Energy Technology Data Exchange (ETDEWEB)

Excitation transfer between the 3S[sub 1/2] states of the lithium isotopes [sup 6]Li and [sup 7]Li is measured in a thermionic diode. The 3S level is excited by off-resonant two-photon transitions with a single mode cw laser. The relative densities of the directly excited and collisionally populated levels are probed by further laser excitation to the 12P levels. An energy transfer cross section of 585 A[sup 2] [+-] 160 A[sup 2] is found at the experimental temperature of about 850 K. A simple semiclassical calculation yields a cross section of 450 A[sup 2]. (orig.)

Science.gov (United States)

The utility of recording Raman spectroscopy under liquid nitrogen, a technique we call Raman Under Nitrogen (RUN), is demonstrated for ferrocene, uranocene and thorocene. Using RUN, low temperature (liquid nitrogen cooled) Raman spectra for these compounds exhibit higher resolution than previous studies and new vibrational features are reported. The first Raman spectra of crystalline uranocene at 77 K are reported using excitation from argon (5145 ) and krypton (6764 ) ion lasers. The spectra obtained showed bands corresponding to vibrational transitions at 212, 236, 259, 379, 753, 897, 1500, and 3042 cm-1 , assigned to ring-metal-ring stretching, ring-metal tilting, out-of-plane CCC bending, in-plane CCC bending, ring-breathing, C-H bending, CC stretching and CH stretching, respectively. The assigned vibrational bands are compared to those of uranocene in THF and thorocene. All ...

International Nuclear Information System (INIS)

The phase transition behaviour of polyethylene-b-poly(ethylene oxide) (PE-b-PEO) diblock copolymer with relatively short chain lengths has been studied on the basis of temperature dependent infrared and Raman spectral measurements and synchrotron WAXD/SAXS simultaneous measurements, from which the concrete structural changes were deduced successfully from the various levels of molecular chain conformation, chain packing mode and higher-order structure. The higher-order structure has been found to transform between lamella, perforated lamella, gyroid, cylinder and sphere structures. The inner structural changes occurring in the polyethylene and poly(ethylene oxide) parts have been related with these morphological changes. The morphological transition from lamella to gyroid occurs with keeping the crystalline state of polyethylene parts. This apparently curious transition can be interpreted reasonably by ...

CERN Document Server

We present a single solid-state laser system to cool, coherently manipulate and detect $^{25}$Mg$^+$ ions. Coherent manipulation is accomplished by coupling two hyperfine ground state levels using a pair of far-detuned Raman laser beams. Resonant light for Doppler cooling and detection is derived from the same laser source by means of an electro-optic modulator, generating a sideband which is resonant with the atomic transition. We demonstrate ground-state cooling of one of the vibrational modes of the ion in the trap using resolved-sideband cooling. The cooling performance is studied and discussed by observing the temporal evolution of Raman-stimulated sideband transitions. The setup is a major simplification over existing state-of-the-art systems, typically involving up to three separate laser sources.

International Nuclear Information System (INIS)

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 ...

International Nuclear Information System (INIS)

The purified integral membrane protein, band 3, from human erythrocytes was inserted into egg lecithin liposomes. The insertion of band 3 was determined from thermal transition data from the analysis of the C-H stretching region bands recorded at temperatures from 25 to -22"oC. Raman spectra show that band 3 considerably broadens and lowers the thermal transition of egg lecithin liposomes, suggesting the insertion of band 3. The band 3-inserted liposomes were irradiated with gamma-rays (40 Gy) and the radiation target groups were determined by the analysis of the structural sensitive Raman bands in the 1600-1700 cm"-"1 (amide I), 1200-1300 cm"-"1 (amide III) and 550-1030 cm"-"1 (side chain amino groups) regions. The radiation-sensitive groups as identified from Raman spectra in the region 550-1030 cm"-"1 are tyrosines and cysteines. The radiation-induced changes in the secondary ...

International Nuclear Information System (INIS)

The structure of the layers formed on a silver electrode by the adsorption of pyridine, Cl"-, CN"- and SO_4"2"- is discussed. A comparison of the amount of the species adsorbed with their Raman spectra shows that there is no simple relation between the species concentration and the enhancement of the Raman intensity. Furthermore, the inhomogeneity of the layers is shown by Raman microscopy observations. These results lead the authors to propose the formation of a new species stabilized in the colloidal silver layer. The Raman enhancement could be explained by the existence of a resonance effect. (Auth.).

Energy Technology Data Exchange (ETDEWEB)

We investigated the Raman coherence characteristics of a solid hydrogen film deposited on a sapphire substrate held at 5.3 K. Using Raman coherence prepared with two single-frequency pulsed lasers, we generated the multiorder coherent Raman sidebands in solid hydrogen film. The highorder Raman sidebands were obtained under strong pumping intensities (>= 230 MW/cm{sup 2}). The generated anti-Stokes(AS)-Raman sidebands extend from the ultraviolet (292 nm for the AS5 band) to the visible (565 nm for the AS1 band) region. The multiorder Raman sideband generation is found to be due to the parametric coupling of pump and coupling lasers. The frequency conversion efficiency from pumping beams to the first AS-Raman sideband shows a maximum (14 %) at a pumping intensity of 360 MW/cm{sup 2}. From an experiment that makes the multimode probe ...

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Short communication.

Energy Technology Data Exchange (ETDEWEB)

It has been discovered that the presence of MoO/sub 3/ lowers the ..cap alpha..-..beta.. transition in Sb/sub 2/O/sub 4/ from 935 to 850/sup 0/C with concurrent dissolution of Mo in the high-temperature (..beta..) form. The structure of Mo-doped ..beta..-Sb/sub 2/O/sub 4/ has been investigated by powder neutron diffraction, extended X-ray absorption fine structure (EXAFS) and Raman spectroscopies, and scanning-electron microscopy (SEM). Cell parameters: a = 12.0571 (12) A, b = 4.8335 (1) A, c = 5.3838 (6) A, ..beta.. = 105.579 (5)/sup 0/, monoclinic, space group C2/c, Z = 4. Combining the results of these techniques leads to the hypothesis that Mo is located interstitially within channels of electron density in the Sb/sub 2/O/sub 4/ structure with concurrent vacancy of two Sb/sup III/ atoms. There is no apparent oxygen deficiency in the resulting structure. 25 references, 6 figures, 3 tables.

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When in resonance, Raman scattering exhibits strong enhancement ranging from four to six orders of magnitude. This physical phenomenon has been applied to remote sensing of the Earth`s atmosphere. With a 16 inch Cassegrain telescope and spectrometer/ CCD-detector system, 70-150 ppm-m of SO{sub 2} in the atmosphere has been detected at a distance of 0.5 kilometer. This system can be used to detect/monitor chemical effluence in the atmosphere by their unique Raman fingerprints. Experimental result together with detailed resonance Raman and atmospheric laser propagation effects will be discussed.

Energy Technology Data Exchange (ETDEWEB)

There have been many recent explosive advances in both IR and Raman spectroscopy which have developed in response to industrial problems of increasing complexity. Probably the biggest factor in these advances has been computerization, which has contributed not only to substantial improvements in data handling but to enormous gains in sensitivities of analyses as well. In this paper numerous examples of Raman and IR applications in industry are given using many of these recent advances, including in-situ techniques, microprobe analyses, unusual combinations of instruments - i.e., hyphenated methods - and new sample handling techniques. The bright future of FT-IR and Raman spectroscopy is also briefly discussed.

Energy Technology Data Exchange (ETDEWEB)

The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m{sup 2}/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO{sub 3}/(MoO{sub 3} + V{sub 2}O{sub 5}). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V{sup +4} and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of ...

Energy Technology Data Exchange (ETDEWEB)

This paper reports on the results of experiments into efficient higher-order anti-Stokes Raman conversion of tunable short-pulse XeCl laser radiation. The maximum output energy of the pumping laser, in which the radiation of a frequency-doubled dye laser is amplified by two XeCl laser amplifiers, is 55 mJ with a pulse duration of 1 ns FWHM. Using hydrogen gas as a Raman medium, a series of anti-Stokes lines up to the 12th order (121.5 nm) is generated in the vacuum ultraviolet (VUV) region. 16 references.

Energy Technology Data Exchange (ETDEWEB)

Intraionic spin-orbit--split multiplet levels have been observed by electronic Raman scattering in the intermediate-valence compound EuPd/sub 2/Si/sub 2/. From the temperature dependence of the Raman peak positions and widths the interconfigurational excitation energy E/sub x/ and an upper limit of the interconfigurational mixing width T/sub f/, respectively, have been obtained. This is the first spectroscopic support for the underlying assumptions of the ionic interconfigurational fluctuation model that has been proposed to describe intermediate valence.

Science.gov (United States)

This report describes the design of, and image reconstruction capacity of a Hadamard Raman Microscopic imager. Microscopy of benzoic acid and graphite electrodes, as well as electrophoretic blotting, are described. (CBS)

International Nuclear Information System (INIS)

The transmutation of minor actinides in-reactor is one solution currently being studied for the long time management of nuclear waste. In the heterogeneous concept the radionuclides are incorporating in an inert ceramic matrix. The support material must be insensitive to radiation damage. Fission product damage is the main radiation damage source during the transmutation process and therefore it is of the utmost importance to study their effects. We irradiated spinels MgAl_2O_4 (matrix of reference) and ZnAl_2O_4 by fast ions (by example: (86)Kr of approximately 400 MeV) simulating the fission products. Under these conditions, the damage is primarily due to the electronic energy losses (Se). One of the structural features of spinel AB_2O_4 is that the two cations (A(2+) and B(3+)) can exchange their site. This phenomenon is quantified by the inversion parameter. We highlight by XRD in grazing incidence that the structural changes observed in MgAl_2O_4 correspond to an order-disorder ...

Energy Technology Data Exchange (ETDEWEB)

Substantial changes in the radial distribution function of amorphous Si films have been observed in neutron-diffraction studies. The spectra indicate changes in short-range order associated with an approx.11% modification in the bond-angle distribution width. The results allow the first direct comparison of structural and vibrational Raman probes of variations in local order in thin-film amorphous solids. Good agreement is obtained between the measured bond-angle variation and that based on Raman estimates.

Energy Technology Data Exchange (ETDEWEB)

We describe a liquid hydrogen droplet as an optical cavity via whispering gallery modes. We show that the droplet leads to an ultrahigh-cavity-Q value of 2.5x10{sup 9} in visible region. We show also that the high-Q droplet results in a huge Raman nonlinearity, generating a stimulated Raman comb series covering whole visible region.

British Library Electronic Table of Contents (United Kingdom)

The aim of this study was to evaluate the potential of low-resolution Raman spectroscopy for monitoring the oxidation status of olive oil. Primary and secondary oxidation parameters such as peroxide value, K"2"3"2 and K"2"7"0 were studied. Low-resolution Raman spectra ranging from 200 to 2700 cm^-^1 in a set of 126 oxidized and virgin olive oil samples were collected directly using a probe. Partial Least Squares was used to calibrate the Raman instrument for the different targeted parameters. The performance of the models was determined by using validation sets, and the best results obtained were: R^2 = 0.91, RMSEP = 2.57 for the peroxide value content; R^2 = 0.88, RMSEP = 0.37 for K"2"3"2; and R^2 = 0.90, RMSEP = 0.08 for K"2"7"0. These results demonstrated that low-resolution Raman spect...

