of bone was about 1.60. These results suggest that injury to bone is possible in those clinical situations where high doses of ...

180

Acquisition of a High Resolution Field Emission Scanning Electron Microscope for the Analysis of Returned Samples

Background information on the high energy physics program and the proposed Stanford linear electron accelerator project

1961-01-01

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181

A method for obtaining programmed beam single shots and pulse trains from a diode gun linear electron accelerator

This grant furnished funds to purchase a state-of-the-art scanning electron microscope (SEM) to

2003-01-01

182

Electron flow in the SABRE linear induction adder in positive polarity

... electron guns linear accelerators magnetrons multivibrators pulse generators

183

Working group report on electron-impact processes: Recommended database for electron impact excitation and ionization

In a positive polarity induction adder each of the induction cavities is a cathode, which emits electrons at a unique potential. These broad spectrum electrons strongly affect Magnetically Insulated Transmission Line (MITL) behavior. Electron flow decreases the cavity-to-MITL coupling efficiency, and reduces the power transport efficiency along the system. Also, the operating impedance of the MITL is lowered, reducing the diode impedance required for good coupling and good total system power efficiency. It is therefore imperative to understand the details of MITL electron flow. In previous work, measurement of MITL electron flow for a twenty-stage linear induction adder (Hermes III), operated in positive polarity, was compared with simulations. There was qualitative agreement, but some differences were noted. For example, measured electron flow in the first ...

1993-05-17

184

Ultrafast Nonadiabatic Dynamics. Theoretical Study of Femtosecond Electron Transfer Processes.

The cross section database for electron impact excitation and electron impact ionization for hydrogen beam kinetic energies greater than 100 eV was considered, giving for each particular process a reference to a recommended publication of cross sections, as well as the accuracy or estimated accuracy. The work is motivated by the application of neutral beam injection in magnetic confinement devices, such as large tokamaks. 9 refs, 2 figs.

1989-07-01

185

Czech Academy of Sciences Repository

Full Text Available

1998-01-01

186

Thermal transport during electron cyclotron heating in the TEXT tokamak

The sup(187m)Ir isomer state and its decay scheme

Electron Cyclotron Heating experiments have been performed on the TEXT tokamak using Varian gyrotron. Some degradation of electron energy confinement is observed for sawtoothing and non-sawtoothing discharges. Sharp electron temperature profiles are produced in high-q discharges by extremely localized ECH power deposition.

1989-05-01

187

The studying of electron motion in crystal lattice by using computer

... beta spectrometers comparative evaluations data decay electrons

188

The electron-phonon coupling constant in vanadium

... 2007, 80 ?. 5. ?????? ?.?. Visual Basic-6.0, ??????, 2000, 449 ?. ????

2010-04-01

189

The Three-Dimensional Morphology of Candida albicans as Seen by High-Resolution Scanning Electron Microscopy

The electron-phonon coupling constant lambda has been calculated for vanadium. The electron energy bands and wave functions were obtained from a model augmented plane wave muffin-tin potential. The electron-phonon matrix elements were evaluated using the rigid-ion approximation and the measured phonon spectra. The results show that lambda is strongly affected by d-f scattering.

190

The Effect of Radiated Electromagnetic Wave by Digital Modulation Signals on the Electronic Devices

Full Text Available

2009-06-01

191

The Darmstadt near-infrared free-electron laser

Full Text Available

2011-02-01

192

Testing of solar cells for communication satellites

The salient features of the near-infrared free-electron laser (FEL) that is under construction at the new Darmstadt superconducting 130-MeV electron accelerator are discussed. Special attention is given to the layout and the parameters of the accelerator, the layout of the planned FEL experiment, the characteristics of the electron gun, the subharmonic chopper-buncher system, and the hybrid undulator system of the Darmstadt FEL. A comparison of the planned Darmstadt FEL with conventional lasers, with respect to the pulse and wavelength region, is presented. 15 refs.

1989-04-24

193

Spreader Design for FERMI@Elettra Free Electron Laser

... cadmium sulfides communications electrons performance testing physical

194

Relativistic effects on chaos. Loss mechanism of runaway electrons in a tokamak

In this note we describe a conceptual design of a part ofthe electron beam delivery system for FERMI@Elettra free electron laser(FEL) located between the end of the linac and the entrance to the FEL.This part includes the emittance diagnostic section, the electron beamswitchyard for two FELs called spreader and matching sections. The designmeets various constrains imposed by the existing and planned buildingboundaries, desire for utilization of existing equipment and demands forvarious diagnostic instruments.

2007-01-18

195

Polarization characteristics of spontaneous emission and off-axis coherent gain in a free-electron laser

The relativistic motion of an electron is numerically analyzed in a tokamak having macroscopic magnetic turbulence. Stochasticity induced by the relativistic motion overwhelms the phase averaging effect, which provides a tokamak with an effective loss mechanism for the avoidance/suppression of runaway electron generation at a major disruption. On the other hand, electrons in the KAM (Kolmogorov-Arnold-Moser) region will be observed as a runaway snake. (author)

2001-12-01

196

PHOTOCATALYST USING OXIDE CONTAINING METAL IONS OF D10 ELECTRON STATE

The polarization characteristics of spontaneous radiation from relativistic electrons moving through helical and planar wiggler fields are evaluated for imperfect beam injection. Maximum coherent gain in free-electron laser systems are seen to occur in optical fields having these polarization characteristics rather than those of the wiggler magnets. Coupling coefficients for an electron beam skewed at an angle to the optical mode are presented.

1995-11-01

197

J-STORE (Japan)

Full Text Available

2003-10-01

198

Optical measurement of electron bunching in vacuum

One-dimensional numerical simulation of free-electron laser (FEL) amplifier with incorporate variable-parameter wiggler magnets

We report the homodyne detection of phase modulation sidebands induced on a laser beam by a coherently bunched electron beam. This provides a sensitive and nonperturbing measurement of complex Fourier time series components of the electron density. A proof-of-principle measurement of the microwave frequency component of electron density in a crossed-field device, which agrees well with a calculation of the same quantity, is reported.

199

Nuclear physics with a free electron laser

A physical model of free-electron laser (FEL) amplifier with variable-parameter wiggler magnets for one-dimensional numerical simulation is presented and a numerical example is given. The wiggler parameters, efficiency of energy conversion between electron beam and laser field, laser intensity, phase-space distributions and energy spectrum of electrons are computed. The period of synchronous oscillation and saturation value of laser intensity agree with estimated one.

200

Nonformity of the electron density in amorphous silicon films

... radiation parity photonuclear reactions polarized beams resonance

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

201

Microstructural characteristics and creep rupture behavior of electron beam and laser welded AISI 316L stainless steel

The authors study the nonuniformity of a-Si:H films obtained by the method of vacuum condensation, with the help of x-ray small-angle scattering (SLS) and transmission electron microscopy. Films of hydrogenated amorphous silicon are greatest interest, because the electronic properties of this material can be controlled by doping. As a result of the compensation of the ruptured bonds, and possibly, effects of melting, the properties of such films are analogous to those of singlecrystalline silicon. XLS enables a quantitative determination of the prameters of the regions of low electron density (RLD) in such objects.

1985-12-01

202

MPIRSPT : a parallelized all-electron DFT program for lanthanide and actinide calculations.

Not Available

1995-12-01

203

Laser-Sintered {TiO}_{2} Films for Dye Solar Cell Fabrication: An Electrical, Morphological, and Electron Lifetime Investigation

No abstract prepared.

2008-08-01

204

Indirect evidence for the existence of tachyons; a unified approach to the pion #-># muon #-># electron conversion problem

Not Available

2011-09-01

205

Identifying Contributing Degradation Phenomena in PEM Fuel Cell Membrane Electrode Assemblies Via Electron Microscopy

Using the experimentally determined cutoff energies of the muon-electron and the pion-electron conversion curves in a tachyon-bradyon model of the electron and the muon, the magnetic moments of these particles have been derived and found to be the Bohr magnetons identically. The tachyons, being bound to the bradyons and unable to drop below the speed of light, cause the bradyons to revolve in an orbit. It is this orbital motion of the charged bradyons that generates the magnetic moments.

206

Free radicals in lysozyme reacted with peroxidizing methyl linoleate

No abstract prepared.

2006-10-01

207

Electrostatic simulation of the modulated electron beam interaction with inhomogeneous plasma

... electron spin resonance gamma radiation lipids lyophilization lysozyme radicals

208

Electronic-vibrational excitations of a hydrogen-bonded molecule in supersonic expansions: 1,4-dihydroxyanthraquinone and its deuterated derivatives

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

2006-09-11

209

Electronic measures of surgical site infection: implications for estimating risks and costs.

Not Available

1983-04-01

210

Electron phonon properties of A-15 compounds and Chevrel phases

PMID:21768762

2011-08-01

211

Electron and phonon properties of A-15 compounds and Chevrel phases

A review of the information on the electron and phonon spectra in the A-15 compounds and Chevrel phase superconductors obtained from nuclear magnetic resonance, heat capacity, and Moessbauer effect experiments is presented. Relationships of the Fermi energy electrons and the soft phonons to the strength of the electron-phonon interaction are discussed.

212

Computer simulation of charging the silicon dioxide surface and subsurface layers by electron bombardment

A review of the information on the electron and phonon spectra in the A-15 compounds and Chevrel phase superconductors obtained from nuclear magnetic resonance, heat capacity, and Moessbauer effect experiments is presented. Relationships of the Fermi energy electrons and the soft phonons to the strength of the electron-phonon interaction are discussed.

213

Comprehensive, nonintercepting electron-beam diagnostics using spontaneous emission

Not Available

2011-08-01

214

Collective acceleration of electrons and ions in a high current relativistic electron beam. Final report

Characterization and optimization of electron-beam parameters are important aspects of optimizing free-electron laser (FEL) performance. The visible spontaneous emission ({lambda}{approximately}650 nm) from the 5-meter long undulator of the Boeing FEL experiment can be characterized in sufficient detail with a streak/spectrometer to deduce time-resolved electron-beam spatial position and profile, micropulse duration, and energy. 7 refs., 13 figs., 2 tabs.

1989-01-01

215

Addition of electronic prescription transmission to computerized prescriber order entry: Effect on dispensing errors in community pharmacies.

The original purpose of this research was an investigation into the use of slow space charge waves on weakly relativistic electron beams for ion acceleration. The work had three main objectives namely, the development of a suitable ion injector, the growth and study of the properties of slow space charge waves on an electron beam, and a combination of the two components parts into a suitable proof of principle demonstration of the wave accelerator. This work focusses on the first two of these objectives.

216

Synchrotron radiation from electron beams in plasma-focusing channels.

PMID:21200064

2011-01-15

217

Size determination of Acipenser ruthenus spermatozoa in different types of electron microscopy

Spontaneous radiation emitted from relativistic electrons undergoing betatron motion in a plasma-focusing channel is analyzed, and applications to plasma wake-field accelerator experiments and to the ion-channel laser (ICL) are discussed. Important similarities and differences between a free electron laser (FEL) and an ICL are delineated. It is shown that the frequency of spontaneous radiation is a strong function of the betatron strength parameter a(beta), which plays a role similar to that of the wiggler strength parameter in a conventional FEL. For a(beta) > or approximately 1, radiation is emitted in numerous harmonics. Furthermore, a(beta) is proportional to the amplitude of the betatron orbit, which varies for every electron in the beam. The radiation spectrum emitted from an electron beam is calculated by averaging the single-electron spectrum over the ...

2002-05-20

218

British Library Electronic Table of Contents (United Kingdom)

In this study three types of scanning electron microscopes were used for the size determination of spermatozoa of sterlet Acipenser ruthenus - high vacuum scanning electron microscope (SEM, JEOL 6300), environmental scanning electron microscope (ESEM, Quanta 200 FEG), field emission scanning electron microscope (FESEM, JEOL 7401F) with cryoattachment Alto 2500 (Gatan) and transmission electron microscope (TEM, JEOL 1010). The use of particular microscopes was tied with different specimen preparation techniques. The aim of this study was to evaluate to what degree the type of used electron microscope can influence the size of different parts of spermatozoa. For high vacuum SEM the specimen was prepared using two slightly different procedures. After chemical fixation with 2.5% glutaraldehyde...

2010-01-01

219

Proposal for a free electron laser driven by the 7 MeV NILPRP linac

Electron detachment cross-sections and secondary-electron emission factors for heavy-negative-ion beams

The proposal made in this paper refers to a free electron laser FEL with small-period electromagnet undulator in SASE regime and a FEL transverse optical klystron in the amplifier regime. The relativistic electron beam source for this FEL is the 7 MeV electron linac of the National Institute for Laser, Plasma and Physics Radiation (NILPRP) in Bucharest. The paper presents the main features of the design and performance of both FELs and discusses the improvements which must be made to the accelerator in order to use it as a free electron source concerning the injection system of electrons and formation of accelerated electron beam. The findings show that this FEL can be employed as a coherent radiation source in the IR range. (author)

220

Electron detachment cross-sections and secondary-electron emission factors for heavy-negative-ion beams

The properties of negative-ion beams are very important for designing negative-ion apparatus and applications of negative-ion beams, especially, electron detachment cross-sections at the interaction between negative-ion beams and gas particles in the transport system, and secondary-electron emission factors when negative ions are incident on solid surfaces. These properties of negative-ion beams were investigated experimentally as a function of the ion energy under 50 keV. The single electron detachment cross-sections are almost constant in the other of 10[sup -15] cm[sup 2] in this energy range, but double electron detachment cross-sections increase in proportion to the ion velocity and much smaller than the single one. As for the secondary-electron emission factor, the emission factors for negative-ion beam are found to be larger by 1 than those for positive-ion beams. (author).

1994-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

221

Convergent Flows: Humanities Scholars and Their Interactions with Electronic Texts

The properties of negative-ion beams are very important for designing negative-ion apparatus and applications of negative-ion beams, especially, electron detachment cross-sections at the interaction between negative-ion beams and gas particles in the transport system, and secondary-electron emission factors when negative ions are incident on solid surfaces. These properties of negative-ion beams were investigated experimentally as a function of the ion energy under 50 keV. The single electron detachment cross-sections are almost constant in the other of 10"-"1"5 cm"2 in this energy range, but double electron detachment cross-sections increase in proportion to the ion velocity and much smaller than the single one. As for the secondary-electron emission factor, the emission factors for negative-ion beam are found to be larger by 1 than those for positive-ion beams. (author).

1994-01-01

222

Calculation of 3-D free electron laser gain: Comparison with simulation and generalization to elliptical cross section

This article reports research findings related to converging formats, media, practices, and ideas in the process of academics' interaction with electronic texts during a research project. The findings are part of the results of a study that explored interactions of scholars in literary and historical studies with electronic texts as primary materials. Electronic texts were perceived by the study participants as fluid entities because the electronic environment promotes seamless interactions with a variety of media and formats. Working with electronic texts combines some traditional information and research practices into new patterns of information behavior. The practice called "netchaining" combines aspects of networking with information-seeking practices to establish and shape online information chains, which link sources and people. Different forms of exploration of participants' ...

2008-07-01

223

A Computer Simulation of the Electronic Structure of Leucine in Aqueous Solution

In the previous paper, we have derived a dispersion relation for the free electron laser (FEL) gain in the exponential regime taking account the diffraction and electron`s betatron oscillation. Here, we compare the growth rates obtained by solving the dispersion relation with those obtained by simulation calculation for the waterbag and the Gaussian models for the electron`s transverse phase space distribution. The agreement is found to be good except for the limiting case where the Rayleigh length is much longer than the gain length (1-D limit). We also generalize the analysis to the case where the electron beam cross section is elliptical as is usually the case in storage rings, and derive the first-order dispersion relation.

1992-08-01

224

British Library Electronic Table of Contents (United Kingdom)

In order to obtain the electronic structure of leucine (Leu) in aqueous solution, we studied three systems: Leu+7H2O, Leu+8H2O and Leu+9H2O. The results indicated that the system Leu+8H2O was the only choice which was both acceptable and doable: its computational effort was affordable, and it could simulate a main part of the solvent effect on the electronic structure of Leu in solution. Based on the system Leu+8H2O, all-electron, ab initio calculations were performed to construct an equivalent potential of water for the electronic structure of Leu with dipoles. The results showed that the main effect of water on the electronic structure of Leu was raising the occupied states about 0.0824 Ry on average, and broadening the energy gap by 11%. The water effect on the electronic structure of L...

2011-01-01

225

A 1-kW power demonstration from the advanced free electron laser

Measurement of electron energy fluence spectra from electron beam therapy machines

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The main objective of this project was to engineer and procure an electron beamline compatible with the operation of a 1-kW free-electron laser (FEL). Another major task is the physics design of the electron beam line from the end of the wiggler to the electron beam dump. This task is especially difficult because electron beam is expected to have 20 kW of average power and to simultaneously have a 25% energy spread. The project goals were accomplished. The high-power electron design was completed. All of the hardware necessary for high-power operation was designed and procured.

1997-08-01

226

Works on the start-up of an infrared free-electron laser in FIAN

A technique capable of measuring the electron energy fluence spectra in a scattering medium was designed. These measurements were performed by setting a bremsstrahlung conversion target on the surface of a phantom, at an intermediate depth, and at a depth equal to electron mean range. The bremsstrahlung produced by the deceleration of electrons in the target was passed through an air channel in the phantom and passed forward by a pinhole collimator into a Na(Tl) detector. The measured pulse height data were unfolded to correct for the distortion of the spectrometer system by using the FORIST unfolding code. The unfolded bremsstrahlung spectra represent the electron energy fluence spectra convolution with the bremsstrahlung produced in the target. To generate the electron energy fluence spectra, the unfolded bremsstrahlung spectra were deconvoluted by using the MAZE2 unfolding code. ...

1984-01-01

227

Stimulated radiation of high - current relativistic electron beams

The description and results of the study on the free-electron laser (FEL) on 100 #mu#m, representing the first line of the FIAN multipurpose radiation complex, are presented. The electron beam with the energy of 6-8 MeV, once accelerated in a racetrack microtron and extracted into the FEL injection tract, is used for exciting this FEL. The system of the electron beam transport, injection and diagnostics are described. Additional works on increasing the beam emittance up to 0.4 A for one energy spread percent are carried out. The obtained electron beam parameters assure generation of the far infrared radiation in the FEL

2000-10-17

228

Simulation on energy deposition process due to anisotropic fast electron transport in high density plasma

The most propagated mechanisms of stimulated radiation of electron beam such as Cherenkov one-particle and collective effects, ondulator and magnetic bremsshrahlung radiations, Doppler anomalous effect, Thompson and Raman scattering and radiation are discussed. Relation of spontaneous radiation mechanisms of individual electron and stimulated radiation effects in electron beams has been elucidated, grounds of linear electrodynamics of radiative beam instabilities are stated, and main mechanisms of their nonlinear stabilization are elucidated as well. Various simulated processes in electron beams are considered from the unique point of view using a simple mathematical apparatus and such physical laws as conservation and Newton laws.

1987-01-01

229

Section 508 and Electronic Information Technology Accessibility at EPA | US EPA

Energy deposition process by relativistic fast electrons produced by ultra-intense laser pulses is discussed. The process is calculated with a two dimensional Fokker-Planck simulation code including binary and collective collisions coupled with electromagnetic field. We focused on Velocity Distribution Function (VDF) dependence in the simulation. The results show that the spread angle of the fast electrons distribution affects energy deposition area and deposited energy is concentrated in the vicinity of the propagation axis of the fast electrons. It may be also suggested that self-pinch effect of a fast electron beam causes large deposition energy. (author)

2008-03-01

230

Wastenet

...Section 508 and Electronic Information Technology Accessibility at EPA | US EPA Jump to main content. Section 508 and Electronic Information Technology ...Us Search: All EPA Advanced search You are here: EPA Home Section 508 and Electronic Information Technology Accessibility at EPA Welcome to the United ... Section 508 of the Rehabilitation Act mandates that Federal departments and agencies make electronic and information technology (EIT) accessible to individuals ... Achieving compliance with Section 508 is an ongoing process. If you have any problems or questions about accessing information on a particular ...

