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Sample records for 5f electron states

  1. Beyond Spin-Orbit: Probing Electron Correlation in the Pu 5f States

    SciTech Connect

    Tobin, J G

    2006-05-08

    Experiments planned to address the issue of electron correlation in the Pu 5f states are described herein. The key is the utilization of the Fano Effect, the observation of spin polarization in nonmagnetic systems, using chiral excitation such as circularly polarized X-rays.

  2. 5f-electron states in uranium dioxide investigated using high-resolution neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Amoretti, G.; Blaise, A.; Caciuffo, R.; Fournier, J. M.; Hutchings, M. T.; Osborn, R.; Taylor, A. D.

    1989-07-01

    High-resolution, high-energy-transfer, inelastic neutron scattering has been used to explore the crystal-field (CF) excitations in UO2. As all the dipole-allowed transitions within the free-ion ground manifold have been identified, the observations provide a complete determination of the crystal-field potential and 5f-electron eigenstates. The fourth- and sixth-degree CF parameters are V4=-123 meV and V6=26.5 meV. In spite of the strength of the CF, the ground state is accurately given by the intermediate-coupling approximation with little modification by J-mixing effects. In the antiferromagnetic phase below TN=30.8 K, a splitting of the cubic CF levels, due to the combined effects of the molecular field and the distortion of the oxygen-ligand cage surrounding the U4+ ions, has been observed. Detailed CF calculations are presented both for the case of a double-k magnetic structure with a monoclinic distortion of the oxygen sublattice, and for a combined triple-k distortion and magnetic order. The observed splittings are shown to be more consistent with the triple-k model.

  3. The Electronic States of U(4+) in U(PO4)Cl: An Example for Angular Overlap Modeling of 5f(n) Systems.

    PubMed

    Bronova, Anna; Bredow, Thomas; Glaum, Robert; Urland, Werner

    2016-07-18

    Detailed experimental data on UPO4Cl comprising single-crystal UV/vis/NIR spectra and temperature-dependent magnetic susceptibilities form the basis for the investigation of the electronic structure of the U(4+) cation in UPO4Cl. For modeling of the observed physical properties the angular overlap model (AOM) was successfully employed. The computations were performed using the newly developed computer program BonnMag. The calculations show that all electronic transitions and the magnetic susceptibility as well as its temperature dependence are well-reproduced within the AOM framework. Using Judd-Ofelt theory BonnMag allows estimation of the relative absorption coefficients of the electronic transitions with reasonable accuracy. Ligand field splitting for states originating from f-electron configurations are determined. Slater-Condon-Shortley parameters and the spin-orbit coupling constant for U(4+) were taken from literature. The good transferability of AOM parameters for U(4+) is confirmed by calculations of the absorption spectra of UP2O7 and (U2O)(PO4)2. The effect of variation of the fit parameters is investigated. AOM parameters for U(4+) (5f) are compared to those of the rare-earth elements (4f) and transition metals (3d). PMID:27355276

  4. Failure of Russell-Saunders Coupling in the 5f States of Plutonium

    NASA Astrophysics Data System (ADS)

    Moore, K. T.; Wall, M. A.; Schwartz, A. J.; Chung, B. W.; Shuh, D. K.; Schulze, R. K.; Tobin, J. G.

    2003-05-01

    Using high energy electron energy loss spectroscopy, transmission electron microscopy, and synchrotron-radiation-based x-ray absorption spectroscopy, we provide the first experimental evidence that Russell-Saunders (LS) coupling fails for the 5f states of Pu. These results support the assumption that only the use of jj or intermediate coupling is appropriate for the 5f states of Pu. High energy electron energy loss spectroscopy experiments were performed by use of a transmission electron microscope and are coupled with image and diffraction data; therefore, the measurements are completely phase specific.

  5. Role of 5f electrons in the structural stability of light actinide (Th-U) mononitrides under pressure.

    PubMed

    Modak, P; Verma, Ashok K

    2016-03-16

    Pressure induced structural sequences and their mechanism for light actinide (Th-U) mononitrides were studied as a function of 5f-electron number using first-principles total energy and electronic structure calculations. Zero pressure lattice constants, bulk module and C11 elastic module vary systematically with 5f-electron number implying its direct role on crystal binding. There is a critical 5f-electron number below which the system makes B1-B2 and above it B1-R3[combining macron]m-B2 structural sequence under pressure. Also, the B1-B2 transition pressure increases with increasing 5f-electron number whereas an opposite trend is obtained for the B1-R3[combining macron]m transition pressure. The ascending of N p anti-bonding states through the Fermi level at high pressure is responsible for the structural instability of the system. Above the critical 5f-electron number in the system a narrow 5f-band occurs very close to the Fermi level which allows the system to lower its symmetry via band Jahn-Teller type lattice distortion and the system undergoes a B1-R3[combining macron]m phase transition. However, below the critical 5f-electron number this mechanism is not favorable due to a lack of sufficient 5f-state occupancy and thus the system undergoes a B1-B2 phase transition like other ionic solids. PMID:26953085

  6. The degree of 5f electron localization in URu2Si2: electron energy-loss spectroscopy and spin-orbit sum rule analysis

    SciTech Connect

    Jeffries, J R; Moore, K T; Butch, N P; Maple, M B

    2010-05-19

    We examine the degree of 5f electron localization in URu{sub 2}Si{sub 2} using spin-orbit sum rule analysis of the U N{sub 4,5} (4d {yields} 5f) edge. When compared to {alpha}-U metal, US, USe, and UTe, which have increasing localization of the 5f states, we find that the 5f states of URu{sub 2}Si{sub 2} are more localized, although not entirely. Spin-orbit analysis shows that intermediate coupling is the correct angular momentum coupling mechanism for URu{sub 2}Si{sub 2} when the 5f electron count is between 2.6 and 2.8. These results have direct ramifications for theoretical assessment of the hidden order state of URu{sub 2}Si{sub 2}, where the degree of localization of the 5f electrons and their contribution to the Fermi surface are critical.

  7. 5f-electron localization in the actinide metals: thorides, actinides and the Mott transition

    NASA Astrophysics Data System (ADS)

    Lawson, A. C.

    2016-03-01

    For the light actinides Ac-Cm, the numbers of localized and itinerant 5f-electrons are determined by comparing various estimates of the f-electron counts. At least one itinerant f-electron is found for each element, Pa-Cm. These results resolve certain disagreements among electron counts determined by different methods and are consistent with the Mott transition model and with the picture of the 5f-electrons' dual nature.

  8. Probing the population of the spin-orbit split levels in the actinide 5f states

    SciTech Connect

    Moore, K; der Laan, G v; Tobin, J; Chung, B; Wall, M; Schwartz, A

    2004-07-14

    Spin-orbit interaction in the 5f states is believed to strongly influence exotic behaviors observed in actinides metals and compounds. Understanding these interactions and how they relate to the actinide series is of considerable importance. To address this issue, the branching ratio of the white-line peaks of the N4,5 edges for the light actinide metals, {alpha}-Th, {alpha}-U, and {alpha}-Pu were recorded using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM) and synchrotron-radiation-based x-ray absorption spectroscopy (XAS). Using the spin-orbit sum rule and the branching ratios from both experimental spectra and many-electron atomic spectral calculations, accurate values of the spin-orbit interaction, and thus the relative occupation of the j = 5/2 and 7/2 levels, are determined for the actinide 5f states. Results show that the spin-orbit sum rule works very well with both EELS and XAS spectra, needing little or no correction. This is important, since the high spatial resolution of a TEM can be used to overcome the problems of single crystal growth often encountered with actinide metals, allowing acquisition of EELS spectra, and subsequent spin-orbit analysis, from nm-sized regions. The relative occupation numbers obtained by our method have been compared with recent theoretical results and show a good agreement in their trend.

  9. Electron correlation and relativity of the 5f electrons in the U-Zr alloy system

    NASA Astrophysics Data System (ADS)

    Söderlind, P.; Sadigh, B.; Lordi, V.; Landa, A.; Turchi, P. E. A.

    2014-01-01

    ] and VASP [4] codes. The Wien2K computations are set up with an APW + lo basis for the expansion of the wave functions within the muffin-tin spheres (with radius RMT = 2.5 a.u.) in partial waves with angular momenta up to l = 3, and an LAPW basis for all higher angular momenta up to l = 10. The plane-wave cutoff (Kmax) for the expansion of the wave functions in the interstitial region is chosen such that RMT × Kmax = 10. We apply the LSDA + U scheme proposed by Anisimov et al. [5] (Wien2K) and Dudarev et al. [6] (VASP) to the uranium f orbitals, which approximately corrects for their electron self interaction. An effective Ueff = U - J is chosen to be 2 eV (J = 0), which appears to be realistic for uranium systems [7]. The spin-orbit interaction is included using the second-variation method with scalar-relativistic orbitals as basis. This basis includes all Eigen states with energy less than 70 eV. For reason to improve the description of the relativistic orbitals, the p1/2 local orbitals are added to the basis set. For actinide metals, this technique for the spin-orbit coupling equals, with good approximation, that of the complete four-spinor Dirac formalism [8-10]. All calculations use a 12 × 12 × 12 Monkhorst-Pack k-point grid and a plane-wave cutoff of 23 Ry.In Table 1 we show our calculated equilibrium volumes (V) and bulk moduli (B) obtained with and without spin-orbit coupling (SOC) for bcc (γ) uranium metal using the Wien2K (VASP) codes. (The other component, Zr, is a light metal where relativistic effects are not important). The changes in V and B due to SOC are indeed quite small, consistent with results from previous studies [9,11], and within the scatter of the experimental data. The reason why the volume expands slightly is that the separation of the 5f5/2 and 5f7/2 states, due to spin-orbit coupling, weakens the cohesion of the bonding electrons. The separation is very small, as seen in Fig. 1[11] where we plot the total electronic density-of-states

  10. Electron correlation and relativity of the 5f electrons in the U-Zr alloy system

    NASA Astrophysics Data System (ADS)

    Söderlind, P.; Sadigh, B.; Lordi, V.; Landa, A.; Turchi, P. E. A.

    2014-01-01

    ] and VASP [4] codes. The Wien2K computations are set up with an APW + lo basis for the expansion of the wave functions within the muffin-tin spheres (with radius RMT = 2.5 a.u.) in partial waves with angular momenta up to l = 3, and an LAPW basis for all higher angular momenta up to l = 10. The plane-wave cutoff (Kmax) for the expansion of the wave functions in the interstitial region is chosen such that RMT × Kmax = 10. We apply the LSDA + U scheme proposed by Anisimov et al. [5] (Wien2K) and Dudarev et al. [6] (VASP) to the uranium f orbitals, which approximately corrects for their electron self interaction. An effective Ueff = U - J is chosen to be 2 eV (J = 0), which appears to be realistic for uranium systems [7]. The spin-orbit interaction is included using the second-variation method with scalar-relativistic orbitals as basis. This basis includes all Eigen states with energy less than 70 eV. For reason to improve the description of the relativistic orbitals, the p1/2 local orbitals are added to the basis set. For actinide metals, this technique for the spin-orbit coupling equals, with good approximation, that of the complete four-spinor Dirac formalism [8-10]. All calculations use a 12 × 12 × 12 Monkhorst-Pack k-point grid and a plane-wave cutoff of 23 Ry.In Table 1 we show our calculated equilibrium volumes (V) and bulk moduli (B) obtained with and without spin-orbit coupling (SOC) for bcc (γ) uranium metal using the Wien2K (VASP) codes. (The other component, Zr, is a light metal where relativistic effects are not important). The changes in V and B due to SOC are indeed quite small, consistent with results from previous studies [9,11], and within the scatter of the experimental data. The reason why the volume expands slightly is that the separation of the 5f5/2 and 5f7/2 states, due to spin-orbit coupling, weakens the cohesion of the bonding electrons. The separation is very small, as seen in Fig. 1[11] where we plot the total electronic density-of-states

  11. Effects of 5f-elements on electronic structures and spectroscopic properties of gold superatom model

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Wang, Zhigang

    2016-08-01

    5f-elements encaged in a gold superatomic cluster are capable of giving rise to unique optical properties due to their hyperactive valence electrons and great radial components of 5f/6d orbitals. Herein, we review our first-principles studies on electronic structures and spectroscopic properties of a series of actinide-embedded gold superatomic clusters with different dimensions. The three-dimensional (3D) and two-dimensional (2D) superatom clusters possess the 18-electron configuration of 1S21P61D10 and 10-electron configuration of 1S21P41D4, respectively. Importantly, their electronic absorption spectra can also be effectively explained by the superatom orbitals. Specifically, the charge transfer (CT) transitions involved in surface-enhance Raman spectroscopy (SERS) spectra for 3D and 2D structures are both from the filled 1D orbitals, providing the enhancement factors of the order of ∼ 104 at 488 nm and ∼ 105 at 456 nm, respectively. This work implies that the superatomic orbital transitions involved in 5f-elements can not only lead to a remarkable spectroscopic performance, but also a new direction for optical design in the future. Project supported by the National Natural Science Foundation of China (Grant No. 11374004), the Science and Technology Development Program of Jilin Province, China (Grant No. 20150519021JH), the Fok Ying Tung Education Foundation, China (Grant No. 142001), and the Support from the High Performance Computing Center (HPCC) of Jilin University, China.

  12. 5f state interaction with inner coordination sphere ligands: einsteinium 3+ ion fluorescence in aqueous and organic phases

    SciTech Connect

    Beitz, J.V.; Wester, D.W.; Williams, C.W.

    1983-01-01

    The interaction between 5f electron states of einsteinium 3+ ion and coordinated ligands in solution has been probed using laser-induced fluorescence. Aquo einsteinium 3+ ion was observed to fluoresce from its first excited J = 5 state in a broad-band peaking at 9260 wavenumbers. The observed fluorescence lifetimes were 1.05 microseconds and 2.78 microseconds in H/sub 2/O and D/sub 2/O (99+ % D atom), respectively. The non-radiative decay rates derived from the lifetime data are compared with previously reported data for Cm, Sm, Eu, Tb, and Dy aquo 3+ ions. The 5f actinide states exhibit substantially greater non-radiative decay rates than do lanthanide 4f states of similar energy gap. This provides evidence that actinide 5f electrons interact more strongly with their inner coordination sphere than do lanthanide ion 4f electrons. The fluorescence lifetime of einsteinium 3+ ion complexed with 1 formal di(2-ethylhexyl)orthophosphoric acid in h-heptane was 2.34 microseconds. 3 figures, 1 table.

  13. Structural phase transition and 5f-electrons localization of PuSe explored by ab initio calculations

    SciTech Connect

    Cui Shouxin; Feng Wenxia; Hu Haiquan; Gong Zizheng; Liu Hong

    2010-04-15

    An investigation into the structural phase transformation, electronic and optical properties of PuSe under high pressure was conducted by using the full potential linearized augmented plane wave plus local orbitals (FP-LAPW+lo) method, in the presence and in the absence of spin-orbit coupling (SOC). Our results demonstrate that there exists a structural phase transition from rocksalt (B 1) structure to CsCl-type (B 2) structure at the transition pressure of 36.3 GPa (without SOC) and 51.3 GPa (with SOC). The electronic density of states (DOS) for PuSe show that the f-electrons of Pu are more localized and concentrated in a narrow peak near the Fermi level, which is consistent with the experimental studies. The band structure shows that B 1-PuSe is metallic. A pseudogap appears around the Fermi level of the total density of states of B 1 phase PuSe, which may contribute to its stability. The calculated reflectivity R(omega) shows agreement with the available experimental results. Furthermore, the absorption spectrum, refractive index, extinction coefficient, energy-loss spectrum and dielectric function were calculated. The origin of the spectral peaks was interpreted based on the electronic structures. - Abstract: Graphical Abstract Legend (TOC Figure): 5f-electrons are more localized by the analysis of the density of states (SOC). The origin spectra peaks was interpreted based on electronic structures.

  14. Influence of cell physiological state on gene delivery to T lymphocytes by chimeric adenovirus Ad5F35

    PubMed Central

    Zhang, Wen-feng; Shao, Hong-wei; Wu, Feng-lin; Xie, Xin; Li, Zhu-Ming; Bo, Hua-Ben; Shen, Han; Wang, Teng; Huang, Shu-lin

    2016-01-01

    Adoptive transfer of genetically-modified T cells is a promising approach for treatment of both human malignancies and viral infections. Due to its ability to efficiently infect lymphocytes, the chimeric adenovirus Ad5F35 is potentially useful as an immunotherapeutic for the genetic modification of T cells. In previous studies, it was found that the infection efficiency of Ad5F35 was significantly increased without enhanced expression of the viral receptor after T cell stimulation; however, little is known about the underlying mechanism. Nonetheless, cell physiology has long been thought to affect viral infection. Therefore, we aimed to uncover the physiologic changes responsible for the increased infection efficiency of Ad5F35 following T cell stimulation. Given the complexity of intracellular transport we analyzed viral binding, entry, and escape using a Jurkat T cell model and found that both cell membrane fluidity and endosomal escape of Ad5F35 were altered under different physiological states. This, in turn, resulted in differences in the amount of virus entering cells and reaching the cytoplasm. These results provide additional insight into the molecular mechanisms underlying Ad5F35 infection of T cells and consequently, will help further the clinical application of genetically-modified T cells for immunotherapy. PMID:26972139

  15. Spectroscopy and dynamics of 5f states of Es{sup 3+} in LaF{sub 3}

    SciTech Connect

    Beitz, J.V.; Williams, C.W.; Liu, G.K.

    1997-11-01

    Using time- and wavelength-resolved laser-induced fluorescence methods, the 5f state spectroscopy and photodynamics of {sup 253}Es{sup 3+} in LaF{sub 3} have been investigated. Based on an effective operator Hamiltonian model and approximating the metal ion site symmetry as C{sub 2V}, a set of crystal field parameters has been obtained that fit the 56 assigned levels associated with the 7 states of Es{sup 3+} that were observed. The {sup 5}F{sub 5} emitting state of Es{sup 3+} exhibited a decay rate that approached the expected purely radiative decay of the state. This suggests that the shorter lifetime previously found for this state of Es{sup 3+} in LaCl{sub 3} arose from radiation damage induced by alpha decay of {sup 253}Es.

  16. The 5f localization/delocalization in square and hexagonal americium monolayers: a FP-LAPW electronic structure study

    NASA Astrophysics Data System (ADS)

    Gao, D.; Ray, A. K.

    2006-04-01

    The electronic and geometrical properties of bulk americium and square and hexagonal americium monolayers have been studied with the full-potential linearized augmented plane wave (FP-LAPW) method. The effects of several common approximations are examined: (1) non-spin polarization (NSP) vs. spin polarization (SP); (2) scalar-relativity (no spin-orbit coupling (NSO)) vs. full-relativity (i.e., with spin-orbit (SO) coupling included); (3) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that both spin polarization and spin orbit coupling play important roles in determining the geometrical and electronic properties of americium bulk and monolayers. A compression of both americium square and hexagonal monolayers compared to the americium bulk is also observed. In general, the LDA is found to underestimate the equilibrium lattice constant and give a larger total energy compared to the GGA calculations. While spin orbit coupling shows a similar effect on both square and hexagonal monolayer calculations regardless of the model, GGA versus LDA, an unusual spin polarization effect on both square and hexagonal monolayers is found in the LDA results as compared with the GGA results. The 5f delocalization transition of americium is employed to explain our observed unusual spin polarization effect. In addition, our results at the LDA level of theory indicate a possible 5f delocalization could happen in the americium surface within the same Am II (fcc crystal structure) phase, unlike the usually reported americium 5f delocalization which is associated with crystal structure change. The similarities and dissimilarities between the properties of an Am monolayer and a Pu monolayer are discussed in detail.

  17. Core electron excitations in U(4+): modelling of the nd(10)5f(2)→nd(9)5f(3) transitions with n = 3, 4 and 5 by ligand field tools and density functional theory.

    PubMed

    Ramanantoanina, Harry; Kuri, Goutam; Daul, Claude; Bertsch, Johannes

    2016-07-28

    Ligand field density functional theory (LFDFT) calculations have been used to model the uranium M4,5, N4,5 and O4,5-edge X-ray absorption near edge structure (XANES) in UO2, characterized by the promotion of one electron from the core and the semi-core 3d, 4d and 5d orbitals of U(4+) to the valence 5f. The model describes the procedure to resolve non-empirically the multiplet energy levels originating from the two-open-shell system with d and f electrons and to calculate the oscillator strengths corresponding to the dipole allowed d(10)f(2)→ d(9)f(3) transitions appropriate to represent the d electron excitation process. In the first step, the energy and UO2 unit-cell volume corresponding to the minimum structures are determined using the Hubbard model (DFT+U) approach. The model of the optical properties due to the uranium nd(10)5f(2)→nd(9)5f(3) transitions, with n = 3, 4 and 5, has been tackled by means of electronic structure calculations based on the ligand field concept emulating the Slater-Condon integrals, the spin-orbit coupling constants and the parameters of the ligand field potential needed by the ligand field Hamiltonian from Density Functional Theory. A deep-rooted theoretical procedure using the LFDFT approach has been established for actinide-bearing systems that can be valuable to compute targeted results, such as spectroscopic details at the electronic scale. As a case study, uranium dioxide has been considered because it is a nuclear fuel material, and both atomic and electronic structure calculations are indispensable for a deeper understanding of irradiation driven microstructural changes occurring in this material. PMID:27356168

  18. Itinerant 5 f Electrons and the Fermi Surface Properties in an Enhanced Pauli Paramagnet NpGe3

    NASA Astrophysics Data System (ADS)

    Aoki, Dai; Yamagami, Hiroshi; Homma, Yoshiya; Shiokawa, Yoshinobu; Yamamoto, Etsuji; Nakamura, Akio; Haga, Yoshinori; Settai, Rikio; Ōnuki, Yoshichika

    2005-08-01

    We succeeded in growing a high-quality single crystal of an enhanced Pauli paramagnet, NpGe3, by the Bi-flux method, and observed the de Haas-van Alphen (dHvA) effect. The topology of a Fermi surface is well explained by the relativistic linear augmented-plane-wave (LAPW) band calculations based on the 5 f itinerant band model. The Fermi surface consists of a nearly spherical electron-Fermi surface with necks along the < 100 > direction, forming a hollow ball, centered at the R point, which is derived from the single band. The cyclotron effective mass is in the range from 2.6 to 16 m0, which is enhanced approximately 3.5 times from the corresponding band mass.

  19. Response to letter "Electron correlation and relativity of the 5f electrons in the Usbnd Zr alloy system"

    NASA Astrophysics Data System (ADS)

    Xie, Wei; Marianetti, Chris A.; Morgan, Dane

    2016-08-01

    In the Letter [Söderlind et al., J. Nucl. Mater. 444, 356 (2014)], Söderlind et al. state their interpretation that 1) we view electron correlation to be strong and including spin-orbit coupling (SOC) to be necessary for U metal and Usbnd Zr alloy in our article [Xiong et al., J. Nucl. Mater. 443, 331 (2013)]. Further, they argue that 2) density functional theory (DFT) without adding the Hubbard U potential, especially when solved using all electron methods, already models U and Usbnd Zr accurately, and 3) adding the Hubbard U potential to DFT in DFT + U models U and Usbnd Zr worse than DFT according to volume, bulk modulus, and magnetic moments predicted from their calculations of the γU phase of elemental U metal. With respect to Söderlind et al.'s interpretation 1), we clarify that our opinions are that U and Usbnd Zr are not strongly, but weakly to moderately correlated and that including SOC is beneficial but not necessary for modeling most ground state properties of U and Usbnd Zr. With respect to Söderlind et al.'s argument 2) we demonstrate that previously neglected and very recent experimental data suggest that DFT in Söderlind's full-potential linear muffin-tin orbital calculations [Söderlind, Phys. Rev. B 66, 085113 (2002)] in fact models the bulk modulus and elastic constants of αU with errors considerably larger than other related elements, e.g., most transition metals. With respect to Söderlind et al.'s argument 3) we argue that they have inappropriately focused on just one phase (the BCC γU phase of U metal), neglecting the other phases which represent the majority of our evidence, and made overgeneralizations based on results at only one Ueff value of 2 eV. We therefore maintain our original conclusion that the accuracy of DFT for modeling U and Usbnd Zr has room for improvement and DFT + U can be of value for this purpose on at least some ground state properties.

  20. Electron-phonon superconductivity in LaO{sub 0.5}F{sub 0.5}BiSe{sub 2}

    SciTech Connect

    Feng, Yanqing; Du, Yongping; Wan, Xiangang Wang, Bogen; Ding, Hang-Chen; Savrasov, Sergey Y.; Duan, Chun-Gang

    2014-06-21

    We report density functional calculations of the electronic structure, Fermi surface, phonon spectrum and electron–phonon coupling for the newly discovered superconductor LaO{sub 0.5}F{sub 0.5}BiSe{sub 2}. It is confirmed that there is a strong Fermi surface nesting at (π,π,0), which results in unstable phonon branches. Combining the frozen phonon total energy calculations and an anharmonic oscillator model, we find that the quantum fluctuation prevents the appearance of static long–range order. The calculation shows that LaO{sub 0.5}F{sub 0.5}BiSe{sub 2} is highly anisotropic, and same as its cousin LaO{sub 0.5}F{sub 0.5}BiS{sub 2}, this compound is also a conventional electron-phonon coupling induced superconductor.

  1. Electronic structure of a new layered bismuth oxyselenide superconductor: LaO0.5F0.5BiSe2.

    PubMed

    Xia, M; Jiang, J; Niu, X H; Liu, J Z; Wen, C H P; Lu, H Y; Lou, X; Pu, Y J; Huang, Z C; Zhu, Xiyu; Wen, H H; Xie, B P; Shen, D W; Feng, D L

    2015-07-22

    LaO(0.5)F(0.5)BiSe(2) is a new layered superconductor discovered recently, which shows the superconducting transition temperature of 3.5 K. With angle-resolved photoemission spectroscopy, we study the electronic structure of LaO(0.5)F(0.5)BiSe(2) comprehensively. Two electron-like bands are located around the X point of the Brillouin zone, and the outer pockets connect with each other and form large Fermi surface around Γ and M. These bands show negligible k(z) dispersion, indicating their two-dimensional nature. Based on the Luttinger theorem, the carrier concentration is about 0.53 e(-) per unit cell, close to its nominal value. Moreover, the photoemission data and the band structure calculations agree very well, and the renormalization factor is nearly 1.0, indicating the electron correlations in this material are rather weak. Our results suggest that LaO(0.5)F(0.5)BiSe(2) is a conventional BCS superconductor without strong electron correlations. PMID:26102451

  2. Probing 5 f -state configurations in URu2Si2 with U LIII-edge resonant x-ray emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Booth, C. H.; Medling, S. A.; Tobin, J. G.; Baumbach, R. E.; Bauer, E. D.; Sokaras, D.; Nordlund, D.; Weng, T.-C.

    2016-07-01

    Resonant x-ray emission spectroscopy (RXES) was employed at the U LIII absorption edge and the Lα 1 emission line to explore the 5 f occupancy, nf, and the degree of 5 f -orbital delocalization in the hidden-order compound URu2Si2 . By comparing to suitable reference materials such as UF4, UCd11, and α -U, we conclude that the 5 f orbital in URu2Si2 is at least partially delocalized with nf=2.87 ±0.08 , and does not change with temperature down to 10 K within the estimated error. These results place further constraints on theoretical explanations of the hidden order, especially those requiring a localized f2 ground state.

  3. CF3+ fragmentation by electron impact ionization of perfluoro-propyl-vinyl-ethers, C5F10O, in gas phase

    NASA Astrophysics Data System (ADS)

    Kondo, Yusuke; Ishikawa, Kenji; Hayashi, Toshio; Miyawaki, Yudai; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

    2015-04-01

    The gas phase fragmentations of perfluoro-propyl-vinyl ether (PPVE, C5F10O) are studied experimentally. Dominant fragmentations of PPVE are found to be the result of a dissociative ionization reaction, i.e., CF3+ via direct bond cleavage, and C2F3O- and C3F7O- via electron attachment. Regardless of the appearance energy of around 14.5 eV for the dissociative ionization of CF3+, the observed ion efficiency for the CF3+ ion was extremely large the order of 10-20 cm-2, compared with only 10-21 cm-2 for the other channels. PPVE characteristically generated CF3+ as the largest abundant ion are advantageous for use of feedstock gases in plasma etching processes.

  4. Gradual Localization of 5f States in Orthorhombic UTX Ferromagnets:Polarized Neutron Diffraction Study of Ru Substituted UCoGe

    NASA Astrophysics Data System (ADS)

    Vališka, Michal; Pospíšil, Jiří; Stunault, Anne; Takeda, Yukiharu; Gillon, Béatrice; Haga, Yoshinori; Prokeš, Karel; Abd-Elmeguid, Mohsen M.; Nénert, Gwilherm; Okane, Tetsuo; Yamagami, Hiroshi; Chapon, Laurent; Gukasov, Arsene; Cousson, Alain; Yamamoto, Etsuji; Sechovský, Vladimír

    2015-08-01

    We report on a microscopic study of the evolution of ferromagnetism in the Ru substituted ferromagnetic superconductor (FM SC) UCoGe crystallizing in the orthorhombic TiNiSi-type structure. For that purpose, two single crystals with composition UCo0.97Ru0.03Ge and UCo0.88Ru0.12Ge have been prepared and characterized by magnetization, AC susceptibility, specific heat and electrical resistivity measurements. Both compounds have been found to order ferromagnetically below TC = 6.5 and 7.5 K, respectively, which is considerably higher than the TC = 3 K of the parent compound UCoGe. The higher values of TC are accompanied by enhanced values of the spontaneous moment μspont = 0.11 μB/f.u. and μspont = 0.21 μB/f.u., respectively in comparison to the tiny spontaneous moment of UCoGe (about 0.07 μB/f.u.). No sign of superconductivity was detected in either compound. The magnetic moments of the samples were investigated on the microscopic scale using polarized neutron diffraction (PND) and for UCo0.88Ru0.12Ge also by soft X-ray magnetic circular dichroism (XMCD). The analysis of the PND results indicates that the observed enhancement of ferromagnetism is mainly due to the growth of the orbital part of the uranium 5f moment μ LU, reflecting a gradual localization of the 5f electrons with Ru substitution. In addition, the parallel orientation of the U and Co moments has been established in both substituted compounds. The results are discussed and compared with related isostructural ferromagnetic UTX compounds (T: transition metals, X: Si, Ge) in the context of a varying degree of the 5f-ligand hybridization.

  5. Fermi energy 5f spectral weight variation in uranium alloys

    SciTech Connect

    Denlinger, J.D.; Clack, J.; Allen, J.W.

    1997-04-01

    Uranium materials display a wide range of thermal, electrical and magnetic properties, often exotic. For more than a decade there have been efforts to use photoemission spectroscopy to develop a systematic and unified understanding of the 5f electron states giving rise to this behavior. These efforts have been hampered by a paucity of systems where changes in transport properties are accompanied by substantial spectral changes, so as to allow an attempt to correlate the two kinds of properties within some model. The authors have made resonant photoemission measurements to extract the 5f spectral weight in three systems which show varying degrees of promise of permitting such an attempt, Y{sub 1{minus}x}U{sub x}Pd{sub 3}, U(Pd{sub x}Pt{sub 1{minus}x}){sub 3} and U(Pd{sub x}Cu{sub 1{minus}x}){sub 5}. They have also measured U 4f core level spectra. The 4f spectra can be modeled with some success by the impurity Anderson model (IAM), and the 5f spectra are currently being analyzed in that framework. The IAM characterizes the 5f-electrons of a single site by an f binding energy {epsilon}{sub f}, an f Coulomb interaction and a hybridization V to conduction electrons. Latent in the model are the phenomena of 5f mixed valence and the Kondo effect.

  6. 5f3 --> 5f 26d1 absorption spectrum analysis of U3+-SrCl2.

    PubMed

    Karbowiak, Mirosław

    2005-04-28

    The 5f3--> 5f26d1 absorption spectra of the U3+ ions incorporated in SrCl2 single crystals were recorded at 4.2 K in the 15,000-50,000 cm(-1) spectral range. From an analysis of the vibronic structure, 32 zero-phonon lines corresponding to transitions from the 4I9/2 ground multiplet of the 5f3 configuration to the 5f26d(eg)1 excited levels were assigned. A theoretical model proposed by Reid et al. (Reid, H. F.; van Pieterson, L.; Wegh, R. T.; Meijerink, A. Phys. Rev. B 2000, 62, 14744) that extends the established model for energy-level calculations of nf N states has been applied for analysis of the spectrum. The Fk(ff) (k = 2, 4), zeta(5f)(ff), B0(4)(ff), B0(6)(ff), Fk(fd) (k = 2, 4), and Gj(fd) (j = 1, 3) Hamiltonian parameters were determined by a least-squares fitting of the calculated energies to the experimental data. A good overall agreement between the calculated and experimentally observed energy levels has been achieved, with the root-mean-square (rms) deviation equal to 95 cm(-1) for 32 fitted levels and 9 varied parameters. Adjusted values of Fk(ff) and zeta(5f)(ff) parameters for the 5f2 core electrons are closer to the values characteristic of the 5f2 (U4+) configuration than to those of the 5f3 (U3+) configuration. For the U3+ ion, the f-d Coulomb interaction parameters are significantly more reduced from the values calculated using Cowan's computer code than they are for lanthanide ions. Moreover, because of weaker f-d Coulomb interactions for the U3+ ion than for the isoelectronic Nd3+ lanthanide ion, the very simple model assuming the coupling of crystal-field levels of the 6d1 electron with the lattice and the multiplet structure of the 5f2 configuration may be employed for the qualitative description of the general structure of the U3+ ion f-d spectrum. PMID:16839023

  7. Rampant changes in 5f 5/2 and 5f 7/2 filling across the light and middle actinide metals

    SciTech Connect

    Moore, K; der Lann, G v; Wall, M; Schwartz, A; Haire, R

    2007-04-03

    We examine the branching ratio of the N{sub 4,5} (4d {yields} 5f ) spectra of Th, U, Np, Pu, Am, and Cm metal using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM), together with many-electron atomic spectral calculations and the spin-orbit sum rule. Our results show that: (1) The actinide metals Pu, Am, and Cm exhibit intermediate coupling. (2) The intermediate coupling values for the 5f states as calculated using a many-electron atomic model are correct for the actinides, this being proven by our new results for curium. (3) The EELS branching ratio is sensitive to the degree of 5f electron delocalization, which is illustrated by the transition from LS to intermediate coupling between U and Pu.

  8. Electronic energy states

    NASA Technical Reports Server (NTRS)

    1976-01-01

    One-electron wave functions are reviewed and approximate solutions of two-electron systems are given in terms of these one-electron functions. The symmetry effects associated with electron spin are reviewed and the effects of electron exchange on energy levels of the two-electron system are given. The coupling of electronic orbital and spin angular momentum is considered next and the Lande interval rule for Russell-Saunders or LS coupling is derived. The configurations possible for various multi-electron LS couplings are enumerated (examples from the first two rows of the periodic table are given), and the meaning of the spectroscopic nomenclature is discussed, particularly with respect to the degeneracies of the electron states involved. Next the nomenclature, symmetries, and degeneracies for electron states of diatomic molecules are discussed, and some examples for N2, O2, and NO are presented. The electronic partition functions and derivative thermodynamic properties are expressed in terms of these energies and degeneracies, and examples are given for some of the simple gas species encountered in the earth's atmosphere.

  9. The 5f2-->5f16d1 absorption spectrum of Cs2GeF6:U4+ crystals: A quantum chemical and experimental study.

    PubMed

    Ordejón, Belén; Karbowiak, Miroslaw; Seijo, Luis; Barandiarán, Zoila

    2006-08-21

    Single crystals of U(4+)-doped Cs2GeF6 with 1% U4+ concentration have been obtained by the modified Bridgman-Stockbarger method in spite of the large difference in ionic radii between Ge4+ and U4+ in octahedral coordination. Their UV absorption spectrum has been recorded at 7 K, between 190 and 350 nm; it consists of a first broad and intense band peaking at about 38,000 cm(-1) followed by a number of broad bands of lower intensity from 39,000 to 45,000 cm(-1). None of the bands observed shows appreciable fine vibronic structure, so that the energies of experimental electronic origins cannot be deduced and the assignment of the experimental spectrum using empirical methods based on crystal field theory cannot be attempted. Alternatively, the profile of the absorption spectrum has been obtained theoretically using the U-F bond lengths and totally symmetric vibrational frequencies of the ground 5f2 - 1A(1g) and 5f16d(t(2g))1 - iT(1u) excited states, their energy differences, and their corresponding electric dipole transition moments calculated using the relativistic ab initio model potential embedded cluster method. The calculations suggest that the observed bands are associated with the lowest five 5f2 - 1A(1g)-->5f16d(t(2g))1 - iT(1u) (i = 1-5) dipole allowed electronic origins and their vibrational progressions. In particular, the first broad and intense band peaking at about 38,000 cm(-1) can be safely assigned to the 0-0 and 0-1 members of the a(1g) progression of the 5f2 - 1A(1g)-->5f16d(t(2g))1 - 1T(1u) electronic origin. The electronic structure of all the states with main configurational character 5f16d(t(2g))1 has been calculated as well. The results show that the lowest crystal level of this manifold is 5f16d(t(2g))1 - 1E(u) and lies about 6200 cm(-1) above the 5f2 level closest in energy, which amounts to some 11 vibrational quanta. This large energy gap could result in low nonradiative decay and efficient UV emission, which suggest the interest of

  10. Giant magnetoresistance effects in 5f-materials

    SciTech Connect

    Havela, L.; Sechovsky, V.; Prokes, K. |

    1995-09-01

    Very large magnetoresistance effects related to reorientation of magnetic moments were observed in a number of U-intermetallics. The resemblance to magnetic multilayers is a basis of discussion of possible mechanisms of these phenomena, in background of which is probably the strong hybridization of 5f- and conduction-electron states. A clear cut evidence of relative contributions of varied scattering rate on one side and carrier concentration on the other side can be presumably obtained from experiments on samples with controlled disorder.

  11. Band structures of 4f and 5f materials studied by angle-resolved photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Fujimori, Shin-ichi

    2016-04-01

    Recent remarkable progress in angle-resolved photoelectron spectroscopy (ARPES) has enabled the direct observation of the band structures of 4f and 5f materials. In particular, ARPES with various light sources such as lasers (hν ∼ 7~\\text{eV} ) or high-energy synchrotron radiations (hν ≳ 400~\\text{eV} ) has shed light on the bulk band structures of strongly correlated materials with energy scales of a few millielectronvolts to several electronvolts. The purpose of this paper is to summarize the behaviors of 4f and 5f band structures of various rare-earth and actinide materials observed by modern ARPES techniques, and understand how they can be described using various theoretical frameworks. For 4f-electron materials, ARPES studies of \\text{Ce}M\\text{I}{{\\text{n}}5} (M=\\text{Rh} , \\text{Ir} , and \\text{Co} ) and \\text{YbR}{{\\text{h}}2}\\text{S}{{\\text{i}}2} with various incident photon energies are summarized. We demonstrate that their 4f electronic structures are essentially described within the framework of the periodic Anderson model, and that the band-structure calculation based on the local density approximation cannot explain their low-energy electronic structures. Meanwhile, electronic structures of 5f materials exhibit wide varieties ranging from itinerant to localized states. For itinerant \\text{U}~5f compounds such as \\text{UFeG}{{\\text{a}}5} , their electronic structures can be well-described by the band-structure calculation assuming that all \\text{U}~5f electrons are itinerant. In contrast, the band structures of localized \\text{U}~5f compounds such as \\text{UP}{{\\text{d}}3} and \\text{U}{{\\text{O}}2} are essentially explained by the localized model that treats \\text{U}~5f electrons as localized core states. In regards to heavy fermion \\text{U} -based compounds such as the hidden-order compound \\text{UR}{{\\text{u}}2}\\text{S}{{\\text{i}}2} , their electronic structures exhibit complex behaviors. Their overall band structures

  12. Excited state reaction dynamics of Ti(a{sup 5}F{sub J}) + O{sub 2} → TiO(A{sup 3}Φ, B{sup 3}Π, C{sup 3}Δ) + O studied by a crossed-beam velocity map imaging technique

    SciTech Connect

    Honma, Kenji Tanaka, Yuhki

    2015-04-21

    Oxidation reactions of the gas-phase titanium atom in its excited state with oxygen molecule, Ti(a{sup 5}F{sub J}) + O{sub 2} → TiO(A{sup 3}Φ, B{sup 3}Π, C{sup 3}Δ) + O, were studied by a crossed-beam velocity map imaging technique at 14.3 kJ/mol of collision energy. Metastable excited Ti, Ti(a{sup 5}F{sub J}), was generated by an optical pumping method and the reaction products were detected by single photon-ionization followed by a time-of-flight mass analysis and a two dimensional detection. Three wavelengths were selected to ionize electronically excited TiO{sup ∗}, TiO(A{sup 3}Φ, B{sup 3}Π, C{sup 3}Δ). Time sliced images were measured, and angular and speed distributions of TiO{sup ∗} were determined. In all three ionization wavelengths, the angular distributions showed a forward-backward symmetry with low intensity at the sideway direction. The speed distributions were represented by the distributions based on the statistical energy partition into products. These results suggested that the reaction of Ti(a{sup 5}F{sub J}) to form TiO(B) and TiO(C) proceeds via a long-lived intermediate and confirmed that the mechanism proposed by the previous chemiluminescence study.