International Nuclear Information System (INIS)

The measurements obtained here indicate ways in which micro-Raman spectroscopy can be used to elucidate structural characteristics and distribution of carbon in meteorites and interplanetary dust particles (IDPs). Existing information about structurally significant aspects of Raman measurements of graphite is combined with structurally relevant findings from the present micro-Raman studies of carbons prepared by carbonization of polyvinylidine chloride (PVDC) at various temperatures and natural material, as well as several acid residues from the Allende and Murchison meteorites in order to establish new spectra-structure relationships. Structural features of many of the materials in this study have been measured by x ray analysis and electron microscopy: thus, their structural differences can be directly correlated with differences in the Raman spectra. The spectral parameters consequently affirmed as ...

Energy Technology Data Exchange (ETDEWEB)

The depletion of stratospheric ozone is caused by chlorine species formed in heterogeneous processes on the surfaces of polar stratospheric cloud (PSC) particles. For studying local PSC formation processes in the Arctic a temperature lidar receiver was developed that makes use of the rotational Raman method, the only lidar technique for measuring atmospheric temperature profiles not perturbed by the presence of aerosols or cloud particles. The receiver was implemented in the mobile GKSS Raman lidar and transferred to Esrange (67.9 N, 21.1 E) near Kiruna in northern Sweden in winter 1997/98. Temperature data measured between January 22 and February 6, 1998, are presented and compared to model data analyzed by the European centre for medium-range weather forecast. Local temperature profiles are studied in three cases of type-Ib PSCs. This type is characterized by a low depolarization ratio. (orig.)

International Nuclear Information System (INIS)

The surface films formed on type 316LN stainless steels (SS) with different nitrogen contents, during potentiodynamic polarization in acidified 1 M NaCl solution, were characterized by Laser Raman Spectroscopy (LRS). LRS confirmed the presence of oxides and oxychlorides of iron and chromium, hydrated chlorides and nitrates in the film. Raman mapping showed increasing nitrate content in the film with increasing nitrogen content. The film on the uncorroded material showed the presence of chromium and molybdenum oxides. The improvement in pitting corrosion resistance of type 316LN SS with increasing nitrogen content was attributed to increased amount of nitrates in the passive film.

Energy Technology Data Exchange (ETDEWEB)

The influence of Cr on the structure and electrochemical properties of LiCoVO{sub 4} was studied using X-Ray diffraction, scanning electron microscopy, Raman Spectroscopy and cycle tests. Doping levels up to 10 mol% were achieved, which improved the electrochemical stability of the structure of LiCoVO{sub 4}, resulting in a significant increase in the initial charge and discharge capacity. The Raman spectroscopy data for the Cr-doped LiCoVO{sub 4} is similar as for LiCoVO{sub 4}. The replacement of a dopant for the Co-ion in the inverse spinel structure causes several Raman shifts. The X-ray diffraction patterns show no new phases and combined with the Raman spectroscopy data it is concluded that the Cr dopant will be located at the octahedral site (16d) where they create an electronic pathway that enhances the electronic conductivity. However, the capacity dropped significantly after prolonged cycling, ...

Energy Technology Data Exchange (ETDEWEB)

We demonstrate the rapid optical characterization of large numbers of individual metal nanoparticles freely diffusing in colloidal solution by confocal laser spectroscopy. We find that hollow gold nanospheres and solid silver nanoparticles linked with a bifunctional ligand, both designed nanostructures, exhibit significantly higher monodispersity in their Rayleigh and Raman scattering response than randomly aggregated gold and silver nanoparticles. We show that measurements of rotational diffusion timescales allow sizing of particles significantly more reliably than can be obtained using translational diffusion timescales.

Energy Technology Data Exchange (ETDEWEB)

Surface layers on lithium electrodes formed in several solvents including dimethyl carbonate (DMC), diethyl carbonate (DEC), polyethylene glycol 400 dimethyl ether (PEG400DME), and propylene carbonate (PC) have been studied by Raman spectroscopy. Both DMC and DEC were used singly, and also mixed with either methyl acetate or methyl formate. The Raman spectra showed that passive films formed on the Li surface in different solvents may have different chemical structures, which changed during the charging and discharging processes. A solid film of fullerene C6O, which could be used as a cathode in Li rechargeable batteries, was examined in the PEG400DME solution by both electrochemical and Raman spectroscopy. Cyclic voltammograms (CVs) showed five redox peaks which suggested the formation of C6O(-), C6O(2-), C6O(3-), C6O(4-), and C6O(5-). Raman spectra obtained from thin C6O film indicated that the thin ...

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron pair, but in silver colloid solution and on the silver nanoparticles modified silver electrode the piperidine molecular lies flat ...

Energy Technology Data Exchange (ETDEWEB)

The confocal Raman micro-spectroscopy has been used for the study of a Lithium/polymer electrolyte-LiTFSI/V{sub 2}O{sub 5} type battery in which the polymer electrolyte thickness is of about 80 {mu}m. The analysis is performed on the side of the battery thanks to a specially designed cell which preserves all the characteristics of the real system. The analysis is performed on 20 points aligned between the anode and the cathode and with a depth of several tenth of {mu}m. The analysis of data obtained during charging/output cycles allows to evaluate the gradients of salt concentration inside the electrolyte, the pollutions of LiOH, Li{sub 2}CO{sub 3}, Li{sub 2}O and Li{sub 3}N -type at the lithium interface, but also the structural modifications of the cathode material. The in-situ study of concentration gradients inside the electrolyte is of prime importance for the understanding of dendrites growth. (J.S.) 11 refs.

Energy Technology Data Exchange (ETDEWEB)

We report a simple method for the label-free detection of double-stranded DNA using surface-enhanced Raman scattering (SERS). We prepared cetyltrimethylammonium bromide (CTAB)-capped silver nanoparticles and a DNA-nanoparticle complex by adding silver nanoparticles to {lambda}-DNA solutions. In the present study, the utilization of CTAB-capped silver nanoparticles facilitates the electrostatic interaction between DNA molecules and silver nanoparticles; at the same time, the introduction of DNA avoids adding aggregating agent for the formation of nanoparticle aggregates to obtain large enhancement of DNA, because the DNA acts as both the probe molecules and aggregating agent of Ag nanoparticles. Atomic force microscopy (AFM) studies show that the morphology of DNA-Ag nanoparticle complexes seems to be determined by the concentrations of the DNA and the nanoparticles. Surface-enhanced Raman scattering (SERS) studies show that the morphology of ...

British Library Electronic Table of Contents (United Kingdom)

Here, a general approach for the preparation of reduced graphite oxide (rGO)-silver nanocomposite has been investigated. Graphite oxide (GO) sheets are used as the nanoscale substrates for the formation of rGO-silver composite. GO sheets and Ag ions can be reduced at the same time, under a mild condition using l-ascorbic acid (l-AA) as reducing agent. This simple approach should find practical applications in the production of rGO-silver nanocomposite. The SEM analysis indicates that the silver particles are dispersed on graphene sheets. Raman signals of rGO in the composite are increased by the attached silver nanoparticles, displaying surface-enhanced Raman scattering activity. The degree of enhancement can be adjusted by varying the quantity of silver nanoparticles in the composite. In ...

British Library Electronic Table of Contents (United Kingdom)

In the present contribution, the innovative in situ Raman micro-spectroscopy was applied to investigate the in vitro reactivity of various bioactive glasses. All the investigated glasses belonged to the Na2O\\K2O-CaO-P2O5-SiO2 system, but contained sensibly different percentages of network modifiers. The glasses were immersed for increasing times, up to 96h, in simulated body fluid (SBF) and in tris-buffered (TRIS) solution. In this way, two fundamental items were addressed, i.e. the effect of the glass composition and the nature of the soaking fluid on the overall reactivity. As regards the SBF, all the glasses were able to promote the formation of a hydroxyl-carbonate apatite (HCA) surface layer in very short times. The reaction rate was particularly quick for the 45S5 Bioglass and for it...

Energy Technology Data Exchange (ETDEWEB)

The use of differential absorption and Raman scattering techniques for the remote sensing of methane in underground coal mines is examined. An analysis of the differential absorption technique showed that non-range resolved systems were incapable of achieving the desired concentration and range specifications and therefore were unsuitable for use in underground coal mines. The Raman scattering technique proved quite successful and a conceptual design which uses the technique is presented. The availability of suitable UV source is critical to the success of the technique however, and to date there is nothing which meets size and portability requirements for a system of this type. Recommendations for further study are included. 19 refs.

International Nuclear Information System (INIS)

This work presents the spectroscopic results of the investigations of ancient pottery remains excavated in ancient Kremna (BURDUR-TURKEY). The micro-Raman and FT-IR spectroscopic studies of the pottery remains belonging to sixth century allowed us to identify the mineral composition. Some examples are described of the use of this technique in the field of art conservation and diagnostics, with regard to pigments, and some products of metal alteration.

Energy Technology Data Exchange (ETDEWEB)

A CO/sub 2/ laser chain able to supply approx.=30 MW on a single mode TEM/sub 00/ is described. The coupling of a modified Lumonics 101 module with a low-pressure cell constitues the oscillator and two further Lumonics 103 stages two amplifiers. The final pulse achieves the energy of 4.0 J with 90% of this energy in a peak of 100 ns FWHM.

CERN Document Server

We report an observation of a delayed all-optical routing/switching phenomenon based on ultraslow group velocity of light via nondegenerate four-wave mixing processes in a defected solid medium. Unlike previous demonstrations of enhanced four-wave mixing processes using the slow light effects, the present observation demonstrates a direct retrieval of the resonant Raman-pulse excited spin coherence into photon coherence through coherence conversion processes.

Energy Technology Data Exchange (ETDEWEB)

This overview of research conducted at ORNL in 1991 presents information on the subjects of biology, physics, and the environment. Specific topics include gene mutations in kidney disease, technology assessments in thermonuclear fusion, submarine hunting technology, ozone-safe refrigerants, optical data storage via surface enhanced raman spectroscopy, and waste mitigating microbes. (GHH)

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Nano-sized particles of a lithium ion conductive solid electrolyte, LiTi{sub 2}(PO{sub 4}){sub 3}, were prepared by laser ablation. The obtained particles were ca. 10nm in diameter. X-ray powder diffraction and Raman spectroscopy showed that they were amorphous with local structure similar to the crystalline counterpart. They were crystallized by the heating at ca. 630{sup o}C. (author)

Energy Technology Data Exchange (ETDEWEB)

This book examines the nonlinear optical properties of laser materials. The physical radiation effects on laser materials are also considered. Topics considered include: nonlinear optical properties; nonlinear and harmonic generation materials; two-photon absorption; nonlinear refractive index; stimulated Raman scattering; radiation damage; crystals; and glasses.

UK PubMed Central (United Kingdom)

In the American educational system, school transitions are frequent and predictable, but they can disrupt student functioning across developmental domains. How students experience school transitions...Full Text Available

CERN Document Server

The phase transition is a performance measure of the sparsity-undersampling tradeoff in compressed sensing (CS). This letter reports, for the first time, the existence of an exact phase transition for the $\\ell_1$ minimization approach to the complex valued CS problem. This discovery is not only a complementary result to the known phase transition of the real valued CS but also shows considerable superiority of the phase transition of complex valued CS over that of the real valued CS. The results are obtained by extending the recently developed ONE-L1 algorithms to complex valued CS and applying their optimal and iterative solutions to empirically evaluate the phase transition.

UK PubMed Central (United Kingdom)

This paper examines theoretically the effects that restraints on the tertiary structure of a superhelical DNA domain exert on the energetics of linking and the onset of conformational transitions. The...Full Text Available

International Nuclear Information System (INIS)

Apart from conventional phase transitions driven by the thermal effects, quantum phase transitions generated by quantum fluctuations have their own mechanisms that are reflected in critical phenomena. Quantum phase transitions have an origin from spontaneous symmetry breaking commonly to thermal phase transitions. Even in this case, inherent quantum fluctuations substantially modify and yield new aspects. Quantum phase transitions have, however, another mechanism caused by topology changes, which gives completely new characters. Recently, a mechanism which connects these two has been found. Proimities from first-order transitions and phase separatins as well as from multiphase coexistence also generate characteristic and unconventional quantum criticalities. Understanding novel quantum criticalities offers a firm basis of recent active researches on fields such ...