231

Rigid muffin-tin approximation for the electron-phonon interaction in transition metals

Radiation effect on optical, electrophysical and surface properties of GaAlAs heterostructures

Progress in calculating the electron-phonon parameters of transition metals has been based on either the rigid muffin-tin approximation (RMTA) or the fitted modified tight-binding approximation (FMTBA). The RMTA has been shown to be remarkably accurate for average electron-phonon properties, but there are indications that RMTA matrix elements may be too small at low momentum transfer. An attempt is made to demonstrate these assertions concerning the accuracy of RMTA and the numerous electron-phonon calculations are placed in a broader perspective by a demonstration of how they can be used to explain the trends in the strength of the electron-phonon coupling among the transition metals and the A-15 compounds. (GHT)

1980-01-01

232

Polaron model of the electronic spectrum and the superconductivity of compounds having the A-15 structure

A study was made on the effect of 3.5 MeV electron irradiation on the properties of light-emissive structure based on GaAlAs. It is shown that a considerable decrease in the emitted light intensity as a result of electron irradiation not accompanied by changes in recombination- and electric properties of the mentioned structures. It is established by the electron-microscopy and Auger-spectroscopy meazurements that electron irradiation causes the occurrence of regions of free aluminium clusters on the external surface of the structure n-layer. The number and the sizes of the regions depend on the electron doze. It was assumed that the mentioned regions can play a role of attenuation filter for the light emitted by the structure.

1984-07-01

233

New techniques for electron-ion collision studies

The existence of a narrow peak in the electronic density of states in A-15 compounds is explained by a strong electron--phonon interaction that leads to the polaron narrowing of the band. An analytic expression relating the transition temperature T/sub c/ to the phonon spectrum is derived under the assumption of a weak and an intermediate-strength coupling. The model allows the explanation of the correlation of T/sub c/ with the number of electrons per atom, the temperature dependence of the resistance, the magnitude and temperature dependence of the magnetic susceptibility, and the electronic specific heat.

1983-02-01

234

MITL - A 2-D code to investigate electron flow through non-uniform field region of magnetically insulated transmission lines

We have constructed an apparatus to study electron impact ionization of ions which should provide additional insight into the mechanisms involved. Using multiparameter coincidence techniques, we will detect both outgoing electrons from ionization process and will be able to analyze the momenta of both particles simultaneously. Coupled with a high resolution electron gun, this information should have broad application to the difficult problem of three bodies interacting via the long range Coulomb force. If sufficient accuracy can be achieved, information regarding the relative phase of the outgoing electron wavefunctions can be obtained.

235

Impact of an initial energy chirp and an initial energy curvature on a seeded free electron laser: free electron laser properties

Self-magnetically insulated, high-voltage transmission lines are used in inertial confinement fusion particle accelerators in order to transmit power from the vacuum insulator to the diode. This paper describes a time-dependent 2-D code (MITL) for calculating (for planar or triplate geometries) the motion of test electrons through the tapered input or output convolutes of such lines. MITL results show that the electron canonical momentum in the direction of the flow changes as the electron passes through the convoluted geometry; it is suggested that these electrons lead to losses observed in long self-magnetically insulated lines.

1979-01-01

236

Experimental study of beam optics and energy recovery for high-energy electron cooling device

In a free electron laser (FEL), the electron bunch energy profile at the undulator entrance can have temporal structures. In this paper, we derive analytical expressions for the FEL in the undulator, in the case of the electron bunch having both energy chirp and energy curvature. The FEL properties are studied analytically by convoluting a Gaussian seed laser with the FEL Green's function obtained by solving the coupled Vlasov-Maxwell equations. In particular, for different ratios of the temporal duration of the seed laser and that of the Green's function, interesting behavior is revealed.

2009-02-27

237

Expansion Rate Measurements at Moderate Pressure of Nonneutral Electron Plasmas in the Electron Diffusion Gauge (EDG) Experiment

The feasibility of a high-energy electron cooling device has been studied through tests on a prototype of the electron device. The apparatus consists of a pulsed ((20-60) keV, 2#mu#s) electron gun, a drift region 1 m long and of a depressed collector for recovering the electron energy. Tests on beam optics and energy recovery have been performed, a high-energy recovery efficiency has been attained. Experimental results are discussed in this paper.

238

Electron transfer with C_6_0 in the gas phase: an overview

Measurements of the expansion rate of pure-electron plasmas have been performed on the Electron Diffusion Gauge (EDG) device at background helium gas pressures in the 5 x 10(superscript -8) Torr to 1 x 10(superscript -5) Torr range, where plasma expansion due to electron-neutral collisions dominates over plasma expansion due to trap asymmetries. It is found that the expansion rate, defined as the time rate of change of the particles' mean-square radius, scales approximately linearly with pressure and inversely as the square of the magnetic field strength in this regime, in agreement with classical predictions.

2001-05-18

239

Design of a tandem accelerator free electron laser

Here I provide a brief overview of recent experimental gas-phase measurements using the Selected-Ion Flow Tube or SIFT technique at 294#+-#2 K with helium buffer gas at 0.35 Torr for reactions which remove electrons from the C_6_0 molecule or donate electrons to singly and multiply-charged C_6_0 cations. The results of these measurements have provided new insight into physicochemical aspects of electron transfer and have revealed the occurrence of unprecedented electron transfer reactions at thermal energies. (author).

1994-03-20

240

Coherent correlation enhancement of outer shell photoionization cross sections of alkali-like ions

The motivation for using a tandem electrostatic accelerator as an electron accelerator for a free electron laser (FEL) is presented. The adaptation of the HVEC EN tandem at the Weizmann Institute for this purpose, electron beam optics and nonlinear FEL computation relevant for this FEL realization are described. In the tandem configuration the terminal is held at a positive potential. The electron beam is accelerated from ground potential to the terminal in one beam tube and then decelerated down the other beam tube. The FEL wiggler and cavity are at the terminal. Due to the beam energy recovery this scheme produces a high power beam at the terminal with a small investment in electrical power. (orig.).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

241

Analysis of the beam bunching produced by a free electron laser

An alkali-like ion interaction with inner electrons of an alkali-like ion leads to a significant increase in the photoionization cross section of the outer s electron. This occurs not only for ground-state ions with one s electron in the outer shell, but also when the outer s electron is in an excited state. The reason for this amplification, in addition to coherent enhancement in summing of the correlation amplitudes, is that the zero in the direct amplitude occurs below threshold. This leads to a constructive interference with the correlation amplitude above the photoionization threshold, in contrast to a destructive interference in the case of a neutral atom with the same electronic configuration, for which the zero occurs above threshold. Results of this research were published.

1995-08-01

242

Measurement of the mean energy of the off-axis incident electron without the beam guide. Using a scintillating fiber beam-energy monitor for electron beam therapy

A high-power microwave Free Electron Laser (FEL) experiment has been performed to study the inherent electron beam bunching that occurs in the FEL interaction. An induction linac delivered a 1 kA, 2.2 MeV electron beam to a FEL amplifier. In the process of amplifying the input signal of frequency 35 GHz to power levels of the order of 10 MW, the electron beam was bunched by the ponderomotive force. In this paper we describe the FEL experiment and the optical technique that was used to observe the bunches. Their properties as functions of the basic FEL parameters are discussed. copyright 1996 American Institute of Physics.

243

Use of primary electron counting for detection of ultrasoft x-rays with a low-pressure multistep gaseous detector

In the case of total skin electron therapy without the beam guide, the electron beam is scattered just outside the gantry exit, dose uniformity in the field is broken, and dose is spread outside the light field. The aims of this study were to measure the mean energy of the off-axis incident electron beam without the beam guide and to establish a reference for the clinical situation. For the measurement, a 4 MeV electron beam was selected among several energies from the linear accelerator. A scintillating fiber beam energy monitor measured the mean energy of the incident electron beam. This energy monitor is a small, light-weight piece of equipment composed of a wedge absorber, scintillation fiber, and photodiode. We found the relationship between electron energy and the indicated value of the energy monitor by means of the estimation of correction factors for ...

2002-06-01

244

The influence of target backing on ion-beam electron spectra

The use of primary electron counting techniques as an alternative to the more usual parallel plate avalanche chamber that has been employed in soft x-ray scattering experiments is being investigated at the National Synchrotron Light Source. The theoretical aspects of primary electron counting and motivation behind building a primary electron counting detector are described, as well as characteristics and future improvements of the device constructed at the NSLS. The detector consists of a low electric field drift region and a low pressure multistep avalanche region which can be operated with two or three stages of electron multiplication. The device has worked well in extensive tests as a simple parallel plate avalanche chamber, providing energy resolutions of 58% and 43% at 277 and 500 eV, respectively. Operated as a primary electron counter, preliminary results show an energy ...

245

The ejected-electron spectra of manganese and samarium vapour atoms arising from autoionizing and Auger transitions following electron impact excitation

Several different aspects of the influence of the target backing on in-beam electron spectra following compound nuclear reactions induced by accelerated ions at tandem energies irradiating backed targets are discussed in detail. This discussion is illustrated by a few typical examples, such as "1"2C"5"+ and "3"1P"1"0"+ beams at 4 MeV/u bombarding Sn(+Be), Sn(+Au), Pb(+C) backed targets. Moreover, the relative influence of electron backscattering, electron Doppler shift and Doppler broadening as well as #delta#-electron emission on the low energy electron spectra (E_e#<=#100 keV) obtained under such conditions are investigated in the frame of the available experimental data. (orig.).

246

Measurement of the relaxation time of hot electrons in laser-solid interaction at relativistic laser intensities

Autoionizing and Auger transitions in atomic manganese and samarium have been experimentally investigated by observation of the ejected electrons in the energy region 0 to 40 eV following electron impact excitation with incident beams in the energy range 15-500 eV. Seventy-four spectral features are tabulated for manganese and a number of new assignments have been made based on pseudo-relativistic Hartree-Fock calculations and quantum defect analysis. A similar study of samarium reveals only a number of broad features in the ejected-electron energy range 8-10 eV. Three features have been observed consistently in the ejected-electron spectrum of samarium and assigned by comparison with previous work. (author).

247

Interfacial Charge Transport in Organic Electronic Materials: the Key to a New Electronics Technology

The authors have measured the relaxation time of hot electrons in short pulse laser-solid interactions using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. Employing laser intensities of 10{sup 17}, 10{sup 18}, and 10{sup 19} W/cm{sup 2}, they find increased laser coupling to hot electrons as the laser intensity becomes relativistic and thermalization of hot electrons at timescales on the order of 10 ps at all laser intensities. They propose a simple model based on collisional coupling and plasma expansion to describe the rapid relaxation of hot electrons. The agreement between the resulting K{sub {alpha}} time-history from this model with the experiments is best at highest laser intensity and less satisfactory at the two lower laser intensities.

2006-08-22

248

Inelastic electron--dipole-molecule scattering at sub-milli-electron-volt energies: CH_3I and CH_2Br_2

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The primary aim of this project is to obtain a basic scientific understanding of electrical transport processes at interfaces that contain an organic electronic material. Because of their processing advantages and the tunability of their electronic properties, organic electronic materials are revolutionizing major technological areas such as information display. We completed an investigation of the fundamental electronic excitation energies in the prototype conjugated polymer MEH-PPV. We completed a combined theoretical/experimental study of the energy relation between charged excitations in a conjugated polymer and the metal at a polymer/metal interface. We developed a theoretical model that explains injection currents at polymer/metal interfaces. We have made ...

1999-06-04

249

Final Report for Award DE-FG02-99ER54554 Kinetics of Electron Fluxes in Low-Pressure Nonthermal Plasmas

Studies of Rydberg-atom destruction in collisions with the polar targets CH_3I and CH_2Br_2 for values of principal quantum number n in the range 100--400 are reported. Analysis of the data using the essentially-free-electron model suggests that, for ultralow electron energies (#approx#80 #mu#eV to 1 meV), the cross section #sigma#(var-epsilon) for rotationally inelastic scattering of electrons by a polar target varies approximately as 1/var-epsilon, where var-epsilon is the electron energy. The Born approximation does not predict such behavior at very low collision energies, and possible reasons for this discrepancy are discussed.

250

Electron cyclotron power absorption in plasmas with non-Maxwellian electron velocity distributions

This grant has focused on the study of several aspects of electron kinetics in low pressure plasmas. Entirely new effects arise from the fact that the electron kinetics is governed by non-local effects, in which the electron distribution function is not equilibrium with the local electric field but is governed by spatial transport effects. In this grant, we were able to demonstrate several previously un-studied effects which are a direct result of the nonlocal transport. These are: (1) The existence of a ''convective cell' in electron phase space. The phenomenon was observed and studied in CW plasma conditions. (2) The occurrence of non-collisional cooling of electrons through an effect known as ''diffusive cooling''.

2004-12-13

251

Electron binding to isolated polar molecules and molecular dipole assemblies

Tokamaks with sufficiently strong supplementary heating develop non-Maxwellian electron velocity distributions. Because the absorption of electron cyclotron power is proportional to #nabla#_Vf, even small deviations from a Maxwellian distribution can significantly affect power deposition. Following an approach used to study microinstabilities in a plasma with an arbitrary, numerically specified, electron distribution, we have developed a computational module to study electron cyclotron power deposition in plasmas that have distributions motivated by those in actual tokamaks. Also, we compare the deposition results obtained using an energy balance approach with those obtained using a Taylor expansion of the dielectric tensor. We illustrate the limitations of the latter approach.

1993-04-01

252

Electron accelerators, present and future applications

In a sufficiently large cluster of several polar molecules, collective interactions lead to localization or 'solvation' of electrons. The existence of the solvated electron is known since 1863 in liquid ammonia and since 1962 for liquid water. In 1984, electron localization in clusters was experimentally demonstrated in (H_2O)_N_#>=#_1_1 and (NH_3)_N_#>=#_3_4 clusters. In cooperation with K. Bowen, we recently initiated a test of the theory of electron binding by a dipole and a new ground state dipole bound dimer anion, (H_2O..NH_3), was predicted and observed. We here describe results of a search for new dipole-bound and solvated electron systems. (author).

1994-03-20

253

Spin freezing in the re-entrant spin glass FeNiMn close to the frustration limit

The development and occurrence of new electron accelerators and applications are according to the human society development law, as a whole. The period of economic standstill is generating an intense creative activity in the domain of science and engineering which also resulting in great achievements in the field of electron accelerators. This paper presents the basic principle of the electron beam applications and the accelerators required characteristics for their present and potential applications in the domains: radiation sources, diagnostics, radiation processing, energetics, environment, defense and basic sciences. All these are correlated to the new generation of accelerators which, for the acceleration process, may employ electromagnetic fields generated by standard sources, atomic lasers, free electron lasers, Cerenkov effect, Smith - Purcell effect, electron beams, plasma, ...

254

NMR studies of the partially disordered state in a triangular antiferromagnet UNi_4B

In the invar alloy (Fe{sub 0.65}Ni{sub 0.35}){sub 1-} {sub x} Mn {sub x} we measured the magnetic form factor s(Q) and the intermediate scattering function s(Q,t) for a sample close to the critical Mn concentration (x {sub c}=0.139), at which the sample turns to a re-entrant spin glass phase. The aim was to check whether the magnetic behaviour would approach the Q-independent relaxation behaviour of a classical spin glass when x=x {sub c}. The experiment showed a quite similar spin freezing as for a more ferromagnetic sample with x=0.113. The intermediate scattering function and the form factor were determined by paramagnetic NSE. The normalized scattering function S(Q,t)=s(Q,t)/s(Q)=exp[(-{gamma}t) {sup n}] was fitted by stretched exponential decay. As a function of temperature T<200 K the inverse time constant {gamma} showed the change of more than four orders of magnitude from frozen spin glass (T=60 K to T=100 K), where the ferromagnetic phase occurred. ...

2007-07-15

255

Magnetocaloric effect of Gd{sub 4}(Bi{sub x}Sb{sub 1{minus}x}){sub 3} alloy series

A triangular antiferromagnet UNi_4B experiences a partially disordered state, in which two-thirds of U 5f moments order in a vertex-like structure and one-third of U 5f moments remain paramagnetic. Magnetization and NMR measurements of UNi_4B have been performed to study the dynamical properties of U magnetic moments in the partially disordered state. The value of the effective moment above T_N derived from the fitting of the Curie-Weiss law suggests a significant crystal field splitting and the Kondo effect. The Weiss temperature was also estimated to be -28 K, which suggests that the exchange interaction is antiferromagnetic. Furthermore, the exchange interaction estimated from the relaxation rate T_1"-"1 above 50 K is 18 K, which is close to the Weiss temperature. These results suggest that the dominant interactions between U moments are antiferromagnetic in the basal plane. The relaxation rate T_1"-"1 decreases abruptly below T_N down to 15 K and is almost ...

2007-04-11

256

Magnetization and magnetic susceptibilities of GdH_3, HoH_3, ErH_3 and YbH_3

Alloys from the Gd{sub 4}(Bi{sub x}Sb{sub 1{minus}x}){sub 3} series were prepared by melting a stoichiometric amounts of pure metals in an induction furnace. The crystal structure is of the anti-Th{sub 3}P{sub 4} type (space group I{bar 4}3d) for all the compounds tested. The linear increase of the lattice parameters with Bi concentration is attributed to the larger atomic radius of Bi than that of Sb. Magnetic measurements show that the alloys order ferromagnetically from 266K to 330K, with the ordering temperature increasing with decreasing Bi concentration. The alloys are soft ferromagnets below their Curie temperatures, and follow the Curie-Weiss law above their ordering temperatures. The paramagnetic effective magnetic moments are low compared to the theoretical value for a free Gd{sup 3+}, while the ordered magnetic moments are close to the theoretical value for Gd. The alloys exhibit a moderate magnetocaloric effect (MCE) whose maxima are located between ...

1999-12-01

257

Magnetic properties of laminated perovskite-like ferroelectromagnetics

The magnetic susceptibility of powdered samples of HoH_3, ErH_3, GdH_3 and YbH_3 have been measured in the temperature range from 4.2 to 1.2 K. Two broad, local maxima are observed in the variation of chi versus T for GdH_3, with maxima in (delta chi/delta T) versus T at 1.8 K and 3.3 K. The inverse susceptibilities for HoH_3 and ErH_3 both obey a Curie--Weiss law over a limited range (4.2 to 2.6 K and 4.2 to 2 K, respectively) with values for the Weiss constant of -4.25 K and -1.11 K, and effective moments of 8.6 and 7.7 Bohr magnetons, respectively. The susceptibility of YbH_3 is independent of temperature over the range investigated. High-field magnetization measurements yield extrapolated saturation moments of 7.0 +- 0.25 Bohr magnetons/ion for GdH_3, 6.1 +- 0.2 Bohr magnetons/ion for HoH_3 and 3.74 +- 0.11 Bohr magnetons/ion for ErH_3. In addition, ErH_3 exhibits a van Vleck paramagnetism in the high-field region.

1976-03-29

258

Magnetic properties of Nd_2CuO_4-type R_2CuO_4 (R=Y, Dy, Ho, Er, Tm) synthesized under high pressure: Weak ferromagnetism of Y_2CuO_4

Magnetic properties of layer ferromagnets against the thickness are investigated. Two new compounds served for studies: Bisub(6)Tisub(2)Nbsub(0,5)Fesub(2,5)Osub(18) and Bi_7Ti_3Fe_3O_2_1. The Moessbauer effect and the magnetic susceptibility measurements were applied in the experiment. The Faraday method was used in magnetic measurements in fields from 1 to 9,5 kOe. The results of Moessbauer measurements show that temperature dependence of the spectra is typical for compounds with superparamagnetic properties. The magnetic fields Hsub(n) on Fe"5"7 nuclei in Bisub(6)Tisub(2)Nbsub(0,5)Fesub(2,5)Osub(18) and Bi_7Ti_3Fe_3O_2_1 are similar and equal to 520+-10 kOe. Therefore it may be concluded that relaxation times of nuclear spins in these compounds are equal or close to each other. The lines of quadrupole splitting appear in spectra together at 20 K. The results of magnetic measurements show that the Curie-Weiss law is satisfied in the range of high temperatures for magnetic ...

1975-01-01

259

Crystal structure and magnetic properties of Sm{sub 2}ReO{sub 5}

Magnetization of R_2CuO_4 (R=Y, Dy, Ho, Er, Tm) crystallizing in the Nd_2CuO_4-type (T') structure has been measured between 4 and 300 K. In Y_2CuO_4 antiferromagnetic ordering of Cu"2"+ spins at 260 K has been detected clearly, without being interfered with by the paramagnetic contribution of rare-earth elements as in the other compositions. Weak ferromagnetic behavior with a moment of 9x10"-"4 #mu#_B/Cu accompanies the antiferromagnetic transition. Dy"3"+, Ho"3"+, Er"3"+, and Tm"3"+ ions obey the Curie-Weiss law at relatively high temperatures, and the effective moments are in good agreement with the values anticipated from their lowest multiplet levels. Various types of deviations from the law occur at low temperatures. Specifically, a sharp kink possibly suggesting antiferromagnetic ordering of the Dy"3"+ moments has been found at 7 K. Anomalies around 200 K for Ho_2CuO_4 and Er_2CuO_4 reflect the weak ferromagnetic contribution of the CuO_2 lattice.