  13. Single electron states in polyethylene

    SciTech Connect

    Wang, Y.; MacKernan, D.; Cubero, D. E-mail: n.quirke@imperial.ac.uk; Coker, D. F.; Quirke, N. E-mail: n.quirke@imperial.ac.uk

    2014-04-21

    We report computer simulations of an excess electron in various structural motifs of polyethylene at room temperature, including lamellar and interfacial regions between amorphous and lamellae, as well as nanometre-sized voids. Electronic properties such as density of states, mobility edges, and mobilities are computed on the different phases using a block Lanczos algorithm. Our results suggest that the electronic density of states for a heterogeneous material can be approximated by summing the single phase density of states weighted by their corresponding volume fractions. Additionally, a quantitative connection between the localized states of the excess electron and the local atomic structure is presented.

  14. Single electron states in polyethylene

    NASA Astrophysics Data System (ADS)

    Wang, Y.; MacKernan, D.; Cubero, D.; Coker, D. F.; Quirke, N.

    2014-04-01

    We report computer simulations of an excess electron in various structural motifs of polyethylene at room temperature, including lamellar and interfacial regions between amorphous and lamellae, as well as nanometre-sized voids. Electronic properties such as density of states, mobility edges, and mobilities are computed on the different phases using a block Lanczos algorithm. Our results suggest that the electronic density of states for a heterogeneous material can be approximated by summing the single phase density of states weighted by their corresponding volume fractions. Additionally, a quantitative connection between the localized states of the excess electron and the local atomic structure is presented.

  15. 5f band dispersion in epitaxial films of UO2

    SciTech Connect

    Durakiewicz, Tomasz; Jia, Quanxi; Roy, Lindsay E; Martin, Richard L; Joyce, John J

    2009-01-01

    Polymer-assisted deposition of epitaxial films utilizes lattice pinning to produce films of very high stability and properties identical with bulk crystal. Dispersion of the 5f band is shown for the first time in a actinide Mott insulator system, which suggestes hybridization as a leading process in establishing the electronic structure. Hybrid density functional is succesfully employed to calculate the electronic structure of UO{sub 2} in agreement with experiments. UO{sub 2} continues to be a mysterious and elusive compound in terms of understanding the physical properties of a material. Most actinide oxides, including UO{sub 2} are predicted to be metallic. However, UO{sub 2} is an antiferromagnetic insulator with a relatively large gap of about 2eV. The f orbital charater of the excitations across the gap places UO{sub 2} in a Mott insulator category, but no states at the gap center have ever been measured directly, in spite of intensive efforts. In this work we present the first results of the electronic structure investigation of a epitaxial film of UO{sub 2}, where we find even more unexpected properties, like the dispersive nature of 5f bands. We also demonstrate the unexpected, very high stability of the epitaxial film of UO{sub 2}. In the lattice-pinning scheme, the crystalline nature of the film is preserved all the way up to the topmost layers even after prolonged exposure to atmospheric conditions. Hybridized, dispersive bands are common in the itinerant uranium compounds. One usually finds hybridization of f-orbitals with conduction band to be quite common in f-electron systems at low temperatures. Such bands may reside in the vicinity of the Fermi level and participate in the construction of the Fermi surface. However, in the insulator like UO{sub 2}, one expects a more atomic band nature, where f-bands are relatively flat and shifted away from the Fermi level by the gap energy scale. Precise location of UO{sub 2} on the localization

  16. Interchain electron states in polyethylene

    NASA Astrophysics Data System (ADS)

    Serra, S.; Tosatti, E.; Iarlori, S.; Scandolo, S.; Santoro, G.

    2000-08-01

    We present a theoretical study of the nature of the lowest empty conduction-band states in crystalline polyethylene (PE), conducted through density-functional electronic structure calculations. Results reveal that the wave function of the conduction-band edge is of interchain character, as opposed to the intrachain character of all the filled valence-band states. Thus, while a hole added to neutral PE will mainly belong to the PE chain backbone bonds, an added electron in PE will mostly reside between the chains, and far from the existing bonds. Moreover, the added electron state charge centroid is predicted to move further out from the chain backbone towards the low-density interstitial region, if and when the chains are pried apart. This suggests that injected electrons will naturally flow to low-density regions inside real PE, and that the experimentally established propensity of PE to expel electrons out of the bulk, should be directly related to the interchain nature of the conduction states.

  17. Multiconfigurational nature of 5f orbitals in uranium and plutonium and their intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Booth, Corwin

    2013-03-01

    The structural, electronic, and magnetic properties of U and Pu elements and intermetallics remain poorly understood despite decades of effort, and currently represent an important scientific frontier toward understanding matter. The last decade has seen great progress both due to the discovery of superconductivity in PuCoGa5 and advances in theory that finally can explain fundamental ground state properties in elemental plutonium, such as the phonon dispersion curve, the non-magnetic ground state, and the volume difference between the α and δ phases. A new feature of the recent calculations is the presence not only of intermediate valence of the Pu 5f electrons, but of multiconfigurational ground states, where the different properties of the α and δ phases are primarily governed by the different relative weights of the 5f4, 5f5, and 5f6 electronic configurations. The usual method for measuring multiconfigurational states in the lanthanides is to measure the lanthanide LIII-edge x-ray absorption near-edge structure (XANES), a method that is severely limited for the actinides because the spectroscopic features are not well enough separated. Advances in resonant x-ray emission spectroscopy (RXES) have now allowed for spectra with sufficient resolution to resolve individual resonances associated with the various actinide valence states. Utilizing a new spectrometer at the Stanford Synchrotron Radiation Lightsource (SSRL), RXES data have been collected that show, for the first time, spectroscopic signatures of each of these configurations and their relative changes in various uranium and plutonium intermetallic compounds. In combination with conventional XANES spectra on related compounds, these data indicate such states may be ubiquitous in uranium and plutonium intermetallics, providing a new framework toward understanding properties ranging from heavy fermion behavior, superconductivity, and intermediate valence to mechanical and fundamental bonding behavior in

  18. Northrop F-5F shark nose development

    NASA Technical Reports Server (NTRS)

    Edwards, O. R.

    1978-01-01

    During spin susceptibility testing of the Northrop F-5F airplane, two erect spin entries were obtained from purely longitudinal control inputs at low speed. Post flight analysis of the data showed that the initial yaw departure occurred at zero sideslip, and review of wind tunnel data showed significant yawing moments present at angles of attack well above stall. Further analysis of this wind tunnel data indicated that the yawing moments were being generated by the long slender nose of the airplane. Redesign of the nose was accomplished, resulting in a nose configuration which completely alleviated the asymmetric yawing moments.

  19. Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics

    PubMed Central

    Booth, C.H.; Jiang, Yu; Wang, D.L.; Mitchell, J.N.; Tobash, P.H.; Bauer, E.D.; Wall, M.A.; Allen, P.G.; Sokaras, D.; Nordlund, D.; Weng, T.-C.; Torrez, M.A.; Sarrao, J.L.

    2012-01-01

    Uranium and plutonium’s 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (e.g., the six different allotropes of elemental plutonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization for which a quantitative measure is lacking. By employing resonant X-ray emission spectroscopy (RXES) and X-ray absorption near-edge structure (XANES) spectroscopy and making comparisons to specific heat measurements, we demonstrate the presence of multiconfigurational f-orbital states in the actinide elements U and Pu and in a wide range of uranium and plutonium intermetallic compounds. These results provide a robust experimental basis for a new framework toward understanding the strongly-correlated behavior of actinide materials. PMID:22706643

  20. Theoretical studies of electronically excited states

    SciTech Connect

    Besley, Nicholas A.

    2014-10-06

    Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

  1. Quasi-relativistic SCF X. cap alpha. study of octahedral 5f/sup 1/ complexes

    SciTech Connect

    Thornton, G.; Roesch, N.; Edelstein, N.

    1980-05-01

    Quasi-relativistic SCF X..cap alpha.. calculations have been carried out for the octahedral 5f/sup 1/ complexes Pa/sup IV/X/sub 6//sup 2 -/, U/sup V/X/sub 6//sup -/(X = F, Cl, Br, I), and Np/sup VI/F/sub 6/. The 5f ..-->.. 5f excitation energies calculated by using the transition-state method agree well with the available absorption spectra. Ionic effects appear to dominate the trends observed in the f-orbital ligand field splitting.

  2. Anomalous confined electron states in graphene superlattices

    SciTech Connect

    Anh Le, H.; Chien Nguyen, D.; Nam Do, V.

    2014-07-07

    We show that periodic scalar potentials can induce the localization of some electronic states in graphene. Particularly, localized states are found at energies outside the potential variation range and embedded in the continuum spectrum of delocalized ones. The picture of the connection of wave functions with typical symmetries defined in relevant-edge nanoribbons is employed to explain the formation of the electronic structure and to characterize/classify eigen-states in graphene superlattices.

  3. ARPES in strongly correlated 4f and 5f systems: Comparison to the Periodic Anderson Model

    SciTech Connect

    Arko, A.J.; Joyce, J.J.; Cox, L.E.

    1997-12-01

    The electronic structure of both Ce and U heavy fermions appears to consist of extremely narrow, nearly temperature independent bands (i.e., no spectral weight loss or transfer with temperature). A small dispersion of the f-bands above the Kondo temperature is easily measurable so that a Kondo resonance, as defined by NCA, is not evident. Preliminary results, however, indicate that the Periodic Anderson Model captures some of the essential physics. Angle-integrated resonant photoemission results on {delta}-Pu indicate a narrow 5f feature at E{sub F}, similar in width to f-states in Ce and U compounds, but differing in that cross-section behavior of the near-E{sub F} feature suggests substantial 6D admixture.

  4. Nearly free electron states in MXenes

    NASA Astrophysics Data System (ADS)

    Khazaei, Mohammad; Ranjbar, Ahmad; Ghorbani-Asl, Mahdi; Arai, Masao; Sasaki, Taizo; Liang, Yunye; Yunoki, Seiji

    2016-05-01

    Using a set of first-principles calculations, we studied the electronic structures of two-dimensional transition metal carbides and nitrides, so called MXenes, functionalized with F, O, and OH. Our projected band structures and electron localization function analyses reveal the existence of nearly free electron (NFE) states in a variety of MXenes. The NFE states are spatially located just outside the atomic structure of MXenes and are extended parallel to the surfaces. Moreover, we found that the OH-terminated MXenes offer the NFE states energetically close to the Fermi level. In particular, the NFE states in some of the OH-terminated MXenes, such as T i2C (OH) 2,Z r2C (OH) 2,Z r2N (OH) 2,H f2C (OH) 2,H f2N (OH) 2,N b2C (OH) 2 , and T a2C (OH) 2 , are partially occupied. This is in remarkable contrast to graphene, graphane, and Mo S2 , in which their NFE states are located far above the Fermi level and thus they are unoccupied. As a prototype of such systems, we investigated the electron transport properties of H f2C (OH) 2 and found that the NFE states in H f2C (OH) 2 provide almost perfect transmission channels without nuclear scattering for electron transport. Our results indicate that these systems might find applications in nanoelectronic devices. Our findings provide new insights into the unique electronic band structures of MXenes.

  5. Fermionic thermocoherent state: Efficiency of electron transport

    NASA Astrophysics Data System (ADS)

    Karmakar, Anirban; Gangopadhyay, Gautam

    2016-02-01

    On the basis of the fermionic coherent state of Cahill and Glauber [Phys. Rev. A 59, 1538 (1999)], 10.1103/PhysRevA.59.1538, we have introduced here the fermionic thermocoherent state in terms of the quasiprobability distribution which shows the appropriate thermal and coherent limits as in the bosonic case or the Glauber-Lachs state. It is shown that the fermionic thermocoherent state can be realized as a displaced thermal state of fermions. Its relation with the fermionic displaced number state and the fermion-added coherent state are explored in the spirit of the bosonic case. We have investigated the nature of the average current and the suppression of noise due to the thermocoherent character of the source. The theory is applied to the problem of electronic conduction. A modification of the Landauer conductance formula is suggested which reflects the role of nonzero coherence of the source in electron transport.

  6. Description of electronic excited states using electron correlation operator.

    PubMed

    Nichols, Bryan; Rassolov, Vitaly A

    2013-09-14

    The electron correlation energy in a chemical system is defined as a difference between the energy of an exact energy for a given Hamiltonian, and a mean-field, or single determinant, approximation to it. A promising way to model electron correlation is through the expectation value of a linear two-electron operator for the Kohn-Sham single determinant wavefunction. For practical reasons, it is desirable for such an operator to be universal, i.e., independent of the positions and types of nuclei in a molecule. The correlation operator models the effect of electron correlation on the interaction energy in a electron pair. We choose an operator expanded in a small number of Gaussians as a model for electron correlation, and test it by computing atomic and molecular adiabatic excited states. The computations are performed within the Δ Self-Consistent Field (ΔSCF) formalism, and are compared to the time-dependent density functional theory model with popular density functionals. The simplest form of the correlation operator contains only one parameter derived from the helium atom ground state correlation energy. The correlation operator approach significantly outperforms other methods in computation of atomic excitation energies. The accuracy of molecular excitation energies computed with the correlation operator is limited by the shortcomings of the ΔSCF methodology in describing excited states. PMID:24050332

  7. Intense steady state electron beam generator

    DOEpatents

    Hershcovitch, Ady; Kovarik, Vincent J.; Prelec, Krsto

    1990-01-01

    An intense, steady state, low emittance electron beam generator is formed by operating a hollow cathode discharge plasma source at critical levels in combination with an extraction electrode and a target electrode that are operable to extract a beam of fast primary electrons from the plasma source through a negatively biased grid that is critically operated to repel bulk electrons toward the plasma source while allowing the fast primary electrons to move toward the target in the desired beam that can be successfully transported for relatively large distances, such as one or more meters away from the plasma source.

  8. Intense steady state electron beam generator

    DOEpatents

    Hershcovitch, A.; Kovarik, V.J.; Prelec, K.

    1990-07-17

    An intense, steady state, low emittance electron beam generator is formed by operating a hollow cathode discharge plasma source at critical levels in combination with an extraction electrode and a target electrode that are operable to extract a beam of fast primary electrons from the plasma source through a negatively biased grid that is critically operated to repel bulk electrons toward the plasma source while allowing the fast primary electrons to move toward the target in the desired beam that can be successfully transported for relatively large distances, such as one or more meters away from the plasma source. 2 figs.

  9. Two electronic states in spherical quantum nanolayer

    NASA Astrophysics Data System (ADS)

    Aghekyan, N. G.; Kazaryan, E. M.; Kostanyan, A. A.; Sarkisyan, H. A.

    2010-10-01

    In this paper two electronic states in spherical quantum nanolayer are discussed. The Coulomb interaction between the electrons is discussed as perturbation. For confinement potential of the nanolayer the three-dimensional radial analog of Smorodinsky-Winternitz potential is considered. The problem is discussed within the frameworks of Russell-Saunders coupling scheme, thus, the spin-orbit interaction is considered weak. Therefore the eigenfunctions of the system is represented as a multiplication of its coordinate wave function and spin wave function. For this system the analogue of helium atom theory is represented. The eigenfunctions and energy states are obtained for one and two electron cases in the spherical quantum nanolayer. For the spherical nanolayer the dependence of perturbation energy, unperturbed system energy and the total energy for the ground state upon the inner radius is represented when the outer radius is fixed.

  10. Floating electron states in covalent semiconductors.

    PubMed

    Matsushita, Yu-ichiro; Furuya, Shinnosuke; Oshiyama, Atsushi

    2012-06-15

    We report first-principles electronic-structure calculations that clarify the floating nature of electron states in covalent semiconductors. It is found that wave functions of several conduction- and valence-band states, including the conduction-band minima, do not distribute near atomic sites, as was taken for granted, but float in interstitial channels in most semiconductors. The directions and shapes of the interstitial channels depend on the crystal symmetry so that mysterious variation of the energy gaps in SiC polymorphs is naturally explained by considering the floating nature. PMID:23004300

  11. Electronically excited states of PANH anions.

    PubMed

    Theis, Mallory L; Candian, Alessandra; Tielens, Alexander G G M; Lee, Timothy J; Fortenberry, Ryan C

    2015-06-14

    The singly deprotonated anion derivatives of nitrogenated polycyclic aromatic hydrocarbons (PANHs) are investigated for their electronically excited state properties. These include single deprotonation of the two unique arrangements of quinoline producing fourteen different isomers. This same procedure is also undertaken for single deprotonation of the three nitrogenation isomers of acridine and the three of pyrenidine. It is shown quantum chemically that the quinoline-class of PANH anion derivatives can only produce a candidate dipole-bound excited state each, a state defined as the interaction of an extra electron with the dipole moment of the corresponding neutral. However, the acridine- and pyrenidine-classes possess valence excited states as well as the possible dipole-bound excited states where the latter is only possible if the dipole moment is sufficiently large to retain the extra electron; the valence excitation is independent of the radical dipolar strength. As a result, the theoretical vertically computed electronic spectra of deprotonated PANH anion derivatives is fairly rich in the 1.5 eV to 2.5 eV range significantly opening the possibilities for these molecules to be applied to longer wavelength studies of visible and near-IR spectroscopy. Lastly, the study of these systems is also enhanced by the inclusion of informed orbital arrangements in a simply constructed basis set that is shown to be more complete and efficient than standard atom-centered functions. PMID:25975430

  12. Electronics: State of the Art No. 2.

    ERIC Educational Resources Information Center

    Gosling, W.

    1979-01-01

    Reviewed is a brief history of electronics technology, from the early beginnings of vacuum devices to development of solid state devices, silicon fabrication in the use of transistors, and integrated circuits. Educational needs at the university or polytechnic level are discussed. (CS)

  13. 5f{sup N} configurations and x-ray spectra of actinides

    SciTech Connect

    Kulagin, N.A.

    1995-04-01

    The electronic structure of 5f{sup N} configurations and the characteristic X-ray radiation energies for an entire actinium series are calculated using the Hartree-Fock-Pauli approximation, and the variations obtained are analyzed. The electrostatic and magnetic parameters of these ions, as well as energies of their K and L lines, exhibit essentially nonlinear dependence on the nuclear charge and number of electrons. This fact evidences that simplified models of atomic structure are inapplicable to heavy ions.

  14. Unoccupied electronic states in adsorbate systems

    NASA Astrophysics Data System (ADS)

    Bertel, E.

    1991-11-01

    Experimental work on unoccupied electronic states in adsorbate systems on metallic substrates is reviewed with emphasis on recent developments. The first part is devoted to molecular adsorbates. Weakly chemisorbed hydrocarbons are briefly discussed. An exhaustive inverse photoemission (IPE) study of the CO bond to the transition metals Ni, Pb, and Pt is presented. Adsorbed NO is taken as an example to demonstrate the persisting discrepancies in the interpretation of IPE spectra. Atomic adsorbates are discussed in the second part. The quantum well state model is applied to interpret the surface states in reconstructing and non-reconstructing adsorption systems of alkali metals and hydrogen. A recent controversy on the unoccupied electronic states of the Cu(110)/O p(2×1) surface is critically reviewed. The quantum well state model is then compared to tight binding and local-density-functional calculations of the unoccupied bands and the deficiencies of the various approaches are pointed out. Finally, the relation between the surface state model and more chemically oriented models of surface bonding is briefly discussed.

  15. Analysis Of The Tank 5F Final Characterization Samples-2011

    SciTech Connect

    Oji, L. N.; Diprete, D.; Coleman, C. J.; Hay, M. S.

    2012-09-27

    The Savannah River National Laboratory (SRNL) was requested by SRR to provide sample preparation and analysis of the Tank 5F final characterization samples to determine the residual tank inventory prior to grouting. Two types of samples were collected and delivered to SRNL: floor samples across the tank and subsurface samples from mounds near risers 1 and 5 of Tank 5F. These samples were taken from Tank 5F between January and March 2011. These samples from individual locations in the tank (nine floor samples and six mound Tank 5F samples) were each homogenized and combined in a given proportion into 3 distinct composite samples to mimic the average composition in the entire tank. These Tank 5F composite samples were analyzed for radiological, chemical and elemental components. Additional measurements performed on the Tank 5F composite samples include bulk density and water leaching of the solids to account for water soluble species. With analyses for certain challenging radionuclides as the exception, all composite Tank 5F samples were analyzed and reported in triplicate. The target detection limits for isotopes analyzed were based on customer desired detection limits as specified in the technical task request documents. SRNL developed new methodologies to meet these target detection limits and provide data for the extensive suite of components. While many of the target detection limits were met for the species characterized for Tank 5F, as specified in the technical task request, some were not met. In a few cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. The Technical Task Request allows that while the analyses of these isotopes is needed, meeting the detection limits for these isotopes is a lower priority than meeting detection limits for the other specified isotopes. The isotopes whose detection limits were not met in all cases included the

  16. ANALYSIS OF THE TANK 5F FINAL CHARACTERIZATION SAMPLES-2011

    SciTech Connect

    Oji, L.; Diprete, D.; Coleman, C.; Hay, M.

    2012-08-03

    The Savannah River National Laboratory (SRNL) was requested by SRR to provide sample preparation and analysis of the Tank 5F final characterization samples to determine the residual tank inventory prior to grouting. Two types of samples were collected and delivered to SRNL: floor samples across the tank and subsurface samples from mounds near risers 1 and 5 of Tank 5F. These samples were taken from Tank 5F between January and March 2011. These samples from individual locations in the tank (nine floor samples and six mound Tank 5F samples) were each homogenized and combined in a given proportion into 3 distinct composite samples to mimic the average composition in the entire tank. These Tank 5F composite samples were analyzed for radiological, chemical and elemental components. Additional measurements performed on the Tank 5F composite samples include bulk density and water leaching of the solids to account for water soluble species. With analyses for certain challenging radionuclides as the exception, all composite Tank 5F samples were analyzed and reported in triplicate. The target detection limits for isotopes analyzed were based on customer desired detection limits as specified in the technical task request documents. SRNL developed new methodologies to meet these target detection limits and provide data for the extensive suite of components. While many of the target detection limits were met for the species characterized for Tank 5F, as specified in the technical task request, some were not met. In a few cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. The Technical Task Request allows that while the analyses of these isotopes is needed, meeting the detection limits for these isotopes is a lower priority than meeting detection limits for the other specified isotopes. The isotopes whose detection limits were not met in all cases included the

  17. ANALYSIS OF THE TANK 5F FINAL CHARATERIZATION SAMPLES-2011

    SciTech Connect

    Oji, L.; Diprete, D.; Coleman, C.; Hay, M.

    2012-01-20

    The Savannah River National Laboratory (SRNL) was requested by SRR to provide sample preparation and analysis of the Tank 5F final characterization samples to determine the residual tank inventory prior to grouting. Two types of samples were collected and delivered to SRNL: floor samples across the tank and subsurface samples from mounds near risers 1 and 5 of Tank 5F. These samples were taken from Tank 5F between January and March 2011. These samples from individual locations in the tank (nine floor samples and six mound Tank 5F samples) were each homogenized and combined in a given proportion into 3 distinct composite samples to mimic the average composition in the entire tank. These Tank 5F composite samples were analyzed for radiological, chemical and elemental components. Additional measurements performed on the Tank 5F composite samples include bulk density and water leaching of the solids to account for water soluble species. With analyses for certain challenging radionuclides as the exception, all composite Tank 5F samples were analyzed and reported in triplicate. The target detection limits for isotopes analyzed were based on customer desired detection limits as specified in the technical task request documents. SRNL developed new methodologies to meet these target detection limits and provide data for the extensive suite of components. While many of the target detection limits were met for the species characterized for Tank 5F, as specified in the technical task request, some were not met. In a few cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. The Technical Task Request allows that while the analyses of these isotopes is needed, meeting the detection limits for these isotopes is a lower priority than meeting detection limits for the other specified isotopes. The isotopes whose detection limits were not met in all cases included the

  18. Electron correlations in solid state physics

    SciTech Connect

    Freericks, J.K.

    1991-04-01

    Exactly solvable models of electron correlations in solid state physics are presented. These models include the spinless Falicov- Kimball model, the t-t{prime}-J model, and the Hubbard model. The spinless Falicov-Kimball model is analyzed in one-dimension. Perturbation theory and numerical techniques are employed to determine the phase diagram at zero temperature. A fractal structure is found where the ground-state changes (discontinuously) at each rational electron filling. The t-t{prime}-J model (strongly interacting limit of a Hubbard model) is studied on eight-site small clusters in the simple-cubic, body-centered-cubic, face-centered-cubic, and square lattices. Symmetry is used to simplify the problem and determine the exact many-body wavefunctions. Ground states are found that exhibit magnetic order or heavy-fermionic character. Attempts to extrapolate to the thermodynamic limit are also made. The Hubbard model is examined on an eight-site square-lattice cluster in the presence of and in the absence of a magnetic field'' that couples only to orbital motion. A new magnetic phase is discovered for the ordinary Hubbard model at half-filling. In the magnetic field'' case, it is found that the strongly frustrated Heisenberg model may be studied from adiabatic continuation of a tight-binding model (from weak to strong coupling) at one point. The full symmetries of the Hamiltonian are utilized to make the exact diagonalization feasibile. Finally, the presence of hidden'' extra symmetry for finite size clusters with periodic boundary conditions is analyzed for a variety of clusters. Moderately sized systems allow nonrigid transformations that map a lattice onto itself preserving its neighbor structure; similar operations are not present in smaller or larger systems. The additional symmetry requires particular representations of the space group to stick together explaining many puzzling degeneracies found in exact diagonalization studies.

  19. An Alternative Model for Electron Correlation in Pu

    SciTech Connect

    Yu, S; Tobin, J; Soderlind, P

    2007-10-23

    Using a density functional theory based approach that treats the 5f electrons relativistically, a Pu electronic structure with zero net magnetic moment is obtained, where the 5f orbital and 5f spin moments cancel each other. By combining the spin and orbital specific densities of states with state, spin and polarization specific transition moments, it is possible to reconstruct the experimentally observed photoemission spectra from Pu. Extrapolating to a spin-resolving Fano configuration, it is shown how this would resolve the extant controversy over Pu electronic structure.

  20. On the Electronically Excited States of Uracil

    SciTech Connect

    Epifanovsky, Evgeny; Kowalski, Karol; Fan, Peng-Dong; Valiev, Marat; Matsika, Spiridoula; Krylov, Anna

    2008-10-09

    Vertical excitation energies in uracil in the gas phase and in water solution are investigated by the equation-of-motion coupled-cluster and multi-reference configuration interaction methods. Basis set effects are found to be important for converged results. The analysis of electronic wave functions reveals that the lowest singlet states are predominantly of a singly excited character and are therefore well described by single-reference equation-of-motion methods augmented by a perturbative triples correction to account for dynamical correlation. Our best estimates for the vertical excitation energies for the lowest singlet n and are 5.0±0.1 eV and 5.3±0.1 eV, respectively. The solvent effects for these states are estimated to be +0.5 eV and ±0.1 eV, respectively. We attribute the difference between the computed vertical excitations and the maximum of the experimental absorption to strong vibronic interaction between the lowest A00 and A0 states leading to intensity borrowing by the forbidden transition.

  1. Electronically shielded solid state charged particle detector

    DOEpatents

    Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.

    1996-08-20

    An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite. 1 fig.

  2. Electronically shielded solid state charged particle detector

    SciTech Connect

    Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.

    1995-12-31

    An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite.

  3. Electronically shielded solid state charged particle detector

    DOEpatents

    Balmer, David K.; Haverty, Thomas W.; Nordin, Carl W.; Tyree, William H.

    1996-08-20

    An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite.

  4. Low-lying electronic states of carotenoids.

    PubMed

    DeCoster, B; Christensen, R L; Gebhard, R; Lugtenburg, J; Farhoosh, R; Frank, H A

    1992-08-28

    Four all-trans carotenoids, spheroidene, 3,4-dihydrospheroidene, 3,4,5,6-tetrahydrospheroidene, and 3,4,7,8-tetrahydrospheroidene, have been purified using HPLC techniques and analyzed using absorption, fluorescence and fluorescence excitation spectroscopy of room temperature solutions. This series of molecules, for which the extent of pi-electron conjugation decreases from 10 to seven carbon-carbon double bonds, exhibits a systematic crossover from S2----S0 (1(1)Bu----1(1)Ag) to S1----S0 (2(1)Ag----1(1)Ag) emission with decreasing chain length. Extrapolation of the S1----S0 transition energies indicates that the 2(1)Ag states of longer carotenoids have considerably lower energies than previously thought. The energies of the S1 states of spheroidenes and other long carotenoids are correlated with the S1 energies of their chlorophyll partners in antenna complexes of photosynthetic systems. Implications for energy transfer in photosynthetic antenna are discussed. PMID:1510992

  5. F-5F Shark Nose radome lightning test

    NASA Technical Reports Server (NTRS)

    Scott, G. W.

    1980-01-01

    A unique F-5F radome wtih a geometry similar to a Shark Nose profile was tested with a high voltage Marx generator, 1,200,000 volts in order to demonstrate the effectiveness of the lightning protection system with currents from 5,000 amperes or greater. An edge discontinuity configuration is a characteristic feature in the forward region of the radome and occasionally serves as an attachment point. The results of nineteen attachment tests at various aspect angles with an air gap of one meter indicated that no damage occurred to the dielectric material of the radom. The test proved the effectiveness of the lightning protection system.

  6. Pressure-induced changes in the electronic structure of americium metal

    SciTech Connect

    Soderlind, P; Moore, K T; Landa, A; Bradley, J A

    2011-02-25

    We have conducted electronic-structure calculations for Am metal under pressure to investigate the behavior of the 5f-electron states. Density-functional theory (DFT) does not reproduce the experimental photoemission spectra for the ground-state phase where the 5f electrons are localized, but the theory is expected to be correct when 5f delocalization occurs under pressure. The DFT prediction is that peak structures of the 5f valence band will merge closer to the Fermi level during compression indicating presence of itinerant 5f electrons. Existence of such 5f bands is argued to be a prerequisite for the phase transitions, particularly to the primitive orthorhombic AmIV phase, but does not agree with modern dynamical-mean-field theory (DMFT) results. Our DFT model further suggests insignificant changes of the 5f valence under pressure in agreement with recent resonant x-ray emission spectroscopy, but in contradiction to the DMFT predictions. The influence of pressure on the 5f valency in the actinides is discussed and is shown to depend in a non-trivial fashion on 5f band position and occupation relative to the spd valence bands.

  7. Oxalate Mass Balance During Chemical Cleaning in Tank 5F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-08

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

  8. The roles of 4f- and 5f-orbitals in bonding: a magnetochemical, crystal field, density functional theory, and multi-reference wavefunction study.

    PubMed

    Lukens, W W; Speldrich, M; Yang, P; Duignan, T J; Autschbach, J; Kögerler, P

    2016-07-28

    The electronic structures of 4f(3)/5f(3) Cp''3M and Cp''3M·alkylisocyanide complexes, where Cp'' is 1,3-bis-(trimethylsilyl)cyclopentadienyl, are explored with a focus on the splitting of the f-orbitals, which provides information about the strengths of the metal-ligand interactions. While the f-orbital splitting in many lanthanide complexes has been reported in detail, experimental determination of the f-orbital splitting in actinide complexes remains rare in systems other than halide and oxide compounds, since the experimental approach, crystal field analysis, is generally significantly more difficult for actinide complexes than for lanthanide complexes. In this study, a set of analogous neodymium(iii) and uranium(iii) tris-cyclopentadienyl complexes and their isocyanide adducts was characterized by electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility. The crystal field model was parameterized by combined fitting of EPR and susceptibility data, yielding an accurate description of f-orbital splitting. The isocyanide derivatives were also studied using density functional theory, resulting in f-orbital splitting that is consistent with crystal field fitting, and by multi-reference wavefunction calculations that support the electronic structure analysis derived from the crystal-field calculations. The results highlight that the 5f-orbitals, but not the 4f-orbitals, are significantly involved in bonding to the isocyanide ligands. The main interaction between isocyanide ligand and the metal center is a σ-bond, with additional 5f to π* donation for the uranium complexes. While interaction with the isocyanide π*-orbitals lowers the energies of the 5fxz(2) and 5fyz(2)-orbitals, spin-orbit coupling greatly reduces the population of 5fxz(2) and 5fyz(2) in the ground state. PMID:27349178

  9. An incompressible state of a photo-excited electron gas

    PubMed Central

    Chepelianskii, Alexei D.; Watanabe, Masamitsu; Nasyedkin, Kostyantyn; Kono, Kimitoshi; Konstantinov, Denis

    2015-01-01

    Two-dimensional electrons in a magnetic field can form new states of matter characterized by topological properties and strong electronic correlations as displayed in the integer and fractional quantum Hall states. In these states, the electron liquid displays several spectacular characteristics, which manifest themselves in transport experiments with the quantization of the Hall resistance and a vanishing longitudinal conductivity or in thermodynamic equilibrium when the electron fluid becomes incompressible. Several experiments have reported that dissipationless transport can be achieved even at weak, non-quantizing magnetic fields when the electrons absorb photons at specific energies related to their cyclotron frequency. Here we perform compressibility measurements on electrons on liquid helium demonstrating the formation of an incompressible electronic state under these resonant excitation conditions. This new state provides a striking example of irradiation-induced self-organization in a quantum system. PMID:26007282

  10. ANALYSIS OF SAMPLES FROM TANK 5F CHEMICAL CLEANING

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-03-07

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. The conclusions from this work are: (1) With the exception of iron, the dissolution of sludge components from Tank 5F agreed with results from the actual waste demonstration performed in 2007. The fraction of iron removed from Tank 5F by chemical cleaning was significantly less than the fraction removed in the SRNL demonstrations. The likely cause of this difference is the high pH following the first oxalic acid strike. (2) Most of the sludge mass remaining in the tank is iron and nickel. (3) The remaining sludge contains approximately 26 kg of barium, 37 kg of chromium, and 37 kg of mercury. (4) Most of the radioactivity remaining in the residual material is beta emitters and {sup 90}Sr. (5) The chemical cleaning removed more than {approx} 90% of the uranium isotopes and {sup 137}Cs. (6) The chemical cleaning removed {approx} 70% of the neptunium, {approx} 83% of the {sup 90}Sr, and {approx} 21% of the {sup 60}Co. (7) The chemical cleaning removed less than 10% of the plutonium, americium, and curium isotopes. (8) The chemical cleaning removed more than 90% of the aluminium, calcium, and sodium from the tank. (9) The cleaning operations removed 61% of lithium, 88% of non-radioactive strontium, and 65% of zirconium. The {sup 90}Sr and non-radioactive strontium were measured

  11. Microscopic theory of the insulating electronic ground states of the actinide dioxides AnO2 (An = U, Np, Pu, Am, and Cm)

    NASA Astrophysics Data System (ADS)

    Suzuki, M.-T.; Magnani, N.; Oppeneer, P. M.

    2013-11-01

    The electronic states of the actinide dioxides AnO2 (with An = U, Np, Pu, Am, and Cm) are investigated employing first-principles calculations within the framework of the local density approximation +U (LDA+U) approach, implemented in a full-potential linearized augmented plane-wave scheme. A systematic analysis of the An-5f states is performed which provides intuitive connections between the electronic structures and the local crystalline fields of the f states in the AnO2 series. Particularly the mechanisms leading to the experimentally observed insulating ground states are investigated. These are found to be caused by the strong spin-orbit and Coulomb interactions of the 5f orbitals; however, as a result of the different configurations, this mechanism works in distinctly different ways for each of the AnO2 compounds. In agreement with experimental observations, the nonmagnetic states of plutonium and curium dioxide are computed to be insulating, whereas those of uranium, neptunium, and americium dioxides require additional symmetry breaking to reproduce the insulator ground states, a condition which is met with magnetic phase transitions. We show that the occupancy of the An-f orbitals is closely connected to each of the appearing insulating mechanisms. We furthermore investigate the detailed constitution of the noncollinear multipolar moments for transverse 3q magnetic ordered states in UO2 and longitudinal 3q high-rank multipolar ordered states in NpO2 and AmO2.

  12. 45 CFR 265.6 - Must States file reports electronically?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (ASSISTANCE PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES DATA COLLECTION AND REPORTING REQUIREMENTS § 265.6 Must States file reports electronically? Each State must...

  13. CHARACTERIZATION AND ACTUAL WASTE TEST WITH TANK 5F SAMPLES

    SciTech Connect

    Hay, M. S.; Crapse, K. P.; Fink, S. D.; Pareizs, J. M.

    2007-08-30

    The initial phase of bulk waste removal operations was recently completed in Tank 5F. Video inspection of the tank indicates several mounds of sludge still remain in the tank. Additionally, a mound of white solids was observed under Riser 5. In support of chemical cleaning and heel removal programs, samples of the sludge and the mound of white solids were obtained from the tank for characterization and testing. A core sample of the sludge and Super Snapper sample of the white solids were characterized. A supernate dip sample from Tank 7F was also characterized. A portion of the sludge was used in two tank cleaning tests using oxalic acid at 50 C and 75 C. The filtered oxalic acid from the tank cleaning tests was subsequently neutralized by addition to a simulated Tank 7F supernate. Solids and liquid samples from the tank cleaning test and neutralization test were characterized. A separate report documents the results of the gas generation from the tank cleaning test using oxalic acid and Tank 5F sludge. The characterization results for the Tank 5F sludge sample (FTF-05-06-55) appear quite good with respect to the tight precision of the sample replicates, good results for the glass standards, and minimal contamination found in the blanks and glass standards. The aqua regia and sodium peroxide fusion data also show good agreement between the two dissolution methods. Iron dominates the sludge composition with other major contributors being uranium, manganese, nickel, sodium, aluminum, and silicon. The low sodium value for the sludge reflects the absence of supernate present in the sample due to the core sampler employed for obtaining the sample. The XRD and CSEM results for the Super Snapper salt sample (i.e., white solids) from Tank 5F (FTF-05-07-1) indicate the material contains hydrated sodium carbonate and bicarbonate salts along with some aluminum hydroxide. These compounds likely precipitated from the supernate in the tank. A solubility test showed the material

  14. Electron states in semiconductor quantum dots

    SciTech Connect

    Dhayal, Suman S.; Ramaniah, Lavanya M.; Ruda, Harry E.; Nair, Selvakumar V.

    2014-11-28

    In this work, the electronic structures of quantum dots (QDs) of nine direct band gap semiconductor materials belonging to the group II-VI and III-V families are investigated, within the empirical tight-binding framework, in the effective bond orbital model. This methodology is shown to accurately describe these systems, yielding, at the same time, qualitative insights into their electronic properties. Various features of the bulk band structure such as band-gaps, band curvature, and band widths around symmetry points affect the quantum confinement of electrons and holes. These effects are identified and quantified. A comparison with experimental data yields good agreement with the calculations. These theoretical results would help quantify the optical response of QDs of these materials and provide useful input for applications.

  15. Trends in solid state electronics, part 2

    NASA Technical Reports Server (NTRS)

    Gassaway, J. D.

    1972-01-01

    Developments in the fields of semiconductors and magnetics are surveyed. Materials, devices, theory, and fabrication technology are discussed. Important events up until the present time are reported, and events are interpreted through historical perspective. A brief analysis of forces which have driven the development of today's electronic technology and some projections of present trends are given. More detailed discussions are presented for four areas of contemporary interest: amorphous semiconductors, bubble domain devices, charge-coupled devices, and electron and ion beam techniques. Beam addressed magnetic memories are reviewed to a lesser extent.

  16. Lanthanide doped Y6O5F8/YF3 microcrystals: phase-tunable synthesis and bright white upconversion photoluminescence properties.

    PubMed

    Wang, Song; Deng, Ruiping; Guo, Hailing; Song, Shuyan; Cao, Feng; Li, Xiyan; Su, Shengqun; Zhang, Hongjie

    2010-10-14

    High-quality Y(6)O(5)F(8)/YF(3) microcrystals have been synthesised by using a hydrothermal and subsequent calcination route. Upon changing the initial solution pH value, the as-prepared microcrystal can be well tuned from YF(3) octahedron microcrystals to YF(3) hollow spheres and finally to Y(6)O(5)F(8) microtubes. The as-obtained microcrystals have been characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence (PL) spectra. When the Y(6)O(5)F(8):Ln(3+) microtubes are excited by a 980 nm continual wave laser diode, bright red, green, and blue room temperature upconversion PL emissions have been observed. A series of white light emissions have been obtained by precisely adjusting dopants concentration in Y(6)O(5)F(8) microtubes. PMID:20714629

  17. Electron and electron-hole quasiparticle states in a driven quantum contact

    NASA Astrophysics Data System (ADS)

    Vanević, Mihajlo; Gabelli, Julien; Belzig, Wolfgang; Reulet, Bertrand

    2016-01-01

    We study the many-body electronic state created by a time-dependent drive of a mesoscopic contact. The many-body state is expressed manifestly in terms of single-electron and electron-hole quasiparticle excitations with the amplitudes and probabilities of creation which depend on the details of the applied voltage. We experimentally probe the time dependence of the constituent electronic states by using an analog of the optical Hong-Ou-Mandel correlation experiment where electrons emitted from the terminals with a relative time delay collide at the contact. The electron wave packet overlap is directly related to the current noise power in the contact. We have confirmed the time dependence of the electronic states predicted theoretically by measurements of the current noise power in a tunnel junction under harmonic excitation.

  18. Electronic states and stability of selenium clusters

    NASA Astrophysics Data System (ADS)

    Li, Z. Q.; Yu, J. Z.; Ohno, K.; Gu, B. L.; Czajka, R.; Kasuya, A.; Nishina, Y.; Kawazoe, Y.