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This report describes the evaluation results for new Orion VII buses at NYCT with CNG propulsion and new hybrid propulsion.

UK PubMed Central (United Kingdom)

ObjectiveThis study investigated transitions between drinking and nondrinking during the first 12 months following treatment and whether transitions in posttreatment...Full Text Available

Science.gov (United States)

Excitonic transitions in metalorganic vapor phase epitaxially grown In[sub [ital x

Energy Technology Data Exchange (ETDEWEB)

Iron undergoes a polymorphic phase transformation from alpha phase (bcc) to the epsilon phase (hcp) when compressed to stresses exceeding 13 CPa. Bccause the epsilon phase is denser than the alpha phase, a single shock wave is unstable and breaks up into an elastic wave, a plastic wave, and a phase transition wave. Examination of this structured wave coupled with various phase transformation models has been used to indirectly examine the transition kinetics. Recently, multimillion atom simulations (molecular dynamics) have been used to examine the shock-induced transition in single crystal iron illustrating an orientation dependence of the transition stress, mechanisms, and kinetics. The objective of the current work was to perform plate impact experiments to examine the shock-response of polycrystalline and single crystal iron with nanosecond resolution for impact stresses spanning the {alpha} - ...

International Nuclear Information System (INIS)

... energy levels intermediate mass nuclei isotopes nuclei odd-even nuclei

CERN Document Server

We combine a limited number of accurately measured transition frequencies in hydrogen and deuterium, recent quantum electrodynamics (QED) calculations, and, as an essential additional ingredient, a generalized least-squares analysis, to obtain precise and optimal predictions for hydrogen and deuterium transition frequencies. Some of the predicted transition frequencies have relative uncertainties more than an order of magnitude smaller than that of the g-factor of the electron, which was previously the most accurate prediction of QED.

CERN Document Server

We develop a theory of Smectic A - Smectic C phase transition with anomalously weak smectic layer contraction. We construct a phenomenological description of this transition by generalizing the Chen-Lubensky model. Using a mean-field molecular model, we demonstrate that a relatively simple interaction potential suffices to describe the transition. The theoretical results are in excellent agreement with experimental data.

International Nuclear Information System (INIS)

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

KoreaScience (Korea)

Full Text Available

International Nuclear Information System (INIS)

The effect of high energy neutron irradiation (E > 1 MeV) on the superconducting transition temperature, Tsub(c), of the A-15 compound Mo_3Os is reported. Tsub(c) was found to decrease with increasing neutron dose, but at a rate considerably less than observed in other A-15 compounds composed of non-transition metals. The results lend support to the idea that the effect of ordering on Tsub(c) is smaller for A-15 compounds composed only of transition metals than those composed of transition and non-transition metals. (author).

Energy Technology Data Exchange (ETDEWEB)

The 8 papers in the report deal with the following areas: Introduction to diesel particulate emissions, alternative fuels, and the transit industry; Technical problems and policy issues associated with the 1991 bus emissions standards; Reducing transit bus emissions: comparative costs and benefits of methanol, particulate traps, and fuel modification; Effects of applying emissions averaging, trading, and banking to transit buses; Strategic review of heavy-duty engine emission regulations and alternate fuels; Meeting bus emissions standards--a perspective; Economic evaluation of bus maintenance contracting; Objectives for a transit-bus-fleet management data, information, and knowledge exchange.

International Nuclear Information System (INIS)

A dense silica glass was prepared by consolidating a highly dispersed silicic acid powder (particle size 1H magic-angle spinning (MAS) NMR confirmed an increase in hydroxyl groups in the sample prepared by SPS relative to that of the conventional SiO2 reference glass. Aside from the comparably high water content, we conclude from the similarity of the IR-reflectance and the 29Si MAS NMR spectra of the SPS sample and the corresponding spectra of the conventionally prepared silica glass, that the short- and medium-range order is virtually the same in both materials. Raman spectroscopy, however, suggests that the number of three- and four-membered rings is significantly smaller in the SPS sample compared to the conventionally prepared sample. Based on these results we conclude that it is possible to prepare glasses by compacting amorphous powders by the SPS process. The SPS process may therefore enable the preparation of glasses with compositions inaccessible by ...

International Nuclear Information System (INIS)

We have performed molecular dynamics simulations of radiation damage in fused silica. In this study, we discuss the role of successive cascade overlap on the saturation and self-healing of oxygen vacancy defects in the amorphous fused silica network. Furthermore, we present findings on the topological changes in fused silica due to repeated energetic recoil atoms. These topological network modifications consistent with experimental Raman spectroscopic observation on neutron and ion irradiated fused silica are indicators of permanent densification that has also been observed experimentally.

Energy Technology Data Exchange (ETDEWEB)

Vibrational dephasing in condensed phases is studied from both a theoretical and experimental standpoint. A theory is presented which describes the dynamics of motional or exchange processes in weakly perturbed systems. This general formalism, which has been previously used to describe motional narrowing in magnetic resonance, is applied to vibrational spectroscopy. The model treats the case of a high frequency vibration anharmonically coupled to a low-frequency vibration. Intermolecular exchange of low frequency vibrational quanta results in a temperature dependent broadening and frequency shift of the high frequency vibration. Analysis of experimental data by this model yields both the exchange rates and the anharmonic couplings.

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This report summarizes the progress of the Solid State Photovoltaic Research Branch of the Solar Energy Research Institute (SERI) from October 1, 1988, through September 30,l 1989. Six technical sections of the report cover these main areas of SERIs in-house research: Semiconductor Crystal Growth, Amorphous Silicon Research, Polycrystalline Thin Films, III-V High-Efficiency Photovoltaic Cells, Solid-State Theory, and Laser Raman and Luminescence Spectroscopy. Sections have been indexed separately for inclusion on the data base.

International Nuclear Information System (INIS)

The existence of characteristic longitudinal optical and transverse optical phonons of cubic ZnO in ZnO nano-tetrapods is determined by Raman spectroscopy and first-principles calculations. Stacking sequence change at the boundary of the core and legs is also identified by high-resolution transmission electron microscopy. Based on this experimental and theoretical evidence, we demonstrate that the lattice structure of ZnO nano-tetrapods is hierarchical with a zinc blende core connecting to four wurtzite legs. Furthermore, we establish the atomic configuration and propose a formation mechanism induced by Laplace pressure in the initial growth stage of ZnO nano-tetrapods.

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[sup 13]C epitaxial diamond films have been grown on [sup 12]C-type IIb diamond substrates doped with boron, using electron assisted chemical vapor deposition. The relation between etch pits to dislocations in [sup 13]C diamond film and the broadening of the first-order Raman peak was examined. The reactant gas was [sup 13]CH[sub 4] of > 99% purity. The substrate temperature was varied from 943 to 1300 C. The uneven surface morphology was confirmed by atomic force microscopy (AFM) and laser microscopy. From 943 to 1030 C, etch pit rows along left angle 100 right angle were observed. At 991 C, the etch pit density on a row was 3300 to 5000 pits/cm. The Ar[sup +] laser beam was focused on a transparent area near the row of etch pits, where the boron impurity of the substrate is less than several 10 ppm. The first-order Raman line of [sup 13]C epitaxial diamond film was broadened to 3.6-4.0 cm[sup -1]. The line broadening was 50-90% compared ...

International Nuclear Information System (INIS)

The magnetic susceptibility and high-field magnetization have been measured for the intermediate valence system Eu(Pd_1_-_xPt_x)_2Si_2 with 0#<=#x#<=#0.15. A first-order valence transition is observed for all the compounds under high field of 100 T at low temperatures. This valence transition is of first order accompanied with a large hysteresis, which is in contrast to a continuous valence change against temperature. Based on the interconfigurational fluctuation (ICF) model, the temperature- and field-induced valence transitions are discussed. It is found that a first-order valence transition can be induced by magnetic field, even if the system shows a continuous valence transition against temperature. Metamagnetic behavior at finite temperatures is also understood qualitatively by the ICF model. copyright 1997 The American Physical Society.

International Nuclear Information System (INIS)

The two-phase flow regime transition in a large diameter (I.D.=200mm) vertical pipe was experimentally investigated using a dual-sensor optical probe. The flow transitions from bubbly to chum without an intermediate slug flow regime as the air flow rate is increased. The transition boundaries developed for bubbly to slug flow in small diameter pipes are compared to the bubbly to chum flow transition of the present experiment. The bubbly to chum transition occurs at a void fraction of about 0.15 compared to 0.25 for bubbly to slug transition in small diameter pipes. The radial distribution of bubble diameter, bubble frequency, bubble velocity and local void fraction were obtained using a dual-sensor optical probe at different flow conditions. The Probability Density Function (PDF) and Cumulative Distribution Function (CDF) of the bubble velocity and size are used ...

UK PubMed Central (United Kingdom)

This study assesses the contribution of smoking to all-cause mortality among a primarily minority cohort of urban transit operators. Survey and medical exam data, obtained from 1,785 workers (61% African...Full Text Available

UK PubMed Central (United Kingdom)

An explicit proposal for experiments leading to abrupt transitions in spatially extended bacterial populations in a Petri dish is presented on the basis of an exact formula obtained through an analytic...Full Text Available

UK PubMed Central (United Kingdom)

Epithelial-mesenchymal transition (EMT), a switch of polarized epithelial cells to a migratory, fibroblastoid phenotype, is considered a key process driving tumor cell invasiveness and metastasis....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The authors report experimental results of heat transfer in the region of transition to turbulence. The augmentation was induced through deployment of periodically placed cylindrical eddy promoters in parallel plane channel flows. Eight different configurations were used. The presence of eddy promoters displaced the point of transition from Reynolds number values of 1500 for the plane channel to around 400 for the least stable case. The value of Nusselt number at the transition for eddy promoters cases was up to 2.5 times higher than the one for the plane channel at the transition. Furthermore, the lower the transition Reynolds number, the higher the Nusselt number at the transition. For the cases where the diameter of the promoters was small and/or the pitch large, the heat transfer results in the transition region were consistent with ...

UK PubMed Central (United Kingdom)

Transitions at 28-32°C in membranes of many kinds of seeds influence their germination and subsequent growth. Changes at 28-32°C in the rates of loss of endogenous amino acids from imbibed...Full Text Available

International Nuclear Information System (INIS)

This work concerns the development of a methodology the objective of which is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. During the first time, the efforts focused on: (1) the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; (2) the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; and (3) the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. During the second time, in order to verify the fundamental assumption, a series of experiments were conducted, the objective of which was to demonstrate the ...

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... capture radioisotopes energy levels excited states intermediate mass nuclei

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... fermions interacting boson model molybdenum 101 neutron-rich isotopes

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... radioisotopes coincidence methods energy-level transitions gamma radiation

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... deformed nuclei eigenvalues even-odd nuclei gold 195 hamiltonians iridium

Science.gov (United States)

... transition to couple the emitted spontaneous radiation with the ammonia molecules and thus provide more amplification [2]. ...

International Nuclear Information System (INIS)

The neutron transition multipole moment, M/sub n/, for (0"+#->#2"+, 1.84 MeV) transition is inferred by measuring the (#alpha#,#alpha#') angular distribution at E/sub #alpha#/ = 50 MeV and comparing it with a microscopic distorted-wave Born approximation calculation. Proton transition densities are taken from electron scattering data. M/sub n//M/sub p/ is found to be substantially less than N/Z in agreement with the (p,p') result.