1990-10-01

260

[Electronic and structural properties of individual nanometer-size supported metallic clusters]. Progress report

Crystals of disamarium rhenium (IV) pentoxide, Sm{sub 2}ReO{sub 5}, were obtained by subsolidus reaction of samariumsesquioxide and rheniumdioxide (ratio 1:1) in sealed Pt 10Rh tubes at 1673 K. The structure was determined by single-crystal X-ray diffraction. Sm{sub 2}ReO{sub 5} crystallizes in the tetragonal system with unit cell dimensions a = 8.646(3) {angstrom} and c = 5.747(2) {angstrom} and space group P4/n (no. 85) with Z = 4. The structure consists of isolated RE{sub 2}O{sub 8} groups and the (Sm{sub 4}O) chains are inter-connected by common oxygen atoms to form a three-dimensional network. Each Re{sub 2}O{sub 8} group is composed of a pair of rhenium each surrounded by four oxygens with a short Re-Re distance of 2.251(1) {angstrom} indicating a metal-metal bond. Rhenium has the formal oxidation state of +4. The observed magnetizations in the temperature range 1.8 < T < 100 K exhibits antiferromagnetic ordering below 2.4(1) K and obey a Curie-Weiss law modified by a ...

1997-08-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

261

Verification of MLC based real-time tumor tracking using an electronic portal imaging device

The research supported by this Department of Energy contract has primarily been devoted to the study of the electronic properties of surfaces with sub-micron size. In previous years, we have studied the photoexcitation of electrons from field emission tips by a focussed Argon-ion laser beam tuned to operate at specific photon energy. The photoexcited electrons escape into the vacuum by tunneling through a surface potential barrier which is distorted by the application of a strong electric field. The interest in these experiments lies in a better understanding of the photoexcitation process at low photon energies. The techniques that have been developed directly measure the excited state energy distribution of electrons emitted through the surface potential barrier. The basic information gained from this research is relevant to opto-electronic devices which rely on photoexcitation of ...

1991-11-01

262

The development and validation of the daily electronic Endometriosis Pain and Bleeding Diary

Purpose: The authors have developed a novel technique using an electronic portal imaging device (EPID) to verify the geometrical accuracy of delivery of dose-rate-regulated tracking (DRRT)....Full Text Available

2010-06-01

263

The Use of Quality Benchmarking in Assessing Web Resources for the Dermatology Virtual Branch Library of the National electronic Library for Health (NeLH)

BackgroundThe objective of this study was to develop and validate a daily electronic Endometriosis Pain and Bleeding Diary (EPBD) for assessing treatment-related changes in endometriosis...Full Text Available

264

Teaching electron diffraction and imaging of macromolecules.

BackgroundIn 1998, the U.K. National Health Service Information for Health Strategy proposed the implementation of a National electronic Library for Health...Full Text Available

265

Superconductivity in A-15 compounds

Electron microscopic analysis can be used to determine the three-dimensional structures of macromolecules at resolutions ranging between 3 and 30 A. It differs from nuclear magnetic resonance spectroscopy...Full Text Available

1993-05-01

266

Status of electron accelerators for linear colliders

Superconductivity in A-15 compounds is examined in terms of electron pairing induced by exchange of acoustic plasmons. The electronic band structure of Nb_3Sn, V_3Si, and similar materials favor transition temperatures of Tsub(c)approximately20 K. (Auth.).

267

Simulation of electron beam therapy employing cone collimation

The paper outlines the basic problems concerning creation of electron-positron linear colliders, as well as their present-day status. More details on the question can be found in the proceedings of recent workshops on linear colliders contained in the References. ((orig.)).

1995-02-01

268

Report Central: Quality Reporting Tool in an Electronic Health Record

A simple device is described which is used to determine treatment distance and beam direction in electron therapy employing one collimation. A technique for the production of irregular field templates and localization films is given.

1983-07-01

269

Proof-of-concept Design and Development of an EN13606-based Electronic Health Care Record Service

Quality reporting tools, integrated with ambulatory electronic health records, can help clinicians and administrators understand performance, manage populations, and improve quality. Report Central...Full Text Available

2006-01-01

270

Peptides of human bronchial mucus glycoproteins. Size determination by electron microscopy and by biosynthetic experiments.

ObjectiveThe authors present an Electronic Healthcare Record (EHR) server, designed and developed as a proof of concept of the revised prEN13606:2005 European standard concerning...Full Text Available

2007-01-01

271

Nuclear Pore Complex Number and Distribution throughout the Saccharomyces cerevisiae Cell Cycle by Three-Dimensional Reconstruction from Electron Micrographs of Nuclear Envelopes

Secreted human bronchial mucins, directly collected from macroscopically healthy bronchial mucosa, were prepared in the presence of six proteinase inhibitors, and analysed by electron microscopy. These...Full Text Available

1987-11-15

272

Maintenance and fabrication of electronic equipment

The number of nuclear pore complexes (NPCs) in individual nuclei of the yeast Saccharomyces cerevisiae was determined by computer-aided reconstruction of entire nuclei from electron...Full Text Available

1997-11-01

273

Maintenance and fabrication of electronic equipment

Solving the maintenance and repair problems of electronic instruments, we have supported the research and development work, and reduced operation costs of the pilot plants in KAERI. In addition, we have improved the maintainability of instruments to use effectively. 18 tabs., 17 figs., 13 refs. (Author) .new.

1995-12-01

274

Localization of gold in synovial membrane of rheumatoid arthritis treated with sodium aurothiomalate. Studies by electron microscope and electron probe x-ray microanalysis.

Solving the maintenance and repair problems of electronic instruments, we have supported the research and development work, and reduced operation costs of the pilot plants in KAERI. In addition, we have imposed the maintainability of instruments to use effectively. 15 tabs., 14 figs., 14 refs. (Author) .new.

1994-12-01

275

In situ nanoindentation in a transmission electron microscope

The localization of gold in the synovial membrane of rheumatoid arthritis patients treated with sodium aurothiomalate was examined and quantitative analysis of epon-embedded sections was carried out...Full Text Available

1977-06-01

276

Impact of an Electronic Medical Record on Diabetes Quality of Care

This dissertation presents the development of the novel mechanical testing technique of in situ nanoindentation in a transmission electron microscope (TEM). This technique makes it possible to simultaneously observe and quantify the mechanical behavior of nano-scale volumes of solids.

2002-12-02

277

Impact of Electronic Health Record Clinical Decision Support on Diabetes Care: A Randomized Trial

PURPOSE This study was designed to evaluate the impact of electronic medical record (EMR) implementation on quality of diabetes care.METHODS We conducted a 5-year longitudinal...Full Text Available

2005-07-01

278

Impact and User Satisfaction of a Clinical Information Portal Embedded in an Electronic Health Record

PURPOSE We wanted to assess the impact of an electronic health record–based diabetes clinical decision support system on control of hemoglobin A_1c (glycated hemoglobin),...Full Text Available

2011-01-01

279

In 2008, a clinical information tool was developed and embedded in the electronic health record system of an academic medical center. In 2009, the initial information tool, Clinical-e, was superseded...Full Text Available

280

Fully quantized many-particle theory of a free-electron laser

Objective To compile and evaluate the evidence on the effects on health and social outcomes of computer based peer to peer communities and electronic self support groups, used by people...Full Text Available

2004-05-15

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

281

A fully quantized many-particle theory of the standard free-electron laser in the small-signal, cold-beam regime is presented. The approach is based on an evaluation of the time-evolution operator in the interaction picture to first order in the quantum-mechanical recoil. For algebraic convenience we use the moving (Bambini-Renieri) frame, in which resonance occurs for zero electron momentum. Though we neglect space-charge effects, genuine many-particle contributions still show up, because the radiation emitted by one electron can be amplified by another electron. Our main results are gross features of the amplification, such as gain and spread, are virtually without many-particle effects. These effects are mainly important in the case of spontaneous emission. For a sufficiently high current, the buildup of the laser field from vacuum is enhanced by amplified spontaneous emission. Incoherence of the ...

1983-02-01

282

Free electron laser

The present article outlines major features of the free electron laser (FEL) and reviews research and development of FEL. Relations among the oscillation frequency, electron beam parameters and wiggler parameters, the physical mechanism of amplification and the physical process of saturation are discussed to identify the difference between FEL and other lasers. The report also outlines techniques for accelerators which are used to generate high-quality, high-energy electron beams required for FEL experiments. Techniques to achieve a short wavelength, high output and high efficiency, and applications of FEL are also discussed. FEL consists of an electron accelerator, wiggler and optical resonator. In FEL, electron beams with a relativistic energy interact resonantly with an electromagnetic field to generate coherent electromagnetic waves. Unlike conventional lasers, FEL does not ...

283

Free electron laser

Examination of the Rotazyme II enzyme immunoassay for the diagnosis of rotavirus gastroenteritis.

Physics and technology of free electron laser (FEL) are reviewed. Mechanisms of stimulated emission in FEL and its present status and future prospects are presented. Electromagnetic wiggler, two stage FEL and so on are also interpreted. Finally, accelerators and wigglers for FEL, recent FEL experiments and FEL applications are noted. (author).

284

Energy-resolved electron particle and energy fluxes in positive column plasmas

Rotazyme II, which is a shorter version of Rotazyme (less than 3 h), was compared with electron microscopy and Rotazyme for sensitivity and specificity on 229 human stool specimens. Compared with electron...Full Text Available

1985-09-01

285

Electronic spectra of semiconductor nanocrystals

This paper deals with electron flux densities and electron energy flux densities in positive column discharges. Recent kinetic calculations by Uhrlandt and Winkler have revealed the interesting physical phenomenon of radially inward directed energy flux densities in positive column plasmas. We have used a self-consistent positive column model, based on an accurate and highly detailed Monte Carlo code, to study this effect in more depth. The results of this study show a rather complex physical picture of electron particle and energy flux densities. Electrons with low energies usually exhibit radially outward directed particle and energy flux densities. At energies above the threshold for electronic excitation particle and energy flux densities are usually inward directed. Only close to the wall, at total energies above the wall potential energy, do these flux densities point towards ...

1999-11-07

286

Electronic and Interfacial Properties of Pd/6H-SiC Schottky Diode ...

Semiconductor nanocrystals smaller than the bulk exciton show substantial quantum confinement effects. Recent experiments including Stark effect, resonance Raman, valence band photoemission, and near edge X-ray adsorption will be used to put together a picture of the nanocrystal electronic states.

1993-12-31

287

Electron spin resonance studies of radiation effects in biological materials. An assessment of current and future research

and palladium silicides (Pd,Si) with a total. AES intensity ratio of Pd to Si of 35/65. Scanning Electron Microscopy. (SEM') of the Pd region shows that ...

288

Electron Spin Resonance Studies of Ionic Permeability Properties of Thylakoid Membranes of Beta vulgaris and Avicennia germinans1

Electron spin resonance spectroscopy can provide a powerful approach to the study of radiation effects in biological materials. This memorandum gives an overview of current and future research. (author).

1987-06-01

289

Electron Flux - 8.0 keV - ISWA wiki - ISWA - NASA

Measurement of intrathylakoid aqueous volumes by electron spin resonance spectroscopy was used to study ionic permeability properties of thylakoid membranes isolated from Beta vulgaris...Full Text Available

1985-05-01

290

Electron Flux - 4.7 keV - ISWA wiki - NASA

Nov 14, 2009 ... Ring Current electrons from the Fok Ring Current Model are computed using plasma and magnetic field values from the SWMF magnetosphere ...

291

Electron Flux - 179 keV - ISWA wiki - ISWA - NASA

Nov 14, 2009 ... Ring Current electrons from the Fok Ring Current Model are computed using plasma and magnetic field values from the SWMF magnetosphere ...

292

Development of an Interference Electron Microscope.

Nov 14, 2009 ... Ring Current electrons from the Fok Ring Current Model are computed using plasma and magnetic field values from the SWMF magnetosphere ...

293

Detection of rotavirus by serological trapping on antibody-coated electron microscope grids.

This report covers a further year's work on the development of an Interference Electron Microscope at Imperial College. The instrument is unlike others of its type which have been operated. The basic innovations are to produce the critical illumination co...

1967-01-01

294

An automated procedure for detecting protein folds from sub-nanometer resolution electron density

A serological trapping technique for detecting rotaviruses is described which involves coating electron microscope grids with protein A and specific rotavirus antiserum. The presence of a layer of antibodies...Full Text Available

1980-07-01

295

Amazon.com: Automotive Embedded Systems Handbook (Industrial Information Technology) (9780849380266): Nicolas Navet, Francoise Simonot-Lion: Books

The use of sub-nanometer resolution electron density as spatial constraints for denovo and ab-initio structure prediction requires knowledge of protein boundaries...Full Text Available

2010-06-01

296

Wastenet

...Electronic equipment,Embedded computer systems,Technology & Engineering,Automotive - General,COMPUTERS / Computer Engineering,TECHNOLOGY & ENGINEERING / Electronics ...

297

45 CFR 170.210 - Standards for health information technology to protect electronic health information created...

45 CFR 170.205 - Content exchange standards and implementation specifications for exchanging electronic health...

...2010-10-01 false Standards for health information technology to protect electronic health information...DEPARTMENT OF HEALTH AND HUMAN SERVICES HEALTH INFORMATION TECHNOLOGY HEALTH INFORMATION TECHNOLOGY STANDARDS, IMPLEMENTATION...

2010-10-01

298

(Electronic and structural properties of individual nanometer-size supported metallic clusters)

...standards and implementation specifications for exchanging electronic health information. 170.205 Section 170.205 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES HEALTH INFORMATION TECHNOLOGY HEALTH INFORMATION TECHNOLOGY...

2010-10-01

299

Variable-dispersion electron spectrometer for the SCA/FEL

The research supported by this Department of Energy contract has primarily been devoted to the study of the electronic properties of surfaces with sub-micron size. In previous years, we have studied the photoexcitation of electrons from field emission tips by a focussed Argon-ion laser beam tuned to operate at specific photon energy. The photoexcited electrons escape into the vacuum by tunneling through a surface potential barrier which is distorted by the application of a strong electric field. The interest in these experiments lies in a better understanding of the photoexcitation process at low photon energies. The techniques that have been developed directly measure the excited state energy distribution of electrons emitted through the surface potential barrier. The basic information gained from this research is relevant to opto-electronic devices which rely on photoexcitation of ...

1991-11-01

300

USSR Report, Electronics and Electrical Engineering.

A variable-dispersion electron spectrometer is being installed for use by the Stanford Superconducting Accelerator in conjunction with its Free Electron Laser program. The system has been designed to operate with electron beam energies from 20 MeV to 200 MeV, with a maximum energy resolution of 0.01% FWHM. The maximum energy acceptance is approximately #+-# 5%, as determined by the bending magnet aperture. Resolution is controlled by adjusting the focal conditions at the entrance to a 90 degree bending magnet, while the dispersion is controlled by changing the magnitude and polarity of the field in a quadrupole magnet which immediately follows the bending magnet. 4 refs., 5 figs.

1989-06-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

301

Transmission electron microscopy of simulated DWPF high level nuclear waste glasses following gamma irradiation

... comparative analysis is made of the sensitivity of two types of spectrometers: instruments employing coherent spontaneous radiation, and classical ...

1985-04-30

302

Theory of zwitterionic molecular-based organic magnets

Thermal analysis testing revealed slight weight changes, which were a function of gamma irradiation, in a highly reduced Defense Waste Processing Facility (DWPF) simulated waste glass. Transmission electron microscopy (TEM) was performed on this glass to determine if the weight change corresponded to microstructural variations. TEM analyses showed that no microstructural changes were attributable to gamma irradiation. Exposure of the samples to the electron beam in the TEM did cause changes in the glass microstructures in some cases. These changes were likely due to localized heating of the glass due to interactions with the transmitted electrons.

1994-04-25

303

British Library Electronic Table of Contents (United Kingdom)

We describe a class of organic molecular magnets based on zwitterionic molecules (betaine derivatives) possessing donor, p bridge, and acceptor groups. Using extensive electronic structure calculations we show the electronic ground-state in these systems is magnetic. In addition, we show that the large energy differences computed for the various magnetic states indicate a high Neel temperature. The quantum mechanical nature of the magnetic properties originates from the conjugated p bridge (only p electrons) in cooperation with the molecular donor-acceptor character. The exchange interactions between electron spin are strong, local, and independent on the length of the p bridge.

2011-01-01

304

The nanoworld through aberration corrected lenses

The electron current to a Langmuir Probe in a flowing high-pressure plasma

The advent of aberration correction for electron microscope lenses has produced a significant advance in the improvement of resolution in microscopy. This improvement, while significant in itself, promises to have its most profound impact in materials science when it delivers quantitative information to challenge models and modellers. This capability for an electron microscope-modelling synergy to deliver useful results at the atomic level is not yet firmly established. For this reason, one of the major challenges for electron microscopy in materials science over this decade is to study systems where electron microscopists and modellers can work collaboratively. This paper explores some examples.

2010-07-01

305

Technology in Coalition Training

This paper reports on the electron current to a Langmuir probe in a moving high-pressure plasma. The plasma is an atmospheric-pressure propane flame, and the probe's speed relative to the plasma is varied from 10 to 30 ms"-"1. The current is linearly dependent on the speed and appears to be comprised of two components - one driven by diffusion and the other by convection. A model is devised which can be used to measure the electron density. By comparing the density computed from this model to that measured from the ion current, it has been possible to measure the electron mobility in the flame gases. The value obtained here is in good agreement with theoretical calculations found in the literature.

306

Synchrotron Probes of Emergent Electronic States of Matter in Solids

... program incorporates the proven concepts of advanced distributed learning, modeling and simulation, and electronic digital libraries (Figure 1) to ...

2004-06-01

307

ScienceCinema

...of this article he quotes um i am told by my english ...

308

Survey of Biodegradation of Electronic Components and ...

Surface characterization of plasma nitriding sintered steels using scanning electron microscopy (SEM) and energy dispersive x-ray microprobe analysis (EDX)

... This pinhole process may be similar to the formation of an oxide layer in aluminum electrolytic capacitors immersed in a borax solution. ...

1991-08-01

309

Study on the Surface Magnetic Domain Structure of Thin-Gauged 3% Si-Fe Strips using Scanning Electron Microscopy with Polarization Analysis

No abstract prepared

1996-10-01

310

Studies about oxygen accumulation in palladium silicide formed at Pd/a-Si interface

Full Text Available

1998-06-01

311

Spontaneous radiation of an electron beam in a free-electron laser with a quadrupole wiggler

... 194 p. auger electron spectroscopy decomposition deposition interfaces oxygen

1986-04-23

312

A calculation is presented of spontaneous radiation emitted by an electron beam passing through a continuously rotating quadrupole magnetic undulator. It is shown that radiation spectrum emitted in forward direction of beam propagation has four peaks, corresponding to four betatron frequencies. Utilizing the Madey theorem, a stimulated emission is calculated and presented as gain versus frequency curves, for different values of the quadrupole magnetic field. A free-electron laser operating at two or three radiation frequencies with a quadrupole magnetic wiggler is suggested.

1986-09-01

313

Smart Acquisition EELS

Self-seeded injection-locked FEL amplifier

Electron energy loss (EEL) spectroscopy and high angle annular dark field (HAADF) imaging in aberration-corrected electron microscopes are powerful techniques to determine the chemical composition and structure of materials at atomic resolution. We have implemented Smart Acquisition, a flexible system of scanning transmission electron microsocpy (STEM) beam position control and EELS collection, on two aberration-corrected dedicated cold field emission gun (FEG) STEMs located at SuperSTEM, Daresbury Laboratory. This allows the collection of EEL spectra from spatially defined areas with a much lower electron dose possible than existing techniques such as spectrum imaging.

2010-07-01

314

Radio-Frequency Beam Conditioner for Fast-Wave Free-Electron Generators of Coherent Radiation

A self-seeded free electron laser (FEL) provides a high gain and extraction efficiency for the emitted light. An accelerator outputs a beam of electron pulses to a permanent magnet wiggler having an input end for receiving the electron pulses and an output end for outputting light and the electron pulses. An optical feedback loop collects low power light in a small signal gain regime at the output end of said wiggler and returns the low power light to the input end of the wiggler while outputting high power light in a high signal gain regime.