    1995-07-01

    Electronic structures and stability of Sen (n=3,4,5,6,7,8) clusters have been studied by using the discrete variational method in the framework of the local-density approximation. Binding energy, ionization potential, affinity energy, and other electronic properties using the structure models of Hohl et al. [Chem. Phys. Lett. 139, 540 (1987)] are presented and compared with the available experiments. In addition, a rectangular lattice arrangement of selenium clusters has been fabricated on highly oriented pyrolytic graphite, and examined by the scanning tunnel microscope image which was found to consist of a 0.72×0.85 nm2 lattice spacing with individual molecules of 0.53+/-0.05 nm in diameter. Theoretical calculations reproduce well the experimental observations.

  19. Photophysical properties of ESIPT inspired fluorescent 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and its derivative: Experimental and DFT based approach

    NASA Astrophysics Data System (ADS)

    Deshmukh, Mininath S.; Sekar, Nagaiyan

    2015-01-01

    The excited-state intramolecular proton transfer chromophores 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and 2-(4-(diethylamino)-2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione are synthesized from 4,5-diamino-N-methylphthalimide. The photophysical behavior of the synthesized chromophores was studied using UV-visible and fluorescence spectroscopy in the polar and non-polar solvents. The synthesized o-hydroxyphenyl benzimidazole derivatives are fluorescent and very sensitive to the solvent polarity. These dyes are thermally stable up to 317 °C. Density Functional Theory computations have been used to understand the structural, molecular, electronic and photophysical properties of the chromophores. The experimental absorption and emission wavelengths are in good agreement with the computed vertical excitation and theoretical emission obtained by Density Functional Theory and Time Dependant Density Functional Theory.

  20. Probing the electronic structures of low oxidation-state uranium fluoride molecules UFx- (x = 2-4)

    SciTech Connect

    Li, Wei-Li; Hu, Han-Shi; Jian, Tian; Lopez, Gary V.; Su, Jing; Li, Jun; Wang, Lai-Sheng

    2013-12-28

    We report the experimental observation of gaseous UFx- (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UFx (x = 2-4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f37s2)F2-, as a result of strong electron correlation effects of the two 7s electrons. The U-F symmetric stretching vibrational modes are resolved for the ground states of all UFx (x = 2-4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UFx- and UFx (x = 1-6) series are considered theoretically to examine the trends of U-F bonding and the electron affinities as a function of fluorine coordination. The increased U-F bond lengths and decreased bond orders from UF2- to UF4- indicate that the U-F bonding becomes weaker as the oxidation state of U increases from I to III.

  1. Probing the electronic structures of low oxidation-state uranium fluoride molecules UFx- (x=2-4)

    SciTech Connect

    Li, Wei-Li; Hu, Hanshi; Jian, Tian; Lopez, Gary V.; Su, Jing; Li, Jun; Wang, Lai-Sheng

    2013-12-28

    We report the experimental observation of gaseous UFx- (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UFx (x = 2-4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f(3)7s(2)) F-2(-), as a result of strong electron correlation effects of the two 7s electrons. The U-F symmetric stretching vibrational modes are resolved for the ground states of all UFx (x = 2-4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UFx- and UFx (x = 1-6) series are considered theoretically to examine the trends of U-F bonding and the electron affinities as a function of fluorine coordination. The increased U-F bond lengths and decreased bond orders from UF2- to UF4- indicate that the U-F bonding becomes weaker as the oxidation state of U increases from I to III. (C) 2013 AIP Publishing LLC.

  2. Probing the electronic structures of low oxidation-state uranium fluoride molecules UF(x)- (x = 2-4).

    PubMed

    Li, Wei-Li; Hu, Han-Shi; Jian, Tian; Lopez, Gary V; Su, Jing; Li, Jun; Wang, Lai-Sheng

    2013-12-28

    We report the experimental observation of gaseous UF(x)(-) (x = 2-4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UF(x) (x = 2-4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f(3)7s(2))F2(-), as a result of strong electron correlation effects of the two 7s electrons. The U-F symmetric stretching vibrational modes are resolved for the ground states of all UF(x) (x = 2-4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UF(x)(-) and UF(x) (x = 1-6) series are considered theoretically to examine the trends of U-F bonding and the electron affinities as a function of fluorine coordination. The increased U-F bond lengths and decreased bond orders from UF2(-) to UF4(-) indicate that the U-F bonding becomes weaker as the oxidation state of U increases from I to III. PMID:24387366

  3. Complex Study of Electronic States and Spectra of 3-Nitroformazans

    NASA Astrophysics Data System (ADS)

    Valiev, R. R.; Drozdova, A. K.; Petunin, P. V.; Postnikov, P. S.; Trusova, M. E.; Cherepanov, V. N.

    2016-06-01

    A theoretical and experimental study of electronic states and the absorption spectra of 3-nitroformazan molecules was conducted. The results of the study show that the first electron transition is σ→π-transition, and the second one is π→π-transition. The energies of the transitions calculated using methods RI-CC2 and TDDFT correlate well with the experimental measurements. The dependence of the first electron transition wavenumber on the degree of electron donating and accepting of substitutituents was studied using empirical constants. High correlation between the constants of Hammett, Braun, and wavenumbers (TDDFT) of the first electron transition shows that the description of electronic states of the studied 3-nitroformazans is correct.

  4. Lifetimes of electronic excitations in unoccupied surface states and the image potential states on Pd(110)

    SciTech Connect

    Tsirkin, S. S. Eremeev, S. V.; Chulkov, E. V.

    2012-10-15

    The contribution of inelastic electron-electron scattering to the decay rate of excitations in the surface states and first two image potential states at the Y-bar point on the surface is calculated in the GW approximation, and the quasi-momentum dependence of the corresponding contribution for the surface states is analyzed. The mechanisms of electron scattering in these states are studied, and the temperature dependence of the excitation lifetime is analyzed with allowance for the contribution of the electron-phonon interaction calculated earlier.

  5. Crossover Phase Diagram and Electronic State in the Heavy-Fermion Metamagnets UIr2Zn20 and UCo2Zn20

    NASA Astrophysics Data System (ADS)

    Hirose, Yusuke; Takeuchi, Tetsuya; Honda, Fuminori; Yoshiuchi, Shingo; Hagiwara, Masayuki; Yamamoto, Etsuji; Haga, Yoshinori; Settai, Rikio; Ōnuki, Yoshichika

    2015-07-01

    Crossover phase diagrams in the magnetic field versus temperature (H-T) plane of the nonmagnetic heavy-fermion metamagnets UT2Zn20 (T:Ir, Co) are studied by measuring the magnetic and electronic transport properties. The crossover phase diagrams of UIr2Zn20 and UCo2Zn20 are composed of a low-magnetic-field region (LFR) and a high-magnetic-field region (HFR), which are characterized by magnetic properties and the Hall effect, respectively. The LFR is found to form a closed area in the H-T plane, which is a quite different feature from the conventional uranium heavy-fermion compounds and the first observation in uranium compounds. From the drastic anomaly in the Hall effect at a metamagnetic field of UIr2Zn20, it is found that the metamagnetic behavior in UIr2Zn20 corresponds to a crossover from the heavy-fermion state to the field-induced ferromagnetic or polarized paramagnetic state accompanied by the reconstruction or topology change of Fermi surfaces. In UCo2Zn20, on the other hand, no sign of abrupt change in the electronic state at the metamagnetic field is observed. These contrastive crossover phase diagrams and the electronic state changes at the metamagnetic field are due to the different hybridization strengths between the 5f electrons of U atoms and the d electrons of Ir and Co atoms, leading to the differences in magnetic correlation and crystalline electric field ground state or the degree of itinerancy of 5f electrons.

  6. Electronic aperture control devised for solid state imaging system

    NASA Technical Reports Server (NTRS)

    Anders, R. A.; Callahan, D. E.; Mc Cann, D. H.

    1968-01-01

    Electronic means of performing the equivalent of automatic aperture control has been devised for the new class of television cameras that incorporates a solid state imaging device in the form of phototransistor mosaic sensors.

  7. Detection of excited-state electron bubbles in superfluid helium.

    PubMed

    Konstantinov, Denis; Maris, Humphrey J

    2003-01-17

    We report on experiments in which the pressure oscillation associated with a sound wave is used to explode electron bubbles in liquid helium. Using this technique, we are able to detect the presence of electron bubbles in excited states. PMID:12570553

  8. REFLECTIONS ON THE TWO-STATE ELECTRON TRANSFER MODEL.

    SciTech Connect

    Brunschwig, B.S.

    2000-01-12

    There is general agreement that the two most important factors determining electron transfer rates in solution are the degree of electronic interaction between the donor and acceptor sites, and the changes in the nuclear configurations of the donor, acceptor, and surrounding medium that occur upon the gain or loss of an electron Ll-51. The electronic interaction of the sites will be very weak, and the electron transfer slow, when the sites are far apart or their interaction is symmetry or spin forbidden. Since electron motion is much faster than nuclear motion, energy conservation requires that, prior to the actual electron transfer, the nuclear configurations of the reactants and the surrounding medium adjust from their equilibrium values to a configuration (generally) intermediate between that of the reactants and products. In the case of electron transfer between , two metal complexes in a polar solvent, the nuclear configuration changes involve adjustments in the metal-ligand and intraligand bond lengths and angles, and changes in the orientations of the surrounding solvent molecules. In common with ordinary chemical reactions, an electron transfer reaction can then be described in terms of the motion of the system on an energy surface from the reactant equilibrium configuration (initial state) to the product equilibrium configuration (final state) via the activated complex (transition state) configuration.

  9. Localization of the 5f level across the UM 5-xT x series

    NASA Astrophysics Data System (ADS)

    Zoł; nierek, Z̵.; Troc, R.; Tran, V. H.

    1990-04-01

    We review the results of bulk measurements on selected pseudoternary compounds within the UM 5- xT x system where M = Cu, Ni and Pt, and T = Ag, Au, Pd and Ir. These ternary compounds crystallize in the cubic AuBe 5 crystal structure. The results obtained on about 20 specimens clearly show that the 5f-localization of the uranium depends on the degree of f-d and/or f-s hybridization. The strength of the hybridization is a function of the concentration of s- and d-conduction electrons and is controlled chemically by the extent of the “M 5- xT x” alloying.

  10. Circularly Polarized Luminescence of Curium: A New Characterization of the 5f Actinide Complexes

    PubMed Central

    Law, Ga-Lai; Andolina, Christopher M.; Xu, Jide; Luu, Vinh; Rutkowski, Philip X.; Muller, Gilles; Shuh, David K.; Gibson, John K.; Raymond, Kenneth N.

    2012-01-01

    A key distinction between the lanthanide (4f) and actinide (5f) transition elements is the increased role of f-orbital covalent bonding in the latter. Circularly polarized luminescence (CPL) is an uncommon but powerful spectroscopy which probes the electronic structure of chiral, luminescent complexes or molecules. While there are many examples of CPL spectra for the lanthanides, this report is the first for an actinide. Two chiral, octadentate chelating ligands based on orthoamide phenol (IAM) were used to complex curium(III). While the radioactivity kept the amount of material limited to micromole amounts, the spectra of the highly luminescent complexes showed significant emission peak-shifts between the different complexes, consistent with ligand field effects previously observed in luminescence spectra. PMID:22920726

  11. Surface-electronic-state effects in electron emission from the Be(0001) surface

    SciTech Connect

    Archubi, C. D.; Gravielle, M. S.; Silkin, V. M.

    2011-07-15

    We study the electron emission produced by swift protons impinging grazingly on a Be(0001) surface. The process is described within a collisional formalism using the band-structure-based (BSB) approximation to represent the electron-surface interaction. The BSB model provides an accurate description of the electronic band structure of the solid and the surface-induced potential. Within this approach we derive both bulk and surface electronic states, with these latter characterized by a strong localization at the crystal surface. We found that such surface electronic states play an important role in double-differential energy- and angle-resolved electron emission probabilities, producing noticeable structures in the electron emission spectra.

  12. Ectopic POU5F1 in the male germ lineage disrupts differentiation and spermatogenesis in mice.

    PubMed

    Zheng, Yu; Phillips, LeAnna J; Hartman, Rachel; An, Junhui; Dann, Christina T

    2016-10-01

    Expression levels of the pluripotency determinant, POU5F1, are tightly regulated to ensure appropriate differentiation during early embryogenesis. POU5F1 is also present in the spermatogonial stem cell/progenitor cell population in mice and it is downregulated as spermatogenesis progresses. To test if POU5F1 downregulation is required for SSCs to differentiate, we produced transgenic mice that ubiquitously express POU5F1 in Cre-expressing lineages. Using a Vasa-Cre driver to produce ectopic POU5F1 in all postnatal germ cells, we found that POU5F1 downregulation was necessary for spermatogonial expansion during the first wave of spermatogenesis and for the production of differentiated spermatogonia capable of undergoing meiosis. In contrast, undifferentiated spermatogonia were maintained throughout adulthood, consistent with a normal presence of POU5F1 in these cells. The results suggest that POU5F1 downregulation in differentiating spermatogonia is a necessary step for the progression of spermatogenesis. Further, the creation of a transgenic mouse model for conditional ectopic expression of POU5F1 may be a useful resource for studies of POU5F1 in other cell lineages, during tumorogenesis and cell fate reprogramming. PMID:27486267

  13. Molecular electronics with single molecules in solid-state devices.

    PubMed

    Moth-Poulsen, Kasper; Bjørnholm, Thomas

    2009-09-01

    The ultimate aim of molecular electronics is to understand and master single-molecule devices. Based on the latest results on electron transport in single molecules in solid-state devices, we focus here on new insights into the influence of metal electrodes on the energy spectrum of the molecule, and on how the electron transport properties of the molecule depend on the strength of the electronic coupling between it and the electrodes. A variety of phenomena are observed depending on whether this coupling is weak, intermediate or strong. PMID:19734925

  14. Multi-pair states in electron-positron pair creation

    NASA Astrophysics Data System (ADS)

    Wöllert, Anton; Bauke, Heiko; Keitel, Christoph H.

    2016-09-01

    Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron-positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron-positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron-positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron-positron pairs.

  15. Tunable topological states in electron-doped HTT-Pt

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoming; Wang, Zhenhai; Zhao, Mingwen; Liu, Feng

    2016-04-01

    Modulating topologically nontrivial states in trivial materials is of both scientific and technological interest. Using first-principles calculations, we propose a demonstration of electron-doping- (or gate-voltage-) induced multiple quantum states; namely, quantum spin Hall (QSH) and quantum anomalous Hall (QAH) states, in a single material of the organometallic framework (HTT-Pt) synthesized from triphenylene hexathiol molecules (HTT) and PtC l2 . At a low doping level, the trivial HTT-Pt converts to a QSH insulator protected by time-reversal symmetry (TRS). When the electronic doping concentration is further increased, TRS will be broken, making the HTT-Pt a QAH insulator. The band gaps of these topologically nontrivial states can be as large as 42.5 meV, suggesting robustness at high temperatures. The possibility of switching between the QSH and QAH states offers an intriguing platform for a different device paradigm by interfacing between QSH and QAH states.

  16. Fast electronic resistance switching involving hidden charge density wave states

    PubMed Central

    Vaskivskyi, I.; Mihailovic, I. A.; Brazovskii, S.; Gospodaric, J.; Mertelj, T.; Svetin, D.; Sutar, P.; Mihailovic, D.

    2016-01-01

    The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T–TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states. PMID:27181483

  17. Fast electronic resistance switching involving hidden charge density wave states

    NASA Astrophysics Data System (ADS)

    Vaskivskyi, I.; Mihailovic, I. A.; Brazovskii, S.; Gospodaric, J.; Mertelj, T.; Svetin, D.; Sutar, P.; Mihailovic, D.

    2016-05-01

    The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T-TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states.

  18. Fast electronic resistance switching involving hidden charge density wave states.

    PubMed

    Vaskivskyi, I; Mihailovic, I A; Brazovskii, S; Gospodaric, J; Mertelj, T; Svetin, D; Sutar, P; Mihailovic, D

    2016-01-01

    The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T-TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states. PMID:27181483

  19. Electronic Ground and Excited State Spectral Diffusion of a Photocatalyst

    NASA Astrophysics Data System (ADS)

    Kiefer, Laura M.; King, John T.; Kubarych, Kevin J.

    2014-06-01

    Re(bpy)(CO)_3Cl is a well studied CO_2 reduction catalyst, known for its ability as both a photosensitizer and a catalyst with a high quantum yield and product selectivity. The catalysis reaction is initiated by a 400 nm excitation, followed by an intersystem crossing (ISC) and re-equilibration in the lowest triplet state. We utilize the quasi-equilibrium nature of this long-lived triplet metal-to-ligand charge-transfer (3MLCT) state to completely characterize the solvent dynamics using the technique of transient two-dimensional infrared (t-2DIR) spectroscopy to extract observables such as the frequency-frequency correlation function (FFCF), an equilibrium function. The electronic ground state solvent dynamics are characterized using equilibrium two-dimensional infrared spectroscopy (2D IR). Our technique allows us to independently observe the solvent dynamics of different electronic states and compare them. In this study, three carbonyl stretching modes were utilized to probe both the intramolecular and solvent environments in each electronic state. In the electronic ground state, the totally symmetric mode exhibits pure homogeneous broadening and a lack of spectral dynamics, while the two other modes have similar FFCF decay times of ˜ 1.5 ps. In the 3MLCT, however, all three modes experience similar spectral dynamics and have a FFCF decay time of ˜ 4.5 ps, three times slower than in the electronic ground state. Our technique allows us to directly observe the differences in spectral dynamics of the ground and excited electronic states and allows us to attribute the differences to specific origins such as solvent-solute coupling and molecular flexibility.

  20. Two-electron states and state exchange time control in parabolic quantum dot

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, D. A.; Kazaryan, E. M.; Sarkisyan, H. A.

    2014-04-01

    Using the Heisenberg uncertainty relationship and the stationary perturbation theory we consider two-electron states in a spherically symmetric parabolic quantum dot (parabolic helium atom). The dependence of ground-state energy on the QD size is studied. The energy of two-electron system monotonically decreases with QD radius increase. The problem of the state exchange time control in QD is discussed, taking into account the spins of the electrons in the Russell-Saunders approximation. With the increase of the QD radius the state exchange time increases.

  1. Relativistic electronic structure of UO2 + + , UO2 + , and UO2

    NASA Astrophysics Data System (ADS)

    Wood, J. H.; Boring, Michael; Woodruff, Susan Beatty

    1981-05-01

    We have calculated the one-electron energy level structures of the isolated species UO2++, UO2+, and UO2 in their linear forms, using a self-consistent relativistic multiple scattering model with Xα exchange. For UO2++, we have used the molecular orbitals of the ground state muffin-tin potential to calculate the energies of a few of the many-electron excited states; these afford a somewhat more fundamental basis for comparison with experiment than do the one-electron energies, and their determination also sheds some light on the coupling scheme (ω-ω vs Λ-Σ) to be expected in these systems. These excited state energies agree well with the experimental absorption data. The calculated one-electron excitation energies for UO2++ are in reasonable agreement with the observed onset of absorption. The behavior of the corresponding one-electron binding energies as a function of U-O distance supports a different interpretation of the XPS than that given by Veal et al. Considering the three species at a common bond distance of 2.0 Å, we find that each contains roughly three 5f electrons; UO2++ has three bonding 5f 's, UO2+ has two bonding 5f 's and one nonbonding (localized) 5f, and UO2 has one bonding 5f and two nonbonding 5f 's. This agrees with XPS which exhibits two localized f electrons in UO2 and none in UO2++.

  2. Electron momentum spectroscopy of aniline taking account of nuclear dynamics in the initial electronic ground state

    NASA Astrophysics Data System (ADS)

    Farasat, M.; Shojaei, S. H. R.; Morini, F.; Golzan, M. M.; Deleuze, M. S.

    2016-04-01

    The electronic structure, electron binding energy spectrum and (e, 2e) momentum distributions of aniline have been theoretically predicted at an electron impact energy of 1.500 keV on the basis of Born-Oppenheimer molecular dynamical simulations, in order to account for thermally induced nuclear motions in the initial electronic ground state. Most computed momentum profiles are rather insensitive to thermally induced alterations of the molecular structure, with the exception of the profiles corresponding to two ionization bands at electron binding energies comprised between ˜10.0 and ˜12.0 eV (band C) and between ˜16.5 and ˜20.0 eV (band G). These profiles are found to be strongly influenced by nuclear dynamics in the electronic ground state, especially in the low momentum region. The obtained results show that thermal averaging smears out most generally the spectral fingerprints that are induced by nitrogen inversion.

  3. Structure of the parainfluenza virus 5 F protein in its metastable, prefusion conformation

    SciTech Connect

    Yin, Hsien-Sheng; Wen, Xiaolin; Paterson, Reay G.; Lamb, Robert A.; Jardetzky, Theodore S.

    2010-03-08

    Enveloped viruses have evolved complex glycoprotein machinery that drives the fusion of viral and cellular membranes, permitting entry of the viral genome into the cell. For the paramyxoviruses, the fusion (F) protein catalyses this membrane merger and entry step, and it has been postulated that the F protein undergoes complex refolding during this process. Here we report the crystal structure of the parainfluenza virus 5 F protein in its prefusion conformation, stabilized by the addition of a carboxy-terminal trimerization domain. The structure of the F protein shows that there are profound conformational differences between the pre- and postfusion states, involving transformations in secondary and tertiary structure. The positions and structural transitions of key parts of the fusion machinery, including the hydrophobic fusion peptide and two helical heptad repeat regions, clarify the mechanism of membrane fusion mediated by the F protein.

  4. Alternative ground states enable pathway switching in biological electron transfer

    PubMed Central

    Abriata, Luciano A.; Álvarez-Paggi, Damián; Ledesma, Gabriela N.; Blackburn, Ninian J.; Vila, Alejandro J.; Murgida, Daniel H.

    2012-01-01

    Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or “invisible” electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein–protein interactions and membrane potential may optimize and regulate electron–proton energy transduction. PMID:23054836

  5. Integrating proton coupled electron transfer (PCET) and excited states

    SciTech Connect

    Gagliardi, Christopher J.; Westlake, Brittany C.; Kent, Caleb A.; Paul, Jared J.; Papanikolas, John M.; Meyer, Thomas J.

    2010-11-01

    In many of the chemical steps in photosynthesis and artificial photosynthesis, proton coupled electron transfer (PCET) plays an essential role. An important issue is how excited state reactivity can be integrated with PCET to carry out solar fuel reactions such as water splitting into hydrogen and oxygen or water reduction of CO2 to methanol or hydrocarbons. The principles behind PCET and concerted electron–proton transfer (EPT) pathways are reasonably well understood. In Photosystem II antenna light absorption is followed by sensitization of chlorophyll P680 and electron transfer quenching to give P680+. The oxidized chlorophyll activates the oxygen evolving complex (OEC), a CaMn4 cluster, through an intervening tyrosine–histidine pair, YZ. EPT plays a major role in a series of four activation steps that ultimately result in loss of 4e-/4H+ from the OEC with oxygen evolution. The key elements in photosynthesis and artificial photosynthesis – light absorption, excited state energy and electron transfer, electron transfer activation of multiple-electron, multiple-proton catalysis – can also be assembled in dye sensitized photoelectrochemical synthesis cells (DS-PEC). In this approach, molecular or nanoscale assemblies are incorporated at separate electrodes for coupled, light driven oxidation and reduction. Separate excited state electron transfer followed by proton transfer can be combined in single semi-concerted steps (photo-EPT) by photolysis of organic charge transfer excited states with H-bonded bases or in metal-to-ligand charge transfer (MLCT) excited states in pre-associated assemblies with H-bonded electron transfer donors or acceptors. In these assemblies, photochemically induced electron and proton transfer occur in a single, semi-concerted event to give high-energy, redox active intermediates.

  6. Computing electronic structures: A new multiconfiguration approach for excited states

    SciTech Connect

    Cances, Eric . E-mail: cances@cermics.enpc.fr; Galicher, Herve . E-mail: galicher@cermics.enpc.fr; Lewin, Mathieu . E-mail: lewin@cermic.enpc.fr

    2006-02-10

    We present a new method for the computation of electronic excited states of molecular systems. This method is based upon a recent theoretical definition of multiconfiguration excited states [due to one of us, see M. Lewin, Solutions of the multiconfiguration equations in quantum chemistry, Arch. Rat. Mech. Anal. 171 (2004) 83-114]. Our algorithm, dedicated to the computation of the first excited state, always converges to a stationary state of the multiconfiguration model, which can be interpreted as an approximate excited state of the molecule. The definition of this approximate excited state is variational. An interesting feature is that it satisfies a non-linear Hylleraas-Undheim-MacDonald type principle: the energy of the approximate excited state is an upper bound to the true excited state energy of the N-body Hamiltonian. To compute the first excited state, one has to deform paths on a manifold, like this is usually done in the search for transition states between reactants and products on potential energy surfaces. We propose here a general method for the deformation of paths which could also be useful in other settings. We also compare our method to other approaches used in Quantum Chemistry and give some explanation of the unsatisfactory behaviours which are sometimes observed when using the latter. Numerical results for the special case of two-electron systems are provided: we compute the first singlet excited state potential energy surface of the H {sub 2} molecule.

  7. Electron delocalization and electron density of small polycyclic aromatic hydrocarbons in singlet excited states.

    PubMed

    Estévez-Fregoso, Mar; Hernández-Trujillo, Jesús

    2016-04-28

    The four lowest singlet electronic states of benzene, the acenes from naphthalene to pentacene, phenanthrene and pyrene were studied by means of theoretical methods. Their vertical excitation energies from the ground electronic states were computed at the CASPT2 approximation. As an attempt to explain the trends observed in the excitation energies, several descriptors based on the electron density were used and the similarity of these molecules with their ground state counterparts was analyzed. It was found that the changes of the topological properties at the C-C bond critical points do not explain the decreasing trends for the excitation energies with the increase of the number of rings, in part because the small changes that take place in the electron density occur above and below the molecular plane. A similarity index based on electron delocalization between quantum topological atoms was defined to compare a molecule in two different electronic states. It was found that, mainly for the acenes, this index goes in line with the excitation energies to the first excited state. Implications of the changes in electron delocalization on the aromatic character of these molecules are also discussed. In general, local aromaticity decreases upon excitation. PMID:26795361

  8. Trapping Image State Electrons on Graphene Layers and Islands

    NASA Astrophysics Data System (ADS)

    Dadap, Jerry; Niesner, Daniel; Fauster, Thomas; Zaki, Nader; Knox, Kevin; Yeh, Po-Chi; Bhandari, Rohan; Osgood, Richard M.; Petrovic, Marin; Kralj, Marko

    2012-02-01

    The understanding of graphene-metal interfaces is of utmost importance in graphene transport phenomena. To probe this interface we use time- and angle-resolved two-photon photoemission to map the bound, unoccupied electronic structure of the weakly coupled graphene/Ir(111) system. The energy, dispersion, and lifetime of the lowest three image-potential states are measured. In addition, the weak interaction between Ir and the smooth, epitaxial graphene permits observation of resonant transitions from an unquenched Shockley-type surface state of the Ir substrate to graphene/Ir image-potential states. The image-potential-state lifetimes are comparable to those of mid-gap clean metal surfaces. Evidence of localization of the excited image-state electrons on single-atom-layer graphene islands is provided by coverage-dependent measurements.

  9. Photoionization of furan from the ground and excited electronic states

    NASA Astrophysics Data System (ADS)

    Ponzi, Aurora; Sapunar, Marin; Angeli, Celestino; Cimiraglia, Renzo; Došlić, Nada; Decleva, Piero

    2016-02-01

    Here we present a comparative computational study of the photoionization of furan from the ground and the two lowest-lying excited electronic states. The study aims to assess the quality of the computational methods currently employed for treating bound and continuum states in photoionization. For the ionization from the ground electronic state, we show that the Dyson orbital approach combined with an accurate solution of the continuum one particle wave functions in a multicenter B-spline basis, at the density functional theory (DFT) level, provides cross sections and asymmetry parameters in excellent agreement with experimental data. On the contrary, when the Dyson orbitals approach is combined with the Coulomb and orthogonalized Coulomb treatments of the continuum, the results are qualitatively different. In excited electronic states, three electronic structure methods, TDDFT, ADC(2), and CASSCF, have been used for the computation of the Dyson orbitals, while the continuum was treated at the B-spline/DFT level. We show that photoionization observables are sensitive probes of the nature of the excited states as well as of the quality of excited state wave functions. This paves the way for applications in more complex situations such as time resolved photoionization spectroscopy.

  10. On the correct electronic ground state of Tc( g )

    SciTech Connect

    Rard, J.A. ); Rand, M.H. ); Thornback, J.R. ); Wanner, H. )

    1991-05-01

    The electronic ground state of Tc({ital g}) is {sup 6}{ital S}{sub 5/2}, which arises from a 4{ital d}{sup 5}5{ital s}{sup 2} valence electron configuration. However, there are several treatises and review articles in which the ground state is incorrectly given as {ital S}{sub 9/2} with a valence electron configuration of 4{ital d}{sup 6}5{ital s}{sup 1}. The origin of this incorrect assignment was traced to the misinterpretation of a paper on the hyperfine splitting of the optical spectrum of technetium, and to confusion between nuclear and electronic spins.

  11. Confined electronic states and their modulations in graphene nanorings

    NASA Astrophysics Data System (ADS)

    Zhu, Jia-Lin; Wang, Xingyuan; Yang, Ning

    2012-09-01

    Confined electronic states in quantum rings formed by spatially modulated finite Dirac gap (FDGQR) in graphene are systematically studied by series-expansion method, and are compared with those in infinite-mass-boundary and one-dimensional quantum rings. The shape-size effect of FDGQR is illustrated to be distinct from that in graphene quantum dots. The Aharonov-Bohm effect in FDGQR is clearly shown by the energy spectrum and the optical-transition probabilities. The FDGQR coupled with the electrostatic-potential induced nanoring is found useful for modulating the Dirac electronic states and the optical-transition probabilities. These results may help us to understand and to control the quantum behaviors of confined electronic states in graphene.

  12. Fragmentation pathwaysfor selected electronic states of theacetylene dication

    SciTech Connect

    Osipov, Timur; Rescigno, Thomas N.; Weber, Thorsten; Miyabe,Shungo; Jahnke, T.; Alnaser, A.; Hertlein, Markus P.; Jagutzki, O.; Schmidt, L.Ph.H.; Schoffler, M.; Foucar, L.; Schossler, S.; Havermeier,T.; Odenweller,M.; Voss, S.; Feinberg, Ben; Landers, Alan; Prior, MichaelH.; Dorner, Reinhart; Cocke, C.L.; Belkacem, Ali

    2007-12-18

    Coincident measurement of the Auger electron and fragmention momenta emitted after carbon core-level photoionization of acetylenehas yielded new understanding of how the dication fragments. Ab initiocalculations and experimental data, including body-frame Auger angulardistributions, are used to identify the parent electronic states andtogether yield a comprehensive map of the dissociation pathways whichinclude surface crossings and barriers to direct dissociation. The Augerangular distributions show evidence of core-holelocalization.

  13. TOPICAL REVIEW Electronic states of graphene nanoribbons and analytical solutions

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Katsunori; Sasaki, Ken-ichi; Nakanishi, Takeshi; Enoki, Toshiaki

    2010-10-01

    Graphene is a one-atom-thick layer of graphite, where low-energy electronic states are described by the massless Dirac fermion. The orientation of the graphene edge determines the energy spectrum of π-electrons. For example, zigzag edges possess localized edge states with energies close to the Fermi level. In this review, we investigate nanoscale effects on the physical properties of graphene nanoribbons and clarify the role of edge boundaries. We also provide analytical solutions for electronic dispersion and the corresponding wavefunction in graphene nanoribbons with their detailed derivation using wave mechanics based on the tight-binding model. The energy band structures of armchair nanoribbons can be obtained by making the transverse wavenumber discrete, in accordance with the edge boundary condition, as in the case of carbon nanotubes. However, zigzag nanoribbons are not analogous to carbon nanotubes, because in zigzag nanoribbons the transverse wavenumber depends not only on the ribbon width but also on the longitudinal wavenumber. The quantization rule of electronic conductance as well as the magnetic instability of edge states due to the electron-electron interaction are briefly discussed.

  14. Two-electron photoionization of ground-state lithium

    SciTech Connect

    Kheifets, A. S.; Fursa, D. V.; Bray, I.

    2009-12-15

    We apply the convergent close-coupling (CCC) formalism to single-photon two-electron ionization of the lithium atom in its ground state. We treat this reaction as single-electron photon absorption followed by inelastic scattering of the photoelectron on a heliumlike Li{sup +} ion. The latter scattering process can be described accurately within the CCC formalism. We obtain integrated cross sections of single photoionization leading to the ground and various excited states of the Li{sup +} ion as well as double photoionization extending continuously from the threshold to the asymptotic limit of infinite photon energy. Comparison with available experimental and theoretical data validates the CCC model.

  15. Integral cross sections for electron impact excitation of vibrational and electronic states in phenol.

    PubMed

    Neves, R F C; Jones, D B; Lopes, M C A; Blanco, F; García, G; Ratnavelu, K; Brunger, M J

    2015-05-21

    We report on measurements of integral cross sections (ICSs) for electron impact excitation of a series of composite vibrational modes and electronic-states in phenol, where the energy range of those experiments was 15-250 eV. There are currently no other results against which we can directly compare those measured data. We also report results from our independent atom model with screened additivity rule correction computations, namely, for the inelastic ICS (all discrete electronic states and neutral dissociation) and the total ionisation ICS. In addition, for the relevant dipole-allowed excited electronic states, we also report f-scaled Born-level and energy-corrected and f-scaled Born-level (BEf-scaled) ICS. Where possible, our measured and calculated ICSs are compared against one another with the general level of accord between them being satisfactory to within the measurement uncertainties. PMID:26001459

  16. Integral cross sections for electron impact excitation of vibrational and electronic states in phenol

    SciTech Connect

    Neves, R. F. C.; Jones, D. B.; Lopes, M. C. A.; Blanco, F.; García, G.; Ratnavelu, K.; Brunger, M. J.

    2015-05-21

    We report on measurements of integral cross sections (ICSs) for electron impact excitation of a series of composite vibrational modes and electronic-states in phenol, where the energy range of those experiments was 15–250 eV. There are currently no other results against which we can directly compare those measured data. We also report results from our independent atom model with screened additivity rule correction computations, namely, for the inelastic ICS (all discrete electronic states and neutral dissociation) and the total ionisation ICS. In addition, for the relevant dipole-allowed excited electronic states, we also report f-scaled Born-level and energy-corrected and f-scaled Born-level (BEf-scaled) ICS. Where possible, our measured and calculated ICSs are compared against one another with the general level of accord between them being satisfactory to within the measurement uncertainties.

  17. Electron-impact excitation of the low-lying electronic states of formaldehyde

    NASA Technical Reports Server (NTRS)

    Chutjian, A.

    1974-01-01

    Electron-impact excitation has been observed at incident electron energies of 10.1 and 20.1 eV to the first five excited electronic states of formaldehyde lying at and below the 1B2 state at 7.10 eV. These excitations include two new transitions in the energy-loss range 5.6-6.2 eV and 6.7-7.0 eV which have been detected for the first time, either through electron-impact excitation or photon absorption. The differential cross sections of these new excitations are given at scattering angles between 15 and 135 deg. These cross-section ratios peak at large scattering angles - a characteristic of triplet - singlet excitations. The design and performance of the electron-impact spectrometer used in the above observations is outlined and discussed.

  18. Nature of ground and electronic excited states of higher acenes.

    PubMed

    Yang, Yang; Davidson, Ernest R; Yang, Weitao

    2016-08-30

    Higher acenes have drawn much attention as promising organic semiconductors with versatile electronic properties. However, the nature of their ground state and electronic excited states is still not fully clear. Their unusual chemical reactivity and instability are the main obstacles for experimental studies, and the potentially prominent diradical character, which might require a multireference description in such large systems, hinders theoretical investigations. Here, we provide a detailed answer with the particle-particle random-phase approximation calculation. The (1)Ag ground states of acenes up to decacene are on the closed-shell side of the diradical continuum, whereas the ground state of undecacene and dodecacene tilts more to the open-shell side with a growing polyradical character. The ground state of all acenes has covalent nature with respect to both short and long axes. The lowest triplet state (3)B2u is always above the singlet ground state even though the energy gap could be vanishingly small in the polyacene limit. The bright singlet excited state (1)B2u is a zwitterionic state to the short axis. The excited (1)Ag state gradually switches from a double-excitation state to another zwitterionic state to the short axis, but always keeps its covalent nature to the long axis. An energy crossing between the (1)B2u and excited (1)Ag states happens between hexacene and heptacene. Further energetic consideration suggests that higher acenes are likely to undergo singlet fission with a low photovoltaic efficiency; however, the efficiency might be improved if a singlet fission into multiple triplets could be achieved. PMID:27528690

  19. Experimental Studies of Interacting Electronic States in NaCs

    NASA Astrophysics Data System (ADS)

    Faust, Carl E.

    This dissertation describes methods and results of spectroscopic studies of the NaCs molecule. NaCs is of particular interest in many labs where experimental studies of ultra-cold molecules are being conducted. Data obtained in the present work will also be useful as benchmarks for various theoretical calculations. Our goals in studying this molecule were to map out high lying electronic states and to understand how these states interact with one another. Sodium and cesium metal were heated in a heat-pipe oven to form a vapor of NaCs molecules. These molecules were excited using narrow band, continuous wave (cw), tunable lasers. We employed the optical-optical double resonance (OODR) technique to obtain Doppler-free spectra of transitions to rotational and vibrational levels of high lying electronic states. One state of particular interest was the 12(0+) electronic state. Rovibrational level energies corresponding to this state were measured and used to generate a potential energy curve using computer programs to implement both the Rydberg-Klein-Rees (RKR) method and the inverted perturbation approach (IPA). By observing fluorescence from the 12(0+) state resolved as a function of wavelength, we determined that this state interacts with the nearby 11(0+) electronic state, which was previously mapped out by Ashman et al. A two-stage coupling model was devised to describe the resolved fluorescence originating from these two interacting states. The electronic states interact via spin-orbit coupling, while the individual rovibrational levels interact via a second mechanism, likely nonadiabatic coupling. This two-stage coupling between the levels of these states causes quantum interference between fluorescence pathways associated with different components of the wavefunctions describing these levels. This interference results in more complicated resolved fluorescence spectra. The model was used to fit parameters describing these interactions so that the resolved

  20. 26 CFR 5f.103-3 - Information reporting requirements for certain bonds.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 14 2010-04-01 2010-04-01 false Information reporting requirements for certain bonds. 5f.103-3 Section 5f.103-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) TEMPORARY INCOME TAX REGULATIONS UNDER THE TAX EQUITY AND FISCAL RESPONSIBILITY ACT OF 1982 §...

  1. 26 CFR 5f.103-3 - Information reporting requirements for certain bonds.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 14 2011-04-01 2010-04-01 true Information reporting requirements for certain bonds. 5f.103-3 Section 5f.103-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) TEMPORARY INCOME TAX REGULATIONS UNDER THE TAX EQUITY AND FISCAL RESPONSIBILITY ACT OF 1982 §...

  2. Inhibitory effect of 5F on development of lung cancer in A/J mice

    PubMed Central

    Ye, Hua; Yang, Xiaoqing; Wu, Kefeng; Li, Li; Lv, Yingnian; Liu, Yi; Zheng, Xuebao

    2015-01-01

    The purpose of the study is to investigate the effect of ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F) on the model of induced A/J mice lung cancer in A/J mice. The expressions of tumor-related molecules including P65 and Bcl-2 at protein level were examined using the immunohistochemical method (IHC). Side effects of 5F were also monitored. The results indicated that 5F significantly suppressed the development of B[a]P and NNK-induced lung cancer in vivo by facilitating cell apoptosis with minimal side effects. Compared to the expressions of P65 and Bcl-2 in model group, the levels were strongly attenuated both in blank and 5F injection groups. Moreover, P65 and Bcl-2 levels varied among different groups receiving 5F treatment. The expressions of P65 and Bcl-2 were much lower in groups receiving high-concentration 5F treatment than those with low-concentration 5F injection. Findings revealed that 5F inhibited the pathogenesis of lung cancer through accelerating apoptosis in a dose-dependent manner. PMID:26097604

  3. Pharmacology of Indole and Indazole Synthetic Cannabinoid Designer Drugs AB-FUBINACA, ADB-FUBINACA, AB-PINACA, ADB-PINACA, 5F-AB-PINACA, 5F-ADB-PINACA, ADBICA, and 5F-ADBICA.