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... beta decay energy levels energy-level transitions internal conversion

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We present results from ab-initio electronic-structure calculations of mechanical properties of the rhombohedral phase of vanadium reported in recent experiments (R Ia), and other predicted high-pressure phases (R Ib and bcc), focusing on properties relevant to dynamic experiments. We find that of the three transitions the largest volume collapse (1.3%) is for the R Ia to R Ib transition. Calculations of the single crystal and polycrystal elastic constants reveal a remarkably small discontinuity across the phase transitions even at zero temperature where the transitions are first order.

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... beta decay coincidence spectrometry energy levels energy-level transitions

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... correlation beta-minus decay coincidence spectrometry experimental data

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A Bianchi type-IX cosmological model has been found as a solution of Einstien's vacuum field equations with a cosmological constant. The solution represents a rotating generalziation fo the de Sitter universe. This universe shows a transition to exponential expansion and the vorticity begins to decay exponentially at the grand-unified-theory time. The point of time for this transition is independent of the magnitude of the vorticity. During the Guth inflationary era the vorticity decays by a factor of the order 10 US.

Science.gov (United States)

We introduce a discrete multiplicative process as a generic model of competition. Players with different abilities successively join the game and compete for finite resources. Emergence of dominant players and evolutionary development occur as a phase transition. The competitive dynamics underlying this transition is understood from a formal analogy to statistical mechanics. The theory is applicable to bacterial competition, predicting novel population dynamics near criticality.

International Nuclear Information System (INIS)

Our studies on K#beta#/K#alpha# X-ray intensity ratios of some of the technologically important 3d-transition metal compounds have been reviewed. Comparison of the experimental results with single-configuration Dirac-Fock calculations provided important information on the valence states of the transition metals in various compounds, which can be helpful in understanding the nature of bonding in the compounds. (author)

CERN Document Server

We report an uncertainty evaluation of an optical lattice clock based on the $^1S_0\\leftrightarrow^3P_0$ transition in the bosonic isotope $^{174}$Yb by use of magnetically induced spectroscopy. The absolute frequency of the $^1S_0\\leftrightarrow^3P_0$ transition has been determined through comparisons with optical and microwave standards at NIST. The weighted mean of the evaluations is $\

CERN Document Server

Classic and recent results for gauge effects on the properties of the normal-to-superconducting phase transition in bulk and thin film superconductors are reviewed. Similar problems in the description of other natural systems (liquid crystals, quantum field theory, early universe) are also discussed. The relatively strong gauge effects on the fluctuations of the ordering field at low spatial dimensionality D and, in particular, in thin (quasi-2D) films are considered in details. A special attention is paid to the fluctuations of the gauge field. It is shown that the mechanism in which these gauge fluctuations affect on the order of the phase transition and other phase transition properties varies with the variation of the spatial dimensionality D. The problem for the experimental confirmation of the theoretical predictions about the order of the phase transitions in gauge systems is discussed.

British Library Electronic Table of Contents (United Kingdom)

The atomic mechanism of a glass-to-liquid transition in a monatomic Lennard-Jones (LJ) glass was studied using the molecular dynamics (MD) method. Glassy models were heated up from low temperature at two different heating rates and a glass-to-liquid transition found to occur at the higher heating rate. The temperature dependence of the potential energy, mean-squared-displacements (MSD) of the atoms and the self-intermediate scattering function indicate clearly that a glass transition occurs in the system. The atomic mechanism of the glass-to-liquid transition was investigated by analyzing the spatio-temporal arrangement of liquid-like atoms in the system upon heating. Liquid-like atoms were detected using the Lindemann-melting-like criterion. Upon heating, liquid-like atoms occur at temper...

British Library Electronic Table of Contents (United Kingdom)

We propose a method for the creation of arbitrary superposition of N atomic states using generalized stimulated Raman adiabatic passage (STIRAP) techniques with laser fields coupling each one of N lower states to a single upper state in a Formula Not Shown -level atomic system. Formula Not Shown dark states that are composed of N lower states span a dark subspace. In the adiabatic limit, the dark and bright subspaces are decoupled, thus the nonadiabatic interaction within this dark subspace dominates the evolution of the system. Different from general methods to create our required coherent superposition state, in a reverse way, here we consider the required state as the starting point of evolution dynamics, and utilize laser fields to drive it into a single lower state step by step. Time ...

International Nuclear Information System (INIS)

The optical spectroscopy measurements of gadolinium gallium garnet (GGG) crystals doped with Yb show evidence of the presence of non-equivalent optical centers with very similar radiative decay rates. The energy level schemes of those centers have been determined on the basis of optical absorption, luminescence and Raman experiments. Crystal field fitting resulted in two sets of slightly different crystal field parameters for two non-equivalent Yb centers. Both sets of parameters describe perfectly the experimentally detected Y b3+ energy levels. Correlation between systematic trends in the experimental energy level schemes and crystal field parameters is discussed.

International Nuclear Information System (INIS)

An experimental study and a theoretical simulation were made of stimulated Raman scattering (SRS) conversion into shifted components. It was found that there were optimal values of the pressure and focal distance for conversion into the first 'blue' satellite of the first Stokes component. A study was made of the spatial and temporal dynamics of SRS conversion, which took into account generation of the shifted components. It was demonstrated theoretically and experimentally that the satellite intensity could be enhanced significantly by additional electron-collision excitation of the vibrational levels in the conversion medium or by the application of pairs of pump pulses. The maximum efficiency of conversion to the first 'blue' satellite of the first Stokes component was 10% and the satellite intensity reached one-third of the intensity of the main Stokes line. (nonlinear optical phenomena and devices)

International Nuclear Information System (INIS)

A backward wave oscillator (BWO) filled with a strongly magnetized plasma supports TM and Trivel-piece-Gould (TG) modes. At large amplitudes these modes may act as wigglers for generating millimeter waves via free electron laser instability. The nonlinear coupling between the wiggler, the beam space charge mode, and the high frequency free electron laser wave is dominated by parallel motions. In the Raman regime the growth rate of instability goes as #approx##omega#_p_b"1"/"2/#gamma#_o"9"/"4, where #omega#_p_b is the beam plasma frequency and #gamma#_o is the relativistic gamma factor.

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The irradiation behavior of Li{sub 2}TiO{sub 3} under a fusion reactor environment was simulated by simultaneous irradiation of Li{sub 2}TiO{sub 3} by the triple ion beams and the respective single ion beams of O{sup 2+}, He{sup +} and H{sup +}. The microstructural changes in Li{sub 2}TiO{sub 3} caused by the irradiation were measured by Raman spectroscopy and FT-IR photoacoustic spectroscopy. The results suggest that the formation of TiO{sub 2} due to displacements by irradiation occurs, and the irradiation defects generated by irradiation trap hydrogen and increase the amount of hydroxyl near the surface. Such phenomena are believed to significantly affect the chemical form of the released tritium and the tritium inventory in the breeding materials of a fusion reactor.

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New results for two types of nano-size silicon, prepared via thermal vapour deposition either with or without a graphite substrate are presented. Their superior reversible charge capacity and cycle life as negative electrode material for lithium-ion batteries have already been shown in previous work. Here the lithiation reaction of the materials is investigated more closely via different electrochemical in situ techniques: Raman spectroscopy, dilatometry and differential electrochemical mass spectrometry (DEMS). The Si/graphite compound material shows relatively high kinetics upon discharge. The moderate relative volume change and low gas evolution of the nano silicon based electrode, both being important points for a possible future use in real batteries, are discussed with respect to a standard graphite electrode. (author)

International Nuclear Information System (INIS)

We report first-principles frozen-phonon calculations for the determination of the force-free geometry and the dynamical matrix of the five Raman-active A_1_g modes in YBa_2Cu_3O_7. To establish the shape of the phonon potentials atomic forces are calculated within the linearized-augmented-plane-wave method. Two different schemes emdash the local-density approximation (LDA) and a generalized gradient approximation (GGA)emdash are employed for the treatment of electronic exchange and correlation effects. We find that in the case of LDA the resulting phonon frequencies show a deviation from experimental values of approximately -10%. Invoking GGA the frequency values are significantly improved and also the eigenvectors are in very good agreement with experimental findings. copyright 1997 The American Physical Society.

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Nanosized CaSnO{sub 3} is synthesized by a hydrothermal process and characterized by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The SEM observation shows the sample has a porous flowerlike morphology. The electrochemical results exhibit that the stable and reversible capacity of 547 mAh g{sup -1} is obtained after 50 cycles at 60 mA g{sup -1} (0.1 C) and the corresponding charge capacity is determined to be 316 mAh g{sup -1} at the current density of 2.5 C. Cyclic voltammetry and electrochemical impedance spectroscopy data are analyzed to complement the galvanostatic results. The observed excellent performance is attributed to the porous structure and large surface area of flowerlike CaSnO{sub 3}.

CERN Document Server

The concept of the 'white-light cavity' has recently generated considerable research interest in the context of gravitational wave detection. Cavity designs are proposed using negative (or anomalous) dispersion in an intracavity medium to make the cavity resonate over a large range of frequencies and still maintain a high cavity build-up. This paper presents the first experimental attempt and demonstration of white-light effect in a meter long ring cavity using an intracavity atomic medium. The medium's negative dispersion is caused by bi-frequency Raman gain in an atomic vapor cell. Although the white light condition was not perfectly achieved and improvements in experimental control are still desirable, significantly broad cavity response over bandwidth greater than 20 MHz has been observed. These devices will have potential applications in new generation laser interferometer gravitational wave detectors.

British Library Electronic Table of Contents (United Kingdom)

Cyclization of deproteinized natural rubber (DPNR) or purified natural rubber latex was effectively performed in latex phase by using trimethylsilyl-trifluoromethane sulfonate or trimethylsilyl triflate (TMSOTF) as a novel catalyst, which is still not reported in the case of natural rubber latex. Various cyclization conditions affecting the degree of cyclization were studied, such as dry rubber contents, temperature, TMSOTF concentrations, and time. The cyclized products were characterized by FTIR, Raman, 1H-, and 13C-NMR spectroscopies, as well as DSC and TGA. The degree of cyclization was estimated by 1H-NMR spectrum. It was found that the degree of cyclization in NR was a function of cyclization conditions. The thermal stability of cyclized DPNR increased with the degree of cyclization....

British Library Electronic Table of Contents (United Kingdom)

Abstract: We have performed petrographic and spectroscopic studies of brown diamonds from an eclogite xenolith from the Udachnaya pipe (Yakutia, Russia). Brown diamonds are randomly intermixed with colorless ones in the rock and often located at the grain boundaries of clinopyroxene and garnet. Brown diamonds can be characterized by a set of defects (H4, N2D and a line at 490.7nm) which are absent in colorless diamonds. This set of defects is typical for plastically deformed diamonds and indicates that diamonds were likely annealed for a relatively short period after deformation had occurred. Excitation of brown colored zones with a 632.8nm He-Ne laser produced the typical diamond band plus two additional bands at 1730cm^-^1 and 3350cm^-^1. These spectral features are not genuine Raman ban...