1998-12-01

315

RESEARCH REPORT 248 ON THE EQUILIBRIUM OF ELECTRON - NASA ...

A method for conditioning electron beams is proposed, making use of the TM{sub 210} mode of microwave cavities, to reduce the axial velocity spread within the beam, in order to enhance gain in resonant electron beam devices, such as the free-electron laser (FEL). Effectively, a conditioner removes the restriction on beam emittance. The conditioner is analyzed using a simple model for beam transport and ideal RF cavities. Analysis of an FEL is employed to evaluate performance with reduced axial velocity spread. Examples of FELs are presented showing the distinct advantage of conditioning.

1991-07-01

316

Plastics with a bright future; Kunststoffe mit leuchtender Zukunft

then, the toroidal containment of charged plasmas by electric fields is comparable to the toroidal containment of neutral plasmas using the ...

317

Plasma nonlinearities in hybrid resonance of powerful electron plasma wave in inhomogeneous plasma

Flexible solar cells or luminous foils have become reality with organic electronic systems.

2010-07-01

318

Optical guiding measurements on the Mark III free electron laser oscillator

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

2006-09-11

319

Optical Processing and Control

It has been predicted for several years that light is focused (optically guided) as well as amplified by the electron beam in a free electron laser (FEL). The degree of focusing depends strongly on both electron beam and optical beam characteristics. In an FEL oscillator the degree of focusing varies with intracavity optical power during the macropulse. We report the first direct measurements of the evolution of transverse optical model size and shape between small signal and saturation in a short wavelength (Compton regime) FEL oscillator. The mode measurements on the Mark III FEL oscillator are shown to be consistent with theory, requiring both refractive and gain contributions to guiding. (orig.).

320

Nuclear structure physics at high resolution

... the application of an acousto- optical tunable filter ... Couplers for Large Switch-Array Applications ... Symmetric Integrated Optic X Junction," Electronics ...

1994-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

321

Techniques for studying nuclear structure are reviewed. Examples are given of charge density determinations by electron and proton inelastic scattering. (AIP)

1985-04-01

322

NRL Fact Book 2010

... Tactical Electronic Warfare Division (Code 5700) Visualization Laboratory Transportable step frequency radar Vehicle development laboratory ...

2011-05-15

323

NRL Fact Book

Mechanism of thermal excitation of the electron states of diatomic molecules behind a shock wave front

... Tactical Electronic Warfare Division (Code 5700) Visualization Laboratory Transportable step frequency radar Vehicle development laboratory ...

2011-05-15

324

Low-energy high-current electron beam generation in plasma systems and beam-plasma interaction

Alternative mechanisms of electron state excitation in diatomic molecules are examined with reference to CN and C2 molecules forming in chemical reactions behind strong shock wave fronts in a CO(CO2)-N2 gas mixture. The temperature range considered is 4000-8000 K. An effective excitation mechanism is proposed which involves rapid vibration-rotation excitation at all electron states and nonradiative transitions between perturbed electron states induced by collisions with the ambient gas particles.

1981-03-01

325

Investigation of "8"8Sr by (e,e') and (p,p') reactions

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

2006-09-11

326

Intraband Absorptoin of Far-Infrared Light by Electrons in ...

... bcs theory electron reactions excited states form factors inelastic scattering

327

Inhomogeneity of electron density in amorphous films

... significant change of spontaneous radiation intensity. It is very sensitive technique allowing the observation of small changes of light absorption. ...

1999-06-18

328

Handbook Prefered Circuits Navy Aeronautical Electronic ...

By the methods of small-angle X-ray scattering and translucent electron microscopy the existence of inhomogeneity of electron density in hydrogenated films of amorphous silicon is confirmed. The decreased density regions are extended and form a branched network of channels oriented mostly by the normal direction to the films surface. The typical size of the decreased density regions network constitutes 10 nm in the 100-800 nm films thickness range. The increase of hydrogen total partial pressure in gas mixture in case of films growth results at first in the decrease of extension of these regions and than to micropores generation in the network nodal points of the decreased electron density regions.

329

Growth, Characterization and Device Development in ...

... 9. Delay Circuits ----- N9-i 10. Main Gate Multivibrators ----- NI0-I 11. ...

1959-04-01

330

Flip-flop sequence for restoring Zeeman order in the laboratory reference frame

... eV. In some instances the spontaneous radiation from a free electron laser system was employed to obtain images. The ...

1998-03-01

331

Experimental investigations of the vortex-chain generated in the two-component plasma with the sheared flow of magnetized electrons

... spin-lattice relaxation angular momentum electronic circuits magnetic

332

Environmental scanning electron microscopy

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

2006-09-11

333

Energy resolution estimation of hemispherical deflector analyzers using electron ray-tracing code

The ElectroScan environmental scanning electron microscope (ESEM) is one of the most exciting new developments in the field of Electron Microscopy. The ESEM differs from conventional Scanning Electron Microscopes (SEM) by being able to examine materials including liquids and oils in their natural state with no prior sample preparation. Accessory equipment, cooling, heating and manipulating devices allow the manipulation of samples thus making it possible for the first time to image dynamic processes such as wetting, drying, absorption, corrosion, melting, crystallisation, curing and fracturing at high magnification. Papers concerning the historical development of the ESEM are given in a bibliography at the end of this paper. 24 refs., 18 figs.

1994-12-31

334

Enabling Lightwave Electronics with Nanotechnology ...

... Authority (Turkey) The Scientific and Technical Research Council of Turkey

2006-08-22

335

Electron-induced luminescence and x-ray spectrometer development: progress report

... Acousto-optic programmable dispersive filters (AOPDF) have been developed for optical signal processing, polarization switching in lasers, and ...

2011-03-29

336

Electron-Induced Luminescence and X-Ray Spectrometer (ELXS) System for Life Detection

The progress in the development of a surface analysis tool based on the excitation of characteristic

2003-01-01

337

Electron momentum density measurements by means of positron annihilation and Compton spectroscopy

The ELXS concept is a novel, portable, micro-instrument targeted for the detection of mineralogic

2002-01-01

338

Electron collisional detachment processes for a 250 keV D/sup -/ ion beam in a partially ionized hydrogen target

The electron momentum density is measured applying positron annihilation and Compton spectroscopy in order to get information about electron wave functions. Compton spectroscopic measurements of Pd-Ag and Cu-Zn alloy systems are carried out taking into account crystal structure, mixability, and order state. Three-dimensional momentum densities of silicon are determined in order to get better information about its electronic structure. The momentum density and the spin density of ferromagnetic nickel are investigated using angular correlation curves.

1982-01-01

339

Electron beam curable phenol-formaldehyde resin

Neutral atom beams with energies above 200 keV may be required for various purposes in magnetic fusion devices following TFTR, JET and MFTF-B. These beams can be produced much more efficiently by electron detachment from negative ion beams than by electron capture by positive ions. We have investigated the efficiency with which such neutral atoms can be produced by electron detachment in partially ionized hydrogen plasma neutralizers.

1980-09-01

340

Electron Spin Resonance Study of Manganese Ion Species Incorporated into Novel Aluminosilicate Nanospheres with Solid Core/Mesoporous Shell Structure

The novolac type phenolic resins were synthesized and electron beam curing was carried out to the prepolymer obtained by the reaction of the phenolic resin and glycidyl meth acrylate in the presence of triethylbenzyl ammonium chloride. When the prepolymer and its mixtures with monomers were irradiated using electron beams at a dose rate of 3 Mrad/sec, the curing were completed at a dose 2.5 and 3 Mrad respectively. The effects of oxygen and that of hydroxyl group in the prepolymer on electron beam curing were also examined. (author).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

341

Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds

Full Text Available

2010-12-01

342

Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds

Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds were studied by electron and proton bombardments. L{sub {gamma}1} X-rays which involve transition of 4d electrons of the valence shell were found to be sensitive to the chemical environment. The L{sub {gamma}1}/L{sub {beta}1} X-ray intensity ratio increased with an increase of the 4d electron occupation of niobium or molybdenum in niobium or molybdenum compounds, showing that the chemical effects can be ascribed to the 4d electron behavior of the metallic atom in its compounds. (orig.).

1990-12-20

343

COST EVALUATION AND COST ESTIMATING FOR ...

Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds were studied by electron and proton bombardments. L_#gamma#_1 X-rays which involve transition of 4d electrons of the valence shell were found to be sensitive to the chemical environment. The L_#gamma#_1/L_#beta#_1 X-ray intensity ratio increased with an increase of the 4d electron occupation of niobium or molybdenum in niobium or molybdenum compounds, showing that the chemical effects can be ascribed to the 4d electron behavior of the metallic atom in its compounds. (orig.).

1990-12-01

344

Band structure and electron-electron interaction in samarium monosulphide

... Accession Number : AD0833945. Title : COST EVALUATION AND COST ESTIMATING FOR SHIPBOARD ELECTRONIC EQUIPMENT. VOLUME II. ...

1967-04-01

345

Analysis of beam emittance in FEL (Free Electron Laser)

The method of augmented plane wave (APW) is used to obtain the band structure of the SmS compound in the semiconductor and metal phases. The noncentral part of the Coulomb electron-electron interaction is taken into account in the first order perturbation theory. In this case the radial part of the wave APW-function is taken as a zero approximation function. A multiplet structure of the excited configuration f"5d, which provides a good description of the X-ray photoelectron spectrum and optical spectrum epsilon_2(#omega#), is obtained. The configuration fd is calculated for the interpretation of the optical absorption spectrum of the samarium monosulfide metal phase. (author).

346

Alopecia associated with unexpected leakage from electron cone

To achieve high efficiency for the conversion of electron kinetic energy in an electron beam to electromagnetic energy in a Free Electron Laser (FEL), it is important to improve the beam quality. And hence, it is necessary to study and minimize the emittance growth of the beam. According to the requirements for the beam quality in an FEL, the author analyzed the emittance growth caused by the jump of the electric field in an accelerator, energy increase, wakefield in a waveguide, space charge effect and distribution of particles in a beam as well as the wakefield in a deflect system etc. The author also estimated the emittance change caused by the variation of the microwave field from the gun to the first accelerator for such case.

347

Absolute, cascade-free cross sections for the "2S#->#"2P transition in Zn"+ using electron-energy-loss and merged-beams methods

Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region.

1989-06-01

348

A measurement of the cross section for electron impact ionization of Ar"2"+, Kr"2"+ and Xe"2"+

Absolute, cascade-free excitation cross sections in an ion have been measured for the resonance "2S#->#"2P transition in Zn"+ using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross sections over the energy range of the calculations.

349

A Medical Integration Framework based on XML for efficient exchange and sharing of Electronic Health Record using HL7

The crossed electron-ion beams technique was used to measure absolute cross sections for single ionization of Ar"2"+, Kr"2"+ and Xe"2"+ ions at electron energies ranging from threshold to 2000 eV. In contrast to some previous measurements, the metastable contents of the ion beams were small even in the case of Xe"2"+. All measured cross section curves show significant contributions from excitation-autoionization and possibly direct ionization of inner-shell electrons. There is evidence for resonance-excitation-double-autoionization in the case of Xe"2"+. (author).

350

X-RAY MICROANALYSIS OF A RADIOACTIVE PARTICLE WITH THE AID OF THE ELECTRON MICROSCOPE

Full Text Available

2002-10-01

351

Ultra high vacuum test setup for electron gun

A radioactive particle was analyzed to discover the composition of the inactive material of the particle. The method uses the x-ray line spectrum of the K series caused by electron irradiation of the particle in the electron microscope. Iron and aluminum or silicon (the last two could not be distinguished) were found as inactive components in the particle. (D.L.C.)

1962-07-28

352

Transient enhanced diffusion of oxygen in Fe mediated by large electronic excitation

Ultra High Vacuum (UHV) test setup for electron gun testing has been developed. The development of next generation light sources and accelerators require development of klystron as a radio frequency power source, and in turn electron gun. This UHV electron gun test setup can be used to test the electron guns ranging from high average current, quasi-continuous wave to high peak current, single pulse etc. An electron gun has been designed, fabricated, assembled and tested for insulation up to 80 kV under the programme to develop high power klystron for future accelerators. Further testing includes the electron emission parameters characterization of the cathode, as it determines the development of a reliable and efficient electron gun with high electron emission current and high life time as well. This needs a clean ultra ...

2008-05-01

353

Time-resolved measurement of a self-amplified free-electron laser

Contrary to the electronic excitation induced phenomena of desorption and sputtering, we observed incorporation of oxygen in a thin Fe film during its irradiation with swift heavy ions. It is observed that the adsorbed oxygen diffuses in to the Fe film. The incorporation of oxygen and its diffusion in the bulk of the film is a manifestation of extremely large electronic energy deposition by the incident ions. It is shown that the experimentally observed high diffusivity of oxygen in Fe during irradiation is due to the existence of transient melt phase of Fe.

2003-10-15

354

The physics of Electron Beam Ion Sources

We report on a time-resolved measurement of self-amplified spontaneous emission free-electron laser (FEL) pulses. We observed that the spikes in such FEL pulses have an intrinsic positive chirp and the energy chirp in the electron bunch mapped directly into the FEL output. The measurement also provides rich information on the statistics of the FEL pulses.

2003-07-11

355

The physics of Electron Beam Ion Sources

There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th[sup 80+] and Xe[sup 53+]. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

1990-01-01

356

The issues in electronics hardening

There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th{sup 80+} and Xe{sup 53+}. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

1990-12-31

357

The first stage of the free electron laser for the Siberian center of photochemical investigations

This paper addresses the background and the continuously evolving topics of hardening and electronic components. Typical radiation environments from 1960 are described. Examples of a civilian satellite and of future particle physics colliders help illustrate hardening problems. Effects in components, limits of shielding, and three methods of providing components are described. The authors conclude by focusing on both future trends of radiation environments and anticipated progress in electronics. (authors). 10 refs., 9 figs., 4 tabs.

358

Physical mechanism in the free-electron laser

The project on the free electron laser (FEL) of continuous action of the IR-range with the average power of 100 kW for conducting photochemical studies is described. The electron energy recovery by means of a linear accelerator-recuperator (AR) is applied in the FEL. The FEL and AR basic parameters are presented. It is supposed that the above project will be accomplished in two stages: the first order FEL-AR stage and the full-scale FEL-AR one. The possibilities of applying these facilities are indicated

2000-10-17

359

Particle acceleration by stimulated emission of radiation near a solid-state active medium

In this paper some physical mechanisms are described, which determine some new free-electron laser configurations. These mechanisms comprise some physical effects of the radiant emission of an electron beam at the interaction with the medium it is crossing. They are based on the Cherenkov effect, Smith-Purcell effect, optical klystron, Rumakhov effect and limited interaction effect. (Author).

1992-09-21

360

British Library Electronic Table of Contents (United Kingdom)

We report acceleration of electrons moving in free space near an active Nd:YAG slab. The power of a non-relativistic beam of electrons has increased by more than 30% when the medium was excited. It is demonstrated experimentally that the energy gained by the electrons is linearly proportional to the energy stored in the medium. Moreover, the energy gain traces closely the population inversion inferred by monitoring the spontaneous radiation.

2011-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

361

Lagrange-Function Approach to Real-Space Order-N Electronic-Structure Calculations

High gain 10.6-micron free-electron laser amplifier

The Lagrange functions are a family of analytical, complete, and orthonormal basis sets that are suitable for efficient, accurate, real-space, order-N electronic-structure calculations. Convergence is controlled by a single monotonic parameter, the dimension of the basis set, and computational complexity is lower than that of conventional approaches. In this paper we review their construction and applications in linearscaling electronic-structure calculations.

2006-04-01

362

Full potential all electron positron lifetime calculations: assessment of local enhancement factors

A 10.6-micron wavelength free-electron laser (FEL) amplifier has been operated using a 45-MeV, 600-A electron beam from the Advanced Test Accelerator (ATA) and a 15.36-meter long electromagnetic wiggler. The peak small signal power gain was 27 dB(500). Gain guiding was observed to confine the amplified laser beam.

1988-11-02

363

Free-electron lasers and related topics

We report the implementation of positron wave function and lifetime calculations in the all-electron full-potential linearized augmented plane wave method. Calculations of lifetimes for more than 30 materials with two different forms of the enhancement factor were done and compared to prior calculations and experiment. We find that reasonable agreement with experiment can be obtained within the local density approximation when all-electron full-potential calculations are done.

2008-04-01

364

Electronic topological transition in an n-BiSb semiconductor alloy in the quantum limit range of magnetic fields for H-parallel C{sub 2}

This past year has been very exciting for the experimental free-electron laser (FEL) programs. At three Laboratories, oscillator experiments were performed with wavelengths from the visible to far infrared. The output powers are steadily advancing. The status of these programs will be discussed. As shorter wavelengths and higher powers are pursued, higher currents with improved beam quality will be required. Advanced electron linacs should be developed to meet these demands. 13 references, 5 figures, 3 tables.

1984-01-01

365

Electronic structure of the Ru(0001) surface

The galvanomagnetic properties of single-crystal samples of the Bi{sub 0.93}Sb{sub 0.07} semiconductor alloy with the electron density n = 1.6 x 10{sup 17} cm{sup -3} in magnetic fields up to 14 T at T = 1.6 K have been investigated. The resistivity {rho} and Hall coefficient R have been measured as functions of the magnetic field directed along the binary axis of a crystal for a current flowing through a sample along the bisector axis; i.e., the components {rho}{sub 22} and R{sub 32,1} have been measured. The strong anisotropy of the electron spectrum of the samples makes it possible to separately observe quantum oscillations of the magnetoresistance {rho}{sub 22}(H) for H -parallel C{sub 2} in low magnetic fields for two equivalent ellipsoids with small extremal cross sections (secondary ellipsoids) and in high magnetic fields for electrons of the ellipsoid with a large extremal cross section (main ellipsoid). An increase ...

2010-08-15

366

Electron scattering in molecular aggregates

This paper deals with the electronic structure of ruthenium. Synchrotron radiation in the range from 15 to 45 eV and angle-resolved ultraviolet photoemission are used to map the energies of the electronic states. The Fermi surface of Ru is determined using angle-resolved ultraviolet photoemission spectroscopy. The experimental results are compared with calculated photoemission spectra obtained within the framework of the one-step model of photoemission. (author)

2000-03-13

367

Electron beam and high-speed optical diagnostics for the Los Alamos HIBAF (High Brightness Accelerator FEL) Facility

In this contribution we compare the electron scattering processes observed in pure O_2 clusters and mixed clusters like O_2/Ne, O_2/Ar and O_2/N_2. The overlap and positions of the potential curves of O_2 states show the different possible electron attachment processes and also explain the formation of O_2 in clusters. (author).

1994-03-20

368

Effect of the electron-electron coupling parameters on the superconducting transition temperature in the compounds with the A-15 structure

Characterization of the electron beam's properties will be a major task after the upgrade of the Los Alamos Free-Electron Laser (FEL) Facility with a photoelectric injector (PEI) and increased acceleration capability to 40 MeV. Adjustments to the previous diagnostics package that address the lower beam emittance, higher energy, and wakefield source reduction issues will be discussed. 6 refs., 8 figs., 1 tab.

1989-01-01

369

ELECTRON MICROSCOPE PREPARATIONS OF RADIOACTIVELY LABELED AEROSOLS

The electron structure of the A-15 compounds is studied by accounting for the Hubbard energy as the highest energy parameter. The conditions for the Cooper instability origination are obtained. The superconducting transition temperature dependence on the degree of filling the d- and p-shells of the transition and nontransition elements is determined. The relationship between the transition temperature and the energy jumpover along the chains, which allows comparison with the experiment, is established. Qualitative explanation of the Mattias empiric rules is presented

2000-09-01

370

Double-electron-capture cross section for I/sup +/ in a magnesium-vapor target

A method is described to smear extremely thin layers of nuclear emulsion on labeled electron microscope preparations and to measure the thicknesses of these layers, Without further separation, preparation and emulsion can be observed after exposure and development in an electron microscope. The source of the tracks formed in the emulsion can be exactly identified and the size and structure determined. This method finds applications in dust research and also in the analysis of medical and biological sections. Further information can be obtained about properties of different emulsions. (auth)

1963-04-01

371

Differential use of two cyclic electron flows around photosystem I for driving CO₂-concentration mechanism in C₄ photosynthesis

Measurements of the double-electron-capture process in which a positive ion of iodine becomes a negative ion in a single collision with a magnesium atom are reported between 20 and 90 keV. The cross section is comparable to that for the rare gases and not as large as might be expected from a two-valence-electron atom. This process is probably insignificant in the production of negative ion beams using a magnesium-vapor target.