    PubMed

    Banister, Samuel D; Moir, Michael; Stuart, Jordyn; Kevin, Richard C; Wood, Katie E; Longworth, Mitchell; Wilkinson, Shane M; Beinat, Corinne; Buchanan, Alexandra S; Glass, Michelle; Connor, Mark; McGregor, Iain S; Kassiou, Michael

    2015-09-16

    Synthetic cannabinoid (SC) designer drugs based on indole and indazole scaffolds and featuring l-valinamide or l-tert-leucinamide side chains are encountered with increasing frequency by forensic researchers and law enforcement agencies and are associated with serious adverse health effects. However, many of these novel SCs are unprecedented in the scientific literature at the time of their discovery, and little is known of their pharmacology. Here, we report the synthesis and pharmacological characterization of AB-FUBINACA, ADB-FUBINACA, AB-PINACA, ADB-PINACA, 5F-AB-PINACA, 5F-ADB-PINACA, ADBICA, 5F-ADBICA, and several analogues. All synthesized SCs acted as high potency agonists of CB1 (EC50 = 0.24-21 nM) and CB2 (EC50 = 0.88-15 nM) receptors in a fluorometric assay of membrane potential, with 5F-ADB-PINACA showing the greatest potency at CB1 receptors. The cannabimimetic activities of AB-FUBINACA and AB-PINACA in vivo were evaluated in rats using biotelemetry. AB-FUBINACA and AB-PINACA dose-dependently induced hypothermia and bradycardia at doses of 0.3-3 mg/kg, and hypothermia was reversed by pretreatment with a CB1 (but not CB2) antagonist, indicating that these SCs are cannabimimetic in vivo, consistent with anecdotal reports of psychoactivity in humans. PMID:26134475

  4. A many-body states picture of electronic friction: The case of multiple orbitals and multiple electronic states.

    PubMed

    Dou, Wenjie; Subotnik, Joseph E

    2016-08-01

    We present a very general form of electronic friction as present when a molecule with multiple orbitals hybridizes with a metal electrode. To develop this picture of friction, we embed the quantum-classical Liouville equation (QCLE) within a classical master equation (CME). Thus, this article extends our previous work analyzing the case of one electronic level, as we may now treat the case of multiple levels and many electronic molecular states. We show that, in the adiabatic limit, where electron transitions are much faster than nuclear motion, the QCLE-CME reduces to a Fokker-Planck equation, such that nuclei feel an average force as well as friction and a random force-as caused by their interaction with the metallic electrons. Finally, we show numerically and analytically that our frictional results agree with other published results calculated using non-equilibrium Green's functions. Numerical recipes for solving this QCLE-CME will be provided in a subsequent paper. PMID:27497534

  5. A many-body states picture of electronic friction: The case of multiple orbitals and multiple electronic states

    NASA Astrophysics Data System (ADS)

    Dou, Wenjie; Subotnik, Joseph E.

    2016-08-01

    We present a very general form of electronic friction as present when a molecule with multiple orbitals hybridizes with a metal electrode. To develop this picture of friction, we embed the quantum-classical Liouville equation (QCLE) within a classical master equation (CME). Thus, this article extends our previous work analyzing the case of one electronic level, as we may now treat the case of multiple levels and many electronic molecular states. We show that, in the adiabatic limit, where electron transitions are much faster than nuclear motion, the QCLE-CME reduces to a Fokker-Planck equation, such that nuclei feel an average force as well as friction and a random force—as caused by their interaction with the metallic electrons. Finally, we show numerically and analytically that our frictional results agree with other published results calculated using non-equilibrium Green's functions. Numerical recipes for solving this QCLE-CME will be provided in a subsequent paper.

  6. Controlling autoionization in strontium two-electron-excited states

    NASA Astrophysics Data System (ADS)

    Fields, Robert; Zhang, Xinyue; Dunning, F. Barry; Yoshida, Shuhei; Burgdörfer, Joachim

    2016-05-01

    One challenge in engineering long-lived two-electron-excited states, i.e., so-called planetary atoms, is autoionization. Autoionization, however, can be suppressed if the outermost electron is placed in a high- n, n ~ 300 - 600 , high- L state because such states have only a very small overlap with the inner electron, even when this is also excited to a state of relatively high n and hence of relatively long lifetime. Here the L-dependence of the autoionization rate for high- n strontium Rydberg atoms is examined during excitation of the core ion 5 s 2S1 / 2 - 5 p 2P3 / 2 transition. Measurements in which the angular momentum of the Rydberg electron is controlled using a pulsed electric field show that the autoionization rate decreases rapidly with increasing L and becomes very small for values larger than ~ 20 . The data are analyzed with the aid of calculations undertaken using complex scaling. Research supported by the NSF and Robert A. Welch Foundation.

  7. Imaging the dynamics of free-electron Landau states

    PubMed Central

    Schattschneider, P.; Schachinger, Th.; Stöger-Pollach, M.; Löffler, S.; Steiger-Thirsfeld, A.; Bliokh, K. Y.; Nori, Franco

    2014-01-01

    Landau levels and states of electrons in a magnetic field are fundamental quantum entities underlying the quantum Hall and related effects in condensed matter physics. However, the real-space properties and observation of Landau wave functions remain elusive. Here we report the real-space observation of Landau states and the internal rotational dynamics of free electrons. States with different quantum numbers are produced using nanometre-sized electron vortex beams, with a radius chosen to match the waist of the Landau states, in a quasi-uniform magnetic field. Scanning the beams along the propagation direction, we reconstruct the rotational dynamics of the Landau wave functions with angular frequency ~100 GHz. We observe that Landau modes with different azimuthal quantum numbers belong to three classes, which are characterized by rotations with zero, Larmor and cyclotron frequencies, respectively. This is in sharp contrast to the uniform cyclotron rotation of classical electrons, and in perfect agreement with recent theoretical predictions. PMID:25105563

  8. OhioLINK Electronic Journal Use at Ohio State University

    ERIC Educational Resources Information Center

    Connell, Tschera Harkness; Rogers, Sally A.; Diedrichs, Carol Pitts

    2005-01-01

    A five-question survey randomly presented to users at Ohio State University (OSU) as they viewed articles in OhioLINK's Electronic Journal Center (EJC) in fall 2002 probed the user's status, academic unit, reason for viewing, path to the article, and frequency of EJC use. Usage by faculty and graduate students, by frequent users, and by those in…

  9. Tuning ground states and excitations in complex electronic materials

    SciTech Connect

    Bishop, A.R.

    1996-09-01

    Modern electronic materials are characterized by a great variety of broken-symmetry ground states and excitations. Their control requires understanding and tuning underlying driving forces of spin-charge-lattice coupling, critical to macroscopic properties and applications. We report representative model calculations which demonstrate some of the richness of the phenomena and the challenges for successful microscopic modeling.

  10. DETERMINING THE ORIGINS OF ELECTRONIC STATES IN SEMICONDUCTOR NANOSTRUCTURES

    SciTech Connect

    Goldman, Rachel

    2014-12-16

    With support from this program, we have generated key results in quantum dot (QD) formation, strain/electronic coupling, measurement and modeling of confined states, and examination of the influence of QDs on thermoelectric and photovoltaic properties of nanocomposite structures. This final report contains a description of our key findings followed by a list of personnel supported and publications generated.

  11. Student Satisfaction with Electronic Library Resources at Wayne State University

    ERIC Educational Resources Information Center

    Holley, Robert P.; Powell, Ronald R.

    2004-01-01

    This paper reports the results of a survey of student satisfaction with electronic library resources other than the online catalog at Wayne State University. Undertaken in Fall Term 2000 as a class project for a marketing course, a student team designed, administered, and analyzed a survey of a random sample of students. Almost 40% of the…

  12. Imaging the dynamics of free-electron Landau states.

    PubMed

    Schattschneider, P; Schachinger, Th; Stöger-Pollach, M; Löffler, S; Steiger-Thirsfeld, A; Bliokh, K Y; Nori, Franco

    2014-01-01

    Landau levels and states of electrons in a magnetic field are fundamental quantum entities underlying the quantum Hall and related effects in condensed matter physics. However, the real-space properties and observation of Landau wave functions remain elusive. Here we report the real-space observation of Landau states and the internal rotational dynamics of free electrons. States with different quantum numbers are produced using nanometre-sized electron vortex beams, with a radius chosen to match the waist of the Landau states, in a quasi-uniform magnetic field. Scanning the beams along the propagation direction, we reconstruct the rotational dynamics of the Landau wave functions with angular frequency ~100 GHz. We observe that Landau modes with different azimuthal quantum numbers belong to three classes, which are characterized by rotations with zero, Larmor and cyclotron frequencies, respectively. This is in sharp contrast to the uniform cyclotron rotation of classical electrons, and in perfect agreement with recent theoretical predictions. PMID:25105563

  13. Electron-state tuning of multilayer graphene by defects

    NASA Astrophysics Data System (ADS)

    Kishimoto, Ken; Okada, Susumu

    2016-06-01

    Electronic band structures of graphene thin films, in which the topmost layer possesses atomic and topological defects, are studied using the density functional theory. Our calculations showed that all graphene thin films studied here have a finite energy gap in their π electron states, although the thin films possess defect-free hexagonal networks, because of the spatially undulated local potential on pristine graphene layers induced by the defects. The energy gap in π states slightly decreases with increasing number of layers, while the gap sensitively depends on the interlayer stacking arrangement. Our analyses clarify that the interlayer interaction plays a crucial role for mediating the effect of the defects on the π electrons of pristine layers.

  14. Charge and electronic states of cuprite: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Kim, Miyoung

    The bonding characteristics of cuprite have been studied by the using convergent beam electron diffraction (CBED) method. The low-order structure factors are closely related to the valence electron density, and the CBED is one of the most accurate methods of measuring the low order structure factors. The multipole model is used for converting the structure factors into charge density. The multipole expansion takes into account non-spherical valence electron density due to atomic bonding based on the crystal symmetry. The charge transfer from copper to oxygen is determined from the multipole fitting parameters. The hybridization state between 4s-3d orbitals of copper is also estimated. Electronic states of CU2O are investigated by studying the fine structure of the electron-energy loss spectrum (EELS). The cross section of the near edge structure is proportional to the density of state times an atomic transition site-projected matrix element which generally varies slowly in the region of interest. Both the fine structure of Cu- L2'3 and O-K of Cu2O are significantly different from those of CuO, which shows the sensitivity of EELS fine structure to the crystal bonding. Full-potential Linearized Augmented Plane Wave (FLAPW) calculations have been used to compare experimental results with theory. The structure factors and bonding charge density are compared with the results obtained by the CBED method, and the density of states is compared with the EELS. The FLAPW method has also been used in the local density approximations CLDA) to calculate values of the mean inner Coulomb potential V 0 for Si, Ge and MgO. These values are compared with recent measurements by electron holography. The supercell calculations are performed for crystal slabs, so that the effects of different crystal orientations and surface structures on V0 can be evaluated.

  15. Foucault's Pendulum, Analog for an Electron Spin State

    NASA Astrophysics Data System (ADS)

    Linck, Rebecca

    2012-11-01

    The classical Lagrangian that describes the coupled oscillations of Foucault's pendulum presents an interesting analog to an electron's spin state in an external magnetic field. With a simple modification, this classical Lagrangian yields equations of motion that directly map onto the Schrodinger-Pauli Equation. This analog goes well beyond the geometric phase, reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  16. Two Electron States in a Quantum Ring on a Sphere

    NASA Astrophysics Data System (ADS)

    Kazaryan, Eduard M.; Shahnazaryan, Vanik A.; Sarkisyan, Hayk A.

    2014-02-01

    Two electron states in a quantum ring on a spherical surface are discussed. The problem is discussed within the frameworks of Russell-Saunders coupling scheme, that is, the spin-orbit coupling is neglected. Treating Coulomb interaction as a perturbation, the energy correction for different states is calculated. The dependence of the Coulomb interaction energy on external polar boundary angle of quantum ring is obtained. In analogue with the helium atom the concept of states exchange time is introduced, and its dependence on geometrical parameters of the ring is shown.

  17. The Electronic Properties of Superatom States of Hollow Molecules

    SciTech Connect

    Feng, Min; Zhao, Jin; Huang, Tian; Zhu, Xiaoyang; Petek, Hrvoje

    2011-05-17

    Electronic and optical properties of molecules and molecular solids are traditionally considered from the perspective of the frontier orbitals and their intermolecular interactions. How molecules condense into crystalline solids, however, is mainly attributed to the long-range polarization interaction. In this Account, we show that long-range polarization also introduces a distinctive set of diffuse molecular electronic states, which in quantum structures or solids can combine into nearly-free-electron (NFE) bands. These NFE properties, which are usually associated with good metals, are vividly evident in sp2 hybridized carbon materials, specifically graphene and its derivatives. The polarization interaction is primarily manifested in the screening of an external charge at a solid/vacuum interface. It is responsible for the universal image potential and the associated unoccupied image potential (IP) states, which are observed even at the He liquid/vacuum interface. The molecular electronic properties that we describe are derived from the IP states of graphene, which float above and below the molecular plane and undergo free motion parallel to it. Rolling or wrapping a graphene sheet into a nanotube or a fullerene transforms the IP states into diffuse atom-like orbitals that are bound primarily to hollow molecular cores, rather than the component atoms. Therefore, we named them the superatom molecular orbitals (SAMOs). Like the excitonic states of semiconductor nanostructures or the plasmonic resonances of metallic nanoparticles, SAMOs of fullerene molecules, separated by their van der Waals distance, can combine to form diatomic molecule-like orbitals of C60 dimers. For larger aggregates, they form NFE bands of superatomic quantum structures and solids. The overlap of the diffuse SAMO wavefunctions in van der Waals solids provides a different paradigm for band formation than the valence or conduction bands formed by interaction of the more tightly bound

  18. Calculation of electron scattering from the ground state of ytterbium

    SciTech Connect

    Bostock, Christopher J.; Fursa, Dmitry V.; Bray, Igor

    2011-05-15

    We report on the application of the convergent close-coupling method, in both relativistic and nonrelativistic formulations, to electron scattering from ytterbium. Angle-differential and integrated cross sections are presented for elastic scattering and excitation of the states (6s6p){sup 3}P{sub 0,1,2}, (6s6p){sup 1}P{sub 1}{sup o}, (6s7p){sup 1}P{sub 1}{sup o}, and (6s5d){sup 1}D{sub 2}{sup e} for a range of incident electron energies. We also present calculations of the total cross section, and angle-differential Stokes parameters for excitation of the (6s6p){sup 3}P{sub 1}{sup o} state from the ground state. A comparison is made with the relativistic distorted-wave method and experiments.

  19. Foucault's pendulum, a classical analog for the electron spin state

    NASA Astrophysics Data System (ADS)

    Linck, Rebecca A.

    Spin has long been regarded as a fundamentally quantum phenomena that is incapable of being described classically. To bridge the gap and show that aspects of spin's quantum nature can be described classically, this work uses a classical Lagrangian based on the coupled oscillations of Foucault's pendulum as an analog for the electron spin state in an external magnetic field. With this analog it is possible to demonstrate that Foucault's pendulum not only serves as a basis for explaining geometric phase, but is also a basis for reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured electron spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  20. Spectroscopic Constants of the Known Electronic States of Lead Monofluoride

    SciTech Connect

    McRaven, C.P.; Sivakumar, P.; Shafer-Ray, N.E.; Hall, G.E.; Sears, T.J.

    2010-08-01

    Based on measurements made by mass-resolved 1 + 1{prime} + 1{double_prime} resonance-enhanced multiphoton ionization spectroscopy, we have determined new molecular constants describing the rotational and fine structure levels of the B, D, E, and F states of the most abundant isotopic variant {sup 208}Pb{sup 19}F, and we summarize the spectroscopic constants for all the know electronic states of the radical. Many spectroscopic constants for the isotopologues {sup 206}Pb{sup 19}F and {sup 207}Pb{sup 19}F have also been determined. The symmetry of the D-state is found to be {sup 2}{pi}{sub 1/2}, and the F-state is found to be an {Omega} = 3/2 state.

  1. Energy-level calculations for the 5f 26d 1 configuration of U 3+ in Cs 2NaYCl 6 single crystals

    NASA Astrophysics Data System (ADS)

    Karbowiak, M.

    2005-07-01

    Energy levels and the 5f 3 → 5f 26d(t 2g) 1 transition intensities of U 3+ in Cs 2NaYCl 6 were calculated using a theoretical model for nf N energy levels extended for interactions related with the presence of d-electron, proposed by Reid et al. [M.F. Reid, L. van Pieterson, R.T. Wegh, A. Meijerink, Phys. Rev. B 62 (2000) 14744]. The Fk(fd) and Gj(fd) parameters for f-d Coulomb interactions, the ζ(dd) spin-orbit interactions parameter for 6d electron as well as B04(ff)andB06(ff) crystal-field parameters for 5f 2 core electrons were adjusted, and a very good agreement between calculated and experimental spectrum has been achieved. The F2(fd), G1(fd) and ζ(dd) parameters were reduced to 37.5%, 45.3% and 77.2% of the ab initio calculated free-ion values, respectively. The values of Bqk(ff) parameters determined for 5f 26d 1 configuration are closer to those of 5f 2 configuration of U 4+ than 5f 3 configuration of U 3+. The results of calculations performed in the frame of the semi-empirical Hamiltonian model are in a very good accordance with those of ab initio theoretical analysis, reported by Seijo and Barandiarán [L. Seijo, Z. Barandiarán, J. Chem. Phys. 118 (2003) 5335].

  2. Surface States and Negative Electron Affinity in Polyethylene

    SciTech Connect

    Righi, M. C.; Scandolo, S.; Serra, S.; Iarlori, S.; Tosatti, E.; Santoro, G.

    2001-08-13

    First-principles calculations are used to investigate the electronic properties of the surfaces of polyethylene. The calculations support the experimental evidence of a negative electron affinity, with calculated values of -0.17 eV and -0.10 eV for surfaces with chains perpendicular and parallel to the surface normal, respectively. Both surfaces exhibit a surface state with binding energy -1.2{+-}0.5 eV with respect to the bulk polyethylene conduction band minimum. Implications of these findings on spectroscopy, as well as on the transport and aging properties of polyethylene for high-voltage applications, are discussed.

  3. Kinetic and electron-electron energies for convex sums of ground state densities with degeneracies and fractional electron number

    SciTech Connect

    Levy, Mel E-mail: mlevy@tulane.edu; Anderson, James S. M.; Zadeh, Farnaz Heidar; Ayers, Paul W. E-mail: mlevy@tulane.edu

    2014-05-14

    Properties of exact density functionals provide useful constraints for the development of new approximate functionals. This paper focuses on convex sums of ground-level densities. It is observed that the electronic kinetic energy of a convex sum of degenerate ground-level densities is equal to the convex sum of the kinetic energies of the individual degenerate densities. (The same type of relationship holds also for the electron-electron repulsion energy.) This extends a known property of the Levy-Valone Ensemble Constrained-Search and the Lieb Legendre-Transform refomulations of the Hohenberg-Kohn functional to the individual components of the functional. Moreover, we observe that the kinetic and electron-repulsion results also apply to densities with fractional electron number (even if there are no degeneracies), and we close with an analogous point-wise property involving the external potential. Examples where different degenerate states have different kinetic energy and electron-nuclear attraction energy are given; consequently, individual components of the ground state electronic energy can change abruptly when the molecular geometry changes. These discontinuities are predicted to be ubiquitous at conical intersections, complicating the development of universally applicable density-functional approximations.

  4. Dynamics and spectroscopy of CH₂OO excited electronic states.

    PubMed

    Kalinowski, Jaroslaw; Foreman, Elizabeth S; Kapnas, Kara M; Murray, Craig; Räsänen, Markku; Gerber, R Benny

    2016-04-28

    The excited states of the Criegee intermediate CH2OO are studied in molecular dynamics simulations using directly potentials from multi-reference perturbation theory (MR-PT2). The photoexcitation of the species is simulated, and trajectories are propagated in time on the excited state. Some of the photoexcitation events lead to direct fragmentation of the molecule, but other trajectories describe at least several vibrations in the excited state, that may terminate by relaxation to the ground electronic state. Limits on the role of non-adiabatic contributions to the process are estimated by two different simulations, one that forces surface-hopping at potential crossings, and another that ignores surface hopping altogether. The effect of non-adiabatic transitions is found to be small. Spectroscopic implications and consequences for the interpretation of experimental results are discussed. PMID:27040614

  5. Electron teleportation via Majorana bound states in a mesoscopic superconductor.

    PubMed

    Fu, Liang

    2010-02-01

    Zero-energy Majorana bound states in superconductors have been proposed to be potential building blocks of a topological quantum computer, because quantum information can be encoded nonlocally in the fermion occupation of a pair of spatially separated Majorana bound states. However, despite intensive efforts, nonlocal signatures of Majorana bound states have not been found in charge transport. In this work, we predict a striking nonlocal phase-coherent electron transfer process by virtue of tunneling in and out of a pair of Majorana bound states. This teleportation phenomenon only exists in a mesoscopic superconductor because of an all-important but previously overlooked charging energy. We propose an experimental setup to detect this phenomenon in a superconductor-quantum-spin-Hall-insulator-magnetic-insulator hybrid system. PMID:20366777

  6. Understanding x-ray driven impulsive electronic state redistribution using a three-state model

    NASA Astrophysics Data System (ADS)

    Ware, Matthew R.; Cryan, James; Bucksbaum, Philip H.

    2016-05-01

    The natural timescale for electron motion is extremely fast; electrons can move across molecular bonds in less than a femtosecond. To understand this fast motion and the role of electronic coherence, we are interested in creating a superposition of valence excited states through excitation with a broad bandwidth (>5eV) laser pulse. In the x-ray regime, the molecular ground state can couple to valence-excited states through an intermediate autoionizing resonance in a process known as stimulated x-ray Raman scattering (SXRS). X-rays excite electrons from the highly localized K-shells in a molecule, creating a superposition of valence-excited states initially localized around a target atom in the molecule. Coherences between states in the superposition will subsequently drive charge transfer as the wavepacket spreads out across the molecule. We use an effective 3-state model coupling the ground, auto-ionizing, and valence-excited states in diatomic systems to study the cross-section of SXRS as function of x-ray intensity, central frequency, bandwidth, and chirp. We also make observations on how the x-ray parameters affect the degree of initial localization to an atom of the wavepacket created in SXRS. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division.

  7. Low-lying electronic states of LiF molecule with inner electrons correlation

    NASA Astrophysics Data System (ADS)

    Wan, Ming-jie; Huang, Duo-hui; Yang, Jun-sheng; Cao, Qi-long; Jin, Cheng-guo; Wang, Fan-hou

    2015-06-01

    The potential energy curves and dipole moments of the low-lying electronic states of LiF molecule are performed by using highly accurate multi-reference configuration interaction with Awcv5z basis sets. 1s, the inner shell of Li is considered as the closed orbit, which is used to characterise the spectroscopic properties of a manifold of singlet and triplet states. 16 electronic states correlate with two lowest dissociation channels Li(2S)+F(2P) and Li(2P)+F(2P) are investigated. Spectroscopic parameters of the ground state X1Σ+ have been evaluated and critically compared with the available experimental values and the other theoretical data. However, spectroscopic parameters of 13Π, 11Δ, 11Σ-, 11Π, 13Σ+, 23Σ+, 13Δ, 13Σ-, 23Π, 21Π, 33Π, 31Π and 33Σ+ states are studied for the first time. These 13 excited states have shallow potential wells, and the dispersion coefficients of these excited states are predicted. In additional, oscillator strengths of excited states at equilibrium distances are also predicted.

  8. Localized Electron States Near a Metal-SemiconductorNanocontact

    SciTech Connect

    Demchenko, Denis O.; Wang, Lin-Wang

    2007-04-25

    The electronic structure of nanowires in contact withmetallic electrodes of experimentally relevant sizes is calculated byincorporating the electrostatic polarization potential into the atomisticsingle particle Schrodinger equation. We show that the presence of anelectrode produces localized electron/hole states near the electrode, aphenomenon only exhibited in nanostructures and overlooked in the past.This phenomenon will have profound implications on electron transport insuch nanosystems. We calculate several electrode/nanowire geometries,with varying contact depths and nanowire radii. We demonstrate the changein the band gap of up to 0.5 eV in 3 nm diameter CdSe nanowires andcalculate the magnitude of the applied electric field necessary toovercome the localization.

  9. Mapping the Electronic States of One Dimensional Peapod Structures

    NASA Astrophysics Data System (ADS)

    Hornbaker, D. J.

    2003-03-01

    A key issue of potential technological importance is how the electronic properties of single wall carbon nanotubes are altered by their interactions with other molecules. We address this question by examining the properties of carbon heterostructures formed by the encapsulation of C_60 molecules within the hollow interiors of single wall nanotubes.^1 We study the properties of these novel macromolecules (dubbed 'peapods') using a low temperature, ultra-high vacuum scanning tunneling microscope (STM). Our experiments reveal that while no discernable change in the atomic structure of the encapsulating nanotubes is evident, the presence of interior C_60 molecules can dramatically affect the electronic structure of the nanotube cage. Constant current STM images of peapods display pronounced spatial modulation of the electronic density at sample biases greater than 1V, with a periodicity consistent with the intermolecular spacing of close-packed C_60 molecules inside the nanotube. This effect has been observed on peapods displaying both semiconducting and metallic densities of states. Coincident with this modulation is the appearance of characteristic features in the electronic band structure measured via tunneling spectroscopy. Theoretical modeling^2,3 indicates these features arise from coupling between the valence states of the encapsulated fullerenes, leading to the formation of a hybrid electronic band. Our experiments demonstrate that encapsulation of molecules is a viable route for selectively altering the electronic properties of carbon nanotubes. ^1B.W. Smith and D.E. Luzzi, Chem. Phys. Lett. 321, 169 (2000). ^2D.J. Hornbaker et al. Science 295, 828 (2002). ^3C. Kane et al. Phys. Rev. B (submitted).

  10. Minimal-excitation states for electron quantum optics using levitons

    NASA Astrophysics Data System (ADS)

    Dubois, J.; Jullien, T.; Portier, F.; Roche, P.; Cavanna, A.; Jin, Y.; Wegscheider, W.; Roulleau, P.; Glattli, D. C.

    2013-10-01

    The on-demand generation of pure quantum excitations is important for the operation of quantum systems, but it is particularly difficult for a system of fermions. This is because any perturbation affects all states below the Fermi energy, resulting in a complex superposition of particle and hole excitations. However, it was predicted nearly 20 years ago that a Lorentzian time-dependent potential with quantized flux generates a minimal excitation with only one particle and no hole. Here we report that such quasiparticles (hereafter termed levitons) can be generated on demand in a conductor by applying voltage pulses to a contact. Partitioning the excitations with an electronic beam splitter generates a current noise that we use to measure their number. Minimal-excitation states are observed for Lorentzian pulses, whereas for other pulse shapes there are significant contributions from holes. Further identification of levitons is provided in the energy domain with shot-noise spectroscopy, and in the time domain with electronic Hong-Ou-Mandel noise correlations. The latter, obtained by colliding synchronized levitons on a beam splitter, exemplifies the potential use of levitons for quantum information: using linear electron quantum optics in ballistic conductors, it is possible to imagine flying-qubit operation in which the Fermi statistics are exploited to entangle synchronized electrons emitted by distinct sources. Compared with electron sources based on quantum dots, the generation of levitons does not require delicate nanolithography, considerably simplifying the circuitry for scalability. Levitons are not limited to carrying a single charge, and so in a broader context n-particle levitons could find application in the study of full electron counting statistics. But they can also carry a fraction of charge if they are implemented in Luttinger liquids or in fractional quantum Hall edge channels; this allows the study of Abelian and non-Abelian quasiparticles in the

  11. Electronic and ground state properties of ThTe

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Purvee; Singh, Sadhna

    2016-05-01

    The electronic properties of ThTe in cesium chloride (CsCl, B2) structure are investigated in the present paper. To study the ground state properties of thorium chalcogenide, the first principle calculations have been calculated. The bulk properties, including lattice constant, bulk modulus and its pressure derivative are obtained. The calculated equilibrium structural parameters are in good agreement with the available experimental and theoretical results.

  12. Launch mission summary: Intelsat 5 (F3) Atlas/Centaur-55

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Intelsat 5 (F3) spacecraft, launch vehicle, and mission are described. Information relative to launch windows, flight plan, radar and telemetry coverage, selected trajectory information, and a brief sequence of flight events is provided.

  13. Death after use of the synthetic cannabinoid 5F-AMB.

    PubMed

    Shanks, Kevin G; Behonick, George S

    2016-05-01

    The use of synthetic cannabinoids and related products has been associated with adverse effects including seizure, acute kidney injury, and sudden death. We report the death of an individual that was associated with the synthetic cannabinoid 5F-AMB. Specimens were extracted via a liquid-liquid extraction at pH 10.2 into hexane:ethyl acetate. Analysis was completed via liquid chromatography tandem mass spectrometry. For this case report, we briefly describe the extraction and instrumental methods for 5F-AMB as well as the blood toxicology results (5F-AMB, 0.3ng/mL) and case circumstances and autopsy findings. Cause and manner of death was certified as accidental death due to synthetic cannabinoid toxicity. We also briefly review any previously published reports in which 5F-AMB was analytically confirmed and determined to be involved with cause of death. PMID:27017174

  14. Liquid-state polaron theory of the hydrated electron revisited

    NASA Astrophysics Data System (ADS)

    Donley, James P.; Heine, David R.; Tormey, Caleb A.; Wu, David T.

    2014-07-01

    The quantum path integral/classical liquid-state theory of Chandler and co-workers, created to describe an excess electron in solvent, is re-examined for the hydrated electron. The portion that models electron-water density correlations is replaced by two equations: the range optimized random phase approximation (RO-RPA), and the Donley, Rajasekaran, and Liu (DRL) approximation to the "two-chain" equation, both shown previously to describe accurately the static structure and thermodynamics of strongly charged polyelectrolyte solutions. The static equilibrium properties of the hydrated electron are analyzed using five different electron-water pseudopotentials. The theory is then compared with data from mixed quantum/classical Monte Carlo and molecular dynamics simulations using these same pseudopotentials. It is found that the predictions of the RO-RPA and DRL-based polaron theories are similar and improve upon previous theory, with values for almost all properties analyzed in reasonable quantitative agreement with the available simulation data. Also, it is found using the Larsen, Glover, and Schwartz pseudopotential that the theories give values for the solvation free energy that are at least three times larger than that from experiment.

  15. Liquid-state polaron theory of the hydrated electron revisited

    SciTech Connect

    Donley, James P.; Heine, David R.; Tormey, Caleb A.; Wu, David T.

    2014-07-14

    The quantum path integral/classical liquid-state theory of Chandler and co-workers, created to describe an excess electron in solvent, is re-examined for the hydrated electron. The portion that models electron-water density correlations is replaced by two equations: the range optimized random phase approximation (RO-RPA), and the Donley, Rajasekaran, and Liu (DRL) approximation to the “two-chain” equation, both shown previously to describe accurately the static structure and thermodynamics of strongly charged polyelectrolyte solutions. The static equilibrium properties of the hydrated electron are analyzed using five different electron-water pseudopotentials. The theory is then compared with data from mixed quantum/classical Monte Carlo and molecular dynamics simulations using these same pseudopotentials. It is found that the predictions of the RO-RPA and DRL-based polaron theories are similar and improve upon previous theory, with values for almost all properties analyzed in reasonable quantitative agreement with the available simulation data. Also, it is found using the Larsen, Glover, and Schwartz pseudopotential that the theories give values for the solvation free energy that are at least three times larger than that from experiment.

  16. Two electronic states and state exchange time control in spherical nanolayer

    NASA Astrophysics Data System (ADS)

    Aghekyan, N. G.; Kazaryan, E. M.; Kostanyan, A. A.; Sarkisyan, H. A.

    2011-09-01

    Two electronic states in impenetrable spherical quantum nanolayer are discussed. The Coulomb interaction between the electrons is considered as perturbation. The problem is discussed within the frameworks of Russell-Saunders coupling scheme, that is, the spin-orbit interaction is neglected. For this system the analogue of helium atom theory is represented. The dependence of the Coulomb interaction energy of the two electronic system is obtained both upon inner and outer radiuses of the studied nanolayer. The exchange interaction in the spherical nanolayer helium atom and its dependence upon the geometrical parameters of the nanolayer are investigated. It is shown that the exchange time of two electron states could be controlled via changing the geometrical parameters of the nanolayer.

  17. Final Version: Orbital Specificity in the Unoccupied States of UO2 from Resonant Inverse Photoelectron Spectroscopy

    SciTech Connect

    Tobin, J G; Yu, S W

    2012-03-12

    One of the crucial questions of all actinide electronic structure determinations is the issue of 5f versus 6d character and the distribution of these components across the density of states. Here, a break-though experiment is discussed, which has allowed the direct determination of the U5f and U6d contributions to the unoccupied density of states (UDOS) in Uranium Dioxide. A novel Resonant Inverse Photoelectron (RIPES) and X-ray Emission Spectroscopy (XES) investigation of UO{sub 2} is presented. It is shown that the U5f and U6d components are isolated and identified unambiguously.

  18. 75 FR 3463 - Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of North...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-21

    ..., the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR... AGENCY Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of North...'s approval, under regulations for Cross-Media Electronic Reporting, of the State of North...

  19. Squeezed states of electrons and transitions of the density of states

    NASA Technical Reports Server (NTRS)

    Lee, Seung Joo; Um, Chung IN

    1993-01-01

    Electron systems which have low dimensional properties have been constructed by squeezing the motion in zero, one, or two-directions. An isolated quantum dot is modeled by a potential box with delta-profiled, penetrable potential walls embedded in a large outer box with infinitely high potential walls which represent the world function with respect to vacuum. We show the smooth crossover of the density of states from the three-dimensional to the quasi-zero dimensional electron gas.

  20. Low-Lying Electronic States of CuAu.

    PubMed

    Alizadeh Sanati, Davood; Andrae, Dirk

    2016-07-28

    Coinage metal diatomic molecules are building blocks for nanostructured materials, electronic devices, and catalytically or photochemically active systems that are currently receiving lively interest in both fundamental and applied research. The theoretical study presented here elucidates the electronic structure in the ground and several low-lying excited states of the diatomic molecule CuAu that result from the combination of the atoms in their ground states nd(10)(n + 1)s(1 2)S and lowest excited d-hole states nd(9)(n + 1)s(2 2)D (n = 3 for Cu, n = 5 for Au). Full and smooth potential energy curves, obtained at the multireference configuration interaction (MRCI) level of theory, are presented for the complete set of the thus resulting 44 Λ-S terms and 86 Ω terms. Our approach is based on a scalar relativistic description using the Douglas-Kroll-Hess (DKH) Hamiltonian, with subsequent perturbative inclusion of spin-orbit (SO) coupling via the spin-orbit terms of the Breit-Pauli (BP) Hamiltonian. The Ω terms span an energy interval of about 7 eV at the ground state's equilibrium distance. Spectroscopic constants, calculated for all terms, are shown to accurately reproduce the observation for those nine terms that are experimentally known. PMID:27379475

  1. Integral elastic, electronic-state, ionization, and total cross sections for electron scattering with furfural

    NASA Astrophysics Data System (ADS)

    Jones, D. B.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; Blanco, F.; García, G.; Brunger, M. J.

    2016-04-01

    We report absolute experimental integral cross sections (ICSs) for electron impact excitation of bands of electronic-states in furfural, for incident electron energies in the range 20-250 eV. Wherever possible, those results are compared to corresponding excitation cross sections in the structurally similar species furan, as previously reported by da Costa et al. [Phys. Rev. A 85, 062706 (2012)] and Regeta and Allan [Phys. Rev. A 91, 012707 (2015)]. Generally, very good agreement is found. In addition, ICSs calculated with our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section for electron-furfural scattering. Where possible, those calculated IAM-SCAR+I ICS results are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, but only for the band I and band II excited electronic states, we also present results from our Schwinger multichannel method with pseudopotentials calculations. Those results are found to be in good qualitative accord with the present experimental ICSs. Finally, with a view to assembling a complete cross section data base for furfural, some binary-encounter-Bethe-level total ionization cross sections for this collision system are presented.

  2. Integral elastic, electronic-state, ionization, and total cross sections for electron scattering with furfural.

    PubMed

    Jones, D B; da Costa, R F; Varella, M T do N; Bettega, M H F; Lima, M A P; Blanco, F; García, G; Brunger, M J

    2016-04-14

    We report absolute experimental integral cross sections (ICSs) for electron impact excitation of bands of electronic-states in furfural, for incident electron energies in the range 20-250 eV. Wherever possible, those results are compared to corresponding excitation cross sections in the structurally similar species furan, as previously reported by da Costa et al. [Phys. Rev. A 85, 062706 (2012)] and Regeta and Allan [Phys. Rev. A 91, 012707 (2015)]. Generally, very good agreement is found. In addition, ICSs calculated with our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section for electron-furfural scattering. Where possible, those calculated IAM-SCAR+I ICS results are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, but only for the band I and band II excited electronic states, we also present results from our Schwinger multichannel method with pseudopotentials calculations. Those results are found to be in good qualitative accord with the present experimental ICSs. Finally, with a view to assembling a complete cross section data base for furfural, some binary-encounter-Bethe-level total ionization cross sections for this collision system are presented. PMID:27083717

  3. Electronic excited states and relaxation dynamics in polymer heterojunction systems

    NASA Astrophysics Data System (ADS)

    Ramon, John Glenn Santos

    , we examine the effect of the nanoscale interfacial morphology and solvation on the electronic excited states of TFB/F8BT. Here, we employ time-dependent density functional theory (TD-DFT) to investigate the relevant excited states of two stacking configurations. We show that the calculated states agree with the excited states responsible for the experimentally observed emission peaks and that these states are blue shifted relative to those of the isolated chain. Furthermore, slight lateral shifts in the stacking orientation not only shift the excited state energies; more importantly, they alter the nature of these states altogether. Lastly, we see that solvation greatly stabilizes the charge-transfer states.

  4. Benzonitrile: Electron affinity, excited states, and anion solvation

    NASA Astrophysics Data System (ADS)

    Dixon, Andrew R.; Khuseynov, Dmitry; Sanov, Andrei

    2015-10-01

    We report a negative-ion photoelectron imaging study of benzonitrile and several of its hydrated, oxygenated, and homo-molecularly solvated cluster anions. The photodetachment from the unsolvated benzonitrile anion to the X ˜ 1 A 1 state of the neutral peaks at 58 ± 5 meV. This value is assigned as the vertical detachment energy (VDE) of the valence anion and the upper bound of adiabatic electron affinity (EA) of benzonitrile. The EA of the lowest excited electronic state of benzonitrile, a ˜ 3 A 1 , is determined as 3.41 ± 0.01 eV, corresponding to a 3.35 eV lower bound for the singlet-triplet splitting. The next excited state, the open-shell singlet A ˜ 1 A 1 , is found about an electron-volt above the triplet, with a VDE of 4.45 ± 0.01 eV. These results are in good agreement with ab initio calculations for neutral benzonitrile and its valence anion but do not preclude the existence of a dipole-bound state of similar energy and geometry. The step-wise and cumulative solvation energies of benzonitrile anions by several types of species were determined, including homo-molecular solvation by benzonitrile, hydration by 1-3 waters, oxygenation by 1-3 oxygen molecules, and mixed solvation by various combinations of O2, H2O, and benzonitrile. The plausible structures of the dimer anion of benzonitrile were examined using density functional theory and compared to the experimental observations. It is predicted that the dimer anion favors a stacked geometry capitalizing on the π-π interactions between the two partially charged benzonitrile moieties.

  5. Electronic structures of interfacial states formed at polymeric semiconductor heterojunctions

    NASA Astrophysics Data System (ADS)

    Huang, Ya-Shih; Westenhoff, Sebastian; Avilov, Igor; Sreearunothai, Paiboon; Hodgkiss, Justin M.; Deleener, Caroline; Friend, Richard H.; Beljonne, David

    2008-06-01

    Heterojunctions between organic semiconductors are central to the operation of light-emitting and photovoltaic diodes, providing respectively for electron-hole capture and separation. However, relatively little is known about the character of electronic excitations stable at the heterojunction. We have developed molecular models to study such interfacial excited electronic excitations that form at the heterojunction between model polymer donor and polymer acceptor systems: poly(9,9-dioctylfluorene-co-bis-N,N-(4-butylphenyl)-bis-N,N-phenyl-1,4-phenylenediamine) (PFB) with poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT), and poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) with F8BT. We find that for stable ground-state geometries the excited state has a strong charge-transfer character. Furthermore, when partly covalent, modelled radiative lifetimes (~10-7s) and off-chain axis polarization (30∘) match observed `exciplex' emission. Additionally for the PFB:F8BT blend, geometries with fully ionic character are also found, thus accounting for the low electroluminescence efficiency of this system.

  6. Progress towards Generating Rydberg State, One Electron Ions

    NASA Astrophysics Data System (ADS)

    Dreiling, Joan; Fogwell Hoogerheide, Shannon; Naing, Aung; Tan, Joseph

    2016-05-01

    We report on progress towards producing hydrogen-like ions in Rydberg states from bare nuclei. Fully stripped neon atoms (Ne10+) are produced by the electron beam ion trap (EBIT) at NIST. These ions are extracted via a beamline from the EBIT into a second apparatus where they are captured at low energy in a unitary Penning trap. The second apparatus has a cross-beam configuration, with a perpendicular beam of laser excited Rb atoms intersecting the ion beam at the Penning trap. While stored in the trap, the ions can interact with the Rb and, through charge exchange interactions, the bare nuclei can capture one or more electrons from the Rb. The ions are then analyzed by dumping the trap to a time-of-flight detector, which allows determination of the ion charge state evolution. This work builds towards laser spectroscopy on hydrogen-like ions in circular Rydberg states to obtain a value for the Rydberg constant independent of nuclear size effects. Such a measurement could shed some light on the proton radius puzzle.

  7. State-resolved three-dimensional electron-momentum correlation in nonsequential double ionization of benzene

    NASA Astrophysics Data System (ADS)

    Winney, Alexander H.; Lin, Yun Fei; Lee, Suk Kyoung; Adhikari, Pradip; Li, Wen

    2016-03-01

    We report state-resolved electron-momentum correlation measurement of strong-field nonsequential double ionization in benzene. With a novel coincidence detection apparatus, highly efficient triple coincidence (electron-electron dication) and quadruple coincidence (electron-electron-cation-cation) are used to resolve the final ionic states and to characterize three-dimensional (3D) electron-momentum correlation. The primary states associated with dissociative and nondissociative dications are assigned. A 3D momentum anticorrelation is observed for the electrons in coincidence with dissociative benzene dication states whereas such a correlation is absent for nondissociative dication states.