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We have mapped and studied the effects of MeV alpha-particle bombardment in polyvinylidene chloride (PVDC) and polyethylene (PE). We used 3.5 and 5.0 MeV alpha-particle incident beams and stacked polymer films to separate the contributing effects of the electronic ({var_epsilon}{sub e}) and nuclear ({var_epsilon}{sub n}) stopping powers. The electrical conductance and change in the chemical structures were measured by direct resistivity measurement, Raman microprobe, RBS and FTIR. The results indicate significant differences in the ({var_epsilon}{sub e}) and ({var_epsilon}{sub n}) effects at higher alpha-particle bombardment fluences. {copyright} {ital 1997 American Institute of Physics.}

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Raman scattering was observed from thin film optical waveguides of cellulose acetate exposed to water vapor from 0% to 100% relative humidity (RH), and from dilute solutions of water in methyl acetate. Spectra of cellulose acetate (CA398, 39.8% acetyl) at low RH and cellulose triacetate (CTA) at low and high RH are consistent with the presence of water monomers that are weakly hydrogen bonded to acetyl C=O groups. Differences between the spectra of water in CA398 and CTA at low RH are attributed to sequential hydrogen bonding involving OH groups in CA398. At high RH, CA398 and CTA (to a lesser extent) show bands attributed to water/water interactions that are similar to those found in sequentially hydrogen-bonded hydrates. CA398 films that are annealed at high temperatures exhibit decreased water/water interactions at high RH. Exposure of CA398 films to D/sub 2/O converts > 90% of all polymer OH groups to OD groups. This indicates that water is accessible to ...

Science.gov (United States)

We have measured the Raman isotropic profiles of the ?(C?N) band at 2235 cm(-1) for five solutions of ME6N (4-cyanophenyl-4'-hexylbenzoate) liquid crystal dissolved in CCl(4) in the range from x = 0.12 to 0.007 (x, mole fraction of ME6N) and then obtained the corresponding vibrational correlation functions, C(v)(t), by time Fourier transformation. The increase with dilution of the dephasing times ?(v) complies with the behavior of the nonmonotonic concentration dependence predicted by the fluctuation concentration model for this concentration range (x Rothschild, which, being based on the assumption that the environmental modulation is described by a stretched exponential decay e(-(t/?(0))(?)), is more appropriate for the interpretation of the vibrational correlation function arising from a distribution of relaxation processes caused, as in the present case, by the persistence of pseudonematic domains. With dilution the dispersion parameter ? and the average ...

Science.gov (United States)

The (Al/sub x/Ga/sub 1-x/)/sub 0.5/In/sub 0.5/P material system, lattice matched to GaAs substrates, is useful for visible laser diodes. Here, low pressure organometallic vapor phase epitaxial growth of Ga/sub 0.5/In/sub 0.5/P and (Al/sub x/Ga/sub 1-x/)/sub 0.5/In/sub 0.5/P is examined. Epitaxial layers of bulk materials are characterized using photoluminescence, electroreflectance, Raman scattering spectroscopy, and surface morphology studies to determine lattice match and optimum growth conditions. Lattice matching at the growth temperature produces featureless growth surfaces, while lattice matching at room temperatures results in minimum photoluminescence linewidth but cracked surface due to tensile strain during growth. Raman scattering spectra of the quaternary reveal a three-mode structure, with spectral peaks due to GaP-like, in P-like, and AIP-like LO phonons. Additionally, (Al/sub x/Ga/sub 1-x/)/sub 0.5/In/sub 0.5/P/Ga/sub 0.5/In/sub ...

Science.gov (United States)

This paper explores effects of differential diffusion in nonpremixed turbulent jet flames. Pulsed Raman scattering spectroscopy is used to measure temperature and species concentrations in chemically reacting jets of H{sub 2}/CO{sub 2} into air, over a range of jet Reynolds numbers from 1,000 to 30,000 based on cold jet fluid properties. Results show significant effects of differential diffusion at all jet Reynolds numbers considered. Differential diffusion between H{sub 2} and C0{sub 2} produces differences between the hydrogen element mixture fraction ({xi}{sub H}) and the carbon element mixture fraction ({xi}{sub c}). The greatest effects occur on the rich side of stoichiometric, where {xi}{sub H} is observed to be smaller than {xi}{sub C} at all Reynolds numbers. Differential diffusion between H{sub 2} and H{sub 2}O creates a net flux of hydrogen element toward the stoichiometric contour and causes a local maximum in {xi}H that occurs near the stoichiometric ...

International Nuclear Information System (INIS)

Borosilicate based glass formulations have been found suitable for fixing the HLW (high level radioactive liquid waste) generated after reprocessing of the spent nuclear fuel. As the glass experiences continuous irradiation by #alpha#, #beta#a, and #gamma# radiations from the radioactive components of HLW, alteration in the glass structure may occur. Understanding of these structural evolutions of the nuclear waste glasses under irradiation is crucial to secure long term disposal and predict their behavior. In the present work, alkali based barium borosilicate glasses, having composition similar to that of Trombay Research Reactor waste glass were irradiated with high energy "1"2C beam and the radiation induced changes were monitored by micro Raman experiment. Since a "1"2C atom can be considered as a cluster of alphas, this beam was chosen to yield linear energy losses (LET) comparable to that in case of a particles. The irradiations were carried out at 30 deg N ...

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A set of computer codes have been developed to produce spectral line shapes of highly stripped ions for a number of transitions in Hydrogenic, Helium-like and Lithium-like species. The choice of the transitions has been dictated largely by the laser compression experiments. The transitions of Hydrogenic species are: Lyman ..cap alpha..; Lyman ..beta..; Lyman ..gamma..; Lyman delta; Balmer ..cap alpha..; and Balmer ..beta... The transitions of Helium-like species are: 1s/sup 2/(/sup 1/S/sub 0/)-1s2p(/sup 1/P); 1s/sup 2/(/sup 1/S/sub 0/)-1s3p(/sup 1/P); 1s/sup 2/(/sup 1/S/sub 0/)-1s4p(/sup 1/P) and the associated dipole-forbidden components. The transitions of Lithium-like species are the entire n = 2 to n = 3 and n = 4 complexes.

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The magnetic susceptibility and high-field magnetization have been measured for the intermediate valence system Eu(Pd{sub 1{minus}x}Pt{sub x}){sub 2}Si{sub 2} with 0{le}x{le}0.15. A first-order valence transition is observed for all the compounds under high field of 100 T at low temperatures. This valence transition is of first order accompanied with a large hysteresis, which is in contrast to a continuous valence change against temperature. Based on the interconfigurational fluctuation (ICF) model, the temperature- and field-induced valence transitions are discussed. It is found that a first-order valence transition can be induced by magnetic field, even if the system shows a continuous valence transition against temperature. Metamagnetic behavior at finite temperatures is also understood qualitatively by the ICF model. {copyright} {ital 1997} {ital The American Physical Society}

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Two-phase pressure drop and fluctuating static pressures were measured in a small horizontal rectangular channel (hydraulic diameter = 5.44 mm). The two-phase fluid was an air/water mixture at atmospheric pressure tested over a mass flux range of 50 to 2,000 kg/m[sup 2] [center dot] s. Two-phase flow patterns were identified and an objective method was found for determining the flow pattern transition from bubble or plug flow to slug flow. The method is based on an RMS static pressure measurement. In particular, it is shown that the transition is accompanied by a clear and abrupt increase in the RMS pressure when plotted as a function of mass quality. Use of the RMS pressure as a two-phase flow pattern transition indicator is shown to have advantages over pressure-versus-time trace evaluations reported in the literature. The transition is substantiated by a clear local change in slope in the curve of ...

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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)

International Nuclear Information System (INIS)

The numerical analysis of the experimental data on viscosity change by time in the period after fast heating and crystal-liquid phase transition for the copper nonequilibrium melts and the Fe_7_0Cr_1_0P_1_3C_7 glass-forming melt near their melting temperatures is accomplished through the method of correlation functions and the Rytov-Dimentberg criterion. The observed dependences have nonmonotonic oscillating character but they do not relate to auto-oscillations. The proposed theoretical model of the properties oscillations origination by relaxation in the nonequilibrium liquids explains them as manifestation of noise-induced transitions in the metastable area near the critical temperatures (melting, structural transitions)

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The E1 and E3 transition operators in the sdf-IBA model are discussed. An effective E1 operator containing one- and two-body terms explains very well the E1 data in transitional and rotational nuclei. The E1 parameters for rotational nuclei are obtained by imposing a constraint on the IBA model namely, the validity of Alaga rules for ``pure K`` states. The systematic behavior of the octupole strength is well reproduced using a one-body octupole operator. The anomalously large fragmentation of the low-energy octupole strength in non-rotational nuclei is shown to be a signature of the O(6) dynamical symmetry.

Science.gov (United States)

... transItion to more capable space-based interceptors as ... ten wtth bmlogtcal, and thirty with chemical weapons. ... are becoming the weapon of choice ...

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PMID:21306364

Science.gov (United States)

The SCF approximation is used in a statistical theory of melting based on equality of the chemical potentials. The results for the melting points of the inert gases are close to the observed values.

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... alpha beams energy-level transitions gamma spectra iridium 187 iridium 189

International Nuclear Information System (INIS)

... 900526-11-8 277 p. MATERIALS SCIENCE antiferromagnetic materials cerium

UK PubMed Central (United Kingdom)

This paper describes a novel psychophysical and analytical technique, called periodic perturbation, for creating and characterizing perceptual waves associated with transitions in visibility...Full Text Available

International Nuclear Information System (INIS)

The unknow parities of five strong dipole states between 6 and 8 MeV in "8"8Sr are shown to be negative. (orig.).

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the probability of its spontaneous radiation de-excitation increases. ... consider spontaneous radiation transitions. We will examine the ...

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BackgroundChanges in levels of estradiol and progesterone that occur with the transition to reproductive senescence may influence nociception or affect.Full Text Available

International Nuclear Information System (INIS)

Published in summary form only. 6 Refs.

Energy Technology Data Exchange (ETDEWEB)

The compound GdPd{sub 2}Si, which is reported to order antiferromagnetically at 13 K, has been investigated by heat capacity and electrical resistivity measurement in the presence of external magnetic fields. In contrast to an earlier report, the zero-field heat capacity and resistivity data indicate two magnetic transitions at 13 and 17 K. The external magnetic field substantially influences the resistivity and heat capacity of the compound around the magnetic ordering temperature. The magnetocaloric effect, which is calculated from in-field heat capacity data, is quite large around the magnetic transition temperature. The magnetoresistance is also large near the magnetic ordering temperature. The metamagnetic transition is observed for 10 kOe magnetic field both in magnetocaloric and in magnetoresistance data. The metamagnetic transition strongly influences the magnetocaloric effect and ...

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Nov 12, 2010 ... The adaptive, nonparametric matched filter algorithm suggested by Kay ... For the point design of a 4 sigma single event SNR the combined NR ...

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The gastrointestinal transit was studied in 20 patients with loop transverse colostomies and previously normal colons. This analysis was performed through radiological observation of progression of 20 radiopaque pellets and measurements of its transit time in the various segments of the digestive tract. An evaluation of other related clinical and radiological events was carried out sentimentality's. In order to better understand the influence of the surgical procedure, the study was performed under similar dietary and supportive care conditions and standard radiological studies before and after the re-establishment of transit, thus enabling a comparison with the same individual. (author)

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... gamma cascades kev range 10-100 lifetime lutetium 171 lutetium 173 lutetium

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be due to flow separation and reattachment, rather than transition. The analysis predicted a .... lations of Transonic Fan Performance," AGARD Propulsion ...

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... No. 52. Metal Complexew-I. Preparation and Physical Properties of Transition Metal Complexes of 6-Mercaptopurine and ,-Mercapto-6, 7-Diphenyl ...

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7.5.6 Conclusions of the Generic Metroplex Queueing Simulation . ...... the systemwide arrival delays incurred at the metroplex terminal-area ...... assignment rules, estimated nominal transit speeds or times by domain, and stochastic ...

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... band theory excited states iridium 187 iridium 189 beta decay radioisotopes

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This suggests that Ms of the iron nanoparticles is about 125 emu/g, about half of M~u.lk, which contradicts previous reports on transition metals. ...