1987-06-15

372

Destabilization of the hot-electron precessional mode in tandem mirrors and bumpy tori

Whereas linear electron flow (LEF) in photosynthesis produces both ATP and NADPH, the cyclic electron flow (CEF) around photosystem I has been shown to produce only ATP. Two alternative routes have...Full Text Available

2005-11-15

373

Ab initio molecular dynamics with born-oppenheimer and extended lagrangian methods using atom centered basis functions

The high-frequency precessional mode of a hot-electron-stabilized magnetic configuration has previously been shown to be stable in a window of core-plasma mass. Under conditions of frequency matching, the resulting stable negative-energy precessional wave can be destabilized by coupling to positive-energy shear-Alfven waves. Coupling is avoided when the hot-electron precession frequency exceeds the core-plasma ion gyrofrequency.

374

Ab initio calculations in a uniform magnetic field using periodic supercells

In ab initio molecular dynamics, whenever information about the potential energy surface is needed for integrating the equations of motion, it is computed 'on the fly' using electronic structure calculations. For Born-Oppenheimer methods, the electronic structure calculations are converged, whereas in the extended Lagrangian approach the electronic structure is propagated along with the nuclei. Some recent advances for both approaches are discussed.

2003-06-01

375

ATLAS tile calorimeter electronics upgrade

We present a formulation of ab initio electronic structure calculations in a finite magnetic field, which retains the simplicity and efficiency of techniques widely used in first principles molecular dynamics simulations, based on plane-wave basis sets and Fourier transforms. In addition we discuss results obtained with this method for the energy spectrum of interacting electrons in quantum wells, and for the electronic properties of dense fluid deuterium in a uniform magnetic field.

2003-10-21

376

5f electron localization in metallic UPd_3

This presentation summarizes the present upgrade R&D projects in the TileCal collaboration. One project studies the possibility to divide the drawers into smaller minidrawers to simplify maintenance. There are three different front-end projects. There are also projects dealing with high voltage and low voltage distribution, projects for developing PMT dividers, low voltage electronics, data transmission and off-detector electronics.

2011-01-01

377

Total skin electron beam therapy in mycosis fungoides. Evaluation of a technique for deceleration of electron beam energy and clinical study

The electronic structure of UPd_3 has been determined by means of XPS and BIS experiments. The core level line shapes and the valence band spectra of occupied and empty states clearly reveal the localized character of the 5f electrons in this actinide compound. From these spectra their Coulomb correlation energy is found to be about 2 eV. (author).

378

Thermal electron attachment and detachment, and electron affinities

The studies using phantoms confirmed that the reduction of electron beam energy and minimization of X-ray contamination could be achieved when electron beam was interposed by an acrylic plate placed 20 cm anterior to a patient. Four patients of mycosis fungoides were treated with 8 MeV electron beam of a linear accelerator at UOEH Hospital from October 1981 to December 1986. Two of them were treated with this technique by placing 2 cm thick acrylic plate anterior to the patients and satisfactory results were obtained. Cutaneous lesions subsided remarkably with the dosage of 2000 cGy given in 2 months. Leucopenia due to bone marrow suppression was mild and the patients tolerated the treatment well.

1988-08-01

379

Theoretical study of the electronic structure of some cubic intermetallic compounds of dysprosium using the augmented plane wave method

Knighton et al. used a pulsed high pressure mass spectrometer to examine thermal electron detachment from C_6F_6"-. This technique had been used earlier for the measurement or detachment rate coefficients for azulene anions as a function of temperature. C_6F_6"- and c-C_4F_6"- have been studied by Datskos et al. using a pulsed drift tube. In our laboratory, we have used a flowing afterglow Langmuir probe (FALP) apparatus to measure the thermal electron detachment rate coefficient for c-C_4F_8"- ions at 375 K. We have also measured the electron attachment rate coefficient for c-C_4F_8 at 303 K and 375 K. (author).

1994-03-20

380

The NIST/NRL free-electron laser facility

The energy bands and the nature of the conduction electrons have been studied for three intermetallic compounds of dysprosium. e.g., DyZn, DyCu and DyRh, following the augmented plane wave method. Density of states results are given and have implications for the stability of the structure of the intermetallic compounds of dysprosium. The charge densities and the number of conduction electrons inside and outside the APW spheres in each of these compounds are calculated; it is shown that the character of conduction electrons within the Dy APW sphere is principally of d type for all the compounds. The consequence of the predominance of d electron in the conduction bands on the various physical parameters is discussed. (author).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

381

Studies of basic parameters of electron-counting detection

A free-electron laser (FEL) user facility is discussed. The FEL, which will be operated as an oscillator, will be driven by the electron beam of the racetrack microtron (RTM) that is nearing completion. Variation of the electron kinetic energy from 17 MeV to 185 MeV will permit the FEL wavelength to be tuned from 200 nm to 10 #mu#m. Performance will be enhanced by the high brightness, low energy spread, and continuous pulse nature of the RTM electron beam. The authors are designing a new injector to increase the peak current of the RTM. A 3.6-m undulator is under construction, and the 9-m optical cavity is under design. The FEL will emit a continuous train of 3-ps pulses at 66 MHz with an average power of 10--200 W, depending on the wavelength, and a peak power of up to several hundred kW. An experimental area is being prepared with up to five stations for research using the FEL beam.

1989-04-24

382

Spinal axis irradiation with electrons: Measurements of attenuation by the spinal processes

Measurements have been made of certain parameters relevant to the operation of electron-counting detectors. An experimental chamber consisting of a uniform-field drift tube and a coaxial proportional counter thas been employed to obtain data, at very low drift fields (E/p<0.02 V/cm Torr), on electron mobility and lifetimes in a range of gas mixtures. These mixtures included argon, methane, nitrogen and carbon dioxide. Measurements of single-electron spectra showed that, unexpectedly for the standard gas mixtures employed, useful departure from an exponential spectrum was not possible without the production of cathode secondaries. Although the present studies employed only the counter electrical signal the information obtained should be directly relevant to the operation of practical light-pulse systems. Examples of electron-counting spectra for soft X-rays are shown. (orig.).

1990-05-21

383

Present status of free electron laser and its utilization research facilities

Electrons may be used beneficially for spinal axis irradiation in medulloblastoma children to avoid some of the long-term sequelae induced by megavoltage photons. However, the attenuation by the intervening bone ought to be considered. Three-dimensional computer treatment planning with inhomogeneity correction for electron beams is not yet generally available, and alternate methods are needed to evaluate the attenuation by the complex bony structure of the spine. Here, we present our experimental data showing the alteration in the electron isodoses due to the intervening spinous processes. Film dosimetric measurements were made in the vertebral columns obtained from autopsies of a goat, a dog, and a child. Our results show that electron beam therapy for the spinal axis is a viable option.

1986-07-01

384

Portal localization images using computed radiography for high-energy electron beam therapy

The historical back ground of free electron laser (FEL) and the present status of development and utilization research of FEL facilities in the world are explained. Eight facilities such as Stanford Univ., UCSB, Duke Univ., Vanderbilt Univ., LANL AFEL (USA), FOM FELIX (Netherlands), N-lands LURE CLIO (France) and FELI (Japan) can be used. The principle of FEL generation process is that free electrons move in a zigzag direction to generate radio waves which interfere with each other to become monochromatic light and then free electron laser. The benefits of FEL, quality of electron beam, limit of wave length of FEL, problems and development of utilization technologies of FEL are explained. (S.Y.)

1997-11-01

385

Plasma density measurement of electron cyclotron resonance ion source for neutron generator

Portal localization images for high-energy electron beam therapy are necessary to confirm the treatment field by comparing them with a simulation image obtained before treatment or portal verification images after treatment. In this study, portal localization images were acquired using the computed radiography (CR) system and bremsstrahlung X-rays generated in the electron beam irradiations. All images obtained with phantom and the irradiations of in the electron energy of 8, 10, 12 and 15 MeV were feasible for clinical use. The CR system used in this study included general diagnostic imaging cassette and storage phosphor plate, but none of other special devices. The system can usually supply portal localization images, which maintains the quality assurance of high-energy electron beam therapy. (author)

2002-09-01

386

Picosecond pulse-conductivity technique applied to study excess-electron reactions in hydrocarbon mixtures

It is a traditional method to diagnose electron-cyclotron-resonance (ECR) plasma source, using a single probe to measure the current-voltage curve of the plasma, based on which and theoretic formula the plasma density can be computed. The article adopts a Langmuir probe having a role of emission electrons to measure two different current-voltage curves with and without emission. It is ease to get the plasma potential via the inflexion of the two curves and compute directly various physical quantities by the assistant computer, such as electron temperature, electron/ion density, plasma potential etc. The deviation is about percent 1.8 between the measurement results by traditional and the new method, but the latter has higher efficiency. (authors)

2007-12-01

387

Photo-emission-electron-microscopy for characterization of an operating organic electronic device

To measure electron reactions on a picosecond timescale the investigators developed a picosecond pulse-conductivity technique, which makes use of the electron fine-structure pulses of our LINAC (pulse width 25 vs FWHM) to produce excess electrons and now detects changes in sample conductance under optimum conditions with an instrumental response of 18 ps. This resolution is in agreement with a theoretical estimate. This technique has been successfully applied to study excess electron reactions in solvents covering a mobility range from 0.24 to 100 cm/sup 2/V/sup -1/s/sup -1/; extension to lower mobility liquids seem possible.

1983-01-01

388

Pencil-like mm-size electron beams produced with linear inductive voltage adders

Photoemission-electron-microscopy (PEEM) is introduced as a tool for the characterization of organic electronic devices. PEEM-measurements are used for imaging as well as for spectroscopic analyses by illumination with light of a Hg-lamp (4.9 eV), a D2 lamp (7.3 eV), and with synchrotron radiation for resonant photoelectron spectroscopy. We determine the charge carrier concentration inside the channel region of the organic device and its lateral distribution. From resonant photoelectron spectroscopy (RPES) we deduce the electronic states which are accessible with the Hg and D2 illumination. Photoelectron-spectroscopy at selected areas ({mu}-PES) gives information on the absolute values of surface potentials in lateral resolution. We are able to perform these studies with applied voltages at the source- and drain-electrode.

2006-01-20

389

One-electron reduction of chloroperoxidase by radiolytically generated electrons

We present the design, analysis, and results of the high brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: energy 12 MeV, current 35 endash 40 kA, rms radius 0.5 mm, and pulse duration 40 ns full width at half-maximum. The accelerator is SABRE, a pulsed linear inductive voltage adder modified to higher impedance, and the electron source is a magnetically immersed foilless electron diode. 20 endash 30 T solenoidal magnets are required to insulate the diode and contain the beam to its extremely small-sized (1 mm) envelope. These experiments are designed to push the technology to produce the highest possible electron current in a submillimeter radius beam. Design, numerical simulations, and experimental results are presented. copyright 1997 American Institute of Physics.

390

One-electron reduction of chloroperoxidase by radiolytically generated electrons

Upon irradiation of aqueous ethylene glycol/water solutions of native chloroperoxidase (CPO) with {sup 60}Co-gamma rays at 77K one observes the one-electron reduction of the enzyme active site by radiolytically generated thermolyzed electrons. In the present study the first absorption spectrum of a low-spin ferrous form of CPO is reported which has peaks at 438, 532 and 563 nm, similar to those observed previously for cytochrome P-450. All previously described ferrous forms of CPO are high spin. In order to observe the final results of the CPO reaction with electrons, the spectral changes of native enzyme after room temperature-gamma-irradiation have also been investigated. Evidence of changes is also presented probably connected with disruption of the tertiary structure of enzyme, correlated with decrease of enzyme activity.

1990-05-16

391

OBSERVATION OF NUCLEAR PARTICLE TRACKS IN THE ELECTRON MICROSCOPE

Upon irradiation of aqueous ethylene glycol/water solutions of native chloroperoxidase (CPO) with "6"0Co-gamma rays at 77K one observes the one-electron reduction of the enzyme active site by radiolytically generated thermolyzed electrons. In the present study the first absorption spectrum of a low-spin ferrous form of CPO is reported which has peaks at 438, 532 and 563 nm, similar to those observed previously for cytochrome P-450. All previously described ferrous forms of CPO are high spin. In order to observe the final results of the CPO reaction with electrons, the spectral changes of native enzyme after room temperature-gamma-irradiation have also been investigated. Evidence of changes is also presented probably connected with disruption of the tertiary structure of enzyme, correlated with decrease of enzyme activity.

1990-05-01

392

Laser Assisted Emittance Exchange: Downsizing the X-ray Free Electron Laser

A fine-grained photosensitive layer was prepared for electron- microscopic radioautography. The layer was obtained by evaporating Ag at low pressure and temperature on electron microscope grids and sensitizing the silvered grids with Br/sub 2/. The resulting particles had an average diameter of -- 100 A. The sensitivity of the layer to ionizing radiation was tested by sprinkling the grids with fine uranium aeetate particles and examining the processed grids in an electron microscope. Shont tracks and side spurs were observed which are probably due to alpha radiation from U/sup 235/ and secondary electrons scattered from the silver, respectively. Tests with P/sup 32/- phosphate are also described. (D.L.C.)

1962-08-01

393

Interplay of the chirps and chirped pulse compression in a high-gain seeded free-electron laser

A technique is proposed to generate electron beam with ultralow transverse emittance through laser assisted transverse-to-longitudinal emittance exchange. In the scheme a laser operating in the TEM10 mode is used to interact with the electron beam in a dispersive region and to initiate the emittance exchange. It is shown that with the proposed technique one can significantly downsize an x-ray free electron laser (FEL), which may greatly extend the availability of these light sources. A hard x-ray FEL operating at 1.5 {angstrom} with a saturation length within 30 meters using a 3.8 GeV electron beam is shown to be practically feasible.

2009-12-11

394

High dielectric constant ceramics for ion-electron sources

In a seeded high-gain free-electron laser (FEL), where a coherent laser pulse interacts with an ultrarelativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above-mentioned two chirps are absent. We examine the interplay of these three chirps. The problem is formulated as an initial value problem and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high-gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that to get a short pulse duration, an energy chirp in the electron ...

2007-03-01

395

Experimental and theoretical study of periodic intensity bursts in the start-up phase of a free-electron laser oscillator

Ferroelectric disks, coated with proper electrodes, can easily produce a dense plasma cloud when excited with a high-voltage pulse. This plasma can be a source of either electrons or ions depending on the sign of the extracting field set in front of the disk. We present the behavior of the disks operating at high frequency as emitters of both electrons and ions in two experimental configurations: (a) without and (b) with two screening grids. These two screening grids are inserted when the plasma must be confined within the cathode region. The system is capable of providing ion pulses of a few hundred milliamperes, whose length can range from a hundred nanoseconds to dozen microseconds. The electron pulses of energetic electrons have typically an amplitude higher than a couple of amperes. Tests at MHz repetition rate were positive as for stable operation.

2002-08-21

396

Enhanced coherent undulator radiation from bunched electron beams

In this paper experimental observations and a theoretical analysis of periodic radiation bursts and macropulse formation in the start-up phase of a free-electron laser (FEL) oscillator are presented. This microwave FEL uses a long pulse electron beam with a slowly decaying voltage. The output radiation consists of a superposition of bell-shaped macropulses, each of which is composed of a periodic sequence of short micropulses. The micropulses are separated by a cavity round-trip time. Each bell-shaped macropulse has a random start-up time and amplitude. The startup of the radiation macropulses is correlated with random current spikes on the continuous electron beam. The observed macropulse signal agrees with a theoretical calculation of the impulse response of the FEL oscillator when the shift in the FEL resonance frequency arising from the slow voltage drop of the electron beam is included in the ...

397

Electron-phonon spectral function and mass enhancement of niobium

When energetic bunches of electrons traverse an undulator field, they can spontaneously emit radiation both coherently and incoherently. Although it has generally been assumed that undulator radiation is incoherent at wavelengths short compared to the longitudinal size of the electron bunch, several recent observations have proved this assumption false. Furthermore, the appearance of coherent radiation is often accompanied by a significant increase in radiated power. Here we report observations of strongly enhanced coherent spontaneous radiation together with direct measurements, using transition radiation techniques, of the electron distributions responsible for the coherent emission. We also report demonstrated enhancements in the predicted spontaneous radiated power by as much as 6x10"4 using electron bunch compression. copyright 1996 American Institute of Physics.

1995-09-28

398

Electron-beam sensitivity study of the Los Alamos Advanced Free-Electron Laser beam line

The electron-phonon spectral distribution function #alpha#"2(#omega#) F (#omega#) has been calculated for niobium. The electron energy bands and wave functions were obtained from a self-consistent augmented-plane-wave muffin-tin potential, and the electron-phonon matrix elements were evaluated using the so-called rigid-ion approximation. With this approximation it is found that #alpha#"2(#omega#) is constant over the whole energy spectrum. The electron-phonon mass enhancement has also been calculated for local regions of the Fermi surface and found to be anisotropic. The calculated local values of the enhancement do not agree with experimental values available for different orbits from de Haas--van Alphen measurements. The discrepancy seems to arise because the bare-rigid-ion matrix elements are relatively small between states with nearly pure l = 2 character.

399

Electron stimulated desorption of anions from adsorbed and condensed CFCl_3 and CF_2Cl_2

A sensitivity study that used the particle tracking code PARMELA was performed on the Advanced Free-Electron Laser (AFEL). The tolerances on the alignment of the beam-line elements and the magnetic-field strengths were examined. Two base-line configurations were determined at the beginning of the study. The electron beam was then matched into the wiggler. The optimized beam-line parameters were varied independently and their sensitivities were judged with the criterion that the free-electron laser (FEL) effective-detuning parameter should not fluctuate more than 10%. The results of this study set the specifications for the alignment, for the sensitivity of the steering magnets, and for the accuracy of the magnetic field in the quadrupoles and dipoles. 5 figs., 3 figs., 3 tabs.

1991-01-01

400

Electron Capture Dissociation Implementation Progress in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Electron simulated desorption of anions from CFCl_3 and CF_2Cl_2 condensed on an Au substrate is studied in the energy range 0-15 eV. The negative fragments are recorded mass spectro metrically as the function of the incident electron energy. Below 10 eV we observe anion desorption via pronounced resonance profiles which are characteristic for dissociative electron attachment (DA) while the continuous rise of the signal at higher energies accounts for dipolar dissociation (DD) and processes involving secondary electrons from the metallic substrate. For both compounds F"- and Cl"- are the only fragment anions we could observe. (author).

1994-03-20

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401

British Library Electronic Table of Contents (United Kingdom)

Successful electron capture dissociation (ECD) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) applications to peptide and protein structural analysis have been enabled by constant progress in implementation of improved electron injection techniques. The rate of ECD product ion formation has been increased to match the liquid chromatography and capillary electrophoresis timescales, and ECD has been combined with infrared multiphoton dissociation in a single experimental configuration to provide simultaneous irradiation, fast switching between the two techniques, and good spatial overlap between ion, photon, and electron beams. Here we begin by describing advantages and disadvantages of the various existing electron injection techniques for ECD in FT-ICR MS. We next ...

2008-01-01

402

Defect creation by electronic processes in MgO bombarded with GeV heavy ions

Construction and development of a UV free electron laser under the cooperation of Nihon U, KEK, PNC, ETL and Tohoku U

To study the defect creation induced by electronic processes in refractory oxides, MgO single crystals were irradiated with high energy tin, uranium and lead ions. Optical absorption measurements showed that F-type centers (oxygen vacancies with trapped electrons) were created during irradiation. The total number of centers per unit area of bombarded sample increases linearly with irradiating fluence. The main part of the point defects was found to arise from electronic processes. The concentration of F-type centers induced by ionization increases with the electronic energy losses. Assuming a saturation of point defect concentration at high fluences, F-type center creation cross sections could be estimated. The influence of irradiation temperature and of the velocity of the bombarding ions are discussed.

1996-12-31

403

An Electronic Payment System to Ensure Cost Effectiveness with Easy Security Incorporation for the Developing Countries

The construction and the development of a UV free electron laser have been started under the cooperation of Nihon U, KEK, PNC, ETL and Tohaku U. The project requires a 100MeV S-band electron linear accelerator to expand the oscillation of FEL using fundamental mode to the UV region. The injection system consists of a thermionic RF-gun with a LaB cathode and an {alpha} magnet for magnetic bunching. We are studying to reduce the back-bombardment electrons to realize the macropulse length of 20{mu}sec. Electron beams, up to the energy of 100MeV, are injected into the optical oscillators. Changing the accelerating energy and/or undulator parameters, this system will cover the range from infrared to ultraviolet for the applications in various fields.