  8. Invisible Electronic States and Their Dynamics Revealed by Perturbations

    NASA Astrophysics Data System (ADS)

    Merer, Anthony J.

    2011-06-01

    Sooner or later everyone working in the field of spectroscopy encounters perturbations. These can range in size from a small shift of a single rotational level to total destruction of the vibrational and rotational patterns of an electronic state. To some workers perturbations are a source of terror, but to others they are the most fascinating features of molecular spectra, because they give information about molecular dynamics, and about states that would otherwise be invisible as a result of unfavorable selection rules. An example of the latter is the essentially complete characterization of the tilde{b}^3A_2 state of SO_2 from the vibronic perturbations it causes in the tilde{a}^3B_1 state. The S_1-trans state of acetylene is a beautiful example of dynamics in action. The level patterns of the three bending vibrations change dramatically with increasing vibrational excitation as a result of the vibrational angular momentum and the approach to the isomerization barrier. Several vibrational levels of the S_1-cis isomer, previously thought to be unobservable, can now be assigned. They obtain their intensity through interactions with nearby levels of the trans isomer.

  9. Differential cross sections for electron-impact excitation of the electronic states of N sub 2

    SciTech Connect

    Brunger, M.J.; Teubner, P.J.O. )

    1990-02-01

    Differential cross sections for the electron-impact excitation of the first ten electronic states of N{sub 2} have been determined at five incident energies ranging from 15 to 50 eV. These differential cross sections were obtained for the scattering range 10{degree}--90{degree} by analyzing electron-energy-loss spectra in N{sub 2} at a number of fixed scattering angles within that range. The present study represents a comprehensive remeasurement of the earlier work of Cartwright and co-workers (Phys. Rev. A 16, 1013 (1977)) and was undertaken with a view to resolving certain anomalies which have been reported in the literature when the earlier cross-section set has been applied to model calculations of swarm parameters.

  10. Probing the electronic structures of low oxidation-state uranium fluoride molecules UF{sub x}{sup −} (x = 2−4)

    SciTech Connect

    Li, Wei-Li; Jian, Tian; Lopez, Gary V.; Wang, Lai-Sheng; Hu, Han-Shi; Li, Jun; Su, Jing

    2013-12-28

    We report the experimental observation of gaseous UF{sub x}{sup −} (x = 2−4) anions, which are investigated using photoelectron spectroscopy and relativistic quantum chemistry. Vibrationally resolved photoelectron spectra are obtained for all three species and the electron affinities of UF{sub x} (x = 2−4) are measured to be 1.16(3), 1.09(3), and 1.58(3) eV, respectively. Significant multi-electron transitions are observed in the photoelectron spectra of U(5f{sup 3}7s{sup 2})F{sub 2}{sup −}, as a result of strong electron correlation effects of the two 7s electrons. The U−F symmetric stretching vibrational modes are resolved for the ground states of all UF{sub x} (x = 2−4) neutrals. Theoretical calculations are performed to qualitatively understand the photoelectron spectra. The entire UF{sub x}{sup −} and UF{sub x} (x = 1−6) series are considered theoretically to examine the trends of U−F bonding and the electron affinities as a function of fluorine coordination. The increased U−F bond lengths and decreased bond orders from UF{sub 2}{sup −} to UF{sub 4}{sup −} indicate that the U−F bonding becomes weaker as the oxidation state of U increases from I to III.

  11. MRCI study on electronic spectrum of 13 electronic states of SiP molecule

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Xing, Wei; Liu, Hui; Sun, Jinfeng; Zhu, Zunlue

    2012-11-01

    The potential energy curves (PECs) of the X2Π, A2Σ+, a4Σ+, B2Π, c4Δ, C2Σ+, d4Σ-, D2Φ, E2Σ-, G2Δ, H2Π, I2Σ+ and f4Δ electronic states of the SiP molecule are calculated employing an ab initio quantum chemical method. The PEC calculations are performed for internuclear separations from 0.10 to 1.10 nm using the complete active space self-consistent field (CASSCF) method, which is followed by the internally contracted multireference configuration interaction (MRCI) approach in combination with a correlation-consistent aug-cc-pV6Z basis set. To improve the quality of the PECs, core-valence correlation and scalar relativistic corrections are included. Scalar relativistic correction calculations are carried out using the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. Core-valence correlation corrections are included using a cc-pCVQZ basis set. The PECs obtained by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification. The PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are obtained by fitting the vibrational levels, which are calculated by solving the ro-vibrational Schrödinger equation. The spectroscopic results are compared in detail with those reported in previous literature. Excellent agreement is found between the present spectroscopic results and the experimental ones. Using the Breit-Pauli operator, the spin-orbit (SO) coupling effect on the spectroscopic parameters is included in the X2Π, D2Φ and H2Π electronic states at the level of a cc-pCVTZ basis set. The energy separation of the X2Π and A2Σ+ electronic states is accurately determined by including the Davidson modification, SO coupling and core-valence correlation and scalar relativistic corrections. Using the PECs determined by the MRCI + Q/CV + DK + 56 calculations, the G(υ), Bυ and Dυ are calculated for each vibrational state of each electronic state, and those

  12. MRCI study on electronic spectrum of 13 electronic states of SiP molecule.

    PubMed

    Shi, Deheng; Xing, Wei; Liu, Hui; Sun, Jinfeng; Zhu, Zunlue

    2012-11-01

    The potential energy curves (PECs) of the X(2)Π, A(2)Σ(+), a(4)Σ(+), B(2)Π, c(4)Δ, C(2)Σ(+), d(4)Σ(-), D(2)Φ, E(2)Σ(-), G(2)Δ, H(2)Π, I(2)Σ(+) and f(4)Δ electronic states of the SiP molecule are calculated employing an ab initio quantum chemical method. The PEC calculations are performed for internuclear separations from 0.10 to 1.10nm using the complete active space self-consistent field (CASSCF) method, which is followed by the internally contracted multireference configuration interaction (MRCI) approach in combination with a correlation-consistent aug-cc-pV6Z basis set. To improve the quality of the PECs, core-valence correlation and scalar relativistic corrections are included. Scalar relativistic correction calculations are carried out using the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. Core-valence correlation corrections are included using a cc-pCVQZ basis set. The PECs obtained by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification. The PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are obtained by fitting the vibrational levels, which are calculated by solving the ro-vibrational Schrödinger equation. The spectroscopic results are compared in detail with those reported in previous literature. Excellent agreement is found between the present spectroscopic results and the experimental ones. Using the Breit-Pauli operator, the spin-orbit (SO) coupling effect on the spectroscopic parameters is included in the X(2)Π, D(2)Φ and H(2)Π electronic states at the level of a cc-pCVTZ basis set. The energy separation of the X(2)Π and A(2)Σ(+) electronic states is accurately determined by including the Davidson modification, SO coupling and core-valence correlation and scalar relativistic corrections. Using the PECs determined by the MRCI+Q/CV+DK+56 calculations, the G(υ), B(υ) and D(υ) are calculated for each

  13. Topology and quantum states: The electron-monopole system

    NASA Astrophysics Data System (ADS)

    Di Cosmo, F.; Marmo, G.; Zampini, A.

    2016-09-01

    This paper starts by describing the dynamics of the electron-monopole system at both classical and quantum level by a suitable reduction procedure. This suggests, in order to realise the space of states for quantum systems which are classically described on topologically non-trivial configuration spaces, to consider Hilbert spaces of exterior differential forms. Among the advantages of this formulation, we present--in the case of the group SU(2) , how it is possible to obtain all unitary irreducible representations on such a Hilbert space, and how it is possible to write scalar Dirac-type operators, following an idea by Kähler.

  14. Cage electron-hydroxyl complex state as electron donor in mayenite

    NASA Astrophysics Data System (ADS)

    Hiraishi, M.; Kojima, K. M.; Miyazaki, M.; Yamauchi, I.; Okabe, H.; Koda, A.; Kadono, R.; Matsuishi, S.; Hosono, H.

    2016-03-01

    It is inferred from the chemical shift of muon spin rotation (μ SR ) spectra that muons implanted in pristine (fully oxidized) mayenite, [Ca12Al14O32] 2 +[□5O2 -] (C12A7, with □ referring to the vacant cage), are bound to O2 - at the cage center to form OMu- (where Mu represents muonium, a muonic analog of the H atom). However, an isolated negatively charged state (Mu-, an analog of H-) becomes dominant when the compound approaches the state of electride [Ca12Al14O32] 2 +[□42 e-] as a result of the reduction process. Moreover, the OMu- state in the pristine specimen exhibits depolarization of paramagnetic origin at low temperatures (below ˜30 K), indicating that OMu- accompanies a loosely bound electron in the cage that can be thermally activated. This suggests that interstitial muons (and hence H) forming a "cage electron-hydroxyl" complex can serve as electron donors in C12A7.

  15. Semiclassical Dynamics of Electron Wave Packet States with Phase Vortices

    SciTech Connect

    Bliokh, Konstantin Yu.; Bliokh, Yury P.; Savel'ev, Sergey; Nori, Franco

    2007-11-09

    We consider semiclassical higher-order wave packet solutions of the Schroedinger equation with phase vortices. The vortex line is aligned with the propagation direction, and the wave packet carries a well-defined orbital angular momentum (OAM) ({Dirac_h}/2{pi})l (l is the vortex strength) along its main linear momentum. The probability current coils around the momentum in such OAM states of electrons. In an electric field, these states evolve like massless particles with spin l. The magnetic-monopole Berry curvature appears in momentum space, which results in a spin-orbit-type interaction and a Berry/Magnus transverse force acting on the wave packet. This brings about the OAM Hall effect. In a magnetic field, there is a Zeeman interaction, which, can lead to more complicated dynamics.

  16. Site-specific Auger electron spectra of ethyl trifluoroacelate molecules studied by magnetic bottle electron spectrometer

    NASA Astrophysics Data System (ADS)

    Iwayama, Hiroshi; Shigemasa, Eiji; Hikosaka, Yasumasa; Nakano, Motoyoshi; Ito, Kenji; Lablanquie, Pascal; Penet, Francis; Andric, Lidija; Selles, Patricia

    2012-11-01

    We performed multielectron coincidence measurements for inner-shell photoionizations of ethyl trifluoroacelate molecules (C4H5F3O2) using a magnetic bottle electron spectrometer. From a two dimensional coincidence map between a photoelectron and Auger electron for C 1s ionizations, we extracted site-specific Auger electron spectra for each carbon site and corresponding binding energy of doubly charged states.

  17. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    SciTech Connect

    Nenov, Artur Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K.; Rivalta, Ivan; Cerullo, Giulio; Mukamel, Shaul; Garavelli, Marco E-mail: marco.garavelli@ens-lyon.fr

    2015-06-07

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  18. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy.

    PubMed

    Nenov, Artur; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K; Rivalta, Ivan; Cerullo, Giulio; Mukamel, Shaul; Garavelli, Marco

    2015-06-01

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040-1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  19. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    NASA Astrophysics Data System (ADS)

    Nenov, Artur; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K.; Rivalta, Ivan; Cerullo, Giulio; Mukamel, Shaul; Garavelli, Marco

    2015-06-01

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040-1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  20. Heavy metal phosphate nanophases in silica: influence of radiolysis probed via f-electron state properties

    SciTech Connect

    Beitz, James V. . E-mail: beitz@anl.gov; Williams, C.W.; Hong, K.-S.; Liu, G.K.

    2005-02-15

    We have assessed the feasibility of carrying out time- and wavelength-resolved laser-induced fluorescence measurements of radiation damage in glassy silica. The consequences of alpha decay of Es-253 in LaPO{sub 4} nanophases embedded in silica were probed based on excitation of 5f states of Cm{sup 3+}, Bk{sup 3+}, and Es{sup 3+} ions. The recorded emission spectra and luminescence decays showed that alpha decay of Es-253 ejected Bk-249 decay daughter ions into the surrounding silica and created radiation damage within the LaPO{sub 4} nanophases. This conclusion is consistent with predictions of an ion transport code commonly used to model ion implantation. Luminescence from the {sup 6}D{sub 7/2} state of Cm{sup 3+}was used as an internal standard. Ion-ion energy transfer dominated the dynamics of the observed emitting 5f states and strongly influenced the intensity of observed spectra. In appropriate sample materials, laser-induced fluorescence provides a powerful method for fundamental investigation of alpha-induced radiation damage in silica.

  1. Electron Microscopy: an Analytical Tool for Solid State Physicists

    NASA Astrophysics Data System (ADS)

    van Tendeloo, Gustaaf

    2013-03-01

    For too long the electron microscope has been considered as ``a big magnifying glass.'' Modern electron microscopy however has evolved into an analytical technique, able to provide quantitative data on structure, composition, chemical bonding and magnetic properties. Using lens corrected instruments it is now possible to determine atom shifts at interfaces with a precision of a few picometer; chemical diffusion at these interfaces can be imaged down to atomic scale. The chemical nature of the surface atoms can be visualized and even the bonding state of the elements (e.g. Mn2+ versus Mn3+) can be detected on an atomic scale. Electron microscopy is by principle a projection technique, but the final dream is to obtain atomic info of materials in three dimensions. We will show that this is no longer a dream, but that it is possible using advanced microscopy. We will show evidence of determining the valence change Ce4+ versus Ce3+ at the surface of a CeO2 nanocrystal; the atomic shifts at the interface between LaAlO3 and SrTiO3 and the 3D relaxation of a Au nanocrystal.

  2. Precursor anion states in dissociative electron attachment to chlorophenol isomers

    NASA Astrophysics Data System (ADS)

    Kossoski, F.; Varella, M. T. do N.

    2016-07-01

    We report a theoretical study on low-energy (<10 eV) elastic electron scattering from chlorophenol isomers, namely, para-chlorophenol (pCP), meta-chlorophenol (mCP), and ortho-chlorophenol (oCP). The calculations were performed with the Schwinger multichannel method with pseudopotentials, and analysis of the computed integral cross sections and virtual orbitals revealed one σCCl ∗ , one σOH ∗ , and three π∗ shape resonances. We show that electron capture into the two lower lying π∗ orbitals initiates dissociative processes that lead to the elimination of the chloride ion, accounting for the two overlapping peaks where this fragment was observed. Despite the relatively small differences on the energetics of the π∗ resonances, a major isomeric effect was found on their corresponding autodetachment lifetimes, which accounts for the observed increasing cross sections in the progression pCP < mCP < oCP. In particular, dissociation from the π1 ∗ anion of pCP is largely suppressed because of the unfavorable mixing with the σCCl ∗ state. We found the intramolecular hydrogen bond present in oCP to have the opposite effects of stabilizing the σCCl ∗ resonance and destabilizing the σOH ∗ resonance. We also suggest that the hydrogen abstraction observed in chlorophenols and phenol actually takes place by a mechanism in which the incoming electron is directly attached to the dissociative σOH ∗ orbital.

  3. Electronic spectrum of 17 electronic states of BN molecule: a theoretical study.

    PubMed

    Shi, Deheng; Xing, Wei; Liu, Hui; Sun, Jinfeng; Zhu, Zunlue; Liu, Yufang

    2012-07-01

    The potential energy curves (PECs) of the X(3)Π, a(1)Σ(+), b(1)Π, A(3)Σ(+), B(3)Σ(-), c(1)Δ, D(3)Π, 1(5)Π, 3(1)Σ(+), 3(3)Π, 2(1)Π, 2(3)Σ(+), 1(3)Δ, 1(5)Σ(+), 4(3)Π, 2(3)Σ(-) and 1(5)Σ(-) electronic states of the BN molecule are calculated using an ab initio quantum chemical method. The PEC calculations have been made for internuclear separations from 0.06 to 1.20 nm using the complete active space self-consistent field (CASSCF) method, which is followed by the valence internally contracted multireference configuration interaction (MRCI) approach in combination with a correlation-consistent aug-cc-pV5Z basis set. To improve the quality of PECs, core-valence correlation and relativistic corrections are included. Relativistic correction calculations are carried out using the third-order Douglas-Kroll Hamiltonian (DKH3) approximation. Core-valence correlation corrections are included using a cc-pCVQZ basis set. Relativistic corrections are calculated at the level of a cc-pVQZ basis set. To obtain more reliable results, the PECs determined by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). These PECs are extrapolated to the complete basis set limit by the total-energy extrapolation scheme. The spectroscopic parameters are determined by fitting the vibrational levels, which are calculated in a direct forward manner from the analytic potential by solving the ro-vibrational Schrödinger equation using Numerov's method. The spectroscopic results have been compared in detail with those reported in the literature. Excellent agreement has been found between the present spectroscopic results and the experimental ones. Using the Breit-Pauli operator, the spin-orbit coupling effect on the spectroscopic parameters is included in the X(3)Π and D(3)Π electronic states. The vibrational level, inertial rotation and centrifugal distortion constants are calculated for each vibrational state of each

  4. A triphenylamine-grafted imidazo[4,5-f][1,10]phenanthroline ruthenium(II) complex: acid-base and photoelectric properties.

    PubMed

    Fan, Su-Hua; Zhang, An-Guo; Ju, Chuan-Chuan; Gao, Li-Hua; Wang, Ke-Zhi

    2010-04-19

    A new heteroleptic ruthenium(II) complex of [Ru(Hipdpa)(Hdcbpy)(NCS)(2)](-).0.5H(+).0.5[N(C(4)H(9))(4)](+) Ru(Hipdpa) {where Hdcbpy = monodeprotonated 4,4'-dicarboxy-2,2'-bipyridine and Hipdpa = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline} was synthesized and characterized by elementary analysis, standard spectroscopy techniques, and cyclic voltammetry. The ground- and excited-state acid-base properties of Ru(Hipdpa) were studied by means of UV-vis absorption spectrophotometric and spectrofluorimetric titrations in 4:1(v/v) Britton-Robinson/dimethylformamide buffer solution. The four-step separate protonation/deprotonation processes were found in the ground states, and one of which taking place near the physiological pH range. The two observable excited-state protonation/deprotonation processes were found for the Ru(Hipdpa), constituting pH-induced "off-on-off" emission switches. The performance of the complexes as photosensitizers in nanocrystalline TiO(2)-based liquid solar cells containing an electrolyte solution (0.05 M I(2), 0.5 M LiI, and 0.5 M 4-tert-butylpyridine in 50% acetonitrile and 50% propylene carbonate) was investigated and found to achieve a much improved device performance (a short-circuit photocurrent density of 18.7 mA cm(-2), an open-circuit voltage of 630 mV, and an overall conversion efficiency of 6.85%) compared to a triphenylamine-free parent complex [Ru(Hpip)(Hdcbpy)(NCS)(2)](-).[N(C(4)H(9))(4)](+)-based device {Hpip = 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline} and a comparable performance to that of cis-bis(isothiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(II) (N3) under identical experimental conditions. A density functional theory calculation of the molecular structures and electronic properties of the complexes was also carried out in an effort to understand their effectiveness in TiO(2)-based solar cells. PMID:20337492

  5. K8(K5F)U6Si8O40: An Intergrowth Uranyl Silicate.

    PubMed

    Morrison, Gregory; Tran, T Thao; Halasyamani, P Shiv; Zur Loye, Hans-Conrad

    2016-04-01

    Single crystals of K8(K5F)U6Si8O40 were grown from a mixed alkali halide flux. K8(K5F)U6Si8O40 is the first intergrowth uranyl silicate, being composed of alternating slabs related to two previously reported uranyl silicates: Cs2USiO6 and [Na9F2][(UO2)(UO2)2(Si2O7)2]. It exhibits intense luminescence, which is influenced by the [(UO2)2O] dimers present in the structure. PMID:26974872

  6. 75 FR 69660 - Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of Hawaii

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... the Federal Register (70 FR 59848) and codified as part 3 of title 40 of the CFR. CROMERR establishes... AGENCY Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of Hawaii... approval, under regulations for Cross-Media Electronic Reporting, of the State of Hawaii's request...

  7. 75 FR 65627 - Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of Arkansas

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-26

    ... the Federal Register (70 FR 59848) and codified as part 3 of title 40 of the CFR. CROMERR establishes... AGENCY Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of...'s approval, under regulations for Cross-Media Electronic Reporting, of the State of...

  8. High-lying electronic states of the rubidium dimer-Ab initio predictions and experimental observation of the 5(1)Σu(+) and 5(1)Πu states of Rb2 by polarization labelling spectroscopy.

    PubMed

    Jastrzebski, Wlodzimierz; Kowalczyk, Pawel; Szczepkowski, Jacek; Allouche, Abdul-Rahman; Crozet, Patrick; Ross, Amanda J

    2015-07-28

    Two-colour polarization labelling experiments have been used to explore the excitation spectrum of the rubidium dimer in the region 25,500-27,000 cm(-1), probing two mutually interacting states, identified from ab initio calculations as the 5(1)Σu(+) and 5(1)Πu states whose atomic dissociation products are Rb(5s) + Rb(5d). Treating the rather irregular progressions observed in the excitation spectra as transitions to single states with (numerous) local perturbations, we propose spectroscopic parameters and potential energy curves to describe the investigated levels. Observations cover more than 20 vibrational levels in the inner minima of both the 5(1)Πu and 5(1)Σu(+) states. Analysis was guided by ab initio calculations performed to describe the (1,3)Λg,u electronic states of Rb2 up to the Rb(5s) + Rb(5f) atomic asymptote. The theoretical potential energy curves are given in ASCII format in an electronic supplement to this paper. PMID:26233130

  9. Electronic structure of the unoccupied electron energy states in FeSe1-xTex

    NASA Astrophysics Data System (ADS)

    Mishra, Pramita; Lohani, Himanshu; Maniraj, M.; Nayak, Jayita; Zargar, R. A.; Awana, V. P. S.; Barman, Sudipta Roy; Sekhar, Biju Raja

    2015-10-01

    Inverse photoemission spectroscopic (IPES) measurements along with LDA based band structure calculations have been used to investigate the unoccupied electronic structure of FeSe1-xTex system. The observed doping and temperature dependent pseudogap in this system is found to be linked to the change in the chalcogen height in their geometric structure. The depletion in spectral weight from the near EF states at low temperature in IPES has been correlated with the enhancement of the 3z2-r2 orbitals in the photoemission spectroscopy (PES). The Coulomb correlation energy U, estimated from the combined PES and IPES spectra, signifies the enhancement in electron correlations in FeSe1-xTex, with doping. The formation of pseudogap in PES and IPES confirms the importance of correlations in the 11 family of Fe superconductors.

  10. Electron excitation from ground state to first excited state: Bohmian mechanics method

    NASA Astrophysics Data System (ADS)

    Yang, Song; Shuang, Zhao; Fu-Ming, Guo; Yu-Jun, Yang; Su-Yu, Li

    2016-03-01

    The excitation process of electrons from the ground state to the first excited state via the resonant laser pulse is investigated by the Bohmian mechanics method. It is found that the Bohmian particles far away from the nucleus are easier to be excited and are excited firstly, while the Bohmian particles in the ground state is subject to a strong quantum force at a certain moment, being excited to the first excited state instantaneously. A detailed analysis for one of the trajectories is made, and finally we present the space and energy distribution of 2000 Bohmian particles at several typical instants and analyze their dynamical process at these moments. Project supported by the Doctoral Research Start-up Funding of Northeast Dianli University, China (Grant No. BSJXM-201332), the National Natural Science Foundation of China (Grant Nos. 11547114, 11534004, 11474129, 11274141, 11447192, and 11304116), and the Graduate Innovation Fund of Jilin University, China (Grant No. 2015091).

  11. A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO(-).

    PubMed

    Roy, Soumendra K; Jian, Tian; Lopez, Gary V; Li, Wei-Li; Su, Jing; Bross, David H; Peterson, Kirk A; Wang, Lai-Sheng; Li, Jun

    2016-02-28

    The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO(-) is linear with an O-U-F structure and a (3)H4 spectral term derived from a U 7sσ(2)5fφ(1)5fδ(1) electron configuration, whereas the ground state of neutral UFO has a (4)H(7/2) spectral term with a U 7sσ(1)5fφ(1)5fδ(1) electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations. PMID:26931704

  12. Two dimensional electron systems for solid state quantum computation

    NASA Astrophysics Data System (ADS)

    Mondal, Sumit

    Two dimensional electron systems based on GaAs/AlGaAs heterostructures are extremely useful in various scientific investigations of recent times including the search for quantum computational schemes. Although significant strides have been made over the past few years to realize solid state qubits on GaAs/AlGaAs 2DEGs, there are numerous factors limiting the progress. We attempt to identify factors that have material and design-specific origin and develop ways to overcome them. The thesis is divided in two broad segments. In the first segment we describe the realization of a new field-effect induced two dimensional electron system on GaAs/AlGaAs heterostructure where the novel device-design is expected to suppress the level of charge noise present in the device. Modulation-doped GaAs/AlGaAs heterostructures are utilized extensively in the study of quantum transport in nanostructures, but charge fluctuations associated with remote ionized dopants often produce deleterious effects. Electric field-induced carrier systems offer an attractive alternative if certain challenges can be overcome. We demonstrate a field-effect transistor in which the active channel is locally devoid of modulation-doping, but silicon dopant atoms are retained in the ohmic contact region to facilitate low-resistance contacts. A high quality two-dimensional electron gas is induced by a field-effect that is tunable over a density range of 6.5x10 10cm-2 to 2.6x1011cm-2 . Device design, fabrication, and low temperature (T=0.3K) characterization results are discussed. The demonstrated device-design overcomes several existing limitations in the fabrication of field-induced 2DEGs and might find utility in hosting nanostructures required for making spin qubits. The second broad segment describes our effort to correlate transport parameters measured at T=0.3K to the strength of the fractional quantum Hall state observed at nu=5/2 in the second Landau level of high-mobility GaAs/AlGaAs two dimensional

  13. Electron and Hole States in Low Dimensional Structures

    NASA Astrophysics Data System (ADS)

    Edwards, Gerard

    Available from UMI in association with The British Library. In this thesis results from microscopic calculations for the electron and hole states in low dimensional heterostructures are presented. The basis for the calculation is the local empirical pseudopotential technique which is used to generate the bulk semiconductor bandstructure. Then an S matrix approach, which is numerically stable, is employed to propagate the solution through the layered structure. The technique is essentially a scattering approach and hence is suitable to describe the experimental situation of finite samples. The fact that a finite system is treated allows the formalism to be naturally extended to include an external E field. The calculations that have been done are for the (001) growth direction. In chapter 1 the basic concepts of semiconductor physics relevant to the material of this thesis are introduced. In Chapter 2 the theoretical technique used in this thesis, for conduction band states, is reviewed and compared and contrasted with alternative methods. The emergence of miniband states and Stark ladders in coupled GaAs/AlAs quantum well structures are dealt with in chapter 3. In Chapter 4 the bound state problem, relevant to optical properties, of the energy versus k_parallel subband dispersion of a AlGaAs-GaAs-AlGaAs quantum well is examined. Chapter 5 contains the extension of the theoretical technique to incorporate the spin-orbit interaction so that heterostructure hole states can be tackled. The validity of the effective mass theory treatment of the semiconductor interface and the Luttinger model of the bulk valence band is questioned and the microscopic nature of the GaAs-AlAs interface scattering investigated. In chapter 6 hole states in GaAs/AlAs double barrier structures and coupled multiple quantum well (MQW) structures are calculated. The anomalous formation of contact interface states instead of heavy hole minibands is observed in MQW structures. In chapter 7 In

  14. Electronic states and spectra of BiH

    NASA Astrophysics Data System (ADS)

    Setzer, Klaus-Dieter; Fink, Ewald H.; Hill, Christian; Brown, John M.

    2015-06-01

    Emission spectra of bismuth monohydride (BiH) radicals excited by energy transfer from O2(a1Δg) or NF(a1Δ) or by a DC discharge in a mixture of bismuth vapor and hydrogen in a fast-flow system were studied in the wavenumber range from 4000 to 25 000 cm-1 with a Fourier-transform spectrometer. The X21 → X10+ transition between the spin components of the X3Σ- ground state was remeasured at high spectral resolution and signal/noise. Six bands of the Δv = 0 and +1 sequences near 4950 and 6600 cm-1 have been observed. The low-J lines of these bands are split into up to 10 hfs components due to magnetic hyperfine structure splitting of the X21 levels. In addition to the previously observed electric dipole lines, weak magnetic dipole lines show up in the Δv = 0 but not in the Δv = +1 bands. The intensities of the Δv = +1 bands are about a factor of 10 higher than expected from Franck-Condon factors indicating that the electric dipole transition moment μX2-X1 shows a strong dependence on internuclear distance. Near 5450 cm-1, the 0-0 and 1-1 bands of the transition a2 → X21 from the hitherto unknown first excited state a1Δ(a2) to the upper component of the ground state have been observed. The lines in these bands show the magnetic hfs splitting of both the a2 and X21 states. In the visible range near 21 300 and 16 300 cm-1, the 0-0 and 1-1 bands of the b0+ → X10+ system and the 0-0 band of the b0+ → X21 transition likewise have been measured at high resolution. The lines of the latter band also show the hfs splitting of the X21 state. Least-squares fits have yielded rotational and vibrational constants of the X10+, X21, a2, and b0+ states as well as hfs parameters of the X21 and a2 states and the electronic energy of the hitherto unknown a1Δ(a2) level.

  15. Electron impact excitation and assignment of the low-lying electronic states of CO2

    NASA Technical Reports Server (NTRS)

    Hall, R. I.; Trajmar, S.

    1973-01-01

    Electron scattering spectra of CO2 are reported in the 7 to 10 eV energy-loss range, at energies of 0.2, 0.35, 0.6, 0.7, and 7.0 eV above threshold, and at a scattering angle of 90 deg. Several new distinct overlapping continua with weak, diffuse bands superimposed are observed to lie in this energy-loss range. The experimental spectra are discussed in the light of recent ab initio configuration-interaction calculations of the vertical transition energies of CO2. The experimental spectra are shown to be consistent with the excitation states of CO2.

  16. Measurement of the electronic momentum distributions of Rydberg Stark states

    SciTech Connect

    Murray-Krezan, J.; Jones, R. R.

    2007-06-15

    Approximate momentum distributions of Rydberg electrons in static electric fields have been obtained using an improved impulsive momentum retrieval (IMR) technique. An imaging detector enables the measurement of half-cycle pulse (HCP) ionization probability across the spatial profile of a focused half-cycle pulse beam. By modulating the HCP amplitude we directly measure the derivative of the ionization vs HCP impulse curve, enabling the recovery of momentum distributions with better resolution than previously demonstrated with IMR. For example, for Stark states with small dipole moments, we observe predicted fine-structure in the projection of the momentum distribution along the Stark field axis. We use a semiclassical model to simulate the effect that the nonzero HCP duration has on our measurements. Good agreement between simulated and measured momentum distributions is obtained.

  17. Electronic states of cuprate superconductors containing halogen or carbon

    NASA Astrophysics Data System (ADS)

    Tohiyama, Takami; Shibata, Yasumasa; Maekawa, Sadamichi

    1996-12-01

    The electronic states of the halo-oxocuprate and oxycarbonate superconductors are examined by means of the ionic and cluster models. The oxycarbonates examined contain the CO3 group on one side of the CuO2 plane. The superconducting critical temperature Tc is found to be correlated with the stability of the Zhang-Rice local singlet in the CuO2 plane. The stability is generally determined by two factors: (1) the energy-level separation between apical ion and in-plane oxygen and (2) the hybridization between apical pz and in-plane orbitals. The former is dominant for the oxycarbonates. It is also found that the CO3 group has no effect on the stabilization. For the halo-oxocuprates, the latter is crucial to stabilize the singlet.

  18. Ultrafast excited state relaxation dynamics of electron deficient porphyrins: Conformational and electronic factors

    NASA Astrophysics Data System (ADS)

    Okhrimenko, Albert N.

    Metallo-tetrapyrroles (MTP) are highly stable macrocyclic pi-systems that display interesting properties that make them potential candidates for various applications. Among these applications are optoelectronics, magnetic materials, photoconductive materials, non-linear optical materials and photo tumor therapeutic drugs. These applications are generally related to their high stability and efficient light absorption ability in the visible and near-infrared region of the optical spectrum. Metallo porphyrins are well known and widely studied representatives of metallotetrapyrroles. Electron deficient substituents in the meso positions are well known to greatly influence the interaction between the metal d-orbitals and the nitrogen orbitals of the tetrapyrrole macrocycle. In this work, a series of electron deficient porphyrins has been studied to gain some knowledge about the change in the excited state dynamics with structural and electronic modifications. Among these porphyrins is nickel and iron modified species bearing perfluoro-, perprotio-, p-nitrophenyl- and perfluorophenyl-meso substituents. Ultrafast transient absorption spectrometry has been used as the main research instrument along with other spectroscopic and electrochemical methods. A new technique has been employed to study the photophysical properties of zinc (II) tetraphenylporphine cation radical. It employs a combination of controlled potential coulometry and femtosecond absorption spectrometry. The fast transient lifetime of 17 ps of the pi-cation species originates in very efficient mixing of the a2u HOMO cation orbital that places electronic density mainly on pyrrolic nitrogens and metal d-orbitals. That explains the lack of any emission of the cationic species. This non-radiative decay process might elucidate the processes taking place in photosynthetic systems when electron is removed from porphyrinic moiety and the hole is produced. In this work zinc(II) meso-tetraphenylporphine radial cation

  19. Pou5f1 contributes to dorsoventral patterning by positive regulation of vox and modulation of fgf8a expression.

    PubMed

    Belting, Heinz-Georg; Wendik, Björn; Lunde, Karen; Leichsenring, Manuel; Mössner, Rebecca; Driever, Wolfgang; Onichtchouk, Daria

    2011-08-15

    Pou5f1/Oct-4 in mice is required for maintenance of embryonic pluripotent cell populations. Zebrafish pou5f1 maternal-zygotic mutant embryos (spiel ohne grenzen; MZspg) lack endoderm and have gastrulation and dorsoventral patterning defects. A contribution of Pou5f1 to the control of bmp2b, bmp4 and vox expression has been suggested, however the mechanisms remained unclear and are investigated in detail here. Low-level overexpression of a Pou5f1-VP16 activator fusion protein can rescue dorsalization in MZspg mutants, indicating that Pou5f1 acts as a transcriptional activator during dorsoventral patterning. Overexpression of larger quantities of Pou5f1-VP16 can ventralize wild-type embryos, while overexpression of a Pou5f1-En repressor fusion protein can dorsalize embryos. Lack of Pou5f1 causes a transient upregulation of fgf8a expression after mid-blastula transition, providing a mechanism for delayed activation of bmp2b in MZspg embryos. Overexpression of the Pou5f1-En repressor induces fgf8, suggesting an indirect mechanism of Pou5f1 control of fgf8a expression. Transcription of vox is strongly activated by Pou5f1-VP16 even when translation of zygotically expressed transcripts is experimentally inhibited by cycloheximide. In contrast, bmp2b and bmp4 are not activated under these conditions. We show that Pou5f1 binds to phylogenetically conserved Oct/Pou5f1 sites in the vox promoter, both in vivo (ChIP) and in vitro. Our data reveals a set of direct and indirect interactions of Pou5f1 with the BMP dorsoventral patterning network that serve to fine-tune dorsoventral patterning mechanisms and coordinate patterning with developmental timing. PMID:21621531

  20. Precursor anion states in dissociative electron attachment to chlorophenol isomers.

    PubMed

    Kossoski, F; Varella, M T do N

    2016-07-28

    We report a theoretical study on low-energy (<10 eV) elastic electron scattering from chlorophenol isomers, namely, para-chlorophenol (pCP), meta-chlorophenol (mCP), and ortho-chlorophenol (oCP). The calculations were performed with the Schwinger multichannel method with pseudopotentials, and analysis of the computed integral cross sections and virtual orbitals revealed one σCCl (∗), one σOH (∗), and three π(∗) shape resonances. We show that electron capture into the two lower lying π(∗) orbitals initiates dissociative processes that lead to the elimination of the chloride ion, accounting for the two overlapping peaks where this fragment was observed. Despite the relatively small differences on the energetics of the π(∗) resonances, a major isomeric effect was found on their corresponding autodetachment lifetimes, which accounts for the observed increasing cross sections in the progression pCP < mCP < oCP. In particular, dissociation from the π1 (∗) anion of pCP is largely suppressed because of the unfavorable mixing with the σCCl (∗) state. We found the intramolecular hydrogen bond present in oCP to have the opposite effects of stabilizing the σCCl (∗) resonance and destabilizing the σOH (∗) resonance. We also suggest that the hydrogen abstraction observed in chlorophenols and phenol actually takes place by a mechanism in which the incoming electron is directly attached to the dissociative σOH (∗) orbital. PMID:27475364

  1. Optical Properties and Electronic States Specific to Solid Fullerene

    NASA Astrophysics Data System (ADS)

    Minami, Nobutsugu; Kazaoui, Said; Wen, Ching-Ju; Byrne, Hugh J.

    1996-03-01

    One of the most intriguing aspects of the fullerene research is to ask what specific phenomena will occur when the soccer-ball shaped molecules aggregate and make a solid. Seeking this question is crucial for the realization of any photonic and electronic application of this new type of carbon allotrope. We have been working on this theme by the study of optical and electrical properties of C60 thin film. An important result is the demonstration of a distinct intermolecular charge transfer excited state (CT exciton) originating from intermolecular electronic interaction specific to the spherical pai conjugation system. This has been shown by the coincidence in the threshold energy of 2.3eV for absorption, luminescence efficiency, field induced luminescence quenching, and photoconductivity. We also found an evidence of the interconnection between optical properties and the structural phase transition at 260K. Moreover, a composite film containing C60 is demonstrated to show intense luminescence under 10mW laser irradiation.

  2. Analysis of the Tank 5F Feed and Bleed Residual Solids

    SciTech Connect

    Poirier, M.; Diprete, D.: Coleman, C.; Washington, A.

    2011-07-07

    Savannah River Remediation (SRR) is preparing Tank 5F for closure. As part of Tank 5F Closure Mechanical Cleaning, SRR conducted a 'Feed and Bleed' process in Tank 5F. Following this 'Feed and Bleed' Mechanical Cleaning in Tank 5F, SRR collected two tank heel samples (referred to as sample 1 and sample 2) under Riser 5 to determine the composition of the material remaining in the tanks. This document describes sample analysis results. The conclusions from this analysis follow. (1) The anions measured all had a concentration less than 250 mg/kg, except for oxalate, which had a concentration of 2100-2400 mg/kg. (2) The measured cations with the highest concentration were iron (432,000-519,000 mg/kg), nickel (54,600-69,300 mg/kg), and manganese (35,200-42,100 mg/kg). All other cations measured less than 13,000 mg/kg. (3) The radionuclides present in the highest concentration are {sup 90}Sr (3.0 x 10{sup 10} dpm/g), {sup 137}Cs (6.8 x 10{sup 8} dpm/g), and {sup 241}Am (1.4 x 10{sup 8} - 1.8 x 10{sup 8} dpm/g). (4) The particle size analysis shows a large fraction of particles greater than 100 {micro}.

  3. 26 CFR 5f.103-2 - Public approval of industrial development bonds.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 14 2013-04-01 2013-04-01 false Public approval of industrial development bonds... RESPONSIBILITY ACT OF 1982 § 5f.103-2 Public approval of industrial development bonds. (a) General rule. An industrial development bond (within the meaning of § 1.103-7(b)(1) issued after December 31, 1982, shall...

  4. 26 CFR 5f.103-2 - Public approval of industrial development bonds.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 14 2012-04-01 2012-04-01 false Public approval of industrial development bonds... RESPONSIBILITY ACT OF 1982 § 5f.103-2 Public approval of industrial development bonds. (a) General rule. An industrial development bond (within the meaning of § 1.103-7(b)(1) issued after December 31, 1982, shall...

  5. 26 CFR 5f.103-2 - Public approval of industrial development bonds.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 14 2011-04-01 2010-04-01 true Public approval of industrial development bonds... RESPONSIBILITY ACT OF 1982 § 5f.103-2 Public approval of industrial development bonds. (a) General rule. An industrial development bond (within the meaning of § 1.103-7(b)(1) issued after December 31, 1982, shall...