International Nuclear Information System (INIS)

The change of superconducting properties after neutron irradiation in A-15 compounds such as Nb_3Sn. Nb_3Al. V_3Ca and V_3Si has been examined. Using the model based on the damage function, the change of transition temperature corresponding to an arbitrary irradiation dose within about 10"2"0n/cm"2 can be predicted with an accuracy of several percent for Nb_3Al. Nb_3Sn and V_3Si if experimental data, namely a pair of irradiation dose and transition temperature, is given. The calculation of transition temperature of neutron irradiated A-15 compounds is much more straightforward than in the case of Pande's model. (author).

Science.gov (United States)

It is shown that the extended softening in k space of the [111] transverse acoustic phonon in Nb3Sn seen recently by neutron measurements is in agreement with the predictions of a phenomenological Landau description of the structural phase transition in the A-15 compounds. This indicates the feasibility of a calculation of the partial phonon density of states of modes directly coupled to the order parameter driving the structural transition, as a function of temperature.

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A hydrous oxide film for the application as dielectric film is synthesized by immersion of pure aluminum in hot water. From a Rutherford backscattering analysis, the ratio of aluminum to oxygen atoms was found to be 3:2 in the anodized aluminum oxide film, and 2:1 in the hydrous oxide layer. Anodization of the hydrous oxide layer was more effective for the transition of amorphous anodic oxides to the crystalline aluminum oxides.

Energy Technology Data Exchange (ETDEWEB)

Theoretical x-ray transition energies, lifetimes and partial multiplet fluorescence yields are presented for all spectroscopic terms of electron configurations with a single K-shell vacancy and varying number of electrons in the L-shell and M/sub 1/-subshell for multiply-ionized silicon. 9 tables.

International Nuclear Information System (INIS)

The defect-induced effect on superconducting transition temperature T_c of A-15 compounds is examined. T_c is found from the Eliashberg equations which take into account the defect-induced changes in the electron-phonon spectral function and electron density of states. The dependence of T_c on the defect type in the superconductor is obtained.

International Nuclear Information System (INIS)

A diode-laser fluorescence experiment was performed in order to study fine-structure transitions between 5"2P states of rubidium atoms colliding with ground-state potassium or caesium atoms. The Rb(5"2P_3_/_2) state was optically excited and the intensity ratio of sensitized to direct fluorescence was measured. (author).

International Nuclear Information System (INIS)

The magnetic #beta#-spectrometer of the #pi# #sq root#2 type with 0.07% pulse resolution is used to measure the intensities of interval conversion electrons on L- and M-subshells of 70.45 keV "1"7"7 Ta gamma-transition. The results are analyzed and the values of mixing parameter #sigma#(E2/M1) and penetration parameter #lambda# are obtained.

Science.gov (United States)

The purpose of this thesis is to explore possible difficulties and their solutions in transitioning the OTCIXS/TADIXS subsystems from the present Navy UHF Fleetwide Satellite System to the EHF/SHF MILSTAR System. The research provides a description of the...

International Nuclear Information System (INIS)

We study the possibility of utilizing the superfluid to Mott-insulator quantum phase transition in an array of quantum well exciton-polariton traps to generate indistinguishable single photons in a massive parallel fashion. By means of analytical and numerical methods, the device operations and system properties are examined using realistic experimental parameters. Such a deterministic, massive parallel generation may find new applications in photonic quantum information processing.

Energy Technology Data Exchange (ETDEWEB)

We report on solid solution CePd[sub 2-x]Mn[sub x]Si[sub 2] which shows an interesting transition of the Ce-ion from magnetism in a Kondo regime to an intermediate valence state coupled with a strongly magnetic 3d sublattice. ((orig.))

International Nuclear Information System (INIS)

The martensitic phase transition in the A-15 compounds is treated by expanding the free energy in terms of the order parameters and its spatial gradients. The model used is a modified version of that recently proposed by Gorkov. The predictions for a wide range of physical properties are in good agreement with experimental results for V_3Si and Nb_3Sn lending support to the veracity of the model. 25 refs.

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Transit time, the time from bridgewire burst until breakout of detonation from the output pellet of an exploding bridgewire detonator, was measured as a function of burst current. From this data, in conjunction with known equations for run distance versus pressure, unreacted explosive Hugoniots, and detonation properties of the initial pressing pellet, the run distance in the initial pressing explosive pellet and shock pressure from the exploding bridgewire were determined, both as a function of burst current.

International Nuclear Information System (INIS)

Two sets of analytical correlations describing transitions between two-phase flow regimes are reviewed and discussed. One, the T-D set, is based on mechanistic models; the other, the Weisman set, on experimental correlations. The T-D set is preferred for horizontal flow, whereas the Weisman set seems preferrable for vertical flow. A computer code (FLOP) based on the T-D theory is described and applied to validate the theory.

International Nuclear Information System (INIS)

Critical power characteristics of tight lattice rod assembly was investigated using a simple-shaped experimental apparatus. An electrically heated rod with four spacers was placed in a circular tube, and boiling transition condition for a rod in an annular geometry was clarified varing annulus clearance. It was found that critical heat flux depends strongly on the clearance accoding as the gap becomes smaller. This results was compared with KfK correlation and the trends were well correlated. (author).

Energy Technology Data Exchange (ETDEWEB)

K beta X-ray lines from partially M-shell-ionized ions of titanium through nickel which are produced in vacuum-spark plasmas have been observed systematically for the first time, using a high-resolution curved-crystal spectrometer. Each K beta line is clearly separated into its corresponding charge state. As a result, it is possible to measure the K beta-type transition energies of the M-shell-ionized ions. The transition energies accurately determined are compared with those calculated for iron ions, and the agreement is excellent except for ions having some additional 3d outer-shell electrons or 3s inner-shell vacancies. The square root of the K beta transition frequency is expressed as a linear function of the nuclear charge for isoelectronic sequences. The effective nuclear charges have been also determined for each K beta transition. The 3p electrons do not affect the effective nuclear charges. 10 ...

International Nuclear Information System (INIS)

The KLL Auger electron spectrum of "8"8Sr generated in the EC-decay of "8"8Y has been analyzed at the instrumental resolution of 11 eV using a combined electrostatic spectrometer. Energies and relative intensities of the all nine transitions were determined and compared with theoretical predictions. Our value of 12067.3(12) eV measured for the absolute energy of the dominant KL_2L_3("1D_2) transition was found to be higher by 7.4 eV (i.e., more than 3#sigma#) than that one obtained in a measurement with external excitation. The discrepancy indicates substantial influence of the 'atomic structure effect' on absolute transition energies in our experiment. Very good agreement of the measured 0.14(3) and predicted 0.12 values for the KL_1L_2("3P_0/"1P_1) Auger transition intensity ratio clearly proved the predicted strong influence of the relativistic effects on the KL_1L_2("3P_0) ...

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The thermal radiation which generated from the patterned Ta/Pt/Ta thin heater achieved a high temperature up to 1010 {sup o}C under applied current of 2.4 A. In order to reduce an electromigration at high current of 2 A, a Ta capping layer was placed on the Pt layer instead of conventional capping layer, such as SiNx and CoWP. Under the thermal radiation at the applied current of 2 A in the Ta/Pt/Ta thin heater, the Ta capping layer enhanced the lifetime of the Pt thin heater up to 5 h. A stamping process for the crystallization of a-Si was performed for 40 samples using the Ta/Pt/Ta thin heater. For all samples, a-Si has been selectively crystallized and Raman peaks were located near 519 cm{sup -} {sup 1}. These results indicated that the thermal radiation of the Ta/Pt/Ta thin heater was maintained constantly due to the Ta capping.

British Library Electronic Table of Contents (United Kingdom)

Abstract A series of compounds with the general formula (La1-xSmx)2Ti2O7 (0-- x --1.0) has been synthesized by a sol-gel method and characterized by XRD, Raman spectroscopy, and scanning electron microscopy (SEM). These compounds are structurally isomorphic to perovskite-type La2Ti2O7 until a substitution rate of x = 0.8. Above this substitution rate (x >-0.8), a biphasic mixture is obtained between the substituted perovskite layered phase and the pyrochlore Sm2Ti2O7 phase. The unusual phosphor (La1-xSmx)2Ti2O7 has been elaborated and its luminescent properties were investigated for low rates of substitution. The emission and excitation spectra were used to study the luminescent properties. The (La1.9Sm0.1)2Ti2O7 powders emit bright red-orange lightunder UV excitation. The emission propert...

British Library Electronic Table of Contents (United Kingdom)

TaC-4wt.% CNT composites were synthesized using spark plasma sintering. Two kinds of CNTs, having long (10-20mm) and short (1-3mm) length, were dispersed by wet chemistry and spray drying techniques respectively. Spark plasma sintering was carried out at 1850^oC at pressures of 100, 255 and 363MPa. Addition of CNTs leads to an increase in the density of 100MPa sample from 89% to 95%. Short CNTs are more effective in increasing the density of the composites whereas long CNTs are more effective grain growth inhibitors. The longer CNTs are more effective in increasing the fracture toughness and an increase up to 60% was observed for 363MPa sample. Hardness and elastic modulus are found to increase by 22% and 18% respectively for 100MPa samples by addition of long CNTs. Raman spectroscopy, SEM...

Energy Technology Data Exchange (ETDEWEB)

Abstract: We report for the selective-area chemical synthesis of semiconductor single-crystal organic nanowires of silver-tetracyanoquinodimethane (Ag-TCNQ). Straight and smooth Ag-TCNQ nanowires can be produced and patterned on micrometer and nanometer scale on silicon substrates covered with a thin layer of Ag film through the reaction of TCNQ and Ag in a simple gas-solid chemical reaction process. Ag-TCNQ nanowires are characterized by UV-vis, IR and Raman spectroscopy, respectively. The Ag-TCNQ nanowires grows preferentially along the [100] direction of strong - stacking of Ag-TCNQ molecules. Nanodevices based on these nanowires are fabricated using focus ion beam (FIB) technique. Electrical properties are characterized and I-V hysteresis is observed, which shows memory effect with electrical switching of three orders on-off ratio. These nanowires could be potential for use in optical storage, ultrahigh-density nanoscale memory and logic devices.

Energy Technology Data Exchange (ETDEWEB)

Monodisperse noble metal nanoparticles are of tremendous interest for numerous applications, such as surface-enhanced Raman spectroscopy, catalysis or biosensing. However, preparation of monodisperse metal nanoparticles is still a challenging task, because typical preparation methods yield nanoparticle ensembles with broad shape and/or size distributions. To overcome this drawback, tailoring of metal nanoparticles with laser light has been developed, which is based on the pronounced shape- and size-dependent optical properties of metal nanoparticles. I will demonstrate that nanoparticle tailoring with ns-pulsed laser light is a suitable method to prepare nanoparticle ensembles with a narrow shape and/or size distribution. While irradiation with ns-pulsed laser light during nanoparticle growth permits a precise shape tailoring, post-grown irradiation allows a size tailoring. For example, the initial broad Gaussian size distribution of silver nanoparticles on quartz ...