1995-12-31

404

A new aspect of superconductivity in A-15 compounds

With the rapid growth of Information and Communication Technology, Electronic commerce is now acting as a new means of carrying out business transactions through electronic means such as Internet environment. To avoid the complexities associated with the digital cash and electronic cash, consumers and vendors are looking for credit card payments on the Internet as one possible time-tested alternative. This gave rise of the on-line payment processing using a third-party verification; which is not suitable for the developing countries in most of the cases because of the excessive costs associated with it for maintenance and establishment of an online third-party processor. As a remedy of this problem, in this paper, we have proposed a framework for easy security incorporation in credit card based electronic payment system without the use of an on-line third- party processor; which tends to be low cost and ...

2006-01-01

405

5f electron localization-delocalization transition from UPd_3 to UPt_3

We present a new aspect of superconductivity in A-15 compounds which is able to explain their exceptional role among the high Tc superconductors. The basic idea is that a strong energy dependence of the the electronic density of states near the Fermi level may greatly reduce the repulsive part of the frequency dependent electron-phonon interaction. This leads to a large enhancement of Tc which is a maximum when the Fermi energy is comparable to a typical phonon energy. Our findings are based on numerical solutions of the Eliashberg equations where both the retardation of the electron-phonon coupling and the energy dependence of the electronic density of states have been included. For the electronic density of states we use the models of Labbe and Friedel and of Cohen et al., while the shape of the Eliashberg function #alpha#"2F(#omega#) is taken from the tunneling results of Shen. ...

406

Valence-electron configuration of Ti and Ni in TixNi1-x alloys from Kbeta-to-Kalpha X-ray intensity ratio studies.

The electronic structures of URh_3, UPd_3, UPt_3 and UAu_3 are calculated with the self-interaction-corrected local-spin-density approximation. We find that only in URh_3 the f-electrons are fully delocalized. UPt_3 has one f-electron localized at each U site, whilst a localized f"2 configuration of the U-ion is found for UPd_3. It is predicted that upon application of pressure, UPd_3 will acquire the f"1 configuration and possibly exhibit heavy-fermion behaviour. We find that UAu_3 is characterized by the same mixed localized-delocalized f-electron manifold as UPd_3. (author)

2002-07-01

407

Valence-electron configuration of Ti and Ni in TixNi1-x alloys from K?-to-K? X-ray intensity ratio studies

Kbeta-to-Kalpha X-ray intensity ratios of Ti and Ni have been measured in pure metals and in alloys of Ti(x)Ni(1-x) (x=0.7, 0.6, 0.5, 0.4 and 0.3) following excitation by 22.69 keV X-rays from a 10 mCi (109)Cd radioactive point source. The valence-electron configurations of these metals were determined by corporation of measured Kbeta-to-Kalpha X-ray intensity ratios with the results of multiconfiguration Dirac-Fock calculation for various valence-electron configurations. Valence-electron configurations of 3d-transition metals in alloys indicate significant differences with respect to the pure metals. Our analysis indicates that these differences arise from delocalization and/or charge transfer phenomena in alloys. Namely, the observed change of the valence-electron configurations of metals in alloys can be explained with the transfer of 3d electrons from one element to the other ...

2010-01-28

408

The validity of the density scaling method in primary electron transport for photon and electron beams

K?-to-K? X-ray intensity ratios of Ti and Ni have been measured in pure metals and in alloys of TixNi1-x (x=0.7, 0.6, 0.5, 0.4 and 0.3) following excitation by 22.69 keV X-rays from a 10 mCi 109Cd radioactive point source. The valence-electron configurations of these metals were determined by corporation of measured K?-to-K? X-ray intensity ratios with the results of multiconfiguration Dirac-Fock calculation for various valence-electron configurations. Valence-electron configurations of 3d-transition metals in alloys indicate significant differences with respect to the pure metals. Our analysis indicates that these differences arise from delocalization and/or charge transfer phenomena in alloys. Namely, the observed change of the valence-electron configurations of metals in alloys can be explained with the transfer of 3d electrons from one element to the other element and/or the ...

2010-06-01

409

Studies on the electronic structure of some cubic intermetallic compounds of dysprosium following the self-consistent augmented-plane-wave method

In the convolution/superposition method of photon beam dose calculations, inhomogeneities are usually handled by using some form of scaling involving the relative electron densities of the inhomogeneities. In this paper the accuracy of density scaling as applied to primary electrons generated in photon interactions is examined. Monte Carlo calculations are compared with density scaling calculations for air and cork slab inhomogeneities. For individual primary photon kernels as well as for photon interactions restricted to a thin layer, the results can differ significantly, by up to 50%, between the two calculations. However, for realistic photon beams where interactions occur throughout the whole irradiated volume, the discrepancies are much less severe. The discrepancies for the kernel calculation are attributed to the scattering characteristics of the electrons and the consequent oversimplified modeling used in the ...

410

Radiotherapy for ocular lesions by electron beam therapy

The energy bands and the nature of the conduction electrons have been studied for two intermetallic compounds of dysprosium, i.e, DyZn and DyRh, following the self-consistent augmented-plane-wave (APW) method. The convergence of energy was found to be rapid for DyZn because the shell of 3d"1"0 electrons for Zn lies below the conduction band. The Fermi energies (E/sub F/) have been calculated to be 0.421 and 0.477 Ry for DyZn and DyRh, respectively. The densities and the numbers of conduction electrons inside and outside the APW spheres in each of these compounds are calculated, and it is shown that the character of conduction electrons inside the APW sphere of Dy is predominantly of d type. In order to see the accuracy of these results, self-consistent calculations were done for DyZn for different choices of the exchange potentials, and the calculated number of conduction electrons ...

411

Quantum computing using molecular electronic and vibrational states

Radiotherapy can be very significant as the treatment for ocular lesions, eyes need to be preserved as properly as possible on their functions and cosmetics. The application of conventional X ray therapy has been gradually abandoned as conventional X ray therapy ceased to be accepted as the general treatment for malignant tumors. Consequently the necessity of electron beam therapy has been rising even as the substituted method for conventional X ray therapy. The department of radiology of Gunma University was obliged to establish a new therapy for ocular lesions, and has been trying electron beam therapy since 1973. It is concluded that electron beam therapy is not at all inferior to conventional X ray therapy as reported above. Basic therapeutic methods for ocular lesions are the following: 1) For epidermoid carcinoma, 600 rads at a time, 3600 - 4200 rads in total is applied by 8 MeV electron twice a ...

1981-11-01

412

Physics of electron beam therapy

We numerically constructed elementary phase-correct global quantum gates by using molecular electronic and vibrational states to encode two qubits and implement the Deutsch-Jozsa algorithm. The calculations were based on optimal control theory (OCT). The molecular species we chose were Na{sub 2} and Li{sub 2}. The electronic X{sup 1}{sigma}{sub g}{sup +} and A{sup 1}{sigma}{sub u}{sup +} states were taken as two orthonormalized energy levels of the electronic qubit. The vibrational qubits were those involved in these electronic states. The time duration of the optimized pulses with high fidelity was typically 500-900 fs, which reflects the wavepacket dynamics in electronically ground and excited states. When implementing the Deutsch-Jozsa algorithm by combining these elementary gates, we obtained a maximum probability 83.12% for Li{sub 2} molecule, which indicates that the ...

2008-01-22

413

Electron and ion beam effects in amorphous SiO_2 and Si_3N_4 films for electronic devices

A book has been written to introduce the physical aspects of the radiotherapy electron beam by presenting a summary of the developments in this field. The first chapter is a brief introduction to the technology of medical accelerators with emphasis on the electron beam production facilities. Chapter 2 describes the interaction processes at the atomic level once the electron beam enters the medium. Chapter 3 is concerned with the various properties of the electron beam purely from the clinical point of view. The electron beam algorithms and models for distribution calculations are covered in Chapter 4 with inclusion of age diffusion and multiple scattering approaches. The factors affecting the beam distribution in a patient, with inhomogeneities, surface irregularities, backscattering etc. are discussed in Chapter 5. The last two chapters are devoted to electron ...

414

Electron and ion beam effects in amorphous SiO/sub 2/ and Si/sub 3/N/sub 4/ films for electronic devices

The effect of electron and ion beam irradiation on the Sisub(LVV) Auger spectra of SiO_2, Si_3N_4 and Si-oxynitride films was measured by the relative intensity of the 92 eV signal, characteristic for the formation of 'free' silicon during irradiation. While in Si-oxynitride the beam effects were almost negligible, some damage was found in Si_3N_4, but SiO_2 appeared to be extremely sensitive for electron and ion beam irradiation. By low energy electron loss spectroscopy of ion bombarded SiO_2 and Si_3N_4 films new electron states due to broken Si-O and Si-N bonds could be determined within the band gap of the insulators. The measured energy losses were interpreted by means of electron energy level schemes of the amorphous films. (author).

1982-01-01

415

Design of electron beam accelerators for microwave application

The effect of electron and ion beam irradiation on the Sisub(LVV) Auger spectra of SiO/sub 2/, Si/sub 3/N/sub 4/ and Si-oxynitride films was measured by the relative intensity of the 92 eV signal, characteristic for the formation of 'free' silicon during irradiation. While in Si-oxynitride the beam effects were almost negligible, some damage was found in Si/sub 3/N/sub 4/, but SiO/sub 2/ appeared to be extremely sensitive for electron and ion beam irradiation. By low energy electron loss spectroscopy of ion bombarded SiO/sub 2/ and Si/sub 3/N/sub 4/ films new electron states due to broken Si-O and Si-N bonds could be determined within the band gap of the insulators. The measured energy losses were interpreted by means of electron energy level schemes of the amorphous films.

1982-10-01

416

Design of electron beam accelerator for microwave application

Relativistic electron beams are used for generating high power microwaves. These microwave sources require electron beam generators spanning significant ranges in voltage and impedance. The pulsed power technology used to generate these electron beams is presented. Electron beam generators that produce beams with pulse durations in the 10-ns to 100-ns regime consist of an energy-storage section, pulse-shaping section, and an electron beam diode. The energy-storage section is either a Marx generator or capacitor bank-pulsed transformer. The pulse shaping is done with high-voltage transmission lines. The electron beam diode is usually a cold-cathode, space-charge-limited flow device. For longer pulses (/approximately/1 ..mu..s) the energy storage and pulse chaping can be combined. Lumped-element pulse-forming networks (PFN) can be designed to produce the desired ...

1988-07-01

417

Micro area analysis and measurement of electronic device material (challenge to utmost limits). Characterization of interface elect`ron structure by photon-and electron-spectroscopies; Denshi debaisu yo zairyo no bisho ryoiki bunseki-keisoku (kyokugen eno chosen). Koshi-denshi bunkoho ni yoru kaimen denshi jotai hyoka

Relativistic electron beams are used for generating high power microwaves. These microwave sources require electron beam generators spanning significant ranges in voltage and impedance. The pulsed power technology used to generate these electron beams is presented. Electron beam generators that produce beams with pulse durations in the 10 ns to 100 ns regime consist of an energy storage section, pulse shaping section, and an electron beam diode. The energy storage section is either a Marx generator or capacitor bank-pulsed transformer. The pulse shaping is done with high-voltage transmission lines. The electron beam diode is usually a cold-cathode, space-charge-limited flow device. For longer pulses (approx.1 ..mu..s) the energy storage and pulse shaping can be combined. Lumped-element pulsed-forming networks (PFN) can be designed to produce the desired pulse ...

1988-01-01

418

Electron acceleration in supernova remnants and diffuse gamma rays above 1 GeV

A method for detecting electrons emitted as secondary particles by photon incidence to a specimen, as well as a method of using the photons emitted by electron incidence as detecting particles are explained. Pd-Si(100)2{times}1 system is adopted for a case study of using photo-electron spectroscopy where synchrotron emitted light in soft X-ray region is used as the incident light. Pd atoms are deposited little by little on clean Si surface to investigate the electron structure of the surface, and the interface electron structure after bonded formation of Pd(thin film)-Si(substrate) is estimated. Radiation soft X-ray spectroscopy is employed to observe the real state of the bonded interface of Pd(thin film)-Si(substrate) prepared by depositing Pd film in a short period of time. In the case of radiation soft X-ray spectroscopy with electron beam excitation, bonded ...

1995-07-20

419

DEFF Research Database (Denmark)

The recently observed X-ray synchrotron emission from four supernova remnants (SNRs) has strengthened the evidence that cosmic-ray electrons are accelerated in SNRs. We show that if this is indeed the case, the local electron spectrum will be strongly time-dependent, at least above roughly 30 GeV. The time dependence stems from the Poisson fluctuations in the number of SNRs within a certain volume and within a certain time interval. As far as cosmic-ray electrons are concerned, the Galaxy looks like actively bubbling Swiss cheese rather than a steady, homogeneously filled system. Our finding has important consequences for studies of the Galactic diffuse gamma-ray emission, for which a strong excess over model predictions above 1 GeV has recently been reported. While these models relied on an electron injection spectrum with index 2.4 (chosen to fit the local electron flux up to 1 ...

1998-01-01

420

Magnetic resonance imaging. Handbook and atlas; Kernspintomographie. Kompendium und Atlas

Rare earth metal rich magnesium compounds RE4NiMg (RE=Y, Pr-Nd, Sm, Gd-Tm, Lu)-Synthesis, structure, and hydrogenation behavior

Magnetic resonance imaging (MRI) as a diagnostic imaging tool relies on the generation of magnetic fields, whereas the computerized tomography (CT) uses X-radiation. The fundamental principle of MRI is the magnetic resonance of paramagnetic atomic nuclei. These nuclei, as e.g. protons (= hydrogen nuclei), are aligned in required orientation by application of a strong magnetic field. Upon simultaneous application of an electromagnetic high-frequency field perpendicular to the axis of the basic magnetic field, and in response to periodical changing of the electromagnetic field at a given frequency, the originally aligned paramagnetic nuclei are forced into a movement similar to that of a ``whipping top``. When the resonance frequency is shut off, the nuclei return to their former, aligned positions, inducing a weak signal in a coil. The series of signals generated by multiple repetition of this process of excitation of nuclei and their return to ...

1999-10-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

421

Phase diagram of SrO-InO1.5-CoOx and a new compound Sr3In0.9Co1.1O6

The rare earth metal rich compounds RE4NiMg (RE=Y, Pr-Nd, Sm, Gd-Tm, Lu) were synthesized from the elements in sealed tantalum tubes in an induction furnace. All compounds were investigated by X-ray diffraction on powders and single crystals: Gd4RhIn type, space group F4-bar 3m, Z=16, a=1367.6(2) pm for Y4NiMg, a=1403.7(3) pm for Pr4NiMg, a=1400.7(1) pm for Nd4NiMg, a=1386.5(2) pm for Sm4NiMg, a=1376.1(2) pm for Gd4NiMg, a=1362.1(1) pm for Tb4NiMg, a=1355.1(2) pm for Dy4NiMg, a=1355.2(1) pm for Ho4NiMg, a=1354.3(2) pm for Er4NiMg, a=1342.9(3) pm for Tm4NiMg, and a=1336.7(3) pm for Lu4NiMg. The nickel atoms have trigonal prismatic rare earth coordination. These NiRE6 prisms are condensed via common edges to a three-dimensional network which leaves voids for Mg4 tetrahedra and the RE1 atoms which show only weak coordination to the nickel atoms. The single crystal data indicate two kinds of solid solutions. The RE1 positions reveal small RE1/Mg mixing and some compounds also show Ni/Mg ...

2009-02-01

422

Strain enhanced electron spin polarization observed in photoemission from InGaAs

Sr3In0.9Co1.1O6, isostructural to Ca3Co2O6, is revealed by the study of the phase relations in the system SrO-InO1.5-CoOx (1000 oC). The structure of Sr3In0.9Co1.1O6 is refined by the combination of powder X-ray and neutron diffraction. Sr3In0.9Co1.1O6 crystallizes in a trigonal lattice with the cell parameters a=b=9.59438(3) A, c=11.02172(4) A with the space group R-3c. Its structure possesses 1D (In/Co)O3 chains running along the c-axis constructed by alternating face-sharing CoO6 octahedra and (In0.9Co0.1)O6 trigonal prisms. The co-occupation of In3+ and Co3+ at the trigonal prismatic site is evidenced by elementary analysis and determined by the structure refinement. Sr3In0.9Co1.1O6 is paramagnetic, and the susceptibility is consistent with the occupation of Co3+ at 10% of the trigonal prismatic positions in a high spin state (HS, S=2). The HS Co3+ is well separated by diamagnetic CoO6 octahedra and InO6 trigonal prisms and shows a g factor of 2.0 in the ...

2011-04-01

423

Radial distribution of superthermal electrons measured with ECE (abstract)

Electron spin polarization in excess of 70% has been observed in photoemission from a 0.1 #mu#m-thick epitaxial layer of In_xGa_1_-_xAs with x #approx# 0.13 grown on a GaAs substrate. Under these conditions, the epitaxial layer is expected to be highly strained by the 0.9% lattice mismatch, as confirmed by x-ray diffractometer measurements of the lattice parameter. The electron polarization and the quantum efficiency have been measured as a function of the excitation photon energy from 1.25 to 2.0 eV. A significant enhancement of the electron polarization occurs in the vicinity of 1.33 eV where the expected strain-induced level splitting permits optical excitation of a single band transition. Measurements made on a control sample of 1.14 #mu#m thickness, significantly larger than the critical thickness for pseudomorphic strain, show no polarization enhancement. These measurements represent the first observation of ...

1991-05-06

424

To aid in the study of lower hybrid current drive as a means of current profile control, the radial profile and velocity distribution of the fast current-carrying electrons and their time evolution must be known. As part of the recent effort to understand this fast electron transport, a diagnostic has been installed on PBX-M to measure the electron cyclotron emission from the fast electrons. An oblique horizontal view of upshifted cyclotron emission in the midplane can give radial as well as velocity space information about the fast electrons. Emission in X mode frequencies refracted by the right-hand cutoff is radially localized. The observed emission at a specific frequency comes only from the radial region r_t_u_r_n=#0. Emission measured by this new diagnostic has been found to be radially localized as predicted. It is also expected that localized moments of the distribution ...

0854-01-01

425

MicroDiffraction in the Scanning Electron Microscope (SEM)

Many important advances in the physics of strongly correlated electron systems have been driven by the development of new materials: for instance the filled skutterudites MT4X12 (M=alkali metal, alkaline earth, lanthanide, or actinide; T=Fe, Ru, or Os; X=P, As, or Sb), certain lanthanide and actinide intermetallic compounds such as URu2-xRexSi2 and CeTIn5 (T=Co, Rh, or Ir), and layered oxypnictides and related materials. These types of complex multinary d- and f-electron compounds have proven to be a vast reservoir of novel strongly correlated electron ground states and phenomena. In these materials, the occurrence of such a wide range of ground states and phenomena arises from a delicate interplay between competing interactions that can be tuned by partial or complete substitution of one element for another, as well as the application of pressure, and magnetic fields, resulting in rich and complex ...

2009-10-15

426

Merged-beams energy-loss technique for electron-ion excitation: Absolute total cross sections for O"5"+(2s#->#2p)

The identification of crystallographic phases in the scanning electron microscope (SEM) has been limited by the lack of a simple way to obtain electron diffraction data of an unknown while observing the micro structure of the specimen. With the development of Charge Coupled Device (CCD) based detectors, backscattered electron Kikuchi patterns (BEKP), alternately referred to as electron backscattered diffraction patterns (EBSP), can be easily collected. Previously, BEKP has been limited to crystallographic orientation studies due to the poor pattern quality collected with video rate detector systems. With CCD detectors, a typical BEKP can now be acquired from a micron or sub-micron-sized crystal using an exposure time of 1-10 seconds with an accelerating voltage of 10-40 kV and a beam current as low as 0.1 nA. Crystallographic phase analysis using BEKP is unique in that the properly equipped SEM permits ...

1997-12-31

427

Measurements of fluctuations in the flux of runaway electrons to the PLT limiter

A merged-beams electron-energy-loss technique is described, by which absolute cross sections can be measured for near-threshold electron-impact excitation of multipy charged ions. Results are reported here for absolute total electron-impact excitation cross sections for the O"5"+(2s#->#2p) transition from below threshold to 1.6 eV above threshold. The experimental data are in good agremeent with a seven-state close-coupling calculation throughout the energy range of the experiment. Results agree with calculations showing that more than 90% of the electrons causing excitation are ejected in the backward direction in the center-of-mass frame. This backscattering is shown in both quantum-mechanical and semiclassical calculations. Evidence is observed for high-lying metastable autoionizing states with a lifetime of approximately 0.9 #mu#s which are made to ionize by electron impact.