  6. Four Postmortem Case Reports with Quantitative Detection of the Synthetic Cannabinoid, 5F-PB-22

    PubMed Central

    Behonick, George; Shanks, Kevin G.; Firchau, Dennis J.; Mathur, Gagan; Lynch, Charles F.; Nashelsky, Marcus; Jaskierny, David J.; Meroueh, Chady

    2014-01-01

    In January 2014, the US government temporarily designated 5F-PB-22, along with three other synthetic cannabinoids (AB-FUBINACA, ADB-PINACA and PB-22), into Schedule I. Over the course of a 4-month time period (July–October 2013), our laboratory quantitatively identified 5F-PB-22 in specimens obtained from four postmortem cases. We describe the four cases, to include pertinent autopsy findings and decedent histories, together with quantitative results for 5F-PB-22 determined in postmortem blood and antemortem serum. Samples were prepared via a liquid–liquid extraction at pH 10.2 into hexane : ethyl acetate. Instrumental analysis was achieved with liquid chromatography coupled with electrospray ionization tandem mass spectrometry operating in multiple reaction monitoring mode. Two ion transitions were monitored for the analyte of interest, and one ion transition was monitored for the internal standard. The observed concentration range of 5F-PB-22 is 1.1–1.5 ng/mL for three postmortem blood specimens and one antemortem serum specimen. Three of the decedents experienced abrupt, sudden death; however, one decedent expired after a rapidly deteriorating hospital course. PMID:24876364

  7. Four postmortem case reports with quantitative detection of the synthetic cannabinoid, 5F-PB-22.

    PubMed

    Behonick, George; Shanks, Kevin G; Firchau, Dennis J; Mathur, Gagan; Lynch, Charles F; Nashelsky, Marcus; Jaskierny, David J; Meroueh, Chady

    2014-10-01

    In January 2014, the US government temporarily designated 5F-PB-22, along with three other synthetic cannabinoids (AB-FUBINACA, ADB-PINACA and PB-22), into Schedule I. Over the course of a 4-month time period (July-October 2013), our laboratory quantitatively identified 5F-PB-22 in specimens obtained from four postmortem cases. We describe the four cases, to include pertinent autopsy findings and decedent histories, together with quantitative results for 5F-PB-22 determined in postmortem blood and antemortem serum. Samples were prepared via a liquid-liquid extraction at pH 10.2 into hexane : ethyl acetate. Instrumental analysis was achieved with liquid chromatography coupled with electrospray ionization tandem mass spectrometry operating in multiple reaction monitoring mode. Two ion transitions were monitored for the analyte of interest, and one ion transition was monitored for the internal standard. The observed concentration range of 5F-PB-22 is 1.1-1.5 ng/mL for three postmortem blood specimens and one antemortem serum specimen. Three of the decedents experienced abrupt, sudden death; however, one decedent expired after a rapidly deteriorating hospital course. PMID:24876364

  8. 26 CFR 5f.103-2 - Public approval of industrial development bonds.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 14 2010-04-01 2010-04-01 false Public approval of industrial development bonds... RESPONSIBILITY ACT OF 1982 § 5f.103-2 Public approval of industrial development bonds. (a) General rule. An... satisfies the public approval requirement of section 103(k) and paragraph (c) of this section or...

  9. Sac2/INPP5F is an inositol 4-phosphatase that functions in the endocytic pathway

    PubMed Central

    Nakatsu, Fubito; Messa, Mirko; Nández, Ramiro; Czapla, Heather; Zou, Yixiao; Strittmatter, Stephen M.

    2015-01-01

    The recruitment of inositol phosphatases to endocytic membranes mediates dephosphorylation of PI(4,5)P2, a phosphoinositide concentrated in the plasma membrane, and prevents its accumulation on endosomes. The importance of the conversion of PI(4,5)P2 to PtdIns during endocytosis is demonstrated by the presence of both a 5-phosphatase and a 4-phosphatase (Sac domain) module in the synaptojanins, endocytic PI(4,5)P2 phosphatases conserved from yeast to humans and the only PI(4,5)P2 phosphatases in yeast. OCRL, another 5-phosphatase that couples endocytosis to PI(4,5)P2 dephosphorylation, lacks a Sac domain. Here we show that Sac2/INPP5F is a PI4P phosphatase that colocalizes with OCRL on endocytic membranes, including vesicles formed by clathrin-mediated endocytosis, macropinosomes, and Rab5 endosomes. An OCRL–Sac2/INPP5F interaction could be demonstrated by coimmunoprecipitation and was potentiated by Rab5, whose activity is required to recruit Sac2/INPP5F to endosomes. Sac2/INPP5F and OCRL may cooperate in the sequential dephosphorylation of PI(4,5)P2 at the 5 and 4 position of inositol in a partnership that mimics that of the two phosphatase modules of synaptojanin. PMID:25869668

  10. 48 CFR 47.303-5 - F.o.b. origin, with differentials.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) Differentials for mode of... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. origin, with... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-5 F.o.b. origin,...

  11. 48 CFR 47.303-5 - F.o.b. origin, with differentials.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) Differentials for mode of... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false F.o.b. origin, with... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-5 F.o.b. origin,...

  12. 48 CFR 47.303-5 - F.o.b. origin, with differentials.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) Differentials for mode of... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false F.o.b. origin, with... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-5 F.o.b. origin,...

  13. 48 CFR 47.303-5 - F.o.b. origin, with differentials.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) Differentials for mode of... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false F.o.b. origin, with... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-5 F.o.b. origin,...

  14. Photophysical properties of ESIPT inspired fluorescent 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and its derivative: experimental and DFT based approach.

    PubMed

    Deshmukh, Mininath S; Sekar, Nagaiyan

    2015-01-25

    The excited-state intramolecular proton transfer chromophores 2-(2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione and 2-(4-(diethylamino)-2-hydroxyphenyl)-6-methylimidazo[4,5-f]isoindole-5,7(1H,6H)-dione are synthesized from 4,5-diamino-N-methylphthalimide. The photophysical behavior of the synthesized chromophores was studied using UV-visible and fluorescence spectroscopy in the polar and non-polar solvents. The synthesized o-hydroxyphenyl benzimidazole derivatives are fluorescent and very sensitive to the solvent polarity. These dyes are thermally stable up to 317 °C. Density Functional Theory computations have been used to understand the structural, molecular, electronic and photophysical properties of the chromophores. The experimental absorption and emission wavelengths are in good agreement with the computed vertical excitation and theoretical emission obtained by Density Functional Theory and Time Dependant Density Functional Theory. PMID:25108369

  15. Electronic States of Nickel Effected By Magnetic Doping

    NASA Astrophysics Data System (ADS)

    Podolak, Ken; Smith, Jamie

    2012-02-01

    Spin currents have a great potential to replace charge currents. This would revolutionize how we read/write information. The generation and switching of spin currents however must be well understood. Transport measurements suggest that magnetic impurities can alter the mean free path of carriers and thereby create spin currents. Angle-resolved photoemission is used to determine the change in the electronic states of Ni induced by doping with iron, chromium, and manganese near the Fermi Energy. The samples were single crystals of nickel(110) with variable amounts of dopant diffused into it. Alloy single crystals were used over epitaxial thin films due to the sharper features at the Fermi Energy that they produced. The mean free path, magnetic splitting, and carrier density are affected by a few percent of each of the dopants. Iron suppresses the mean free path of minority spins only, while chromium and manganese suppresses both spins and decreases the magnetic splitting. The strong variation of these affects from one impurity to the other supports the concept of tailoring spin transport by magnetic doping. [1] K. N. Altmann et al., Phys. Rev. Lett. 87, 137201 (2001) [2] K.R. Podolak, Ph.D. Thesis, Penn. State (2008)

  16. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    NASA Astrophysics Data System (ADS)

    Morini, Filippo; Watanabe, Noboru; Kojima, Masataka; Deleuze, Michael Simon; Takahashi, Masahiko

    2015-10-01

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b1, 6a1, 4b2, and 1a2 orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A1, B1, and B2 symmetries, which correspond to C-H stretching and H-C-H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  17. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state.

    PubMed

    Morini, Filippo; Watanabe, Noboru; Kojima, Masataka; Deleuze, Michael Simon; Takahashi, Masahiko

    2015-10-01

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b1, 6a1, 4b2, and 1a2 orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A1, B1, and B2 symmetries, which correspond to C-H stretching and H-C-H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing. PMID:26450316

  18. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    SciTech Connect

    Morini, Filippo; Deleuze, Michael Simon; Watanabe, Noboru; Kojima, Masataka; Takahashi, Masahiko

    2015-10-07

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b{sub 1}, 6a{sub 1}, 4b{sub 2}, and 1a{sub 2} orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A{sub 1}, B{sub 1}, and B{sub 2} symmetries, which correspond to C–H stretching and H–C–H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  19. Excited state structural dynamics in higher lying electronic states: S2 state of malachite green

    NASA Astrophysics Data System (ADS)

    Laptenok, Sergey P.; Addison, Kiri; Heisler, Ismael A.; Meech, Stephen R.

    2014-06-01

    The S2 fluorescence of malachite green is measured with sub 100 fs time resolution. Ultrafast spectral dynamics in the S2 state preceding S2 decay are resolved. Measurements in different solvents show that these sub 100 fs dynamics are insensitive to medium polarity and viscosity. They are thus assigned to ultrafast structural evolution between the S2 Franck-Condon and equilibrium configurations.

  20. The electron-furfural scattering dynamics for 63 energetically open electronic states.

    PubMed

    da Costa, Romarly F; do N Varella, Márcio T; Bettega, Márcio H F; Neves, Rafael F C; Lopes, Maria Cristina A; Blanco, Francisco; García, Gustavo; Jones, Darryl B; Brunger, Michael J; Lima, Marco A P

    2016-03-28

    We report on integral-, momentum transfer- and differential cross sections for elastic and electronically inelastic electron collisions with furfural (C5H4O2). The calculations were performed with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (N(open)) at either the static-exchange (N(open) ch-SE) or the static-exchange-plus-polarisation (N(open) ch-SEP) approximation was employed to calculate the scattering amplitudes at impact energies lying between 5 eV and 50 eV, using a channel coupling scheme that ranges from the 1ch-SEP up to the 63ch-SE level of approximation depending on the energy considered. For elastic scattering, we found very good overall agreement at higher energies among our SMCPP cross sections, our IAM-SCAR+I cross sections and the experimental data for furan (a molecule that differs from furfural only by the substitution of a hydrogen atom in furan with an aldehyde functional group). This is a good indication that our elastic cross sections are converged with respect to the multichannel coupling effect for most of the investigated intermediate energies. However, although the present application represents the most sophisticated calculation performed with the SMCPP method thus far, the inelastic cross sections, even for the low lying energy states, are still not completely converged for intermediate and higher energies. We discuss possible reasons leading to this discrepancy and point out what further steps need to be undertaken in order to improve the agreement between the calculated and measured cross sections. PMID:27036451

  1. The electron-furfural scattering dynamics for 63 energetically open electronic states

    NASA Astrophysics Data System (ADS)

    da Costa, Romarly F.; do N. Varella, Márcio T.; Bettega, Márcio H. F.; Neves, Rafael F. C.; Lopes, Maria Cristina A.; Blanco, Francisco; García, Gustavo; Jones, Darryl B.; Brunger, Michael J.; Lima, Marco A. P.

    2016-03-01

    We report on integral-, momentum transfer- and differential cross sections for elastic and electronically inelastic electron collisions with furfural (C5H4O2). The calculations were performed with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (Nopen) at either the static-exchange (Nopen ch-SE) or the static-exchange-plus-polarisation (Nopen ch-SEP) approximation was employed to calculate the scattering amplitudes at impact energies lying between 5 eV and 50 eV, using a channel coupling scheme that ranges from the 1ch-SEP up to the 63ch-SE level of approximation depending on the energy considered. For elastic scattering, we found very good overall agreement at higher energies among our SMCPP cross sections, our IAM-SCAR+I cross sections and the experimental data for furan (a molecule that differs from furfural only by the substitution of a hydrogen atom in furan with an aldehyde functional group). This is a good indication that our elastic cross sections are converged with respect to the multichannel coupling effect for most of the investigated intermediate energies. However, although the present application represents the most sophisticated calculation performed with the SMCPP method thus far, the inelastic cross sections, even for the low lying energy states, are still not completely converged for intermediate and higher energies. We discuss possible reasons leading to this discrepancy and point out what further steps need to be undertaken in order to improve the agreement between the calculated and measured cross sections.

  2. Binding sites, rotational conformers, and electronic states of Sc-C6H5X (X=F, CH3, OH, and CN) probed by pulsed-field-ionization electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Changhua; Krasnokutski, Serge A.; Zhang, Bing; Yang, Dong-Sheng

    2009-08-01

    Scandium (Sc) complexes of fluorobenzene (C6H5F), toluene (C6H5CH3), phenol (C6H5OH), and benzonitrile (C6H5CN) are produced in a laser-vaporization molecular beam source. These complexes are studied with pulsed-field-ionization zero-electron-kinetic-energy (ZEKE) spectroscopy and density functional theory calculations. Adiabatic ionization energies and low-frequency metal-ligand and ligand-based vibrational modes are measured from the ZEKE spectra. Metal binding sites and strengths and electronic states are obtained by comparing the ZEKE spectra with the theoretical calculations. The ionization energies of Sc-C6H5X (X=F, CH3, OH, and CN) follow the trend of CN>F>OH>CH3, whereas the bond energies are in the order of CN>CH3˜OH>F. The metal-ligand stretching frequency of Sc+-C6H5CN is nearly twice as those of the other three complexes. All neutral complexes are in low-spin doublet ground states and singly-charged cations are in singlet states. The preferred Sc binding site in these complexes are the phenyl ring with X=F, CH3, and OH and the nitrile group with CN. For the phenol complex, two rotational conformers are identified in different OH orientations.

  3. Harvesting singlet fission for solar energy conversion: one versus two-electron transfer electron transfer from the quantum superposition state

    NASA Astrophysics Data System (ADS)

    Chan, Wai-Lun; Tritsch, John; Zhu, Xiaoyang

    2013-03-01

    Singlet fission (SF) is being explored to increase the efficiency of organic photovoltaics. A key question is how to effectively extract multiple electron-hole pairs from multiple excitons with the presence of other competing channels such as electron transfer from the singlet state. Recent experiments on the pentacene and tetracene show that a quantum superposition of the singlet (S1) and multiexciton (ME) state is formed during SF. However, little is known about the kinetics of electron transfer from this quantum superposition. Here, we apply time-resolved photoemission spectroscopy to the tetracene/C60 interface to probe one and two electron transfer from S1 and ME states, respectively. Because of the relatively slow (7 ps) SF in tetracene, both one- and two-electron transfer are allowed. We show evidence for the formation of two distinct charge transfer states due to electron transfer from photo-excited tetracene to the lowest unoccupied molecular orbital (LUMO) and the LUMO+1 levels in C60. Kinetic analysis shows that 60% of the quantum superposition transfers one electron through the S1 state to C60 while 40% undergoes two-electron transfer through the ME state.

  4. Electronic ground state properties of Coulomb blockaded quantum dots

    NASA Astrophysics Data System (ADS)

    Patel, Satyadev Rajesh

    Conductance through quantum dots at low temperature exhibits random but repeatable fluctuations arising from quantum interference of electrons. The observed fluctuations follow universal statistics arising from the underlying universality of quantum chaos. Random matrix theory (RMT) has provided an accurate description of the observed universal conductance fluctuations (UCF) in "open" quantum dots (device conductance ≥e 2/h). The focus of this thesis is to search for and decipher the underlying origin of similar universal properties in "closed" quantum dots (device conductance ≤e2/ h). A series of experiments is presented on electronic ground state properties measured via conductance measurements in Coulomb blockaded quantum dots. The statistics of Coulomb blockade (CB) peak heights with zero and non-zero magnetic field measured in various devices agree qualitatively with predictions from Random Matrix Theory (RMT). The standard deviation of the peak height fluctuations for non-zero magnetic field is lower than predicted by RMT; the temperature dependence of the standard deviation of the peak height for non-zero magnetic field is also measured. The second experiment summarizes the statistics of CB peak spacings. The peak spacing distribution width is observed to be on the order of the single particle level spacing, Delta, for both zero and non-zero magnetic field. The ratio of the zero field peak spacing distribution width to the non-zero field peak spacing distribution width is ˜1.2; this is good agreement with predictions from spin-resolved RMT predictions. The standard deviation of the non-zero magnetic field peak spacing distribution width shows a T-1/2 dependence in agreement with a thermal averaging model. The final experiment summarizes the measurement of the peak height correlation length versus temperature for various quantum dots. The peak height correlation length versus temperature saturates in small quantum dots, suggesting spectral scrambling

  5. Delocalization and occupancy effects of 5f orbitals in plutonium intermetallics using L3-edge resonant X-ray emission spectroscopy

    SciTech Connect

    Booth, C. H.; Medling, S. A.; Jiang, Yu; Bauer, E. D.; Tobash, P. H.; Mitchell, J. N.; Veirs, D. K.; Wall, M. A.; Allen, P. G.; Kas, J. J.; Sokaras, D.; Nordlund, D.; Weng, T. -C.

    2014-06-24

    Although actinide (An) L3 -edge X-ray absorption near-edge structure (XANES) spectroscopy has been very effective in determining An oxidation states in insulating, ionically bonded materials, such as in certain coordination compounds and mineral systems, the technique fails in systems featuring more delocalized 5f orbitals, especially in metals. Recently, actinide L3-edge resonant X-ray emission spec- troscopy (RXES) has been shown to be an effective alternative. This technique is further demonstrated here using a parameterized partial unoccupied density of states method to quantify both occupancy and delocalization of the 5f orbital in ?-Pu, ?-Pu, PuCoGa5 , PuCoIn5 , and PuSb2. These new results, supported by FEFF calculations, highlight the effects of strong correlations on RXES spectra and the technique?s ability to differentiate between f-orbital occupation and delocalization.

  6. Novel magnetic and electronic states in manganite-iridate heterostructures

    NASA Astrophysics Data System (ADS)

    Nichols, John; Lee, Shinbuhm; Petrie, Jon; Meyer, Tricia; Gao, Xiang; Guo, Erjia; Freeland, John; Yi, Di; Liu, Jian; Haskel, Daniel; Ward, Thomas Zac; Eres, Gyula; Lauter, Valeria; Fitzsimmons, Michael R.; Lee, Ho Nyung

    Strong correlation between spin, charge, lattice, and orbital order parameters has proven to give rise to exotic physical phenomena, while epitaxial design of materials with strong interfacial coupling is an efficient technique to tune such parameters. Although there have been numerous studies of interfaces between 3 d-3 d and 4 d-3 d compounds, only few studies reported work on 3 d and 5 d materials and there has been no report on strong interfacial coupling in such systems. We have synthesized high quality [(AMnO3)m /(SrIrO3)n ]z (A = Sr, La) heterostructures by pulsed laser epitaxy on SrTiO3 (001) substrates and have observed interesting novel magnetic and electronic ground states, which are highly sensitive to the degree of dimensional confinement in the heterostructures. Based on studies with x-ray diffraction, SQUID, dc-transport, x-ray circular dichroism, and polarized neutron reflectometry measurements, we will report intriguing magnetic and transport properties that provide the first evidence of strong interfacial coupling between 5 d and 3 d materials. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  7. Electronic structure of proteins and DNA: solid-state aspects.

    PubMed

    Ladik, J J

    1978-01-01

    The generalization of the Hartree-Fock method to periodic systems (polymers or crystals) using a linear combination of atomic orbitals (LCAO) makes it possible to calculate ab initio self-consistent-field LCAO band structures of periodic protein and DNA models. The results obtained for polyglycine, polyalanine, and for the mixed poly(Gly-Ala) periodic chain, as well as for the four homopolynucleotides, are presented. The correction of these band structures for excitonic effects (in the excited state) and for long-range correlation effects is shown also. Furthermore, it is outlined how the short-range correlation in insulator biopolymers and correlation effects in proteins with a partially filled valence band (for instance, due to charge transfer) can be calculated. The Coherent Potential Approximation is outlined and its possible application to aperiodic proteins and DNA is pointed out. Finally the effect of an electron acceptor on proteins or of a chemical carcinogen bound to DNA is discussed as a local perturbation of the band structures of these systems on the basis of the self-consistent resolvent method. PMID:259504

  8. Overlap of electron core states for very high compressions

    NASA Astrophysics Data System (ADS)

    Straub, G.

    At normal density and for modest compressions, the electronic structure of a metal can be accurately described by treating the conduction electrons and their interactions with the usual methods of band theory. The core electrons remain essentially the same as for an isolated free atom and do not participate in the bonding forces responsible for creating a condensed phase. As the density increases, the core electrons begin to see one another as the overlap of the tails of wave functions can no longer be neglected. The electronic structure of the core electrons is responsible for an effective repulsive interaction that eventually becomes free-electron-like at very high compressions. The electronic structure of the interacting core electrons may be treated in a simple manner using the Atomic Surface Method (ASM). The ASM is a first-principles treatment of the electronic structure involving a rigorous integration of the Schroedinger equation within the atomic-sphere approximation. Solid phase wave functions are constructed from isolated atom wave functions and the band width W sub 1 and the center of gravity of the band C sub 1 are obtained from simple formulas. The ASM can also utilize analytic forms of the atomic wave functions and thus provide direct functional dependence of various aspects of the electronic structure. Of particular use in understanding the behavior of the core electrons, the ASM provides the analytic density dependence of the band widths and positions.

  9. Extraction of a steady state electron beam from HCD (hollow cathode discharge) plasmas for EBIS (electron beam ion source) applications

    SciTech Connect

    Hershcovitch, A.; Kovarik, V.; Prelec, K.

    1988-01-01

    Experiments to extract high brightness electron beams from hollow cathode discharge plasmas are now in progress. A unique feature of these plasmas, which in principle can facilitate the extraction of large current low emittance electron beams, is the existence of a relatively high energy electron population with a very narrow energy spread. This electron population was identified in a self-extraction experiment, which yielded a 35 eV, 600 mA electron beam with parallel energy spread of less than 0.5 eV. Preliminary, crude application of 2.5 kV extraction voltage yielded a steady state electron beam current of 1.2 A. The end result of this endeavor would be an Electron Beam Ion Source (EBIS) with an electron beam current of 6 A. 4 refs., 2 figs.

  10. Thermodynamic Properties of 4f- and 5f-SHELL Metals at Finite Temperatures:

    NASA Astrophysics Data System (ADS)

    Bhatt, N. K.; Vyas, P. R.; Jani, A. R.; Gohel, V. B.

    The thermodynamic properties of 4f- and 5f-shell metals have been studied at high temperatures using mean-field potential approach. The MFP seen by the lattice ion is constructed in terms of the total energy-volume relation using local pseudopotentials due to Pandya et al. [Physica B 307, 138 (2001)]. We have calculated static compression, shock-wave compression, volume thermal expansion, isothermal and adiabatic bulk moduli (BT and BS), specific heats (CV and CP), thermodynamic Grüneisen parameter (γth), anharmonic contribution to the specific heat and temperature along shock Hugoniot for 4f (γ-Ce)- and 5f (fcc-Th)-shell metals. The results are well compared with the other theoretical and experimental findings, which ensure the use of pseudopotentials for studying thermodynamic properties at higher temperatures in case of lanthanides and actinides.

  11. Electronic transport, density of states and ground state properties of Li In binary alloy

    NASA Astrophysics Data System (ADS)

    Kumar, Ashwani; Rafique, S. M.; Sinha, T. P.

    2008-10-01

    The electronic transport properties of Li-In binary alloy have been studied by Harrison's first principle pseudopotential technique. The Percus-Yevik hard sphere model is used to compute the partial structure factors S ij( k) for the alloy at the desired composition. We have also calculated the ground state properties of Li-In alloy employing full-potential linearized augmented plane wave (FLAPW) method. The equilibrium values of bulk modulus and its pressure derivative have been estimated through optimization of the crystal structure of the Li-In alloy. The calculated total density of states (DOS) and the partial DOS around the Fermi energy are used to explain the variation of resistivity of the alloy with carrier concentration.

  12. Minimal parametrization of an n-electron state

    SciTech Connect

    Kutzelnigg, Werner; Mukherjee, Debashis

    2005-02-01

    The Hamiltonian H for an n-electron system in a finite one-electron basis of dimension m is characterized by d=O(m{sup 4}) matrix elements. The eigenstates of this Hamiltonian - i.e., the full-CI states {psi} - depend, however, on the usually much larger set of N=O(m{sup n}) parameters. One can, nevertheless, write a full-CI state as {psi}=e{sup S}{phi} with {phi} a reference function and S an operator familiar from traditional coupled cluster (TCC) theory. The 'exact' operator S can be expressed (though in an implicit and rather complicated way) in terms of d parameters. An alternative ansatz {psi}=e{sup T}{phi} with T depending in a very simple way on d parameters only (namely, with T having the same structure in Fock space as H) has been studied by Nooijen and by Nakatsuji and been called coupled-cluster with generalized single and double excitations (CCGSD). Nooijen has conjectured that the full-CI equations can be fulfilled with this ansatz. This paper is devoted to a comprehensive analysis of the Nooijen conjecture (NC). Several features make this analysis difficult and even intriguing. (a) One deals with coupled nonlinear systems of equations, for which theorems concerning the existence of their solution are hardly available. (b) There are different possible interpretations of the NC, especially as far as the choice of the reference function {phi} is concerned. (c) There are solutions of the CCGSD equations, for which some elements of T becomes negative infinite, and e{sup T} becomes a projection operator. Such solutions are undesired but difficult to eliminate. We show by direct comparison of the exact wave operator with that of CCGSD theory, for a closed-shell state with {phi} a single Slater determinant, using a perturbation expansion, that CCGSD cannot be exact. This required a reformulation of the CCGSD operator e{sup T} to an equivalent exponential form e{sup R}, with R similar to the S of TCC theory, but with constraints on the cluster amplitudes

  13. Hyperglycemia and hyperlipidemia blunts the Insulin-Inpp5f negative feedback loop in the diabetic heart

    PubMed Central

    Bai, Danna; Zhang, Yajun; Shen, Mingzhi; Sun, Yongfeng; Xia, Qing; Zhang, Yingmei; Liu, Xuedong; Wang, Haichang; Yuan, Lijun

    2016-01-01

    The leading cause of death in diabetic patients is diabetic cardiomyopathy, in which alteration of Akt signal plays an important role. Inpp5f is recently found to be a negative regulator of Akt signaling, while its expression and function in diabetic heart is largely unknown. In this study, we found that in both the streptozotocin (STZ) and high fat diet (HFD) induced diabetic mouse models, Inpp5f expression was coordinately regulated by insulin, blood glucose and lipid levels. Increased Inpp5f was inversely correlated with the cardiac function. Further studies revealed that Insulin transcriptionally activated Inpp5f in an Sp1 dependent manner, and increased Inpp5f in turn reduced the phosphorylation of Akt, forming a negative feedback loop. The negative feedback plays a protective role under diabetic condition. However, high blood glucose and lipid, which are characteristics of uncontrolled diabetes and type 2 diabetes, increased Inpp5f expression through activation of NF-κB, blunts the protective feedback. Thus, our study has revealed that Inpp5f provides as a negative feedback regulator of insulin signaling and downregulation of Inpp5f in diabetes is cardioprotective. Increased Inpp5f by hyperglycemia and hyperlipidemia is an important mediator of diabetic cardiomyopathy and is a promising therapeutic target for the disease. PMID:26908121

  14. Involvement of 5f-orbitals in the bonding and reactivity of organoactinide compounds: thorium(IV) and uranium(IV) bis (hydrazonato) complexes

    SciTech Connect

    Cantat, Thibault; Graves, Christopher R; Morris, David E; Kiplinger, Jaqueline L

    2008-01-01

    Migratory insertion of diphenyldiazomethane into both metal-carbon bonds of the bis(alkyl) and bis(aryl) complexes (C5Me5)2AnR2 yields the first f-element bis(hydrazonato) complexes (C5Me5)2An[2-(N,N')-R-N-NCPh2]2 [An = Th, R = CH3 (18), PhCH2 (15), Ph (16); An = U, R = CH3 (17), PhCH2 (14)], which have been characterized by a combination of spectroscopy, electrochemistry, and X-ray crystallography. The two hydrazonato ligands adopt an 2-coordination mode leading to 20-electron (for Th) and 22-electron (for U) complexes that have no transition-metal analogues. In fact, reaction of (C5H5)2Zr(CH3)2 or (C5Me5)2Hf(CH3)2 with diphenyldiazomethane is limited to the formation of the corresponding mono(hydrazonato) complex (C5R5)2M[2-(N,N')-CH3-N-NCPh2](CH3) (M = Zr, R = H or M = Hf, R = CH3). The difference in the reactivities of the group 4 metal complexes and the actinides was used as a unique platform for investigating in depth the role of 5f orbitals on the reactivity and bonding in actinide organometallic complexes. The electronic structure of the (C5H5)2M[2-(N,N')-CH3-N-NCH2]2 (M = Zr, Th, U) model complexes was studied using density functional theory (DFT) calculations and compared to experimental structural, electrochemical, and spectroscopic results. Whereas transition-metal bis(cyclopentadienyl) complexes are known to stabilize three ligands in the metallocene girdle to form saturated (C5H5)2ML3 species, in a bis(hydrazonato) system, a fourth ligand is coordinated to the metal center to give (C5H5)2ML4. DFT calculations have shown that 5f orbitals in the actinide complexes play a crucial role in stabilizing this fourth ligand by stabilizing both the s and p electrons of the two 2-coordinated hydrazonato ligands. In contrast, the stabilization of the hydrazonato ligands was found to be significantly less effective for the putative bis(hydrazonato) zirconium(IV) complex, yielding a higher energy structure. However, the difference in the reactivities of the group 4

  15. Inhibition of insulin production by cyproheptadine in RINm5F rat insulinoma cells.

    PubMed

    Miller, C P; Reape, T J; Fischer, L J

    1993-09-01

    The clonal insulin producing cell line RINm5F was evaluated as a model for the action of cyproheptadine (CPH)-like diabetogenic compounds in the rat pancreas. Treatment with 10 microM CPH and selected structural analogs under culture conditions produced a progressive loss of cellular insulin which reached 30% of control within 24 hours. Comparison of the activities of the analogs 4-diphenylmethylpiperidine (4-DPMP) and 2-diphenylmethylpiperidine (2-DPMP) to produce cellular insulin depletion showed that 4-DPMP was as active as CPH but 2-DPMP had no activity at the highest concentration employed (10 microM). The CPH metabolite desmethyl CPH-epoxide was five times more active than the parent compound in producing loss of insulin in RINm5F cells. These results are consistent with previously published results of CPH actions in vivo. An inhibition of insulin biosynthesis with no loss of preproinsulin mRNA occurred in RINm5F cells treated with CPH or DMCPH-epoxide. This suggests that an effect on transcription may not be the primary action by which CPH and its analogs inhibit insulin synthesis in vivo. PMID:8263899

  16. Transduced Tat-DJ-1 protein inhibits cytokines-induced pancreatic RINm5F cell death.

    PubMed

    Jo, Hyo Sang; Yeo, Hyeon Ji; Cha, Hyun Ju; Kim, Sang Jin; Cho, Su Bin; Park, Jung Hwan; Lee, Chi Hern; Yeo, Eun Ji; Choi, Yeon Joo; Eum, Won Sik; Choi, Soo Young

    2016-05-01

    Loss of pancreatic β-cells by oxidative stress or cytokines is associated with diabetes mellitus (DM). DJ-1 is known to as a multifunctional protein, which plays an important role in cell survival. We prepared cell permeable wild type (WT) and mutant type (M26I) Tat-DJ-1 proteins to investigate the effects of DJ-1 against combined cytokines (IL-1β, IFN-γ and TNF-α)-induced RINm5F cell death. Both Tat-DJ-1 proteins were transduced into RINm5F cells. WT Tat-DJ-1 proteins significantly protected against cell death from cytokines by reducing intracellular toxicities. Also, WT Tat-DJ-1 proteins markedly regulated cytokines-induced pro- and anti-apoptosis proteins. However, M26I Tat-DJ-1 protein showed relatively low protective effects, as compared to WT Tat-DJ-1 protein. Our experiments demonstrated that WT Tat-DJ-1 protein protects against cytokine-induced RINm5F cell death by suppressing intracellular toxicities and regulating apoptosisrelated protein expression. Thus, WT Tat-DJ-1 protein could potentially serve as a therapeutic agent for DM and cytokine related diseases. [BMB Reports 2016; 49(5): 297-302]. PMID:26996344

  17. Azide interaction with 4f and 5f ions in aqueous solutions. I. Trivalent ions

    SciTech Connect

    Musikas, C.; Cuillerdier, C.; Livet, J.; Forchioni, A.; Chachaty, C.

    1983-08-31

    Solvent extraction and UV, Raman, and NMR spectroscopic studies were carried out on trivalent actinide and lanthanide aqueous azido complexes. Unlike trivalent d transition ions (..beta../sub 11/ approx. = 10/sup 5/) 5f and 4f aqueous azido complexes are weak (..beta../sub 11/ approx. = 2.5 for neodymium azide complexes (Nd(N/sub 3/)/sup 2 +/)), but the trivalent actinides exhibit formation constants 1 order of magnitude higher than the lanthanides. All the spectroscopic methods indicate that we are dealing with inner-sphere complexes and actinide-lanthanide differences must be attributed to higher covalent contributions in the 5f azides. /sup 15/N NMR combined with /sup 1/H NMR served to investigate the azide binding properties. With the trivalent 5f and 4f ions the binding occurs by one of the terminal nitrogen atoms. The M-N bond distance is close to 2.75 A. The lanthanide(III)-(linear azide) moieties are bent with a bond angle close to 135/sup 0/, unlike the homologous linear thiocyanate complexes. 7 figures, 4 tables.

  18. Separating the Spin States of a Free Electron Beam

    NASA Astrophysics Data System (ADS)

    Rifkin, Neil

    2008-10-01

    In 1922 Otto Stern and Walther Gerlach set out to test the spacial quantization of the electron by passing a beam of neutral silver atoms through a transverse magnetic field. The interaction of the two projections of the electron's magnetic moment with the magnetic field resulted in a splitting of the beam. However, for some sixty years it was generally accepted that the spin of free electrons, and thus their magnetic moment, could not be measured with an experiment similar to that of Stern and Gerlach. The reason being that the lorentz force on charged particles is far greater than the force due to the magnetic moment of the electron, thus blurring any desired results. To reduce the lorentz force, the electrons could be passed through a magnetic field whose gradient is in the direction of the electrons' momentum. This longitudinal Stern-Gerlach device, with a superconducting magnet, could polarize the tails of a low energy electron beam.

  19. On the electronic configuration in Pu: spectroscopy and theory

    SciTech Connect

    Tobin, J G; Soderlind, P; Landa, A; Moore, K T; Schwartz, A J; Chung, B W; Wall, M; Wills, J M; Eriksson, O; Haire, R; Kutepov, A L

    2006-10-11

    Photoelectron spectroscopy, synchrotron-radiation-based x-ray absorption, electron energy-loss spectroscopy, and density-functional calculations within the mixed-level and magnetic models, together with canonical band theory have been used to study the electron configuration in Pu. These methods suggest a 5f{sup n} configuration for Pu of 5 {le} n < 6, with n {ne} 6, contrary to what has recently been suggested in several publications. We show that the n = 6 picture is inconsistent with the usual interpretation of photoemission and x-ray absorption spectra. Instead, these spectra support the traditional conjecture of a 5f{sup 5} configuration in Pu as is obtained by density-functional theory. We further argue, based on 5f-band filling, that an n = 6 hypothesis is incompatible with the position of Pu in the actinide series and its monoclinic ground-state phase.

  20. The impacts of electronic state hybridization on the binding energy of single phosphorus donor electrons in extremely downscaled silicon nanostructures

    SciTech Connect

    The Anh, Le Manoharan, Muruganathan; Moraru, Daniel; Tabe, Michiharu; Mizuta, Hiroshi

    2014-08-14

    We present the density functional theory calculations of the binding energy of the Phosphorus (P) donor electrons in extremely downscaled single P-doped Silicon (Si) nanorods. In past studies, the binding energy of donor electrons was evaluated for the Si nanostructures as the difference between the ionization energy for the single P-doped Si nanostructures and the electron affinity for the un-doped Si nanostructures. This definition does not take into account the strong interaction of donor electron states and Si electron states explicitly at the conductive states and results in a monotonous increase in the binding energy by reducing the nanostructure's dimensions. In this paper, we introduce a new approach to evaluate the binding energy of donor electrons by combining the projected density of states (PDOS) analysis and three-dimensional analysis of associated electron wavefunctions. This enables us to clarify a gradual change of the spatial distribution of the 3D electron wavefunctions (3DWFs) from the donor electron ground state, which is fully localized around the P donor site to the first conductive state, which spreads over the outer Si nanorods contributing to current conduction. We found that the energy of the first conductive state is capped near the top of the atomistic effective potential at the donor site with respect to the surrounding Si atoms in nanorods smaller than about 27 a{sub 0}. This results in the binding energy of approximately 1.5 eV, which is virtually independent on the nanorod's dimensions. This fact signifies a good tolerance of the binding energy, which governs the operating temperature of the single dopant-based transistors in practice. We also conducted the computationally heavy transmission calculations of the single P-doped Si nanorods connected to the source and drain electrodes. The calculated transmission spectra are discussed in comparison with the atomistic effective potential distributions and the PDOS-3DWFs method.

  1. The impacts of electronic state hybridization on the binding energy of single phosphorus donor electrons in extremely downscaled silicon nanostructures

    NASA Astrophysics Data System (ADS)

    The Anh, Le; Moraru, Daniel; Manoharan, Muruganathan; Tabe, Michiharu; Mizuta, Hiroshi

    2014-08-01

    We present the density functional theory calculations of the binding energy of the Phosphorus (P) donor electrons in extremely downscaled single P-doped Silicon (Si) nanorods. In past studies, the binding energy of donor electrons was evaluated for the Si nanostructures as the difference between the ionization energy for the single P-doped Si nanostructures and the electron affinity for the un-doped Si nanostructures. This definition does not take into account the strong interaction of donor electron states and Si electron states explicitly at the conductive states and results in a monotonous increase in the binding energy by reducing the nanostructure's dimensions. In this paper, we introduce a new approach to evaluate the binding energy of donor electrons by combining the projected density of states (PDOS) analysis and three-dimensional analysis of associated electron wavefunctions. This enables us to clarify a gradual change of the spatial distribution of the 3D electron wavefunctions (3DWFs) from the donor electron ground state, which is fully localized around the P donor site to the first conductive state, which spreads over the outer Si nanorods contributing to current conduction. We found that the energy of the first conductive state is capped near the top of the atomistic effective potential at the donor site with respect to the surrounding Si atoms in nanorods smaller than about 27 a0. This results in the binding energy of approximately 1.5 eV, which is virtually independent on the nanorod's dimensions. This fact signifies a good tolerance of the binding energy, which governs the operating temperature of the single dopant-based transistors in practice. We also conducted the computationally heavy transmission calculations of the single P-doped Si nanorods connected to the source and drain electrodes. The calculated transmission spectra are discussed in comparison with the atomistic effective potential distributions and the PDOS-3DWFs method.

  2. Ultrafast electronic relaxation of excited state vitamin B 12 in the gas phase

    NASA Astrophysics Data System (ADS)

    Shafizadeh, Niloufar; Poisson, Lionel; Soep, Benoıˆt

    2008-06-01

    The time evolution of electronically excited vitamin B 12 (cyanocobalamin) has been observed for the first time in the gas phase. It reveals an ultrafast decay to a state corresponding to metal excitation. This decay is interpreted as resulting from a ring to metal electron transfer. This opens the observation of the excited state of other complex biomimetic systems in the gas phase, the key to the characterisation of their complex evolution through excited electronic states.

  3. Formation and nonlinear dynamics of the squeezed state of a helical electron beam with additional deceleration

    NASA Astrophysics Data System (ADS)

    Egorov, E. N.; Koronovskii, A. A.; Kurkin, S. A.; Hramov, A. E.

    2013-11-01

    Results of numerical simulations and analysis of the formation and nonlinear dynamics of the squeezed state of a helical electron beam in a vircator with a magnetron injection gun as an electron source and with additional electron deceleration are presented. The ranges of control parameters where the squeezed state can form in such a system are revealed, and specific features of the system dynamics are analyzed. It is shown that the formation of a squeezed state of a nonrelativistic helical electron beam in a system with electron deceleration is accompanied by low-frequency longitudinal dynamics of the space charge.

  4. Formation and nonlinear dynamics of the squeezed state of a helical electron beam with additional deceleration

    SciTech Connect

    Egorov, E. N. Koronovskii, A. A.; Kurkin, S. A.; Hramov, A. E.

    2013-11-15

    Results of numerical simulations and analysis of the formation and nonlinear dynamics of the squeezed state of a helical electron beam in a vircator with a magnetron injection gun as an electron source and with additional electron deceleration are presented. The ranges of control parameters where the squeezed state can form in such a system are revealed, and specific features of the system dynamics are analyzed. It is shown that the formation of a squeezed state of a nonrelativistic helical electron beam in a system with electron deceleration is accompanied by low-frequency longitudinal dynamics of the space charge.

  5. Stability of Surface State Electrons on Helium Films

    NASA Astrophysics Data System (ADS)

    Leiderer, P.; Scheer, E.; Kono, K.; Lin, J.-J.; Rees, D. G.

    2016-05-01

    Electrons on helium substrates form a model Coulomb system in which the transition from classical electron liquid to Wigner crystal is readily observed. However, attempts to increase the electron density in order to observe the `quantum melting' of the system to a Fermi degenerate gas are hindered by an instability of the helium surface. Here we describe experimental efforts to reach the degenerate regime on thin helium films and microstructured substrates, for which the surface instability is suppressed. We demonstrate that, although the electron densities obtained exceed those for bulk helium substrates, observation of quantum melting remains challenging. We discuss possible solutions to the technical challenges involved.

  6. Modeling of free electronic state density in hydrogenic plasmas based on nearest neighbor approximation

    SciTech Connect

    Nishikawa, Takeshi

    2014-07-15

    Most conventional atomic models in a plasma do not treat the effect of the plasma on the free-electron state density. Using a nearest neighbor approximation, the state densities in hydrogenic plasmas for both bound and free electrons were evaluated and the effect of the plasma on the atomic model (especially for the state density of the free electron) was studied. The model evaluates the electron-state densities using the potential distribution formed by the superposition of the Coulomb potentials of two ions. The potential from one ion perturbs the electronic state density on the other. Using this new model, one can evaluate the free-state density without making any ad-hoc assumptions. The resulting contours of the average ionization degree, given as a function of the plasma temperature and density, are shifted slightly to lower temperatures because of the effect of the increasing free-state density.