Energy Technology Data Exchange (ETDEWEB)

Influence of residual K{sup +} on the preferential oxidation of CO in excess hydrogen (PROX) over CuO-CeO{sub 2} catalysts was investigated. CuO-CeO{sub 2} catalysts were characterized by BET, ICP, XRD, UV-Raman and TPR techniques. The results showed that the existence of residual K{sup +} made {alpha} peak in TPR of CuO-CeO{sub 2} catalysts shift to higher temperatures and depressed the PROX in the absence of CO{sub 2} and H{sub 2}O in the feed over CuO-CeO{sub 2} catalysts. However, small amount of residual K{sup +} was beneficial to the catalytic performance of CuO-CeO{sub 2} catalysts in the PROX in the presence of CO{sub 2} and H{sub 2}O in the feed. Consequently, residual K{sup +} with an appropriate content was beneficial to improve the catalytic performance of CuO-CeO{sub 2} catalysts in the presence of CO{sub 2} and H{sub 2}O. (author)

International Nuclear Information System (INIS)

The transport properties of a 'thin' polycrystalline diamond film are analyzed after the sample exposure to 8.06-keV x-ray radiation. Structure and morphology of the as-grown film have been evaluated by Raman, x-ray diffraction, and scanning electron microscopy techniques. The transport properties have been investigated by measuring dark current-voltage characteristics in the temperature range of 60 to 360 K. Ohmic transport has been evidenced on the as-grown film up to 1.16x10"5 V/cm. After irradiation, nonlinear contributions to the dark current have been evidenced and related to field-assisted thermal ionization of traps. Below 200 K, hopping mechanisms have been observed. Correlations have been found among x-ray irradiation, density of traps involved in the transport processes, and the nonhomogeneous nature of the sample. A simple model of the grain boundary structure is proposed to explain the observations.

International Nuclear Information System (INIS)

Nitrogen doped Diamond-like carbon thin films were deposited on n-Si and SiO_2 substrates by rf magnetron sputtering using pure graphite (99.999%) as the target material and mixtures of Ar, N_2 and H_2 for plasma generation. The dependence of structural and optical properties on nitrogen content was investigated using XPS, Raman spectroscopy, FT-IR spectroscopy, and Ellipsometry studies. It was found that as the nitrogen content was increased in the plasma, sp"2 bonding favored. Also it was observed that oxygen contamination increased with nitrogen content. Typical C-H stretching modes connected with diamond-like carbon could be seen in FT-IR spectra. The I_D and I_G bands were well defined and it was observed that as nitrogen content increased I_G band was enhanced. Ellipsometry studies revealed that the optical constants like refractive index (n) and extinction co-efficient (k) increased with increase in nitrogen content as well as substrate temperature. (author)

Energy Technology Data Exchange (ETDEWEB)

For high-efficiency coal gasification, investigations were given on effect of coal chars with different conversion rates on coal gasification reactivity. In coal gasification, reactivity of char after pyrolysis governs the efficiency. The reference char conversion in CO2 gasification of coal (weight loss) changes linearly in the initial stage of the reaction, but the reactivity declines as the end point is approached. Char surface area is as large as 400 m{sup 2}/g in the initial stage with the conversion at 20%, but it decreases in the final stage. This phenomenon relates closely with changes in pore size and crystalline structure. Change in the Raman value R which shows incompleteness of char graphite structure and amorphous carbon ratio suggests that an active portion with high reactivity is oxidized preferentially, and a portion with low reactivity remains finally. Minerals in coal are known to accelerate the gasification. However, their catalytic effect is ...

Energy Technology Data Exchange (ETDEWEB)

The aim of this work is to combine the MCFC cathode Li{sub x}Ni{sub 1-x}O properties to those of the protective coatings of LiCoO{sub 2}, Li{sub 2}TiO{sub 3} or of CeO{sub 2}, less soluble in the molten carbonates. In the cases of LiCoO{sub 2}, have been carried out by controlled potential coulometry in aqueous solution, a deposition of Co{sub 3}O{sub 4} on dense Ni. The cobalt oxide reacts rapidly in the Li{sub 2}CO{sub 3}-Na{sub 2}CO{sub 3} medium at 650 C to give LiCoO{sub 2}, a spinel cubic phase revealed by Raman spectroscopy. (O.M.)

International Nuclear Information System (INIS)

The formation and breakdown of the passive films on stainless steels are mainly controlled by ionic and electronic transport processes. Both these processes are in part controlled by the electronic properties of the oxide film. Consequently, it is vital to gain a detailed perception of the electronic properties of the passive films together with structural and compositional information for a comprehensive understanding of mechanisms behind passivity and localised corrosion. As a step towards this goal the passive films formed on two main austenitic stainless steels AISI 316L and AISI 304L in borate solution were characterised by in situ Raman spectroscopy and photocurrent spectroscopy coupled with electrochemical measurements. This revealed the formation of an Fe-Cr spinel as the dominant constituent in the passive films with more Cr enrichment in the oxide film on 316L than that of 304L. Bandgap readings and semiconductivities of the two stainless steels suggested ...

International Nuclear Information System (INIS)

For many centuries paper was the main material for recording cultural achievements all over the world. Paper is mostly made from cellulose with small amounts of organic and inorganic additives, which allow its identification and characterization and may also contribute to its degradation. Prior to 1850, paper was made entirely from rags, using hemp, flax and cotton fibres. After this period, due to the enormous increase in demand, wood pulp began to be commonly used as raw material, resulting in rapid degradation of paper. Spectroscopic techniques represent one of the most powerful tools to investigate the constituents of paper documents in order to establish its identification and its state of degradation. This review describes the application of selected spectroscopic techniques used for paper characterization and conservation. The spectroscopic techniques that have been used and will be reviewed include: Fourier-Transform Infrared spectroscopy, Raman ...

Energy Technology Data Exchange (ETDEWEB)

Chromium containing amorphous hydrogenated carbon films (a-C : H/Cr) have been prepared by simultaneous rf plasma activated chemical vapour deposition of methane and magnetron sputtering of a chromium target. During deposition the substrates were heated (up to 300C) and DC biased (-200 and -600 V) in order to obtain films with high chemical stability. Constant temperature tests were performed at 250C in air with coatings deposited on silicon substrates. The degradation of the coatings was monitored by Raman spectroscopy and reflectance and transmission measurements. The main degradation mechanisms are discussed and the relevant parameters which improve the durability of the coatings are presented. Furthermore, the durability of solar selective, multilayered coatings which were deposited on copper sheets was investigated. Based on accelerated aging tests at different temperature loads in air (at 220C, 250C and 300C) and in a humid environment (80C sample temperature ...

International Nuclear Information System (INIS)

We report on the ultraviolet laser absorption spectroscopy of atomic Gd at 394-554 nm where two transition lines are place very closely by using a frequency-doubled beam of external-cavity diode laser (ECDL). One is from 999.121 to 26337.071 cm-1 and the other from 0 to 25337.755 cm-1. If two transition lines are placed closely within a continuous fine tuning range, the real-time measurement of the atomic excitation temperature is possible without any significant time consumption because at least two transition lines originating from different low-lying energy levels need to be investigated for the Boltzmann-plot. Since the spectral difference between the two transitions is only about 0.195 cm-1 (5.85 GHz), it is possible to record both the absorption spectra simultaneously as shown in Fig. 1. But the transition probabilities (or oscillator strengths) of these lines have not been ...

International Nuclear Information System (INIS)

The structural transition and anomalous properties of the high temperature A-15 superconductors have been investigated from two different standpoints. The first is a Landau theory based on Gorkov's physical model of a Peierls-like charge density wave (CDW) transition involving electronic CDW order parameters coupled to phonon coordinates. Pretransition elastic anomalies, softening of the [1 anti 10] transverse ([1 anti 10] polarized) phonon, sublattice distortions, variation of transition temperature with stress and alloying and other effects have been accurately predicted, and a detailed comparison is made with experimental results. Central peaks in neutron scattering are shown to be non-dynamic in nature and no pretransition forbidden (300) reflection is predicted. The GAMMA_1_2 optic mode does not go soft at the transition, though its frequency is expected to be temperature dependent right up to room ...

International Nuclear Information System (INIS)

The thermal conductivity of liquid CHCl3, C6H6, and CCl4 is measured by a steady-state method under saturated vapor pressure in the temperature regions corresponding to pre-crystallization temperatures. The experimental results obtained are used to investigate the isobaric thermal conductivity jump ? ?p at the crystal-liquid phase transition in CHCl3, C6H6, and CCl4. The contributions of the phonon-phonon and phonon-rotational interaction to the total thermal resistance in solid and liquid state are specified using a modified method of reduced coordinates. The decrease in the thermal conductivity at the crystal-liquid phase transition, ? ?p, is explained by a combined effect of variations in positional distribution of molecules and in the form of rotational molecular motion.

CERN Document Server

We study the finite temperature electroweak transition with non-perturbative lattice Monte Carlo simulations. We find that it is of first order, at least for Higgs masses up to 80 GeV. The critical temperature of the phase transition is found to be smaller than that determined by a 2-loop renormalization group improved effective potential. The jump of the order parameter at the critical temperature is considerably larger than the perturbative value. By comparing lattice data and perturbation theory, we demonstrate that the latter, for the computation of the vacuum expectation value of the Higgs field v(T) in the broken phase at given temperature, converges quite well, provided v(T)/T>1. An upper bound on the Higgs mass necessary for electroweak baryogenesis in the light of the lattice data is briefly discussed.

CERN Document Server

We analyze the driven resonantly coupled Jaynes-Cummings model in terms of a quasienergy approach by switching to a frame rotating with the external modulation frequency and by using the dressed atom picture. A quasienergy surface in phase space emerges whose level spacing is governed by a rescaled effective Planck constant. Moreover, the well-known multiphoton transitions can be reinterpreted as resonant tunneling transitions from the local maximum of the quasienergy surface. Most importantly, the driving defines a quasienergy well which is nonperturbative in nature. The quantum mechanical quasienergy state localized at its bottom is squeezed. In the Purcell limited regime, the potential well is metastable and the effective local temperature close to its minimum is uniquely determined by the squeezing factor. The activation occurs in this case via dressed spin flip transitions rather than via quantum activation as in other ...

CERN Document Server

We report a new tetragonal ground-state for perovskite-structured PbCrO3 from DFT+U calculations, and explain its anomalously large volume. The new structure is stabilized due to orbital ordering of Cr-d in the presence of a large tetragonal crystal field, mainly due to off-centering of the Pb atom. At higher pressures (smaller volumes) there is a first-order transition to a cubic phase where the Cr-d orbitals are orbitally liquid. This phase-transition is accompanied by a ~11.5% volume collapse, one of the largest known for transition-metal oxides. The large ferroelasticity and its strong coupling to the orbital degrees of freedom could be exploited to form potentially useful magnetostrictive materials

British Library Electronic Table of Contents (United Kingdom)

This paper describes a state-of-the-art online monitoring system using multivariate statistical technologies for continuous steel casting process, which was commissioned at Dofasco's No. 2 caster to provide consistent indication of process health for caster's start-up, continuous production and transitional operations. The paper particularly focuses on development of a novel scheme to synchronize process trajectories for monitoring specific transitional operations such as equipment or steel product grade changes. The proposed scheme is demonstrated by several industrial examples with the results showing good detectability of various process abnormalities. With the aid of this fully integrated, innovative monitoring system, Dofasco has generated significant value through improved productivi...

International Nuclear Information System (INIS)

We compare standard nuclear polarization mechanisms, #DELTA#-hole-polarization and meson-exchange-current effects in the q-dependent quenching of isovector spin transitions. Calculations are performed for the M1-transition form factors of the 1"+ states in "4"8Ca (10.23 MeV) and "8"8Sr (3.48 MeV). We obtain a satisfactory description of both form factors if the repulsive part of the residual interaction in the #DELTA#-hole channel is of similar strength to that in the nucleon-hole channel. Meson-exchange currents lead to an enhancement of M1 transitions by an amount which is small in general, but sensitive to the particular nuclear state involved. (orig.).