428

Measurements and elimination of Cherenkov light in fiber-optic scintillating detector for electron beam therapy dosimetry

Fluctuations in the flux of runaway electrons to the limiter have been measured during many PLT discharges. Oscillations at 60, 120, and 720 Hz are driven by variations in the vertical magnetic field which moves the plasma major radius. Fluctuations are seen in the range of 2 ..-->.. 20 kHz due to MHD magnetic islands which extend to the plasma surface. A continuous spectrum of fluctuations is observed up to 200 kHz which correlates with drift-wave turbulence. The magnitude of the driven fluctuations can be used to measure transport properties of the runaway electrons. The amplitude of electron motion due to the MHD and drift-wave oscillations, and hence a measure of the radial size of the instability, can be determined as a function of frequency. The slope of the frequency power spectrum of the drift-wave-induced fluctuations steepens with increasing runaway electron drift orbit displacement during ...

1982-07-01

429

Low-energy measurements of electron capture by multicharged ions from excited hydrogen atoms

In this study, a miniature fiber-optic radiation detector has been developed using a water-equivalent organic scintillator for electron beam therapy dosimetry. Usually, two kinds of light signals such as fluorescent and Cherenkov lights are generated in a fiber-optic radiation detector when a high-energy electron beam is irradiated. The fluorescent light signal is produced in the scintillator and is transmitted through a plastic optical fiber to a remote light-measuring device such as a PMT or a photodiode. The Cherenkov light could be also produced in the plastic optical fiber itself and be detected by a light-measuring device. Therefore, it could cause problems or limit the accuracy of the detection of a fluorescent light signal that is proportional to dose. The objectives of this study are to measure, characterize and eliminate Cherenkov light generated in a plastic optical fiber used as a component of a fiber-optic radiation detector and to ...

2007-08-21

430

Inelastic electron--dipole-molecule scattering at sub-milli-electron-volt energies: Possible role of dipole-supported states

For very low collision energies electron capture from excited hydrogen by multicharged ions is characterized by enormous cross sections, the predicted maximum being comparable to the geometric size of the Rydberg atom. The ion-atom merged-beams technique is being used to study these collisions for the variety of charge states and the wide range of energies (0.1 to 1000 eV/amu) accessible to the apparatus. A neutral D beam containing a Rydberg atom population proportional to 1/n"3 is produced by collisional electron detachment of 8 keV D"- in N_2 gas. An applied electric field results in the range (n=24--11) depending on the strength of the field applied. This beam is then merged with O"3"+ or O"5"+ ion beams at low relative collision velocities where the resultant beam-beam signal of D"+ due to electron loss is dominated by electron capture. From the sharp decrease in the observed beam-beam signal as ...

431

High frequency limit of vacuum microelectronic grating free-electron laser

Studies of collisions between Rydberg atoms with values of principal quantum number n in the range 100 approx-lt n approx-lt 400 and H_2S and C_6H_5NO_2 are reported. These targets were selected because they have very different dipole moments: 0.97 and 4.22 D, respectively. Analysis of the data using the essentially-free-electron model shows that at micro-electron-volt energies the cross sections for rotationally inelastic electron scattering by these targets have very different energy dependences. This difference suggests that, in the case of C_6H_5NO_2, dipole-supported states might be important in the scattering. To examine this further, the data are compared with the results of calculations using a free-electron cross section that assumes the presence of dipole-supported states, and it is demonstrated that, with a reasonable choice of parameters, it is possible to reproduce the experimental ...

432

Free electron laser and accelerator

The dependencies that limit high frequency operation of a vacuum microelectronic grating free-electron laser are examined. The important parameters are identified as the electron beam energy, emittance, and generalized perveance. The scaling of power with emittance and frequency is studied in the far-infrared spectral range using a modified scanning electron microscope (SEM) and submillimeter diffraction gratings. The SEM is suited to the task of generating and positioning a low emittance (10"-"2#pi#-mm-mrad), low current (100 #mu#A), but high current density (50-500 A cm"-"2) electron beam. It has been used to demonstrate the spontaneous emission process known as the Smith-Purcell effect. A vacuum microelectronic grating free-electron laser has the potential of generating radiation throughout the entire far-infrared spectral range which extends from approximately 10 to 10"3#mu#m. ...

1995-08-21

433

Dosimetric properties of an applicator system for intraoperative electron-beam therapy utilizing a Clinac--18 accelerator

The present report addresses several aspects of the free electron laser (FEL) and accelerator, including their features, potentials, mechanisms, beams emitted from undulator, FEL produced by helical mangnetic field, major problems with FEL, etc. In FEL, relativistic electron beams interact with an electromagnetic field with periodically changing intensity to produce coherent electromagnetic waves with variable wavelength. The capability of varying its wavelength represents the greatest advantage over conventional lasers. Any periodic magnetic field can serve as a wiggler. A wiggler can be used both in an amplifier and oscillator. A periodic magnetic field used may be either of a parallel type or of a helical type. The polarization of emitted beams depends on the shape of the magnet regardless of whether its field is parallel or helical. An equation is derived in the report which expresses the wavelength of an electromagnetic wave produced by an ...

1988-08-01

434

Dosimetric characteristics of backscattered electrons in lead

A prototype electron applicator system providing circular and rectangular fields for use in intraoperative electron beam therapy with a Varian Clinac 18 linear accelerator has been fabricated. The dosimetric properties of this system for a variety of electron-beam energies, applicator sizes, and x-ray collimator settings was documented. Significant findings include: (a) surface dose values are in excess of 90% for electron energies of 12 MeV and above; (b) for the 18-MeV beam, the deepest depth where the central axis dose is 90% of its maximum value is in excess of 50 mm for circular applicators whose diameters are in excess of 5 cm; and (c) the treatment time to deliver 1000 rads ''given dose'' (at a given dose rate of 300 MU/min) is on the order of 3--4 min. Cross-field behavior is acceptable for the intended application and x-ray contamination is less than 4% for any ...

435

Dose planning and dose delivery in radiation therapy

In electron beam therapy, tissue overdose due to electrons backscattered from lead has been profusely studied. To quantify this dose enhancement effect, an electron backscatter factor (EBF) wasdefined as the ratio of dose at the tissue-inhomogeneity interface with and without the scatterer present. The dependence of the EBF on energy at the scatterer surface is not well known for energies lower than 3 MeV which is the most frequent clinical situation. In this work, we have done Monte Carlo calculations with the GEANT code to study EBF in lead at this energy range. The applicability of this code and the developed procedure for dose estimation has been experimentally verified. The dependence of the EBF on the beam energy incident on the scatterer has been studied for different nominal beam energies incident at the phantom's surface. The results show a trend of increase of EBF with the beam energy incident on the ...

2000-07-01

436

Thomson scattering: a powerful diagnostic tool of plasma physics

A method has been developed for calibration of CT-numbers to volumetric electron density distributions using tissue substitutes of known elemental composition and experimentally determined electron density. This information have been used in a dose calculation method based on photon and electron interaction processes. The method utilizes a convolution integral between the photon fluence matrix and dose distribution kernels. Inhomogeneous media are accounted for using the theorems of Fano and O'Connor for scaling dose distribution kernels in proportion to electron density. For clinical application of a calculated dose plan, a method for prediction of accelerator output have been developed. The methods gives the number of monitor units that has to be given to obtain a certain absorbed dose to a point inside an irregular, inhomogeneous object. The method for verification of dose distributions outlined in ...

2008-08-01

437

The AMS-02 electromagnetic calorimeter

Thomson scattering is the process in which a low-energy photon scatters from a free electron. When a laser pulse propagates through a plasma, the spectrum of the scattered light due to the Thomson scattering is proportional to the power spectrum of the electron density fluctuations, i.e., dynamic form factor, from which various plasma parameters can be inferred, such as electron temperature and plasma flow velocity. After years of development. Thomson scattering has now become a powerful diagnostic tool of plasma physics. (authors)

2008-08-01

438

Some physical considerations in whole skin electron beam therapy

The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a lead-scintillating fibers sampling calorimeter characterized by high granularity that allows to image the longitudinal and lateral showers development, a key issue to provide high electron/hadron discrimination. The light collection system and the FE electronics are designed to let the calorimeter operate over a wide energy range from few GeV up to 1 TeV. A full-scale prototype of the e.m. calorimeter was tested at CERN in October 2001 using electrons and pions beams with energy ranging from 3 to 100 GeV. Effective sampling thickness, linearity and energy resolution were measured. (8 refs).

2002-01-01

439

Self-organized amorphous material in silicon (0 0 1) by focused ion beam (FIB) system

The short range of low-energy electrons has made them suitable for the treatment of skin lesions, especially when extensive areas must be irradiated with special considerations to save the normal underlying tissue. This report covers some salient features of total body electron irradiation: the construction of the large fields required, x-ray contamination levels, and multiple-field techniques. While the investigation is essentially experimental, we also indicate the results of calculations. We conclude most generally that treatment planning with whole skin irradiations can be as precise as with smaller fields.

1982-09-01

440

Self-organized amorphous material in silicon (0 0 1) by focused ion beam (FIB) system

A method using a focused ion beam (FIB) to prepare a silicon amorphous material is presented. The method involves the redeposition of sputtered material generated during the interaction of the Ga{sup +} ion beam with a silicon substrate material. The shape and dimensions of this amorphous material are self-organized and reproducible. The stability of this amorphous material under electron irradiation was investigated in the transmission electron microscopy (TEM). Electron irradiation can induce recrystallization of the amorphous material, resulting in the lateral and vertical growth, starting at an amorphous-crystalline interface, of polysilicon containing defects.

2005-12-15

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

441

Reflection of electromagnetic waves by a nonuniform plasma layer covering a metal surface

A method using a focused ion beam (FIB) to prepare a silicon amorphous material is presented. The method involves the redeposition of sputtered material generated during the interaction of the Ga"+ ion beam with a silicon substrate material. The shape and dimensions of this amorphous material are self-organized and reproducible. The stability of this amorphous material under electron irradiation was investigated in the transmission electron microscopy (TEM). Electron irradiation can induce recrystallization of the amorphous material, resulting in the lateral and vertical growth, starting at an amorphous-crystalline interface, of polysilicon containing defects.

2005-12-15

442

Radiation control aspects of the civil construction for a high power free electron laser (FEL) facility

Reflection coefficients of electromagnetic waves in a nonuniform plasma layer with electrons, positive ions and negative ions, covering a metal surface are investigated by using the finite-difference-time-domain method. It is shown that the reflection coefficients are influenced greatly by the density gradient on the layer edge, layer thickness and electron proportion, i.e., the effect of the negative ions. It is also found that low reflection or high attenuation can be reached by properly choosing high electron proportion, thick plasma layer, and smooth density gradient in the low frequency regime, but sharp density gradient in the high frequency regime. (authors)

2008-07-01

443

Prospects for lithium imaging using annular bright field scanning transmission electron microscopy: A theoretical study

The paper discusses some of the assumptions and methods employed for the control of ionizing radiation in the specifications for the civil construction of a planned free electron laser facility based on a 200 MeV, 5 mA superconducting recirculation electron accelerator. Consideration is given firstly to the way in which the underlying building configuration and siting aspects were optimized on the basis of the early assumptions of beam loss and radiation goals. The various design requirements for radiation protection are then considered, and how they were folded into an aesthetically pleasing and functional building. copyright 1997 American Institute of Physics.

1996-11-06

444

British Library Electronic Table of Contents (United Kingdom)

There is strong interest in lithium imaging, particularly because of its significance in battery materials. However, light atoms only scatter electrons weakly and atomic resolution direct imaging of lithium has proven difficult. This paper explores theoretically the conditions under which lithium columns can be expected to be directly visible using annular bright field scanning transmission electron microscopy. A detailed discussion is given of the controllable parameters and the conditions most favourable for lithium imaging.

2011-01-01

445

Positron-Electron Pair Creation Near Threshold

Polarizing a stored proton beam by spin flip?

Positron-electron pair creation near the threshold energy is extremely difficult to investigate by both experiments and theory. First test experiments were performed at the ILL to determine the cross sections for positron-electron pair creation near threshold using prompt {gamma}-rays from different targets after neutron capture and conventional radioactive sources. Pair creation was studied in a Ge detector, which simultaneously acted as sample and detector. First results are presented which show a significant deviation from theoretical values near threshold.

2009-01-28

446

Plasma production and flow in negative ion beams

We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

2009-04-27

447

Plasma Dynamics in the Vicinity of the Local Plasma resonance Point Excited by Pumping Electric Field or Modulated Electron Beam

Plasma generated in low-density vapor by a negative ion beam has been studied experimentally and computationally. We show that space charge neutralization of the beam occurs at very low vapor density, and that correspondingly the electron density may be much less than the beam and plasma ion densities. When there is a large local gas density, as in a charge changing cell, the resulting high electron density is also localized to the same region. Therefore, very few electrons will reach a negative ion accelerator even if it is placed one or two beam diameters from such a cell.

1977-09-21

448

Picosecond timing of terawatt laser pulses with the SLAC 46 GeV electron beam

Excitation of the HF electric field in the local plasma resonance region (LPRR) of inhomogeneous plasma by pumping electric field or modulated electron beam results to appearance of the ponderomotive force that presses plasma out of this region. Density cavity is formed in the LPRR due to this field. Further dynamics in this region depends on the plasma properties. For plasma with hot electrons ion-acoustic pulses run away from the cavity. at the local density maximum the new peak of electric field is excited. It results to the formation of new density cavity, etc. For isothermal plasma the density jump is formed.

2006-01-01

449

Phonon damping by and Raman scattering from interband electronic excitations in normal and superconducting A-15 compounds

We report on the collision of 1.5 ps (FWHM) laser pulses traversing at 17 a short similar 7 ps (FWHM) 46.6 GeV electron bunch. The phase-locked system used to maintain the correct timing of the laser pulses and the appropriate diagnostics are described. The jitter between the laser and electron pulses is determined from the stability of the observed rate of Compton scatters and can be described by a Gaussian distribution with #sigma#_j#approx =#2.2 ps. (orig.).

450

On the influence of silicon oxide nanoparticles on the optical and surface properties of hybrid (inorganic-organic) barrier materials

Raman scattering measurements of the Esub(g) and Tsub(2g) optical phonons in V"3Si, Nb"3Sn, V"3Ge, Cr"3Si, V"3Pt, and Nb"3Pt are presented and discussed in terms of interaction with interband electronic excitations. Data on superconducting Nb"3Sn is presented and modifications to the phonon spectral function and the spectrum of Raman active interband electronic excitations in the superconducting state are discussed. (orig.).

451

Nondestructive transfer of complex molecular systems of various origins into aerosol phase by means of submillimeter irradiation of free-electron laser (FEL) of the Siberian center for photochemical research

One of the major scientific and technological challenges for the production of flexible organic electronic devices is the device protection against atmospheric molecule permeation, which causes corrosion reducing its operation and lifetime. In this work, Spectroscopic Ellipsometry has been implemented to investigate the influence of silicon dioxide nanoparticles on the optical properties of hybrid polymers. The spectra analysis revealed valuable information about the electronic and vibrational response as well as the cross-linking mechanisms of these materials. The correlation of the optical properties with the synthesis parameters and the barrier response will contribute towards their optimization in order to be used as high barrier coatings for flexible organic electronics applications.

2009-10-01

452

New method for determining the energy gap of a superconductor using the maximum in differential conductance of electron tunneling spectrum

Original investigations of ablation of minerals, fullerene-like compounds, polymers and complicated biological macromolecules under the action of submillimeter radiation of the free-electron laser (FEL) developed and built at Budker Institute of Nuclear Physics [V.P. Bolotin et al., First experiments on high-power Novosibirsk terahertz free-electron laser, Budker INP, 2005, p. 37 [1

2007-05-21

453

Multigrid Particle-in-cell Simulations of Plasma Microturbulence

A new method for determining the energy gap of a superconductor using the maximum in the differential conductance curve of electron tunneling spectrum is given in this paper. The V/sub max//kT versus ..delta../kT curve was calculated from tunneling theory. V/sub max/, the voltage of the conductance maximum, can be measured from electron tunneling spectrum. ..delta../kT can be found from this curve, then the energy gap ..delta.. can be calculated. This method is simple, fast and accurate. The accuracy almost approaches that of the curve fitting method.

1986-02-01

454

Megavoltage electron beam therapy in the treatment of basal and squamous cell carcinomata of the pinna

A new scheme to accurately retain kinetic electron effects in particle-in-cell (PIC) simulations for the case of electrostatic drift waves is presented. The splitting scheme, which is based on exact separation between adiabatic and on adiabatic electron responses, is shown to yield more accurate linear growth rates than the standard df scheme. The linear and nonlinear elliptic problems that arise in the splitting scheme are solved using a multi-grid solver. The multi-grid particle-in-cell approach offers an attractive path, both from the physics and numerical points of view, to simulate kinetic electron dynamics in global toroidal plasmas.

2003-06-17

455

Local-density-functional approximation to the energy band structure of TmS using the self-consistent relativistic linearized-augmented-plane-wave method

Forty-three patients with basal and squamous cell carcinomata arising on the pinna were treated radically using a 10 MeV electron beam. The technique and dosage are described and discussed. Primary cancer control with retention of the pinna was achieved in 34 patients. Salvage pinnectomy was performed in four patients for recurrence and one patient for radiation necrosis. Two patients with large primary tumours failed to resolve and died of their disease. The advantages for the patient of the policy of primary radical electron beam therapy are discussed.

1982-05-01

456

Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

The self-consistent relativistic linearized-augmented-plane-wave method is applied to local-density calculation of electronic structure of TmS. It is found that thulium monosulphide is a compound with a trivalent state of thulium. The influence of spin-orbital interaction is shown for different symmetry states of electrons. Calculated densities of states are used for the estimation of the electron-phonon coupling constant. And in conclusion it is shown that TmS is a high temperature Kondo-like system. (author).

457

Linac based free-electron laser

Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

2009-11-25

458

Interferometry and refraction measurements in plasmas of elliptical cross-section

A basic treatment of the principle of the linac-driven free-electron laser (FEL) is given. The first part of the paper describes the FEL in low-gain approximation, and in the second part the high-gain FEL theory is given. The majority of the treatment describes FELs in one dimensional approximation, neglecting effects by diffraction of radiation and by electron beam emittance. Only in the final section a few remarks on these issues are given. The ambition of the paper is by no means any progress in FEL theory but a clear presentation of basic FEL theory concepts with explicit derivation of the formulae from first principles. (orig.)

459

Initial electron-beam characterizations for the Los Alamos APEX Facility

The measurement of electron densities using interferometry and refraction measurements in plasmas with cross-sections where the electron density contours are concentric ellipses is examined. Transforms are found for both interferometrically deduced optical path-length differences and refraction angle data obtained from elliptical cross-section plasmas. The transformed data can be inverted to give electron densities using standard techniques developed for circular cross-section plasmas. Refraction of light in elliptical cross-section plasmas is examined using numerical ray tracing.

1984-04-14

460

Initial electron-beam characterizations for the Los Alamos APEX Facility

The ongoing upgrade of the Los Alamos Free-Electron Laser (FEL) Facility involves the addition of a photoelectric injector (PEI) and acceleration capability to about 40 MeV. The electron-beam and high-speed diagnostics provide key measurements of charge, beam position and profile, divergence emittance, energy (centroid, spread, slew, and extraction efficiency), micropulse duration, and phase stability. Preliminary results on the facility include optical transition radiation interferometer measurements of divergence (1 to 2 mrad), FEL extraction efficiency (0.6 {plus minus} 0.2%), and drive laser phase stability (< 2 ps (rms)). 10 refs.

1991-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

461

Inelastic scattering of electrons by close-lying levels of isomeric nuclei

The ongoing upgrade of the Los Alamos Free-Electron Laser (FEL) Facility involves the addition of a photoelectric injector (PEI) and acceleration capability to about 40 MeV. The electron-beam and high-speed diagnostics provide key measurements of charge, beam position and profile, divergence emittance, energy (centroid, spread, slew, and extraction efficiency), micropulse duration, and phase stability. Preliminary results on the facility include optical transition radiation interferometer measurements of divergence (1 to 2 mrad), FEL extraction efficiency (0.6 {plus_minus} 0.2%), and drive laser phase stability (< 2 ps [rms]). 10 refs.