  7. Computational simulation and interpretation of the low-lying excited electronic states and electronic spectrum of thioanisole.

    PubMed

    Li, Shaohong L; Xu, Xuefei; Truhlar, Donald G

    2015-08-21

    Three singlet states, namely a closed-shell ground state and two excited states with (1)ππ* and (1)nσ* character, have been suggested to be responsible for the radiationless decay or photochemical reaction of photoexcited thioanisole. The correct interpretation of the electronic spectrum is critical for understanding the character of these low-lying excited states, but the experimental spectrum is yet to be fully interpreted. In the work reported here, we investigated the nature of those three states and a fourth singlet state of thioanisole using electronic structure calculations by multireference perturbation theory, by completely-renormalized equation-of-motion coupled cluster theory with single and double excitations and noniterative inclusion of connected triples (CR-EOM-CCSD(T)), and by linear-response time-dependent density functional theory (TDDFT). We clarified the assignment of the electronic spectrum by simulating it using a normal-mode sampling approach combined with TDDFT in the Tamm-Dancoff approximation (TDA). The understanding of the electronic states and of the accuracy of the electronic structure methods lays the foundation of our future work of constructing potential energy surfaces. PMID:26088195

  8. 78 FR 46686 - Privacy Act of 1974; Treasury/United States Mint .013-United States Mint National Electronic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-01

    ...In accordance with the requirements of the Privacy Act of 1974, as amended, 5 U.S.C. 552a, the Department of the Treasury (``Treasury'') and the United States Mint proposes to establish a new system of records entitled, ``Treasury/United States Mint .013--United States Mint National Electronic Incident Reporting System of...

  9. Structural evolution and valence electron-state change during ultra thin silicon-oxide growth

    NASA Astrophysics Data System (ADS)

    Shimizu, A.; Abe, S.; Nakayama, H.; Nishino, T.; Iida, S.

    2000-06-01

    We have studied valence electron-state changes of Si during initial oxidation of Si(111) clean surface, HF-treated Si(001) and Si(111) surfaces by Auger valence electron spectroscopy (AVES). The results showed that the valence electron-state changes during initial oxidation were sensitively reflected in Si[2s,2p,V] (V=3s,3p) AVES spectra and that they depended on both initial surface treatment and surface orientation. The local valence electron-states, local density of states in other words, showed the characteristic-structure evolution depending on the initial surface treatment and surface orientation.

  10. Excited electronic states of complex heteroatomic molecules in series and in different aggregation states of matter

    NASA Astrophysics Data System (ADS)

    Obukhov, Alexandr E.

    1995-01-01

    We investigate the spectroscopic and photophysical properties of new series complex molecules, which is capable of fluorescence and some generating light in solvents of various kinds within the wavelength region 308 - 420 nm with a high fluorescence quantum yield (gamma) equals 0.01 - 0.97 and a low threshold pump density Elp(Plp). We worked from the measured lifetimes and to calculate the rate constants for radiative decay (Kfl) and intercombinational conversion, (KST), the cross section for a stimulated emission ((sigma) 31osc), and the characteristic time tlp in solvents of various types and in the vapor. The latter is the limiting rise time of the pump pulse (tlp) at which the generation of electromagnetic radiation is still possible. The cross sections for the induced singlet-singlet ((sigma) 3S*) and triplet-triplet ((sigma) 2T*) absorption in the generation band, required for calculating tlp, were taken from a variety of sources: experimental and for all other complex molecules, we used results calculated by some semiempirical methods SCF MO LKAO the Pariser-Parr-Pople (PPP/CI) and in complete neglect of differential overlap (INDO/S-CI). The results show that the decrease or increase of in the switch from solution to vapor, or as the properties of the solvent change, stems from dynamic separation or overlap of the lasing and induced absorption bands of the S1* yields Sn* and T1 yields Tn transitions. Lasing does not occur in concentrated acids because of the nearly complete overlap of the limiting gain and induced absorption T1 yields Tn transitions (compare it with the behavior of dyes in their chemo absorbed state). Using the density matrix method, we show that the solvent affects the distribution of electron density among the individual atoms and fragments of the complex geteratomic molecule in the ground state, leading to systematic changes in geometry. As a result, there are changes in the distribution of bond lengths in the rings of the azo

  11. Ultrafast electronic state conversion at room temperature utilizing hidden state in cuprate ladder system

    PubMed Central

    Fukaya, R.; Okimoto, Y.; Kunitomo, M.; Onda, K.; Ishikawa, T.; Koshihara, S.; Hashimoto, H.; Ishihara, S.; Isayama, A.; Yui, H.; Sasagawa, T.

    2015-01-01

    Photo-control of material properties on femto- (10−15) and pico- (10−12) second timescales at room temperature has been a long-sought goal of materials science. Here we demonstrate a unique ultrafast conversion between the metallic and insulating state and the emergence of a hidden insulating state by tuning the carrier coherence in a wide temperature range in the two-leg ladder superconductor Sr14-xCaxCu24O41 through femtosecond time-resolved reflection spectroscopy. We also propose a theoretical scenario that can explain the experimental results. The calculations indicate that the holes injected by the ultrashort light reduce the coherence among the inherent hole pairs and result in suppression of conductivity, which is opposite to the conventional photocarrier-doping mechanism. By using trains of ultrashort laser pulses, we successively tune the carrier coherence to within 1 picosecond. Control of hole-pair coherence is shown to be a realistic strategy for tuning the electronic state on ultrafast timescales at room temperature. PMID:26481604

  12. Nonadiabtic electron dynamics in densely quasidegenerate states in highly excited boron cluster

    NASA Astrophysics Data System (ADS)

    Yonehara, Takehiro; Takatsuka, Kazuo

    2016-04-01

    Following the previous study on nonadiabatic reaction dynamics including boron clusters [T. Yonehara and K. Takatsuka, J. Chem. Phys. 137, 22A520 (2012)], we explore deep into highly excited electronic states of the singlet boron cluster (B12) to find the characteristic features of the densely quasi-degenerate electronic state manifold, which undergo very frequent nonadiabatic transitions and thereby intensive electronic state mixing among very many of the relevant states. So much so, isolating the individual adiabatic states and tracking the expected potential energy surfaces both lose the physical sense. This domain of molecular situation is far beyond the realm of the Born-Oppenheimer approximation. To survey such a violent electronic state-mixing, we apply a method of nonadiabatic electron wavepacket dynamics, the semiclassical Ehrenfest method. We have tracked those electron wavepackets and found the electronic state mixing looks like an ultrafast diffusion in the Hilbert space, which results in huge fluctuation. Furthermore, due to such a violent mixing, the quantum phases associated with the electronic states are swiftly randomized, and consequently the coherence among the electronic states are lost quickly. Besides, these highly excited states are mostly of highly poly-radical nature, even in the spin singlet manifold and the number of radicals amounts up to 10 electrons in the sense of unpaired electrons. Thus the electronic states are summarized to be poly-radical and decoherent with huge fluctuation in shorter time scales of vibrational motions. The present numerical study sets a theoretical foundation for unknown molecular properties and chemical reactivity of such densely quasi-degenerate chemical species.

  13. Nonadiabtic electron dynamics in densely quasidegenerate states in highly excited boron cluster.

    PubMed

    Yonehara, Takehiro; Takatsuka, Kazuo

    2016-04-28

    Following the previous study on nonadiabatic reaction dynamics including boron clusters [T. Yonehara and K. Takatsuka, J. Chem. Phys. 137, 22A520 (2012)], we explore deep into highly excited electronic states of the singlet boron cluster (B12) to find the characteristic features of the densely quasi-degenerate electronic state manifold, which undergo very frequent nonadiabatic transitions and thereby intensive electronic state mixing among very many of the relevant states. So much so, isolating the individual adiabatic states and tracking the expected potential energy surfaces both lose the physical sense. This domain of molecular situation is far beyond the realm of the Born-Oppenheimer approximation. To survey such a violent electronic state-mixing, we apply a method of nonadiabatic electron wavepacket dynamics, the semiclassical Ehrenfest method. We have tracked those electron wavepackets and found the electronic state mixing looks like an ultrafast diffusion in the Hilbert space, which results in huge fluctuation. Furthermore, due to such a violent mixing, the quantum phases associated with the electronic states are swiftly randomized, and consequently the coherence among the electronic states are lost quickly. Besides, these highly excited states are mostly of highly poly-radical nature, even in the spin singlet manifold and the number of radicals amounts up to 10 electrons in the sense of unpaired electrons. Thus the electronic states are summarized to be poly-radical and decoherent with huge fluctuation in shorter time scales of vibrational motions. The present numerical study sets a theoretical foundation for unknown molecular properties and chemical reactivity of such densely quasi-degenerate chemical species. PMID:27131547

  14. Serials and New Technology: The State of the "Electronic Journal."

    ERIC Educational Resources Information Center

    Piternick, Anne B.

    1989-01-01

    Reviews reasons why electronic journals have not replaced printed materials, and describes ways in which new technologies such as online searching, full text databases, facsimile transmission, optical disk, and other electronic storage methods are offering alternative methods of access to printed journals. Future technological developments and…

  15. Some Chemical and Electronic Considerations of Solid State Semiconductor Crystals.

    ERIC Educational Resources Information Center

    Hinitz, Herman J.

    1986-01-01

    Describes the trend toward the use of electronic instrumentation to monitor and measure various parameters in chemical reactions. Stresses that a knowledge of the operational relationships involved in such instruments is essential for students beginning in science. Discusses electrostatic charges, semiconductor crystals, electronic conductors,…

  16. Pulsed-field ionization zero electron kinetic energy spectrum of the ground electronic state of BeOBe+.

    PubMed

    Antonov, Ivan O; Barker, Beau J; Heaven, Michael C

    2011-01-28

    The ground electronic state of BeOBe(+) was probed using the pulsed-field ionization zero electron kinetic energy photoelectron technique. Spectra were rotationally resolved and transitions to the zero-point level, the symmetric stretch fundamental and first two bending vibrational levels were observed. The rotational state symmetry selection rules confirm that the ground electronic state of the cation is (2)Σ(g)(+). Detachment of an electron from the HOMO of neutral BeOBe results in little change in the vibrational or rotational constants, indicating that this orbital is nonbonding in nature. The ionization energy of BeOBe [65480(4) cm(-1)] was refined over previous measurements. Results from recent theoretical calculations for BeOBe(+) (multireference configuration interaction) were found to be in good agreement with the experimental data. PMID:21280724

  17. Pulsed-field ionization zero electron kinetic energy spectrum of the ground electronic state of BeOBe+

    NASA Astrophysics Data System (ADS)

    Antonov, Ivan O.; Barker, Beau J.; Heaven, Michael C.

    2011-01-01

    The ground electronic state of BeOBe+ was probed using the pulsed-field ionization zero electron kinetic energy photoelectron technique. Spectra were rotationally resolved and transitions to the zero-point level, the symmetric stretch fundamental and first two bending vibrational levels were observed. The rotational state symmetry selection rules confirm that the ground electronic state of the cation is 2Σg+. Detachment of an electron from the HOMO of neutral BeOBe results in little change in the vibrational or rotational constants, indicating that this orbital is nonbonding in nature. The ionization energy of BeOBe [65480(4) cm-1] was refined over previous measurements. Results from recent theoretical calculations for BeOBe+ (multireference configuration interaction) were found to be in good agreement with the experimental data.

  18. Fast probe of local electronic states in nanostructures utilizing a single-lead quantum dot

    PubMed Central

    Otsuka, Tomohiro; Amaha, Shinichi; Nakajima, Takashi; Delbecq, Matthieu R.; Yoneda, Jun; Takeda, Kenta; Sugawara, Retsu; Allison, Giles; Ludwig, Arne; Wieck, Andreas D.; Tarucha, Seigo

    2015-01-01

    Transport measurements are powerful tools to probe electronic properties of solid-state materials. To access properties of local electronic states in nanostructures, such as local density of states, electronic distribution and so on, micro-probes utilizing artificial nanostructures have been invented to perform measurements in addition to those with conventional macroscopic electronic reservoirs. Here we demonstrate a new kind of micro-probe: a fast single-lead quantum dot probe, which utilizes a quantum dot coupled only to the target structure through a tunneling barrier and fast charge readout by RF reflectometry. The probe can directly access the local electronic states with wide bandwidth. The probe can also access more electronic states, not just those around the Fermi level, and the operations are robust against bias voltages and temperatures. PMID:26416582

  19. Fast probe of local electronic states in nanostructures utilizing a single-lead quantum dot

    NASA Astrophysics Data System (ADS)

    Otsuka, Tomohiro; Amaha, Shinichi; Nakajima, Takashi; Delbecq, Matthieu R.; Yoneda, Jun; Takeda, Kenta; Sugawara, Retsu; Allison, Giles; Ludwig, Arne; Wieck, Andreas D.; Tarucha, Seigo

    2015-09-01

    Transport measurements are powerful tools to probe electronic properties of solid-state materials. To access properties of local electronic states in nanostructures, such as local density of states, electronic distribution and so on, micro-probes utilizing artificial nanostructures have been invented to perform measurements in addition to those with conventional macroscopic electronic reservoirs. Here we demonstrate a new kind of micro-probe: a fast single-lead quantum dot probe, which utilizes a quantum dot coupled only to the target structure through a tunneling barrier and fast charge readout by RF reflectometry. The probe can directly access the local electronic states with wide bandwidth. The probe can also access more electronic states, not just those around the Fermi level, and the operations are robust against bias voltages and temperatures.

  20. The Low-Lying Electronic States of LiB

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The spectroscopic constants for the triplet and singlet states of LiB below about 30 000/ cm are determined using an internally contracted multireference configuration interaction approach in conjunction with [6s 5p 3d 2f] atomic natural orbital basis sets. The ground state is (sup 3)Pi as found in previous work. No excited triplet states are found to be ideal for characterizing the ground state; the (1)(sup 3)Sigma(sup -) state has a transition energy that is too small for many experimental approaches and the (2)(sup 3)Pi and (3)(sup 3)Pi states have bond lengths that are significantly longer than the ground state, resulting in transition intensities that are spread out over many vibrational levels of the ground state.

  1. Electron impact spectroscopy. [for atom and molecule quantum state investigation

    NASA Technical Reports Server (NTRS)

    Trajmar, S.

    1980-01-01

    The concepts of electron impact spectroscopy are discussed, comparing the electron spectroscopy techniques with those of the optical spectroscopy. The main advantage of the electron spectroscopy is to be found in the elimination of optical selection rules in excitation processes and the ability to scan the spectrum from the infrared to the X-ray region. The range of the method is indicated through a review of several examples, including electron impact excitation of Ba and rotational excitation of H2. The sensitivity of the method is demonstrated by vibrational excitation spectrum of N2. It is shown that the application of the method to the inner-shell excitation allows to obtain information about molecular species which are not commonly available, while spectroscopy of negative ions yields information about their energy and symmetry properties. However, the techniques are still under development and more data are expected to become available in the coming years.

  2. Broadband 2D Electronic Spectroscopy Reveals Coupling Between Dark 1Bu- State of Carotenoid and Qx State of Bacteriochlorophyll

    NASA Astrophysics Data System (ADS)

    Ostroumov, Evgeny E.; Jumper, Chanelle C.; Mulvaney, Rachel M.; Cogdell, Richard J.; Scholes, Gregory D.

    2013-03-01

    The study of LH2 protein of purple bacteria by broadband 2D electronic spectroscopy is presented. The dark 1Bu- carotenoid state is directly observed in 2D spectra and its role in carotenoid-bacteriochlorophyll interaction is discussed.

  3. Anchor balloons assisted deep intubation of 5F catheters for uncrossable lesions.

    PubMed

    Zhang, S; Xu, K; Yang, N; Li, C

    2016-01-01

    A number of treatment strategies for complex coronary lesions have been utilized in varying clinical settings over the last decade. However, cardiologists still encounter some difficult scenarios such as variant coronary artery origins, severely calcified and highly tortuous lesions. We report four cases in which the stents failed to cross lesions using the conventional percutaneous coronary intervention techniques, but all the target lesions were successfully stented finally using a new combined technique of anchor balloon assisted deep intubation of 5F "child-in-mother" catheter. PMID:27022813

  4. State of the Art in Electronic Dosemeters for Neutrons

    SciTech Connect

    Luszik-Bhadra, Marlies

    2011-05-05

    The paper presents an overview of electronic personal dosemeters for neutrons in mixed neutron/photon fields. The energy response of commercially available electronic dosemeters in quasi-monoenergetic neutron fields and their performance in working places is discussed. The response curves are extended to high-energy neutrons up to 100 MeV, new prototype dosemeters are described and discussed especially for use at high-energy accelerators and in space.

  5. Excited State Electronic Properties of Sodium Iodide and Cesium Iodide

    SciTech Connect

    Campbell, Luke W.; Gao, Fei

    2013-05-01

    We compute from first principles the dielectric function, loss function, lifetime and scattering rate of quasiparticles due to electronic losses, and secondary particle spectrum due to plasmon decay in two scintillating alkali halides, sodium iodide and cesium iodide. Particular emphasis is placed on quasiparticles within several multiples of the band gap from the band edges. A theory for the decay spectra of plasmons and other electronic excitations in crystals is presented. Applications to Monte Carlo radiation transport codes are discussed.

  6. State of the Art in Electronic Dosemeters for Neutrons

    NASA Astrophysics Data System (ADS)

    Luszik-Bhadra, Marlies

    2011-05-01

    The paper presents an overview of electronic personal dosemeters for neutrons in mixed neutron/photon fields. The energy response of commercially available electronic dosemeters in quasi-monoenergetic neutron fields and their performance in working places is discussed. The response curves are extended to high-energy neutrons up to 100 MeV, new prototype dosemeters are described and discussed especially for use at high-energy accelerators and in space.

  7. Pt{sub 3}Au and PtAu clusters: Electronic states and potential energy surfaces

    SciTech Connect

    Dai, D.; Balasubramanian, K.

    1994-03-15

    We carried out complete active space multiconfiguration self-consistent-field calculations followed by multireference singles+doubles configuration interaction with the Davidson correction which included up to 3.55 million configurations employing relativistic effective core potentials on Pt{sub 3}+Au and PtAu clusters. Four low-lying electronic states were identified for Pt{sub 3}+Au. The {sup 2}{ital A}{sub 2} electronic state ({ital C}{sub 3{ital v}}) was found to be the ground state of Pt{sub 3}Au. Spin--orbit effects were found to be significant. We also computed six low-lying electronic states of PtAu and four low-lying electronic states of PtAu{sup +}. The 5/2 ({sup 2}{Delta}) and 0{sup +}({sup 1}{Sigma}{sup +}) states were found to be the ground states of PtAu and PtAu{sup +}, respectively.

  8. 77 FR 65379 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Wyoming

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title 40 of the CFR. CROMERR establishes electronic... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Wyoming...

  9. 75 FR 983 - Cross-Media Electronic Reporting Rule State Approved Program Revision/Modification Approvals...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-07

    ... Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as Part 3 of ] title 40... AGENCY Cross-Media Electronic Reporting Rule State Approved Program Revision/Modification Approvals... announces EPA's approval, under regulations for Cross-Media Electronic Reporting, of the State...

  10. The In-Gap Electronic State Spectrum of Methylammonium Lead Iodide Single-Crystal Perovskites.

    PubMed

    Adinolfi, Valerio; Yuan, Mingjian; Comin, Riccardo; Thibau, Emmanuel S; Shi, Dong; Saidaminov, Makhsud I; Kanjanaboos, Pongsakorn; Kopilovic, Damir; Hoogland, Sjoerd; Lu, Zheng-Hong; Bakr, Osman M; Sargent, Edward H

    2016-05-01

    The density of trap states within the bandgap of methylammonium lead iodide single crystals is investigated. Defect states close to both the conduction and valence bands are probed. Additionally, a comprehensive electronic characterization of crystals is carried out, including measurements of the electron and hole mobility, and the energy landscape (band diagram) at the surface. PMID:26932458

  11. Structures and electronic states of halogen-terminated graphene nano-flakes

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Iyama, Tetsuji

    2015-12-01

    Halogen-functionalized graphenes are utilized as electronic devices and energy materials. In the present paper, the effects of halogen-termination of graphene edge on the structures and electronic states of graphene flakes have been investigated by means of density functional theory (DFT) method. It was found that the ionization potential (Ip) and electron affinity of graphene (EA) are blue-shifted by the halogen termination, while the excitation energy is red-shifted. The drastic change showed a possibility as electronic devices such as field-effect transistors. The change of electronic states caused by the halogen termination of graphene edge was discussed on the basis of the theoretical results.

  12. Low-lying electronic excited states of pentacene oligomers: a comparative electronic structure study in the context of singlet fission.

    PubMed

    Coto, Pedro B; Sharifzadeh, Sahar; Neaton, Jeffrey B; Thoss, Michael

    2015-01-13

    The lowest-lying electronic excited states of pentacene and its oligomers are investigated using accurate multireference wave function methods (CASPT2/CASSCF) and the many-body Greens's function approach (GW/BSE). The results obtained for dimers and trimers of different geometry reveal a complex electronic structure, which includes locally excited, charge transfer, and multiexciton states. For singlets of single-excitation character, both approaches yield excitation energies that are in good overall quantitative agreement. While the multiexciton states are located relatively high in energy in all systems investigated, charge transfer states exist in close proximity to the lowest-lying absorbing states. The implications of the results for the mechanisms of singlet fission in pentacene are discussed. PMID:26574213

  13. Electron propagator calculations on the ground and excited states of C60(-).

    PubMed

    Zakrzewski, V G; Dolgounitcheva, O; Ortiz, J V

    2014-09-01

    Electron propagator calculations in two approximations—the third-order algebraic, diagrammatic construction and the outer valence Green’s function (OVGF)—have been performed on the vertical electron affinities of C60 and the vertical electron detachment energies of several states of C60(–) with a variety of basis sets. These calculations predict bound (2)T1u and (2)T1g anions, but fail to produce (2)T2u or (2)Hg anionic states that are more stable than ground-state C60. The electron affinity for the (2)Ag state is close to zero, but no definitive result on its sign has been obtained. This state may be a resonance or marginally bound anion. The OVGF prediction for the vertical electron detachment energy of (2)T1u C60(–), 2.63 eV, is in excellent agreement with recent anion photoelectron spectra. PMID:24813804

  14. Electron-impact excitation of the low-lying electronic states of HCN

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Tanaka, H.; Srivastava, S. K.; Wicke, B. G.

    1977-01-01

    The first study of the low-energy electron-impact excitation of low-lying electronic transitions in the HCN molecule is reported. Measurements were made at incident electron energies of 11.6 and 21.6 eV in the energy-loss range of 3-10 eV, and at scattering angles of 20-130 deg. Inelastic scattering spectra were placed on the absolute cross-section scale by determining first the ratio of inelastic-to-elastic scattering cross sections, and then separately measuring the absolute elastic scattering cross section. Several new electronic transitions are observed which are intrinsically overlapped in the molecule itself. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-sections measurements, high-energy electron scattering spectra, optical absorption spectra, and ab initio molecular orbital calculations.

  15. Gain in the non-steady-state free-electron laser

    SciTech Connect

    Wu, D.; Min, Y.

    1995-09-01

    The non-steady-state self-consistent equation in the linear regime of the free-electron laser (FEL) and the low gain formulas in the non-steady-state FEL are derived in this paper. It is found that due to slippage the nonuniformity effect in the longitudinal distribution of the electron beam density is dominant in the influence of the electron pulse length on the gain of the FEL. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  16. Present State of Electron Backscatter Diffraction and Prospective Developments

    SciTech Connect

    Schwarzer, R A; Field, D P; Adams, B L; Kumar, M; Schwartz, A J

    2008-10-24

    Electron backscatter diffraction (EBSD), when employed as an additional characterization technique to a scanning electron microscope (SEM), enables individual grain orientations, local texture, point-to-point orientation correlations, and phase identification and distributions to be determined routinely on the surfaces of bulk polycrystals. The application has experienced rapid acceptance in metallurgical, materials, and geophysical laboratories within the past decade (Schwartz et al. 2000) due to the wide availability of SEMs, the ease of sample preparation from the bulk, the high speed of data acquisition, and the access to complementary information about the microstructure on a submicron scale. From the same specimen area, surface structure and morphology of the microstructure are characterized in great detail by the relief and orientation contrast in secondary and backscatter electron images, element distributions are accessed by energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS), or cathodoluminescence analysis, and the orientations of single grains and phases can now be determined, as a complement, by EBSD.

  17. A new organic-inorganic hybrid oxyfluorotitanate [Hgua]2·(Ti5O5F12) as a transparent UV filter.

    PubMed

    Lhoste, J; Rocquefelte, X; Adil, K; Dessapt, R; Jobic, S; Leblanc, M; Maisonneuve, V; Bujoli-Doeuff, M

    2011-06-20

    A new generation UV absorber is obtained by microwave-heating-assisted hydrothermal synthesis: [Hgua](2)·(Ti(5)O(5)F(12)). The structure of this hybrid titanium(IV) oxyfluoride is ab initio determined from powder X-ray data by combining a direct space method, Rietveld refinement [orthorhombic, Cmm2, a = 22.410(1) Å, b = 11.191(1) Å, c = 3.802(1) Å], and density functional theory geometry optimization. The three-dimensional network is built up from infinite inorganic layers (∞)(Ti(5)O(5)F(12)) separated by guanidinium cations. The theoretical optical gap (3.2 eV) estimated from density of state calculations is in good agreement with the experimental gap (3.3 eV) obtained by UV-vis diffuse reflectivity. The optical absorption is mainly due to O(2p) → Ti(3d) and F(2p) → Ti(3d) transitions at higher energies. The refraction index is low in the visible range (n ≈ 1.9) compared to that of TiO(2) and, consequently, [Hgua](2)·(Ti(5)O(5)F(12)) shows a good transparency adapted to UV shielding. Under UV irradiation at 254 nm for 40 h, the white microcrystalline powder turns to light purple-gray. This color change is caused by the reduction of Ti(IV) to Ti(III), confirmed by magnetic measurements. PMID:21545091

  18. Entropy, fidelity, and double orthogonality for resonance states in two-electron quantum dots

    SciTech Connect

    Pont, Federico M.; Osenda, Omar; Serra, Pablo; Toloza, Julio H.

    2010-04-15

    Resonance states of a two-electron quantum dots are studied using a variational expansion with both real basis-set functions and complex scaling methods. The two-electron entanglement (linear entropy) is calculated as a function of the electron repulsion at both sides of the critical value, where the ground (bound) state becomes a resonance (unbound) state. The linear entropy and fidelity and double orthogonality functions are compared as methods for the determination of the real part of the energy of a resonance. The complex linear entropy of a resonance state is introduced using complex scaling formalism.

  19. Generation of tunable entangled states of two electrons and their characterization without entanglement witness

    NASA Astrophysics Data System (ADS)

    Chandra, N.; Ghosh, R.

    2004-12-01

    In this Rapid Communication, we show that a simple process of two-step double ionization taking place in an atom A , following the absorption of a single photon, produces a spin-entangled state of two electrons. The degree of entanglement of this state can be tuned to the desired value by selecting appropriate total spin quantum numbers of the electronic states of each of the three atomic species (i.e., A, A+ , A2+ ) participating in the process in Russell-Saunders coupling. These entangled states are readily characterized by measuring only energies of two emitted electrons, without requiring the entanglement witness, or any other such protocol.

  20. Does electron-transfer theory explain large rate differences in singlet and triplet excited state electron-transfer reactions?

    SciTech Connect

    Zusman, L.D.; Kurnikov, I.V.; Beratan, D.N.

    1995-12-31

    Gray and coworkers have shown that intramolecular electron-transfer rates from singlet and triplet excited states in iridium(spacer)pyridinium complexes can be vastly different (>5 orders of magnitude). We have analyzed the possible sources of these differences, including effects that may arise from reorganization energies, free energies, and tunneling matrix elements. When distance dependent reorganization energies and energy dependent tunneling matrix elements are included, a systematic framework emerges to describe these electron-transfer reactions.

  1. Relativistic electrons spin states and spin light in dense neutrino fluxes

    NASA Astrophysics Data System (ADS)

    Balantsev, Ilya; Studenikin, Alexander

    2016-05-01

    Relativistic electrons can produce electromagnetic radiation in moving background composed of neutrinos, that is the “spin light of electron in neutrino flux” (SLev ) [1, 2]. In this paper we further specify the electron quantum states in moving neutrino background by introdusing the electron spin operator that enables one to define the electron wave function in an exact and close form. This justifies our previous studies of SLev in dense neutrino fluxes and derivations of the electron energy spectrum, the radiation rate and power, and also the emitted photon energy. We argue that the SLev can have important consequences in different astrophysical settings.

  2. Excited states of a hydrated electron and aqueous chloride by computer simulation

    NASA Astrophysics Data System (ADS)

    Borgis, Daniel; Staib, Arnulf

    1994-12-01

    Results of adiabatic molecular dynamics simulations for a hydrated electron and the aqueous chloride anion are reported. A novel technical feature is the efficient representation of solute electronic wavefunctions in terms of floating spherical Gaussian orbitals. The simulations account for the coupling of the excess electron to the solvent electronic polarization in an explicit and self-consistent fashion. The computed electronic ground state absorption spectrum for e(-)/H2O and the charge-transfer-to-solvent spectra for Cl(-)/H2O are analyzed. The energetic aspects of the models and the short time solute electronic dynamics are discussed.

  3. Understanding the nuclear initial state with an electron ion collider

    NASA Astrophysics Data System (ADS)

    Toll, Tobias

    2013-09-01

    In these proceedings I describe how a future electron-ion collider will allow us to directly measure the initial spatial distribution of gluons in heavy ions, as well as its variance ("lumpiness") in exclusive diffraction. I show the feasibility of such a measurement by means of simulated data from the novel event generator Sartre.

  4. Determination and Comparison of Carbonyl Stretching Frequency of a Ketone in Its Ground State and the First Electronic Excited State

    ERIC Educational Resources Information Center

    Bandyopadhyay, Subhajit; Roy, Saswata

    2014-01-01

    This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…

  5. Control of the electronic ground state on an electron-transfer copper site by second-sphere perturbations.

    PubMed

    Morgada, Marcos N; Abriata, Luciano A; Zitare, Ulises; Alvarez-Paggi, Damian; Murgida, Daniel H; Vila, Alejandro J

    2014-06-10

    The Cu(A) center is a dinuclear copper site that serves as an optimized hub for long-range electron transfer in heme-copper terminal oxidases. Its electronic structure can be described in terms of a σ(u)* ground-state wavefunction with an alternative, less populated ground state of π(u) symmetry, which is thermally accessible. It is now shown that second-sphere mutations in the Cu(A) containing subunit of Thermus thermophilus ba3 oxidase perturb the electronic structure, which leads to a substantial increase in the population of the π(u) state, as shown by different spectroscopic methods. This perturbation does not affect the redox potential of the metal site, and despite an increase in the reorganization energy, it is not detrimental to the electron-transfer kinetics. The mutations were achieved by replacing the loops that are involved in protein-protein interactions with cytochrome c, suggesting that transient protein binding could also elicit ground-state switching in the oxidase, which enables alternative electron-transfer pathways. PMID:24777732

  6. Electronic states in epitaxial graphene fabricated on silicon carbide

    SciTech Connect

    Davydov, S. Yu.

    2011-08-15

    An analytical expression for the density of states of a graphene monolayer interacting with a silicon carbide surface (epitaxial graphene) is derived. The density of states of silicon carbide is described within the Haldane-Anderson model. It is shown that the graphene-substrate interaction results in a narrow gap of {approx}0.01-0.06 eV in the density of states of graphene. The graphene atom charge is estimated; it is shown that the charge transfer from the substrate is {approx}10{sup -3}-10{sup -2}e per graphene atom.

  7. The Low-Lying Electronic States of YCu

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The spectroscopic constants for the singlet and triplet states of YCu below about 15 000 per centimeter are determined using an internally contracted multireference configuration-interaction approach. These calculations are calibrated by studies of fewer states using higher levels of correlation treatment and/or larger basis sets. The computed T(sub e) values and radiative lifetimes are in reasonable agreement with experiment. The calculations confirm the previous experimental assignment for all but one state, where theory helps resolve between two possible assignments.

  8. A selection rule for the directions of electronic fluxes during unimolecular pericyclic reactions in the electronic ground state

    NASA Astrophysics Data System (ADS)

    Manz, Jörn; Yamamoto, Kentaro

    2012-05-01

    Unimolecular pericyclic reactions in a non-degenerate electronic ground state proceed under the constraint of zero electronic angular momentum. This restriction engenders a selection rule on the directions of electronic fluxes. Accordingly, clockwise or counter-clockwise fluxes are 'forbidden', whereas pincer-like fluxes (which consist of concerted clockwise and counter-clockwise fluxes) are 'allowed'. The selection rule is illustrated for three reactions: the degenerate Cope rearrangement of hexadiene, hydrogen transfer in malonaldehyde, and double proton transfer in the formic acid dimer.

  9. Electronic states and potential energy surfaces of rhodium carbide (RhC)

    NASA Astrophysics Data System (ADS)

    Tan, Hang; Liao, Muzhen; Balasubramanian, K.

    1997-12-01

    Potential energy curves and spectroscopic constants of 23 electronic states of the rhodium carbide (RhC) have been studied using the complete-active-space multi-configuration self-consistent field (CASMCSCF) followed by first-order configuration interaction (FOCI) calculations. Multi-reference singles + doubles configuration interaction (MRSDCI) were used to determine the properties of low-lying electronic states. The nature of chemical bond formation in different states is discussed in terms of their wave function and Mulliken populations.

  10. Microwave assisted SPPS of amylin and its toxicity of the pure product to RIN-5F cells.

    PubMed

    Muthusamy, Karen; Albericio, Fernando; Arvidsson, Per I; Govender, Patrick; Kruger, Hendrik G; Maguire, Glenn E M; Govender, Thavendran

    2010-01-01

    The 37-amino acid polypeptide islet amyloid polypeptide (IAPP), or amylin, is found as amyloid aggregates in the islets of Langerhans in patients with type II diabetes. Herein, we report an efficient microwave assisted solid phase peptide synthesis of amylin (IAPP). The most efficient synthesis used double and triple couplings and 10 equiv. of amino acids. Double couplings were used for most amino acids, whereas triple couplings were utilized for amino acids in selected regions. The most effective method for formation of the disulfide bond in amylin was found to be iodine oxidation. The highest purity amylin was obtained when the crude peptide was purified with HPLC before formation of the disulfide bond. The cytotoxicity of the synthesized amylin product to RIN-5F cells was determined. The synthesized amylin exhibits an exponential increase of cytotoxicity at concentrations >35 microM. Transmission electron microscope studies of a sample of amylin shows that insoluble amyloid fibrils spontaneously formed when 45 microM solution of synthesized amylin was incubated in a suitable buffer for 6 h. PMID:20069542

  11. Fluorinated Peptide Nucleic Acids with Fluoroacetyl Side Chain Bearing 5-(F/CF3)-Uracil: Synthesis and Cell Uptake Studies.

    PubMed

    Ellipilli, Satheesh; Palvai, Sandeep; Ganesh, Krishna N

    2016-08-01

    Fluorine incorporation into organic molecules imparts favorable physicochemical properties such as lipophilicity, solubility and metabolic stability necessary for drug action. Toward such applications using peptide nucleic acids (PNA), we herein report the chemical synthesis of fluorinated PNA monomers and biophysical studies of derived PNA oligomers containing fluorine in in the acetyl side chain (-CHF-CO-) bearing nucleobase uracil (5-F/5-CF3-U). The crystal structures of fluorinated racemic PNA monomers reveal interesting base pairing of enantiomers and packing arrangements directed by the chiral F substituent. Reverse phase HPLC show higher hydrophobicity of fluorinated PNA oligomers, dependent on the number and site of the fluorine substitution: fluorine on carbon adjacent to the carbonyl group induces higher lipophilicity than fluorine on nucleobase or in the backbone. The PNA oligomers containing fluorinated bases form hybrids with cDNA/RNA with slightly lower stability compared to that of unmodified aeg PNA, perhaps due to electronic effects. The uptake of fluorinated homooligomeric PNAs by HeLa cells was as facile as that of nonfluorinated PNA. In conjunction with our previous work on PNAs fluorinated in backbone and at N-terminus, it is evident that the fluorinated PNAs have potential to emerge as a new class of PNA analogues for applications in functional inhibition of RNA. PMID:27391099

  12. A DMC study on FePc electronic state

    NASA Astrophysics Data System (ADS)

    Ichibha, Tom; Hongo, Kenta; Maezono, Ryo

    We performed fixed-node DMC calculations on an isolated FePc [Iron(II) Phthalocyanine] using CASSCF nodal surfaces, getting its ground state, 3A2 g [dz22dxz, yz 2dxy2 ]. Virial ratios for each state are achieved to be within 0.042% around 2.0. Recent studies are proposing a mixed state with 3Eg (b) and 3B2 g as the ground state, while past ab-initio calculations are predicting 3A2 g or 3Eg (a) , giving still controversial arguments even within isolated/no-LS coupling model. Under D4 h ligand field parameter space, (10Dq , Dt, Ds), the state, 3A2 g , is reported to be possible as a ground state, while it is not when we restrict the space into 2-dim sub-space corresponding to more specified symmetry as in FePc with plane square alignment of neighboring N to Fe ('superposition model'). Our optimized geometry also satisfies the same symmetry, and hence appears to be contradicting to the ligand theory.

  13. Electronic state dependence of heterogeneous electron transfer: injection from the S1 and S2 state of phlorin into TiO2

    PubMed Central

    Nieto-Pescador, Jesus; Abraham, Baxter; Pistner, Allen J.; Rosenthal, Joel

    2016-01-01

    Ultrafast time-resolved measurements were performed on a novel pentafluorophenyl substituted 5,5-dimethyl phlorin derivative in solution and when attached to TiO2 colloidal films. The complex excited state dynamics of this porphyrinoid after S1 and S2 excitation was compared at different wavelengths and can be assigned to several subsequent relaxation mechanisms. The difference between excited state dynamics in the free molecule and when attached to an electron accepting electrode was measured. For both cases the dynamics was compared after excitation to the S1 and the S2 state. For the free molecule in solution an intermediate relaxation step was identified and assigned to a buckling motion of the tetrapyrrole ring. On the electrode, heterogeneous electron transfer (HET) times from both states were very similar and around 50 fs. Surprisingly, the large difference in the density of acceptor states that are resonant with the respective donor level of the molecule does not significantly influence HET dynamics. This result indicates that HET proceeds into intermediate transition states that are different from steady state surface states obtained from experiments or computations. The density of states (DOS) of these transient acceptor states appears not to be directly related to the corresponding surface or bulk DOS. PMID:25721314

  14. Strongly separated pairs of core electrons in computed ground states of small molecules

    PubMed Central

    Gottlieb, Alex D.; Weishäupl, Rada M.

    2013-01-01

    We have performed full configuration interaction computations of the ground states of the molecules Be, BeH2, Li, LiH, B, and BH and verified that the core electrons constitute “separated electron pairs.” These separated pairs of core electrons have nontrivial structure; the core pair does not simply occupy a single spatial orbital. Our method of establishing the presence of separated electron pairs is direct and conclusive. We do not fit a separated pair model; we work with the wavefunctions of interest directly. To establish that a given group of spin–orbitals contains a quasi-separated pair, we verify by direct computation that the quantum state of the electrons that occupy those spin–orbitals is nearly a pure 2-electron state. PMID:23459686

  15. Charge-state dependence of kinetic electron emission induced by slow ions in metals

    SciTech Connect

    Juaristi, J.I.; Dubus, A.; Roesler, M.

    2003-07-01

    A calculation is performed in order to analyze the charge-state dependence of the kinetic electron emission induced by slow ions in metals. All stages of the emission process are included: the excitation of the electrons, the neutralization of the projectile during its passage through the solid, and the transport of the excited electrons from where they are created to the surface. It is shown that the number of excited electrons depends strongly on the ion charge state. Nevertheless, due to the fast neutralization of the ions within the escape depth of the excited electrons, no significant initial charge-state dependence is expected in the kinetic electron yield. This result is consistent with available experimental data.

  16. Fast coherent manipulation of three-electron states in a double quantum dot

    NASA Astrophysics Data System (ADS)

    Shi, Zhan; Simmons, C. B.; Ward, Daniel R.; Prance, J. R.; Wu, Xian; Koh, Teck Seng; Gamble, John King; Savage, D. E.; Lagally, M. G.; Friesen, Mark; Coppersmith, S. N.; Eriksson, M. A.

    2014-01-01

    An important goal in the manipulation of quantum systems is the achievement of many coherent oscillations within the characteristic dephasing time T2*. Most manipulations of electron spins in quantum dots have focused on the construction and control of two-state quantum systems, or qubits, in which each quantum dot is occupied by a single electron. Here we perform quantum manipulations on a system with three electrons per double quantum dot. We demonstrate that tailored pulse sequences can be used to induce coherent rotations between three-electron quantum states. Certain pulse sequences yield coherent oscillations fast enough that more than 100 oscillations are visible within a T2* time. The minimum oscillation frequency we observe is faster than 5 GHz. The presence of the third electron enables very fast rotations to all possible states, in contrast to the case when only two electrons are used, in which some rotations are slow.