British Library Electronic Table of Contents (United Kingdom)

The n3 and n4 vibrational transitions of CH3 and CD3 isolated in solid parahydrogen were studied by high-resolution infrared spectroscopy. The radicals were produced by in situ UV photolysis of methyl iodides trapped in solid parahydrogen. The observed spectra showed clear rotational fine structures, which were subjected to further splitting due to the electrostatic field of solid parahydrogen. The molecular constants and crystal field parameters of the radicals in solid parahydrogen were determined by analyzing the spectral structures of the n3 and n4 transitions of CD3 by the crystal field theory. The rotational constants of the CD3 radical were found to be only a few percent smaller than those in the gas phase. The determined crystal field parameters indicated significant quantum effect...

International Nuclear Information System (INIS)

An analysis system for the long-term mechanical behavior of barrier materials (MACBECE: Mechanical Analysis system considering Chemical transitions of BEntonite-based and CEment-based materials) was developed in order to improve the reliability of the evaluation of the hydraulic field which is one of the important environmental conditions in the safety assessment of the TRU waste disposal. MACBECE is the system that calculates the deformation of barrier materials using their chemical property changes as inputs, and subsequently calculates their hydraulic conductivity taking both their chemical property changes and deformation into consideration. By using MACBECE, the long-term deformation and the transition of hydraulic field for the round-type disposal cavities were evaluated, assuming some sets of chemical evolution data as input. Based on the analysis result, it is considered that the influence of the long-term deformation of the barrier ...

CERN Document Server

The optical birefringence of rod-like nematogens (7CB, 8CB), imbibed in parallel silica channels with 10 nm diameter and 300 micrometer length, is measured and compared to the thermotropic bulk behavior. The orientational order of the confined liquid crystals, quantified by the uniaxial nematic ordering parameter, evolves continuously between paranematic and nematic states, in contrast to the discontinuous isotropic-to-nematic bulk phase transitions. A Landau-de Gennes model reveals that the strength of the orientational ordering fields, imposed by the silica walls, is beyond a critical threshold, that separates discontinuous from continuous paranematic-to-nematic behavior. Quenched disorder effects, attributable to wall irregularities, leave the transition temperatures affected only marginally, despite the strong ordering fields in the channels.

Energy Technology Data Exchange (ETDEWEB)

Various measurement tools that are used in chaos theory were applied to analyze two-phase pressure signals with the objective of identifying and interpreting flow pattern transitions for two-phase flows in a small, horizontal rectangular channel. These measurement tools included power spectral density function, autocorrelation function, pseudo-phase-plane trajectory, Lyapunov exponent,s and fractal dimensions. It was demonstrated that the randomlike pressure fluctuations characteristic of two-phase flow in small rectangular channels are chaotic, and governed by a high-order deterministic system. The correlation dimension is potentially a new approach for identifying certain two-phase flow patterns and transitions.

International Nuclear Information System (INIS)

To develop the advanced subchannel analysis code, the dominant factors that influence the boiling transitional process must be taken into account in the mechanistic constitutive equations based on the flow geometries and the fluid properties. The dominant factors that influence the boiling transitional processes are (1) the gas-liquid re-distribution by cross flow, (2) the liquid film dryout, (3) the two-phase flow regime transition, (4) the droplet deposition, and (5) the spacer-droplet interaction. At first, we indicated the strategy for the development of the constitutive equations for the five dominant factors based on the experimental database by the latest measurement technique and the latest computational fluid dynamics method. Then, the problems of the present constitutive equations and the improvement plan of the constitutive equations were indicated. Finally, the layered structure for the two-phase/three-field ...

International Nuclear Information System (INIS)

The decay of "1"0"1Mo to levels in "1"0"1Tc has been studied using the three-parameter (#gamma#-#gamma#-t) coincidence system of HpGe-HpGe detectors. According to the coincidence data, the decay scheme was modified. The positions of 221.80, 318.00, 377.90, 452.50, 515.42, 1011.05 and 1759.72 keV transitions have been arranged again, the transition positions of 104.70, 105.95 and 774.15 keV gamma-rays have been assigned for the first time, the positions of 169.00, 590.91, 980.52 and 1431.68 keV transitions have been reconfirmed, the 1508.01 keV gamma-ray was observed simultaneously for the first time and its transition position has been assigned. The #beta#-intensities and the values of log ft of most levels were calculated. (author)

Energy Technology Data Exchange (ETDEWEB)

Systematics of neutron capture radiative width were studied in the target element range from Th to Cm. Reduced radiative widths were analyzed with a simple radiative width formula based on E1 transition. Average radiative width is presented with the standard deviation of 15%. (author)

International Nuclear Information System (INIS)

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.).

International Nuclear Information System (INIS)

The properties of the triplet of low-lying states in "1"0"1Mo have been studied through spectroscopy of the #gamma# radation following thermal neutron capture in "1"0"0Mo and #beta#-decay of "1"0"1Nb and through a measurement of the proton angular distributions in the "1"0"0Mo(d, p) reaction with 14 MeV deuteron energy. The half-lives of the 13.5 keV state and the 57.0 keV 5/2"+ state have been measured as 226(7) and 133(7) ns, respectively. These values and the quadrupole/dipole mixing ratios of the 13.5 keV and 43.5 keV transitions yield spin and parity 3/2"+ for the 13.5 keV level. The E2 components in the 13.5 (3/2"+#->#1/2"+) and 43.5 keV (5/2"+#->#3/2"+) transitions are #<=# 8x10"-"4 and 54(9)%, respectively. The possibility of an additional state near to the 57.0 keV level is discussed. IBFM/PTQM calculations, taking into consideration the transitional character of the "1"0"0Mo boson core, account for the ...

UK PubMed Central (United Kingdom)

The rate-limiting step in the transit of dietary fat across the intestinal absorptive cell is its exit from the endoplasmic reticulum (ER) in a specialized ER-to-Golgi transport vesicle, the prechylomicron...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In a recent publication [I. Galanakis, K. Ozdog-tilde an, E. Sasiog-tilde lu, B. Aktas, Phys. Rev. B 74 (2006) 140408(R)] we have shown that in the case of CrAs and related transition-metal chalcogenides and pnictides, crystallizing in the zinc-blende structure, the excess of the transition-metal atoms leads to half-metallic ferrimagnetism. The latter property is crucial for spintronic applications with respect to ferromagnets due to the lower stray fields created by these materials. We extend this study to cover the case where the transition-metal atoms sitting at antisites are not identical to the ones in the perfect sites. In Cr-based compounds, the creation of Mn antisites keeps the half-metallic ferrimagnetic character produced also by the Cr antisites. In the case of VAs, Cr and Mn antisites keep the half-metallic character of VAs (contrary to V antisites) due to the larger exchange splitting exhibited by these atoms.

International Nuclear Information System (INIS)

Lithium ammonium sulfate (LAS) undergoes a phase transition at Tsub(c1) = 459.5deg K from a paraelectric phase (phase 1) to a ferroelectric phase (phase II) and again at Tsub(c2) = 283deg K to a polar ferroelastic phase (phase III). Proton spin lattice relaxation investigations in the temperature range 480-77deg K at 10 MHz show discontinuous changes in Tsub(1) at the transition temperatures, indicating first order phase transitions. The absence of the slow motion region (#omega#sub(not)tausub(not)>>1) shows that the ammonium ions are reorienting fast enough to keep the resonance absorption line narrow down to liquid nitrogen temperatures. The possibility of a second minimum and a low activation energy, Esub(a) = 2.659 kcal/mole, in phase III suggest the possibility of tunnelling of the protons at low temperatures. The nature of the transitions have been discussed in the light of the available ...

Energy Technology Data Exchange (ETDEWEB)

The federating theme of superconductivity has given rise to a number of experimental studies of point defects in solids as different as transition metals (V, Nb, ...), A-15 compounds (V{sub 3}Si, Nb{sub 3}Ge, ...), or perovskite-like copper oxides. Some of these experiments are presented here. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The aim of this paper is to obtain the effective potential of the non-topological soliton model at finite temperature with the assumption that the chemical potential {mu} of the system is different from zero and to analyse how the effective potential is influenced by changes in the chemical potential and temperature. (author)

Wastenet

...links ensure all of our managed accommodation is easily accessible to both campus sites and our special student arrangement makes travelling on the Metro rapid transit system easily affordable. Our halls are comfortable and they are very reasonable. Download the rents table here Rents 2009-2010 Students living in ...

Energy Technology Data Exchange (ETDEWEB)

This plan details the methods and procedures necessary to ensure a safe transition in the operation of the Light Duty Utility Arm (LDUA) System. The steps identified here outline the work scope and identify responsibilities to complete startup, and turnover of the LDUA to Characterization Project Operations (CPO).

UK PubMed Central (United Kingdom)

SummaryAttention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder which is most often diagnosed in childhood with symptoms often persisting into adulthood....Full Text Available

International Nuclear Information System (INIS)

Nov 1983. p. 32-33. Germany Corcalciuc, V. Institutul Central de Fizica,

Science.gov (United States)

Spontaneous radiation by an atom in a Rydberg state is inhibited by use of parallel conducting planes to eliminate the vacuum modes at the transition frequency. Spontaneous radiation emission is observed to turn off abruptly at the cutoff frequency of the waveguidelike structure, and the natural lifetime is measured to increase by a factor of at least 20.

International Nuclear Information System (INIS)

An important application of metal hydrides is as a moderator material in nuclear reactors. The fundamental properties of hydrides are illustrated and an impression given of the current research into hydrogen in transition metals. Phase diagrams, magnetic properties, temperature dependence of the diffusion coefficient, energy level schemes and superconductivity are considered. (C.F.).

Science.gov (United States)

The present article studies the electret state of polymers when moving through an alternating-current corona discharge plasma and investigates means for the determination of the transition of the polymeric material from the initial state of the electret when the corona-displaying voltage is increased.

Energy Technology Data Exchange (ETDEWEB)

In this letter we report the outcome for the microscopic approach for the semi-magic nuclei /sup 88/Sr and /sup 90/Zr. For comparison, we have also treated the semi-phenomenological version for the Migdal and SDI force.

Science.gov (United States)

The Global Road Safety Partnership (GRSP) is a global partnership of business, civil society and government working for sustained reduction of road accidents in developing and transition countries. GRSP, which started operations in 1999, has a global secr...

International Nuclear Information System (INIS)

The symmetric noncoplanar (e,2e) cross sections (momentum profiles) of H_2 and D_2 for the transitions to the 2p#sigma#_u and 2s#sigma#_g excited ion states have been measured, relative to the ground-state ion transition, using a high-sensitivity multichannel momentum-dispersive electron momentum spectrometer (EMS) at an impact energy of 1200 eV. Newly calculated plane-wave impulse approximation (PWIA) cross sections, based on a full-configuration-interaction H_2 wave function, are compared to the experimental results. These calculations are in better agreement with the experimental results for the transition to the 2s#sigma#_g ion state than the earlier theoretical work of Liu and Smith, Jr. [Phys. Rev. A 31, 3003 (1985)] which has been found to be in error. Nevertheless, significant discrepancies between the relative experimental and theoretical cross sections are observed for the transitions to ...

Science.gov (United States)

Various measurement tools that are used in chaos theory were applied to analyze two-phase pressure signals with the objective of identifying and interpreting flow pattern transitions for two-phase flows in a small, horizontal rectangular channel. These me...

UK PubMed Central (United Kingdom)

In rats and primates, the central nucleus of the amygdala (CeN) is most known for its role in responses to fear stimuli. Recent evidence also shows that the CeN is required for directing attention...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The 52 papers discuss the following subjects: 1. Preparation and structural development; 2. Structural constitution; 3. Structural formation and phase transition; 4. Structure and mechanical properties; 5. Structural formation of metallic and nonmetallic materials; 6. Quantitative metallography, and 7. Quality assurance.