1991-12-31

462

Implantation of an electronic system for real time neutron graphic images acquisition at the IPEN/CNEN Argonaut reactor

The process of inelastic scattering of hot plasma electrons with energies upto 3 keV by a pair of close-lying nuclear levels (..delta../ital E/less than or equal to2keV), one of whichis isomeric, is discussed. The transition cross sections in the nuclei/sup 242/Am, /sup 171/Lu, and /sup 73/Se are calculated. Estimates of the numberof isomeric nuclei de-excited as a result of electron-stimulated processes in aplasma with parameters characteristic of present-day experiments in controlledthermonuclear fusion are given.

1988-11-01

463

Impact of profile resilience on energy confinement

The aim of this work is the implantation and characterization of a neutron radiography system that uses an electronic device for attainment of images in real time, for its implementation in the nuclear research reactor Argonauta at IEN/CNEN (Nuclear Engineering Institute of the Brazilian Nuclear Energy Commission). The Electronic Imaging System in Real Time is composed by a scintillator screen for neutron, a video camera (CCD), a digital plate and a computer with specific computational programs for digital processing of the images. The System in installed real time is apt to carry through neutron radiography inspections of static and dynamic events of several types of samples. (author)

2004-04-01

464

High resolution transmission electron microscopy of partial states of oxygen order in YBa_2Cu_3O_z

Multi-machine experimental observations indicate resilience in the temperature profiles at low pedestal temperatures,whereas at high pedestal temperatures the profile stiffness seems to disappear.The change of the profile behavior impacts the energy confinement,basically due to a strong non-linear dependence of the energy transport on the pedestal temperature together with different critical conditions for the onset of turbulence in the ions and electrons.This possible explanation for the different observations is based on the assumption that both ion and electron energy transport is governed by turbulence which sets in at a critical temperature gradient as well as on a significant energy equipartition between electrons and ions.

465

Grid-controlled plasma cathodes

This paper reports on high resolution electron microscopy used to investigate the effect of electron irradiation induced oxygen loss on the states of partial order in YBa_2Cu_3O_z. Contrast effects visible in the [001] zone image as a result of the degree of the out-of-plane correlation of these ordered states are investigated. Using statistical simulations to aid in the analysis of the HREM images, an interpretation based on a kinetically limited evolution of the variation of long range [001] ordering is proposed.

1990-04-16

466

Generation of high-energy electrons and ions at propagation of relativistic laser pulses through supercritical plasma

Experiments are described on a plasma cathode with biased grids to prevent entry of ions into the electron extraction gap. The cathode has potential applications to the generation of high-current pulsed electron beams. Operation at 20 A/cm"2 is theoretically possible. The source combines the low average power consumption of a plasma cathode with many of the attractive features of thermionic cathodes, such as space-charge-limited extractor gap electron flow, fast turn-on, and no diode closure. Initial experiments are reported at the 2 A/cm"2 level for pulse lengths to 160 #mu#s.

467

Free electron radiation and the Beijing Free Electron Laser

In terms of the kinetic theory of the interaction between the high-power short-time laser pulses with plasma based on the propagator plotting for the plasma particle distribution functions one studied the generation of the hot electrons and of the fast ions as the relativistic femtosecond laser pulses travelled through the supercritical density plasma. One performed calculations based on the various values of the laser pulse intensity, types of the multiple-charged ions, the plasma inhomogeneity degree. One studied the acceleration mechanisms both of the plasma electrons and ions

2007-12-01

468

Forward directed Smith-Purcell radiation from relativistic electrons

Various particle-photon or beam-wave interactions are discussed. To be of use as intense radiation sources, it is necessary that these interactions produce coherent radiation. The free electron laser (FEL), developed on the basis of undulator radiation, is the result of many years of interaction between physics and technology. It has many features, such as continuous tunability over a wide wavelength range, excellent optical quality, high power and short pulse capability, and thus has many potential applications. FEL development in China and abroad are mentioned and the Beijing FEL presented to illustrate the physics and technology involved in an FEL project.

469

Field emission dark current of technical metallic electrodes

The requirements for the generation of forward directed Smith-Purcell emission from relativistic electrons are introduced, and the first experimental evidence of this phenomenon is presented. The experiments were conducted with a 2.8 MeV/c electron beam interacting with a 1 cm period grating. Radiation emitted in two bands with wavelengths ranging from 600 to 650 #mu#m and 1.2 to 1.7 mm were measured. Grating period to wavelength ratios were as high as 16. The measured intensities are higher than that predicted by incoherent emission.

470

Energy-spectroscopic studies of electron-capture processes of low-energy, highly stripped F and Ne ions in collisions with He atoms

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration, a -500 kV, 250 ns FWHM, pulse will be applied between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgas and must not emit electrons. Ion back bombardment, and dark current will be damaging to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel (SS), titanium and molybdenum were tested, following different procedures including plasma glow discharge cleaning.

2007-04-21

471

Electronic structure calculations of vacancies and their influence on materials properties

The electron-capture processes of highly stripped ions of Fq+ (q=6,7,8) and Neq+ (q=7,8,9) in collisions with He atom were investigated using the energy-gain spectroscopy technique. A single dominant peak is observed in most of the energy-gain spectra except for the Ne7+ and Ne9+ spectra, in which two peaks are observed corresponding to the one-electron capture process into levels with different principal quantum number n.

1984-03-01

472

Electron temperature diagnostics in the RFX reversed field pinch experiment

We provide two examples to illustrate how electronic structure calculations contribute to our understanding of vacancies and their role in determining material properties. Diffusion and elctromigration in aluminium are known to depend strongly on vacancies. Electronic structure calculations show that the vacancy-impurity interaction oscillates with distance, and this leads to an explanation for both the increased elctromigration resistance and the slow impurity diffusion for copper in aluminium. Calculations of vacancies in plutonium have been used in conjunction with positron annihilation lifetime measurements to identify the presence of helium-filled vacanies. Helium stabilization of vacancies can provide the precursors for subsequent vacancy-related changes in materials properties.

1997-08-01

473

Effect of isopropyl alcohol on the surface localization and recombination of conduction-band electrons in Degussa P25 TiO_2. A pulse-radiolysis time-resolved microwave conductivity study

The paper presents an integrated approach to the problem of electron temperature diagnostics of the plasma in a reversed field pinch. Three different methods, sampling different portions of the electron distribution function, are adopted, namely Thomson scattering, soft X-ray spectroscopy by pulse-height analysis and filtered soft X-ray intensity ratio. A careful analysis of the different sources of systematic errors is performed and a novel statistical approach is adopted to mutually validate the three independent measurements. A satisfactory agreement is obtained over a large range of experimental conditions, indicating that in the plasma core the energy distribution function is well represented by a maxwellian. (author)

2000-08-01

474

Drug eruptions presenting at sites of prior radiation damage (sunlight and electron beam)

Conduction-band electrons, formed by pulse radiolysis of Degussa P25 TiO_2 particles, have been monitored by time-resolved microwave conductivity and found to undergo equilibrium localization and eventual recombination at the particle surface. In the presence of isopropyl alcohol recombination is retarded due to surface hole scavenging. The particle bulk can then be pumped with mobile electrons, which survive for seconds.

475

Development of superconducting cryo-electron microscope and its applications

Two patients are described in whom sunburn and electron beam radiodermatitis, respectively, were critical determinants in localizing the initial presentation of drug eruptions. In the first instance, a severe sunburn of the back and thighs was followed 7 months later by the appearance of a toxic epidermal necrolysis drug reaction to trimethoprim-sulfamethoxazole in the exact sites of the previous bullous sunburn reaction. In the second patient, a radiodermatitis of the left upper arm due to electron beam therapy for metastatic breast cancer was followed 7 weeks later by a codeine drug reaction confined to the area of the radiodermatitis. In both instances, oral rechallenge with the offending drug reproduced the eruption.

1984-07-01

476

Dephasing of two electron states in a double quantum-dot system irradiated by a microwave field with a nearby Quantum Point Contact

Recently, a superconducting cryo-electron microscope in which specimens are cooled to the liquid helium temperature (4.2 K) has been developed. The main components and functional features of this new microscope are reported together with application data on polyethylene, poly (4-methyl-1-pentene), valonia cellulose, rock salt, ice crystallites and ceramic superconductor. The resistance to electron radiation damage, of beam-sensitive specimens including polymers has been increased more than ten times. Thus, the microscope has made it possible to take high resolution images and to analyze the crystal-structure of micro-areas. (orig.).

1988-01-01

477

Decommissioning and dismantling. Examination of the radiation hardening of electronic components. Final report

In this work we study the dephasing mechanism of a double quantum-dot system, which includes two electrons and a nearby quantum point contact (QPC) as a measurement device. We obtain that the QPC-induced decoherence is on time scales of microseconds. We also find that the electrons will be delocalized after continuous measurement, irrespectively of the initial conditions, and the frequent repeated measurements will localize the system, which is consistent with the quantum Zeno effect. Further, we consider the situation that the double quantum-dot system is irradiated by a microwave field.

2008-01-01

478

Convoy electron production in polycrystalline and monocrystalline targets

Remote-controlled handling systems are required for work to be done in the decommissioning and dismantling of nuclear facilities. These systems are equipped with electronic devices suitable for use in working environments affected by ionizing radiation. The publication explains the step-wise progress achieved for improving the radiation resistance of electronic devices with the example of a four-quadrant controlling device for the motors of a manipulator. The radiation resistance of the device could be enhanced to radiation energies of 5.500 Gy. This means that a manipulator vehicle equipped with this controlling device can take up to approx. 15 kGy all in all, taking into account its own shielding properties. (DG).

479

Collective ion acceleration by a reflexing electron beam: model and scaling. Memorandum report

The velocity distribution of electrons ejected close to the forward direction by 0.8-2 MeV/A ions traversing various solid targets, including a Au monocrystal, is measured in coincidence with emerging charge-selected ions. The velocity spectrum is observed to be independent of outgoing projectile velocity and charge state for polycrystalline targets. Measurements on the Au crystal under channeling conditions show dependences on final charge state, and are tentatively explained by assuming that the main contribution to the production yield comes from the non-channeled fraction of the ions. A simple model for the creation of the forward-ejected electrons is proposed, which accounts for most of the experimental findings.

1980-01-01

480

Anion formation from gaseous and condensed molecules on low-energy electron impact

Analytical and numerical calculations are presented for a reflexing electron beam type of collective ion accelerator. These results are then compared to those obtained through experiment. By constraining one free parameter to experimental conditions, the self-similar solution of the ion energy distribution agrees closely with the experimental distribution. Hence the reflexing beam model appears to be a valid model for explaining the experimental data. Simulation shows in addition to the agreement with the experimental ion distribution that synchronization between accelerated ions and electric field is phase unstable. This instability seems to further restrict the maximum ion energy to several times the electron energy.

1984-05-11

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

481

A new scheme of the longitudinal emittance measurement for negative ion beams

The interaction of free electrons in the energy range from 0 to 10 eV with molecules at different stages of aggregation is investigated. The mechanism in the gas phase under single collision conditions is described. Fullerenes C_6_0 and C_7_0 are used as targets. Electron impact on condensed molecules can lead to temporary negative ions. The formation of Cl"- from gas phase CCl_4 and the desorption of Cl"- from 6 monolayer CCl_4 film on an Au substrate is determined experimentally. (Suda).

1994-03-20

482

Spontaneous radiation from relativistic electrons in a taper undulator. Technical report

A new scheme of the longitudinal emittance measurement for high energy negative ion beam is proposed. The energy distribution of the detached electron from the negative ions by the photodetachment process, if the photon energy is almost equal to the electron binding energy of the negative ion (=electron affinity of the atom), reflects that of the original negative ions. Therefore, by introducing the photon in a short width comparing with the bunch width of the negative ion beam, the longitudinal energy distribution of each phase of the beam, that is the longitudinal emittance, can be measured. (author).

1995-08-01

483

Spin-polarized Auger-electron diffraction study of the magnetic poisoning of Fe(001) by sulfur

The spectrum, angular distribution, polarization and coherence properties of the radiation emitted by relativistic electrons undulating through a quasiperiodic tapered magnetic field are studied. Tapering the wavelength and/or field strength along the undulator's axis has the effect of spreading the spectral line to higher frequencies; interference over this broader spectral range results in a more complex line shape. The angular dependence, on the other hand, is not affected by the amount of taper. The polarization of the radiation in the forward direction is determined by the transverse polarization of the undulator, but the polarization changes off axis. The radiation patterns predicted here are distinct from those of untapered undulators, and their detection is now feasible. They will provide useful diagnostics of electron trajectories and threshold behavior in free-electron-laser oscillators using tapered ...

1983-06-01

484

Pulse source of electron and X-ray radiations of subnanosecond duration

Spin-polarized angle-resolved sulfur L_2_,_3VV Auger-electron spectra have been recorded for the c(2x2)S/Fe(001) system. The data show the modulation of the sulfur Auger spin polarization as a function of emission angle, which represents an observation of spin-polarized Auger-electron diffraction (SPAED), a potentially powerful tool for the study of local magnetic structure at surfaces, interfaces, and thin films. Theoretical modeling of the SPAED data indicates a large decrease in the magnetization of the top iron layer, suggesting a magnetic poisoning induced by the sulfur overlayer. These findings are independently supported by the observation of a large decrease of secondary electron spin polarization upon sulfur adsorption.

485

Observation of strain-enhanced electron-spin polarization in photoemission from InGaAs

The time and dose characteristics of the electron and X-ray radiations of a tube, connected to a subnanosecond mega volt accelerator, are measured. By the pulse of the accelerating voltage of #>=# 600 kV with duration of #approx =# 0.3 ns the tube generates approximately 5 x 10"1"2 electrons pulse. The current amplitude equals approximately 5 kA/pulse and the radiation dose-about 5 kGy/pulse. The X-ray radiation dose from the tantalum external target constitutes 0.15 Gy/pulse. The prototypes of the electron and X-ray tubes sufficiently lower volumes, opening new applications in the technique and medicine, are developed

486

Non-destructive Imaging of Individual Bio-Molecules

Electron-spin polarization in excess of 70% has been observed in photoemission from a 0.1-#mu#m-thick epitaxial layer of In_xGa_1_-_xAs with x#approx#0.13 grown on a GaAs substrate. Under these conditions, the epitaxial layer is expected to be highly strained by the 0.9% lattice mismatch. The electron polarization and the quantum efficiency have been measured as a function of the excitation photon energy from 1.25 to 2.0 eV. A significant enhancement of the electron polarization occurs in the vicinity of 1.33 eV where the expected strain-induced level splitting permits optical excitation of a single-band transition.

487

British Library Electronic Table of Contents (United Kingdom)

Radiation damage is considered to be the major problem that still prevents imaging an individual biological molecule for structural analysis. So far, all known mapping techniques using sufficient short wave-length radiation, be it X-rays or high energy electrons, circumvent this problem by averaging over many molecules. Averaging, however, leaves conformational details uncovered. Even the anticipated use of ultra-short but extremely bright X-ray bursts of a Free Electron Laser shall afford averaging over 10^6 molecules to arrive at atomic resolution. Here we present direct experimental evidence for non-destructive imaging of individual DNA molecules. In fact, we show that DNA withstands coherent low energy electron radiation with deBroglie wavelength in the Angstrom regime despite a vast dose of 10^8 electrons/nm^2 accumulated over more than one hour.

2009-01-01

488

Many important advances in the physics of strongly correlated electron systems have been driven by the development of new materials: for instance the filled skutterudites Formula Not Shown ( Formula Not Shown metal, alkaline earth, lanthanide, or actinide; Formula Not Shown , Ru, or Os; Formula Not Shown , As, or Sb), certain lanthanide and actinide intermetallic compounds such as Formula Not Shown and Formula Not Shown ( Formula Not Shown , Rh, or Ir), and layered oxypnictides and related materials. These types of complex multinary d- and f-electron compounds have proven to be a vast reservoir of novel strongly correlated electron ground states and phenomena. In these materials, the occurrence of such a wide range of ground states and phenomena arises from a delicate interplay between com...

2009-01-01

489

MODIFIED AMBIENT TEMPERATURE PERCEPTION AFFECTS DAILY ACTIVITY PATTERNS IN THE EUROPEAN GROUND SQUIRREL (SPERMOPHILUS ...

Fabrication and characterization of low aberration micrometer-sized electron lenses

... in full sun and in shade, using an infrared thermometer (MiniTemp Noncontact, Conrad Electronic, Nürnberg, Germany). Time intervals ... ...

490

British Library Electronic Table of Contents (United Kingdom)

Intrinsic spherical aberrations of electron lenses have been the major resolution limiting factor in electron microscopes for several decades. While effective correctors have recently been implemented, an alternative to correct these aberrations is to circumvent them by scaling down lens dimensions by several orders of magnitude. We have fabricated electrostatic lenses exhibiting one micrometer diameter apertures and evaluated their beam forming properties against predictions from numerical ray tracing simulations. It turns out that it is routinely possible to shape a paraxial low-energy electron beam by such micron-sized lenses. Beam profiles have been measured both at a distant detector as well as in a plane close to the lens. It is shown that the lens can form a parallel beam extending ...

2010-01-01

491

Evidence for significant backscattering in near-threshold electron-impact excitation of Ar"7"+(3s#->#3p)

Electron-impact excitation of Si"3"+(3s#->#3p) using a merged-beam electron-energy-loss technique

Measurements of absolute total cross sections for electron-impact excitation of Ar"7"+(3s#->#3p) using a merged-beams electron-energy-loss technique show that near threshold the inelastically scattered electrons are ejected primarily in the backward direction. This unusual angular scattering has not been previously observed for atoms or ions, but may be typical for multiply charged ions. The total cross sections, measured over an energy range to 2.2 eV above threshold, agree with seven-state R-matrix close-coupling calculations. Both close-coupling and distorted-wave calculations also confirm the backscattering observed in these measurements.

492

Electron beam, ion beam, X-ray optical techniques for fabricating surface-acoustic-wave and thin-film optical devices

For the first time, absolute cross sections for electron-impact excitation of a multiply charged ion have been measured using an electron-energy-loss technique. Cross sections for e+Si"3"+(3s "2S_1_/_2)#->#e+Si"3"+(3p "2P_1_/_2_,_3_/_2)-8.88 eV have been measured with an accuracy of #+-#20% (at 90% confidence level) over a narrow energy range (#+-#0.6 eV) about the threshold energy with an energy resolution of 0.2 eV. Results are in good agreement with close-coupling calculations.

493

Dissociative electron attachment to CCl_4: Lifetime of the CCl_4"- intermediate

Most surface-acoustic-wave and thin-film optical devices are made by the planar fabrication process. The exposure of the pattern in the polymer film is the first and most crucial step in ensuring desired device geometry, dimensional control, and freedom from pattern distortion. The methods of exposing the polymer film include: optical projection, conventional contact printing, conformable photomask contact printing, holographic recording, scanning electron beam lithography, projection electron lithography, and x-ray lithography. In this paper scanning electron beam lithography, conformable photomask contact printing, holographic recording, and x-ray lithography are discussed. In the last section, ion beam etching of relief structures is discussed.

494

CoSpell CheckSpell Checkherent Charge Qubits Based on ...

Dissociative electron capture to CCl_4 is studied by measuring the angular and velocity distribution of Cl"- ions produced in collisions with velocity selected K(np) Rydberg atoms. Analysis of the data using a Monte Carlo collision code that models the detailed kinematics of the reaction indicates that the lifetime of the CCl_4"- intermediate formed by Rydberg electron capture is 7.5 #+-# 2.5 ps and that, upon dissociation, only a small fraction of the excess energy of reaction appears as translational energy of the Cl"- and CCl_3 fragments. The present approach is one of the few experimental techniques yet devised that can probe the lifetimes of collisionally-produced excited states on a picosecond timescale, and demonstrates that Rydberg atoms provide a unique tool with which to investigate the dynamics of dissociative electron attachment. Measurements are being extended to additional species, including CFCl_3.

1996-05-15

495

Capturing energy in the air to power electronics | SmartPlanet

... We considered spontaneous radiation of quanta and acoustic phonons (both due to deformational and piezoelectric electron-phonon interaction ...

2000-06-23

496

Wastenet

...smart grid applications where you could place them very close to the high-voltage transmission lines , very close to transformers and so on. Photo:...

497

Absolute electron scattering cross sections for the "2S#->#"2P transition in Zn"+ using energy-loss and merged-beams methods