  17. Polarized electron correlations near auto-ionizing states of zinc atoms

    NASA Astrophysics Data System (ADS)

    Williams, James; Pravica, Luka; Samarin, Sergey

    2015-09-01

    Multi-electron metal atoms find new applications in diverse structures with spin and momentum-dependent properties having significance in determining material functionalities. Electron correlations effects are determined from scattering kinematics of spin-polarized electrons exciting zinc atoms near autoionizing states up to 16 eV. Previous studies of the 4p 3 , 1P1 , 4 d,5 d,6d3D1 , 2 , 3 and 4 d,5d1D1 excited states observed photon decay intensities and scattered electron energies and angles in the energy region of the 3d94s24 p autoionizing states up to 12 eV. Strong electron correlations and active roles of 3 d electrons were evident. Our observations of the 53S excited state for electron energies up to 16 eV show dominant 3 d core-excited negative-ion resonances and strong Post-Collision Interaction (PCI). For low energies of scattered and ejected electrons, after near-threshold excitation of the 3d94s24 p autoionizing states, a large transfer of orbital angular momentum is evident. Results include angular differential elastic scattering and excitation functions, ``integrated'' Stokes polarization parameters and spin up/down asymmetries indicating spin-orbit interaction and electron exchange effects. School of Physics

  18. Meissner Effect of Dirac Electrons in Superconducting State Due to Inter-Band Effect

    NASA Astrophysics Data System (ADS)

    Mizoguchi, Tomonari; Ogata, Masao

    2015-08-01

    Dirac electrons in solids show characteristic physical properties due to their linear dispersion relation and two-band nature. Although the transport phenomena of Dirac electrons in a normal state have intensively been studied, the transport phenomena in a superconducting state have not been fully understood. In particular, it is not clear whether Dirac electrons in a superconducting state show Meissner effect (ME), since a diamagnetic term of a current operator is absent as a result of the linear dispersion. We investigate the ME of three dimensional massive Dirac electrons in a superconducting state on the basis of Kubo formula, and clarify that Meissner kernel becomes finite by use of the inter-band contribution. This mechanism of the ME for Dirac electrons is completely different from that for the electrons in usual metals. Our result shows that the Meissner kernel remains finite even when the superconducting gap vanishes. This is an unavoidable problem in the Dirac electron system as reported in the previous works. Thus, we use a prescription in which we subtract the normal state contribution. In order to justify this prescription, we develop a specific model where the Meissner kernel is obtained by the prescription. We also derive the result for the electron gas by taking the non-relativistic limit of Dirac Hamiltonian, and clarify that the diamagnetic term of the Meissner kernel can be regarded as the inter-band contribution between electrons and positrons in terms of the Dirac model.

  19. Electron impact excitation of autoionising states of krypton

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.; Trajmar, S.

    1978-01-01

    Energy-loss spectra of krypton in the region between 21 and 29 eV have been obtained at electron impact energies of 30, 60 and 100 eV. For each energy, the angular distribution of intensities has been measured at 5, 10 and 15 deg scattering angles. Assignments of spectral features found in this region are suggested and a comparison is made with previous measurements.

  20. Determination of state-to-state electron-impact rate coefficients between Ar excited states: a review of combined diagnostic experiments in afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Zhu, Xi-Ming; Cheng, Zhi-Wen; Carbone, Emile; Pu, Yi-Kang; Czarnetzki, Uwe

    2016-08-01

    Electron-impact excitation processes play an important role in low-temperature plasma physics. Cross section and rate coefficient data for electron-impact processes from the ground state to excited states or between two excited states are required for both diagnostics and modeling works. However, the collisional processes between excited states are much less investigated than the ones involving the ground state due to various experimental challenges. Recently, a method for determining electron excitation rate coefficients between Ar excited states in afterglow plasmas was successfully implemented and further developed to obtain large sets of collisional data. This method combines diagnostics for electron temperature, electron density, and excited species densities and kinetic modeling of excited species, from which the electron excitation rate coefficients from one of the 1s states to the other 1s states or to one of 2p or 3p states are determined (states are in Paschen’s notation). This paper reviews the above method—namely the combined diagnostics and modeling in afterglow plasmas. The results from other important approaches, including electron-beam measurement of cross sections, laser pump-probe technique for measuring rate coefficients, and theoretical calculations by R-matrix and distorted-wave models are also discussed. From a comparative study of these results, a fitted mathematical expression of excitation rate coefficients is obtained for the electron temperature range of 1–5 eV, which can be used for the collisional-radiative modeling of low-temperature Ar plasmas. At last, we report the limitations in the present dataset and give some suggestions for future work in this area.

  1. Exotic Self-trapped States of an Electron in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Elser, Veit

    2015-09-01

    We explore the possibility that the fast and exotic negative ions in superfluid helium are electrons bound to quantized vortex structures, the simplest being a ring. In the states we consider, the electron energy is only slightly below the conduction band minimum of bulk helium. To support our proposal, we present two calculations. In the first, we show that the electron pressure on the vortex core is insufficient to cavitate the helium and form an electron bubble. In the second, we estimate the equilibrium radius of the vortex ring that would bind an electron and find it is much smaller than the electron bubble, about 7 Å. The many exotic ions reported in experiments might be bound states of an electron with more complex vortex structures.

  2. Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

    SciTech Connect

    Huang, Danhong; Gumbs, Godfrey; Abranyos, Yonatan; Pepper, Michael; Kumar, Sanjeev

    2015-11-15

    For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

  3. 78 FR 24386 - Electronic Fund Transfers; Determination of Effect on State Laws (Maine and Tennessee)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ... with the Bureau's rules on disclosure of records and information. See 12 CFR part 1070. \\6\\ 77 FR 50404... PROTECTION Electronic Fund Transfers; Determination of Effect on State Laws (Maine and Tennessee) AGENCY..., identified a different kind of conflict between Federal and State law. This commenter stated that...

  4. Self-Assembly of Hexanuclear Clusters of 4f and 5f Elements with Cation Specificity

    SciTech Connect

    Diwu, J.; Good, Justin J.; DiStefano, Victoria H.; Albrecht-Schmitt, Thomas E.

    2011-02-10

    Six hexanuclear clusters of 4f and 5f elements were synthesized by room-temperature slow concentration experiments. Cerium(IV), thorium(IV), and plutonium(IV) each form two different hexanuclear clusters, among which the cerium and plutonium clusters are isotypic, whereas the thorium clusters show more diversity. The change in ionic radii of approximately 0.08 Å between these different metal ions tunes the cavity size so that NH{sub 4}{sup +} (1.48 Å) has the right dimensions to assemble the cerium and plutonium clusters, whereas Cs{sup +} (1.69 Å) is necessary to assemble the thorium clusters. If these cations are not used in the reactions, only amorphous material is obtained.

  5. Quasi-One-Dimensional Electronic States Inside and Outside Helium-Plated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Motta, M.; Galli, D. E.; Liebrecht, M.; Del Maestro, A.; Cole, M. W.

    2016-06-01

    About one-half a century ago, it was realized that electrons experience a repulsive barrier when approaching the surface of condensed phases of helium, hydrogen, and neon. This led to the proposal and subsequent observation of image-potential surface-bound electronic states, which exhibit intriguing quasi-two-dimensional behavior. In the present work, we report similar quasi-one-dimensional electronic states by exploring single-wall carbon nanotubes coated both inside and outside by thin helium films. Electrons near such structures are localized in the radial direction, but free to move along the nanotube axis. The many-body aspects of the system are discussed qualitatively.

  6. The low-lying electronic states of LiC

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The spectroscopic constants for the doublet and quartet states of LiC below about 30,000/cm are determined using an internally contracted multireference configuration-interaction approach in conjunction with a [6s 5p 3d 2f] atomic natural orbital basis sets. All of the strongly bound states, X(sup 4)(SIGMA)(sup -),(1)(sup 2)(DELTA), (1)(sup 2)(SIGMA)(sup +), and (2)(sup 2) II, very ionic in character. The only bound-bound quartet transition in this energy range is (2)(sup 4)SIGMA(sup -) and Franck-Condon factors, Einstein A values, and lifetimes are reported for this transition.

  7. Promoter analysis of the rabbit POU5F1 gene and its expression in preimplantation stage embryos

    PubMed Central

    Kobolak, Julianna; Kiss, Katalin; Polgar, Zsuzsanna; Mamo, Solomon; Rogel-Gaillard, Claire; Tancos, Zsuzsanna; Bock, Istvan; Baji, Arpad G; Tar, Krisztina; Pirity, Melinda K; Dinnyes, Andras

    2009-01-01

    Background The POU5F1 gene encodes the octamer-binding transcription factor-4 (Oct4). It is crucial in the regulation of pluripotency during embryonic development and widely used as molecular marker of embryonic stem cells (ESCs). The objective of this study was to identify and to analyse the promoter region of rabbit POU5F1 gene; furthermore to examine its expression pattern in preimplantation stage rabbit embryos. Results The upstream region of rabbit POU5F1 was subcloned sequenced and four highly conserved promoter regions (CR1-4) were identified. The highest degree of similarity on sequence level was found among the conserved domains between rabbit and human. Among the enhancers the proximal enhancer region (PE-1A) exhibited the highest degree of homology (96.4%). Furthermore, the CR4 regulator domain containing the distal enhancer (DE-2A) was responsible for stem cell-specific expression. Also, BAC library screen revealed the existence of a processed pseudogene of rabbit POU5F1. The results of quantitative real-time PCR experiments showed that POU5F1 mRNA was abundantly present in oocytes and zygotes, but it was gradually reduced until the activation of the embryonic genome, thereafter a continuous increase in POU5F1 mRNA level was observed until blastocyst stage. By using the XYClone laser system the inner cell mass (ICM) and trophoblast portions of embryos were microdissected and examined separately and POU5F1 mRNA was detected in both cell types. Conclusion In this study we provide a comparative sequence analysis of the regulatory region of rabbit POU5F1 gene. Our data suggest that the POU5F1 gene is strictly regulated during early mammalian development. We proposed that the well conserved CR4 region containing the DE-2A enhancer is responsible for the highly conserved ESC specific gene expression. Notably, we are the first to report that the rabbit POU5F1 is not restricted to ICM cells only, but it is expressed in trophoblast cells as well. This

  8. Study of low-lying electronic states of ozone by anion photoelectron spectroscopy of O - 3

    NASA Astrophysics Data System (ADS)

    Arnold, Don W.; Xu, Cangshan; Kim, Eun H.; Neumark, Daniel M.

    1994-07-01

    The low-lying electronic states of ozone are studied using anion photoelectron spectroscopy of O-3. The spectra show photodetachment transitions from O-3 to the X˜ 1A1 ground state and to the five lowest lying electronic states of the ozone molecule, namely the 3A2, 3B2, 1A2, 3B1, and 1B1 states. The geometry of the ozonide anion determined from a Franck-Condon analysis of the O3 X 1A1 ground state spectrum agrees reasonably well with previous work. The excited state spectra are dominated by bending vibrational progressions which, for some states, extend well above the dissociation asymptote without noticeable lifetime broadening effects. Preliminary assignments are based upon photoelectron angular distributions and comparison with ab initio calculations. None of the excited states observed lies below the ground state dissociation limit of O3 as suggested by previous experimental and theoretical results.

  9. Quantitative Electron Probe Microanalysis: State of the Art

    NASA Technical Reports Server (NTRS)

    Carpernter, P. K.

    2005-01-01

    Quantitative electron-probe microanalysis (EPMA) has improved due to better instrument design and X-ray correction methods. Design improvement of the electron column and X-ray spectrometer has resulted in measurement precision that exceeds analytical accuracy. Wavelength-dispersive spectrometer (WDS) have layered-dispersive diffraction crystals with improved light-element sensitivity. Newer energy-dispersive spectrometers (EDS) have Si-drift detector elements, thin window designs, and digital processing electronics with X-ray throughput approaching that of WDS Systems. Using these systems, digital X-ray mapping coupled with spectrum imaging is a powerful compositional mapping tool. Improvements in analytical accuracy are due to better X-ray correction algorithms, mass absorption coefficient data sets,and analysis method for complex geometries. ZAF algorithms have ban superceded by Phi(pz) algorithms that better model the depth distribution of primary X-ray production. Complex thin film and particle geometries are treated using Phi(pz) algorithms, end results agree well with Monte Carlo simulations. For geological materials, X-ray absorption dominates the corretions end depends on the accuracy of mass absorption coefficient (MAC) data sets. However, few MACs have been experimentally measured, and the use of fitted coefficients continues due to general success of the analytical technique. A polynomial formulation of the Bence-Albec alpha-factor technique, calibrated using Phi(pz) algorithms, is used to critically evaluate accuracy issues and can be also be used for high 2% relative and is limited by measurement precision for ideal cases, but for many elements the analytical accuracy is unproven. The EPMA technique has improved to the point where it is frequently used instead of the petrogaphic microscope for reconnaissance work. Examples of stagnant research areas are: WDS detector design characterization of calibration standards, and the need for more complete

  10. The Low-Lying Electronic States of Mg2(+)

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.

    1994-01-01

    The low-lying doublet and quartet states of Mg+ have been studied using a multireference configuration interaction approach. The effect of inner-shell correlation has been included using the core-polarization potential method. The computed spectroscopic constants, lifetimes, and oscillator strengths should help resolve the difference between the recent experiments and previous theoretical calculations.

  11. An Expressed Retrogene of the Master Embryonic Stem Cell Gene POU5F1 Is Associated with Prostate Cancer Susceptibility

    PubMed Central

    Breyer, Joan P.; Dorset, Daniel C.; Clark, Travis A.; Bradley, Kevin M.; Wahlfors, Tiina A.; McReynolds, Kate M.; Maynard, William H.; Chang, Sam S.; Cookson, Michael S.; Smith, Joseph A.; Schleutker, Johanna; Dupont, William D.; Smith, Jeffrey R.

    2014-01-01

    Genetic association studies of prostate and other cancers have identified a major risk locus at chromosome 8q24. Several independent risk variants at this locus alter transcriptional regulatory elements, but an affected gene and mechanism for cancer predisposition have remained elusive. The retrogene POU5F1B within the locus has a preserved open reading frame encoding a homolog of the master embryonic stem cell transcription factor Oct4. We find that 8q24 risk alleles are expression quantitative trait loci correlated with reduced expression of POU5F1B in prostate tissue and that predicted deleterious POU5F1B missense variants are also associated with risk of transformation. POU5F1 is known to be self-regulated by the encoded Oct4 transcription factor. We further observe that POU5F1 expression is directly correlated with POU5F1B expression. Our results suggest that a pathway critical to self-renewal of embryonic stem cells may also have a role in the origin of cancer. PMID:24581739

  12. Ozone absorption spectroscopy in search of low-lying electronic states

    NASA Technical Reports Server (NTRS)

    Anderson, S. M.; Mauersberger, K.

    1995-01-01

    A spectrometer capable of detecting ozone absorption features 9 orders of magnitude weaker than the Hartley band has been employed to investigate the molecule's near-infrared absorption spectrum. At this sensitivity a wealth of information on the low-lying electronically excited states often believed to play a role in atmospheric chemistry is available in the form of vibrational and rotational structure. We have analyzed these spectra using a combination of digital filtering and isotope substitution and find evidence for three electronically excited states below 1.5 eV. The lowest of these states is metastable, bound by approximately 0.1 eV and probably the (3)A2 rather than the (3)B2 state. Its adiabatic electronic energy is 1.24 +/- 0.01 eV, slightly above the dissociation energy of the ground state. Two higher states, at 1.29 +/- 0.03 and 1.48 +/- 0.03 eV are identified as the (3)B2 and the (3)B1, respectively. Combined with other recent theoretical and experimental data on the low-lying electronic states of ozone, these results imply that these are, in fact, the lowest three excited states; that is, there are no electronically excited states of ozone lying below the energy of O(3P) + O2((3)Sigma(-), v = 0). Some of the implications for atmospheric chemistry are considered.

  13. Characterizing the Locality of Diabatic States for Electronic Excitation Transfer by Decomposing the Diabatic Coupling

    SciTech Connect

    Vura-Weis, Josh; Newton, M. D.; Wasielewski, Michael R; Subotnik, J.E.

    2010-12-09

    A common strategy to calculate electronic coupling matrix elements for charge or energy transfer is to take the adiabatic states generated by electronic structure computations and rotate them to form localized diabatic states. In this paper, we show that, for intermolecular transfer of singlet electronic excitation, usually we cannot fully localize the electronic excitations in this way. Instead, we calculate putative initial and final states with small excitation tails caused by weak interactions with high energy excited states in the electronic manifold. These tails do not lead to substantial changes in the total diabatic coupling between states, but they do lead to a different partitioning of the total coupling between Coulomb (Förster), exchange (Dexter), and one-electron components. The tails may be reduced by using a multistate diabatic model or eliminated entirely by truncation (denoted as “chopping”). Without more information, we are unable to conclude with certainty whether the observed diabatic tails are a physical reality or a computational artifact. This research suggests that decomposition of the diabatic coupling between chromophores into Coulomb, exchange, and one-electron components may depend strongly on the number of states considered, and such results should be treated with caution.

  14. UDP-(5F)-GlcNAc acts as a slow-binding inhibitor of MshA, a retaining glycosyltransferase.

    PubMed

    Frantom, Patrick A; Coward, James K; Blanchard, John S

    2010-05-19

    Glycosyltransferase enzymes play important roles in numerous cellular pathways. Despite their participation in many therapeutically relevant pathways, there is a paucity of information on how to effectively inhibit this class of enzymes. Here we report that UDP-(5F)-GlcNAc acts as a slow-binding, competitive inhibitor of the retaining glycosyltransferase MshA from Corynebacterium glutamicum (K(i) approximately 1.6 muM). The kinetic data are consistent with a single-step inhibition mechanism whose equilibration is slow relative to catalysis. We believe that this is the first slow-onset inhibitor to be reported for the glycosyltransferase family of enzymes. The potent inhibition of the enzyme by the fluoro-substituted substrate is consistent with the involvement of an oxocarbenium transition-state structure, which has been previously proposed for this family of enzymes. Additionally, although several members of the GT-B enzyme family, including MshA, have been shown to undergo a conformational change upon UDP-GlcNAc binding, the kinetic data are inconsistent with a two-step inhibition mechanism. This suggests that there may be other conformations of the enzyme that are useful for the design of inhibitors against the large family of GT-B glycosyltransferase enzymes. PMID:20411981

  15. High current, low emittance, steady state electron guns with plasma cathodes

    SciTech Connect

    Hershcovitch, A.

    1995-12-31

    Major limitations of plasma cathodes have been overcome in an electron gun based on extraction of superthermal electrons from a discharge characterized by a large component of high energy electrons with a low thermal spread. A grid is employed to select these electrons for extraction while retaining the bulk electrons in the discharge. Steady state extraction of electron beams corresponding to over 60% of the total arc discharge current has been observed. A perveance of over 280 microperv was reached with the extraction of 9A at 1 keV from a 6 nun aperture. Some of the characteristics of the electron beam described in this paper are very attractive for electron beam melting.

  16. Experimental efforts at NIST towards one-electron ions in circular Rydberg states

    NASA Astrophysics Data System (ADS)

    Tan, Joseph N.; Brewer, Samuel M.; Guise, Nicholas D.

    2011-06-01

    Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

  17. Three electronic state model of the primary phototransformation of bacteriorhodopsin.

    PubMed Central

    Humphrey, W; Lu, H; Logunov, I; Werner, H J; Schulten, K

    1998-01-01

    The primary all-trans --> 13-cis photoisomerization of retinal in bacteriorhodopsin has been investigated by means of quantum chemical and combined classical/quantum mechanical simulations employing the density matrix evolution method. Ab initio calculations on an analog of a protonated Schiff base of retinal in vacuo reveal two excited states S1 and S2, the potential surfaces of which intersect along the reaction coordinate through an avoided crossing, and then exhibit a second, weakly avoided, crossing or a conical intersection with the ground state surface. The dynamics governed by the three potential surfaces, scaled to match the in situ level spacings and represented through analytical functions, are described by a combined classical/quantum mechanical simulation. For a choice of nonadiabatic coupling constants close to the quantum chemistry calculation results, the simulations reproduce the observed photoisomerization quantum yield and predict the time needed to pass the avoided crossing region between S1 and S2 states at tau1 = 330 fs and the S1 --> ground state crossing at tau2 = 460 fs after light absorption. The first crossing follows after a 30 degrees torsion on a flat S1 surface, and the second crossing follows after a rapid torsion by a further 60 degrees. tau1 matches the observed fluorescence lifetime of S1. Adjusting the three energy levels to the spectral shift of D85N and D212N mutants of bacteriorhodospin changes the crossing region of S1 and S2 and leads to an increase in tau1 by factors 17 and 10, respectively, in qualitative agreement with the observed increase in fluorescent lifetimes. PMID:9746511

  18. Imaging Excited State Dynamics with 2d Electronic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Engel, Gregory S.

    2012-06-01

    Excited states in the condensed phase have extremely high chemical potentials making them highly reactive and difficult to control. Yet in biology, excited state dynamics operate with exquisite precision driving solar light harvesting in photosynthetic complexes though excitonic transport and photochemistry through non-radiative relaxation to photochemical products. Optimized by evolution, these biological systems display manifestly quantum mechanical behaviors including coherent energy transfer, steering wavepacket trajectories through conical intersections and protection of long-lived quantum coherence. To image the underlying excited state dynamics, we have developed a new spectroscopic method allowing us to capture excitonic structure in real time. Through this method and other ultrafast multidimensional spectroscopies, we have captured coherent dynamics within photosynthetic antenna complexes. The data not only reveal how biological systems operate, but these same spectral signatures can be exploited to create new spectroscopic tools to elucidate the underlying Hamiltonian. New data on the role of the protein in photosynthetic systems indicates that the chromophores mix strongly with some bath modes within the system. The implications of this mixing for excitonic transport will be discussed along with prospects for transferring underlying design principles to synthetic systems.

  19. Combined study of the ground and unoccupied electronic states of graphite by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Löffler, Stefan; Eder, Franz; Meyer, Jannik C.; Su, Dangsheng; Schattschneider, Peter

    2013-11-14

    Both the unoccupied and ground electronic states of graphite have been studied by electron energy-loss spectroscopy in a transmission electron microscope. Electron energy-loss near-edge structures of the K-edge of carbon have been investigated in detail for scattering angles from 0 to 2.8 mrad. The π{sup *} and σ{sup *} components were separated. The angular and energy dependences of the π{sup *} and σ{sup *} structures were in fair agreement with theory. Electron energy loss Compton spectra of graphite were recorded at scattering angles from 45 to 68 mrad. One Compton scattering spectrum was obtained in 1 min compared with several hours or days using photons. The contributions of core electrons were calculated by the exact Hartree-Slater method in the Compton scattering region. The electron Compton profile for graphite is in good agreement with other conventional Compton profile measurements, as well as with theory, thus establishing the validity of the technique.

  20. Soft x-ray spectroscopy for probing electronic and chemical states of battery materials

    NASA Astrophysics Data System (ADS)

    Wanli, Yang; Ruimin, Qiao

    2016-01-01

    The formidable challenge of developing high-performance battery system stems from the complication of battery operations, both mechanically and electronically. In the electrodes and at the electrode-electrolyte interfaces, chemical reactions take place with evolving electron states. In addition to the extensive studies of material synthesis, electrochemical, structural, and mechanical properties, soft x-ray spectroscopy provides unique opportunities for revealing the critical electron states in batteries. This review discusses some of the recent soft x-ray spectroscopic results on battery binder, transition-metal based positive electrodes, and the solid-electrolyte-interphase. By virtue of soft x-ray’s sensitivity to electron states, the electronic property, the redox during electrochemical operations, and the chemical species of the interphases could be fingerprinted by soft x-ray spectroscopy. Understanding and innovating battery technologies need a multimodal approach, and soft x-ray spectroscopy is one of the incisive tools to probe the chemical and physical evolutions in batteries.

  1. Antiferromagnetic superconducting state in the electron-doped cuprates?

    NASA Astrophysics Data System (ADS)

    Das, Tanmoy; Markiewicz, Robert S.; Bansil, Arun

    2006-03-01

    Recent angle-resolved photoemission (ARPES) studies of the electron-doped cuprate Nd2-xCexCuO4 (NCCO)[1] have been interpreted in terms of a uniform antiferromagnetic (AF) metal, with doping into the upper magnetic band and gap collapse close to optimal doping[2]. An open question is whether the system remains uniform in the simultaneous presence of AF and (d- wave) superconducting (SC) order. Here, we explore the properties of a uniform AF-SC model for NCCO, to ascertain to what extent we can explain anomalous features, such as the nonmonotonic angle dependence of the superconducting gap[3]. Work supported by the USDOE. [1] N.P. Armitage, et al., PRL 87, 147003 (2002). [2] C. Kusko, et al., PRB66, 140513 (2002); A.-M.S. Tremblay, et al., cond-mat/0511334. [3] H. Matsui, et al., PRL 95, 017003 (2005).

  2. Aryl Hydrocarbon Receptor Ligand 5F 203 Induces Oxidative Stress That Triggers DNA Damage in Human Breast Cancer Cells

    PubMed Central

    McLean, Lancelot S.; Watkins, Cheri N.; Campbell, Petreena; Zylstra, Dain; Rowland, Leah; Amis, Louisa H.; Scott, Lia; Babb, Crystal E.; Livingston, W. Joel; Darwanto, Agus; Davis, Willie L.; Senthil, Maheswari; Sowers, Lawrence C.; Brantley, Eileen

    2015-01-01

    Breast tumors often show profound sensitivity to exogenous oxidative stress. Investigational agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) induces aryl hydrocarbon receptor (AhR)-mediated DNA damage in certain breast cancer cells. Since AhR agonists often elevate intracellular oxidative stress, we hypothesize that 5F 203 increases reactive oxygen species (ROS) to induce DNA damage, which thwarts breast cancer cell growth. We found that 5F 203 induced single-strand break formation. 5F 203 enhanced oxidative DNA damage that was specific to breast cancer cells sensitive to its cytotoxic actions, as it did not increase oxidative DNA damage or ROS formation in nontumorigenic MCF-10A breast epithelial cells. In contrast, AhR agonist and procarcinogen benzo[a]pyrene and its metabolite, 1,6-benzo[a]pyrene quinone, induced oxidative DNA damage and ROS formation, respectively, in MCF-10A cells. In sensitive breast cancer cells, 5F 203 activated ROS-responsive kinases: c-Jun-N-terminal kinase (JNK) and p38 mitogen activated protein kinase (p38). AhR antagonists (alpha-naphthoflavone, CH223191) or antioxidants (N-acetyl-l-cysteine, EUK-134) attenuated 5F 203-mediated JNK and p38 activation, depending on the cell type. Pharmacological inhibition of AhR, JNK, or p38 attenuated 5F 203-mediated increases in intracellular ROS, apoptosis, and single-strand break formation. 5F 203 induced the expression of cytoglobin, an oxidative stress-responsive gene and a putative tumor suppressor, which was diminished with AhR, JNK, or p38 inhibition. Additionally, 5F 203-mediated increases in ROS production and cytoglobin were suppressed in AHR100 cells (AhR ligand-unresponsive MCF-7 breast cancer cells). Our data demonstrate 5F 203 induces ROS-mediated DNA damage at least in part via AhR, JNK, or p38 activation and modulates the expression of oxidative stress-responsive genes such as cytoglobin to confer its anticancer action. PMID:25781201

  3. Vibronic coupling in the first four electronic states of CH2F+2

    NASA Astrophysics Data System (ADS)

    Sarkar, Rudraditya; Mahapatra, Susanta

    2015-10-01

    Vibronic coupling in the energetically lowest first four electronic states of CH2F+2 is studied in this paper. A model 4×4 Hamiltonian is constructed in a diabatic electronic representation employing normal coordinates of vibrational modes and standard vibronic coupling theory. Extensive ab initio quantum chemistry calculations are carried out to determine the parameters of the Hamiltonian and energetic ordering of the electronic states. The topographical features of the latter are examined at length and several conical intersections are established. Nuclear dynamics calculations on coupled electronic states are carried out from first principles by propagating wave packet. Theoretically calculated broad band vibronic structure of the four states are found to be in good accord with the experimental results. Dedicated to Professor Sourav Pal on the occassion of his 60th birthday.

  4. Carotenoid Excited State Kinetics in Bacterial RCs with the Primary Electron Donor Oxidized

    NASA Astrophysics Data System (ADS)

    Lin, Su; Katilius, Evaldas; Woodbury, Neal W.

    Carotenoid singlet excited state kinetics in wild type reaction centers from Rhodobacter sphaeroides was investigated using ultrafast laser spectroscopy under conditions where the primary electron donor is either neutral or oxidized.

  5. Initial state dependence of convoy electrons emitted from the excited ions by resonant coherent excitation

    NASA Astrophysics Data System (ADS)

    Azuma, T.; Nakano, Y.; Metoki, K.; Hatakeyama, A.; Nakai, Y.; Komaki, K.; Yamazaki, Y.; Takada, E.; Murakami, T.

    2009-11-01

    Convoy electrons emitted from 416 MeV/u heliumlike Ar16+ ions excited by three-dimensional resonant coherent excitation (3D-RCE) have been explored. The 1s electron in the ground state was excited to the 2p state by a periodic crystal field during the passage through a Si crystal and released into the continuum by collisions with target atoms to form a cusp-shaped peak in the energy distribution, referred to as convoy electron. Under the resonance condition, we found not only enhancement of the convoy electron yield but also significant narrowing in the energy distribution, reflecting the initial bound state momentum distribution of the excited ions. This suggests that RCE is well-suited to study fast ion collisions involving the specific excited state.

  6. Reactions of ground-state and electronically excited sodium atoms with methyl bromide and molecular chlorine

    SciTech Connect

    Weiss, P.S.; Mestdagh, J.M.; Schmidt, H.; Covinsky, M.H.; Lee, Y.T. )

    1991-04-18

    The reactions of ground- and excited-state Na atoms with methyl bromide (CH{sub 3}Br) and chlorine (Cl{sub 2}) have been studied by using the crossed molecular beams method. For both reactions, the cross sections increase with increasing electronic energy. The product recoil energies change little with increasing Na electronic energy, implying that the product internal energies increase substantially. For Na + CH{sub 3}Br, the steric angle of acceptance opens with increasing electronic energy.

  7. 76 FR 24020 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Illinois

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-29

    ... . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as Part 3 of title 40 of the CFR. CROMERR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Illinois...

  8. 76 FR 30342 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Ohio

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-25

    ....gov . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as Part 3 of title 40 of the CFR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Ohio...

  9. 76 FR 25333 - Cross-Media Electronic Reporting: Authorized Program Revision/Modification Approvals, State of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    ... final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848... From the Federal Register Online via the Government Publishing Office ENVIRONMENTAL PROTECTION AGENCY Cross-Media Electronic Reporting: Authorized Program Revision/ Modification Approvals, State...

  10. 78 FR 77121 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of New York

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-20

    ...-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and... From the Federal Register Online via the Government Publishing Office ENVIRONMENTAL PROTECTION AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of New York...

  11. 76 FR 76971 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Indiana

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-09

    ... . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as Part 3 of title 40 of the CFR. CROMERR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Indiana...

  12. 77 FR 13123 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Ohio

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ..., seeh.karen@epa.gov . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Ohio...

  13. 77 FR 71792 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Georgia

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-04

    ...@epa.gov . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title 40... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Georgia...

  14. 77 FR 68770 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Vermont

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-16

    ... . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title 40 of the CFR. CROMERR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Vermont...

  15. 76 FR 76971 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Arkansas

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-09

    ... . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as Part 3 of title 40 of the CFR. CROMERR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Arkansas...

  16. 76 FR 76970 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Montana

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-09

    ... . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as Part 3 of title 40 of the CFR. CROMERR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Montana...

  17. 78 FR 35030 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Nevada

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-11

    ... . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title 40 of the CFR. CROMERR... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Nevada...

  18. 78 FR 32386 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Arkansas

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-30

    ..., the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR... From the Federal Register Online via the Government Publishing Office ENVIRONMENTAL PROTECTION AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Arkansas...

  19. 77 FR 25474 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Florida

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ... final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848... From the Federal Register Online via the Government Publishing Office ENVIRONMENTAL PROTECTION AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Florida...

  20. Records for Electronic Databases in the Online Catalog at Middle Tennessee State University

    ERIC Educational Resources Information Center

    Geckle, Beverly J.; Pozzebon, Mary Ellen; Williams, Jo

    2008-01-01

    This article recounts a project at the Middle Tennessee State University library to include records for electronic databases in the online catalog. Although electronic databases are accessible via the library's Databases A-Z list and related subject guides, cataloging these resources also provides access via the online catalog, allowing more of…

  1. Quantized Electron Accumulation States in Indium Nitride Studied by Angle-Resolved Photoemission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Colakerol, Leyla; Veal, T. D.; Jeong, Hae-Kyung; Plucinski, Lukasz; Demasi, Alex; Learmonth, Timothy; Glans, Per-Anders; Wang, Shancai; Zhang, Yufeng; Piper, L. F. J.; Jefferson, P. H.; Fedorov, Alexei; Chen, Tai-Chou; Moustakas, T. D.; McConville, C. F.; Smith, Kevin E.

    2006-12-01

    Electron accumulation states in InN have been measured using high resolution angle-resolved photoemission spectroscopy (ARPES). The electrons in the accumulation layer have been discovered to reside in quantum well states. ARPES was also used to measure the Fermi surface of these quantum well states, as well as their constant binding energy contours below the Fermi level EF. The energy of the Fermi level and the size of the Fermi surface for these quantum well states could be controlled by varying the method of surface preparation. This is the first unambiguous observation that electrons in the InN accumulation layer are quantized and the first time the Fermi surface associated with such states has been measured.

  2. Nonadiabatic excited-state molecular dynamics: Treatment of electronic decoherence

    NASA Astrophysics Data System (ADS)

    Nelson, Tammie; Fernandez-Alberti, Sebastian; Roitberg, Adrian E.; Tretiak, Sergei

    2013-06-01

    Within the fewest switches surface hopping (FSSH) formulation, a swarm of independent trajectories is propagated and the equations of motion for the quantum coefficients are evolved coherently along each independent nuclear trajectory. That is, the phase factors, or quantum amplitudes, are retained. At a region of strong coupling, a trajectory can branch into multiple wavepackets. Directly following a hop, the two wavepackets remain in a region of nonadiabatic coupling and continue exchanging population. After these wavepackets have sufficiently separated in phase space, they should begin to evolve independently from one another, the process known as decoherence. Decoherence is not accounted for in the standard surface hopping algorithm and leads to internal inconsistency. FSSH is designed to ensure that at any time, the fraction of classical trajectories evolving on each quantum state is equal to the average quantum probability for that state. However, in many systems this internal consistency requirement is violated. Treating decoherence is an inherent problem that can be addressed by implementing some form of decoherence correction to the standard FSSH algorithm. In this study, we have implemented two forms of the instantaneous decoherence procedure where coefficients are reinitialized following hops. We also test the energy-based decoherence correction (EDC) scheme proposed by Granucci et al. and a related version where the form of the decoherence time is taken from Truhlar's Coherent Switching with Decay of Mixing method. The sensitivity of the EDC results to changes in parameters is also evaluated. The application of these computationally inexpensive ad hoc methods is demonstrated in the simulation of nonradiative relaxation in two conjugated oligomer systems, specifically poly-phenylene vinylene and poly-phenylene ethynylene. We find that methods that have been used successfully for treating small systems do not necessarily translate to large polyatomic

  3. Spectroscopic Properties and Potential Energy Curves of Low-lying electronic States of RuC

    SciTech Connect

    Balasubramanian, K; Guo, R

    2003-12-22

    The RuC molecule has been a challenging species due to the open-shell nature of Ru resulting in a large number of low-lying electronic states. We have carried out state-of-the-art calculations using the complete active space multi-configuration self-consistent field (CASSCF) followed by multireference configuration interaction (MRCI) methods that included up 18 million configurations, in conjunction with relativistic effects. We have computed 29 low-lying electronic states of RuC with different spin multiplicities and spatial symmetries with energy separations less than 38 000 cm{sup -1}. We find two very closely low-lying electronic states for RuC, viz., {sup 1}{Sigma}{sup +} and {sup 3}{Delta} with the {sup 1}{Sigma}{sup +} being stabilized at higher levels of theory. Our computed spectroscopic constants and dipole moments are in good agreement with experiment although we have reported more electronic states than those that have been observed experimentally. Our computations reveal a strongly bound X{sup 1}{Sigma}{sup +} state with a large dipole moment and an energetically close {sup 3}{Delta} state with a smaller dipole moment. Overall our computed spectroscopic constants of the excited states with energy separations less than 18000 cm{sup -1} agree quite well with those of the corresponding observed states.

  4. Quantitative tests of a steady state theory of solar wind electrons

    NASA Technical Reports Server (NTRS)

    Feldman, W. C.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.

    1982-01-01

    A comparison is made of IMP 6, 7 and 8 electron data with the predictions of a solar wind electron steady state theory in which the control of transport by the macroscopic interplanetary electric and magnetic fields, as well as elastic Coulomb collisions with solar wind protons and thermal electrons, is assumed. While a ratio of forward to backward phase density for field-aligned extrathermal electrons of 6:1 is predicted, electron distribution measurements within the high speed solar wind show this ratio to be typically about an order of magnitude larger. A set of solar wind bulk speed anticorrelations predicted by the theory on the basis of a larger set of assumptions cannot be found in the IMP electron data set, so that improved agreement may require such modifications of the theory's assumptions as the inclusion of inelastic Coulomb and/or wave electron collisions.

  5. The Investigation of The Relationship Electronic Energy ˜ 1/ (Internuclear Distance) Regarding The Vibrational Electronic States of Hydrogen Molecule

    NASA Astrophysics Data System (ADS)

    Yarman, Tolga; Yarman, Faruk; Ozaydin, Fatih

    2003-05-01

    The first author has previously shown the following [1]: Theorem 1: In a ``real" atomic or molecular wave-like description (i.e. a description embodying potential energy terms, in only Coulombian form), if different masses involved by the object are all over multiplied by the arbitrary number C, then the size of space R in which this object is installed, shrinks as much, and the total energy E of the object, is increased as much. We shall call M, the characteristic mass, a compound mass carrying the labour delineated by the internal motion of the object in hand. Since this is a mass, multiplying all of the different particles masses taking place in the object by C, makes it that M too is multiplied by C. This leads Theorem 2, as well as Theorem 3. Theorem 2: For any real wave like object, the product EMR^2 remains invariant, were M multiplied by the arbitrary number C. Theorem 3: The quantity EMR^2 is strapped to h^2. Thus, EMR^2 ˜ h^2 (1). Herein, we consider the cast EMR^2 , along the Born and Oppenheimer (B and O) Approximation [2], applied to the Schrodinger description of a diatomic molecule. It is known that, through the B and O Approximation, the nuclei motion of a diatomic molecule on the one hand, and the electronic motion associated with it on the other hand, can be handled through separate descriptions. In this work we are interested in only the electronic motion, for which the Schrodinger equation embodies only one mass, that of the electron mass; furthermore the overall potential energy input to this equation is made of just Coulomb potential energy terms, which makes that the description of concern is a real one. Thus Eq.(1), for the electronic motion of the bond in consideration, becomes 8π^2Emg_(in)R=n_in_jh^2 (2) ; m is the electron mass (here playing the role of the characteristic mass); E is the magnitude of the electronic energy of the molecule in hand, at the given state, and R the internuclear distance of the molecule at this state; ni and

  6. Study of intermediates from transition metal excited-state electron-transfer reactions

    SciTech Connect

    Hoffman, M.Z.

    1992-07-31

    Conventional and fast-kinetics techniques of photochemistry, photophysics, radiation chemistry, and electrochemistry were used to study the intermediates involved in transition metal excited-state electron-transfer reactions. These intermediates were excited state of Ru(II) and Cr(III) photosensitizers, their reduced forms, and species formed in reactions of redox quenchers and electron-transfer agents. Of particular concern was the back electron-transfer reaction between the geminate pair formed in the redox quenching of the photosensitizers, and the dependence of its rate on solution medium and temperature in competition with transformation and cage escape processes. (DLC)

  7. Ferroelectric-like metallic state in electron doped BaTiO3

    PubMed Central

    Fujioka, J.; Doi, A.; Okuyama, D.; Morikawa, D.; Arima, T.; Okada, K. N.; Kaneko, Y.; Fukuda, T.; Uchiyama, H.; Ishikawa, D.; Baron, A. Q. R.; Kato, K.; Takata, M.; Tokura, Y.

    2015-01-01

    We report that a ferroelectric-like metallic state with reduced anisotropy of polarization is created by the doping of conduction electrons into BaTiO3, on the bases of x-ray/electron diffraction and infrared spectroscopic experiments. The crystal structure is heterogeneous in nanometer-scale, as enabled by the reduced polarization anisotropy. The enhanced infrared intensity of soft phonon along with the resistivity reduction suggests the presence of unusual electron-phonon coupling, which may be responsible for the emergent ferroelectric structure compatible with metallic state. PMID:26289749

  8. Evolution of the local electronic states in Mn-doped Sr3 Ru2 O7

    NASA Astrophysics Data System (ADS)

    Leshen, Justin; Petryk, Matthew; Giannakis, Ioannis; Trager, Michael; Kavai, Mariam; Singer, Noah; Kaneko, Yoshio; Tokura, Yoshi; Aynajian, Pegor

    2015-03-01

    Thermal and quantum phase transitions have been central to the study of the strongly correlated electron systems. The double layer Sr3Ru2O7 is a particularly interesting candidate for such studies where a few percent of Mn-doping, replacing the Ru atoms, drives the system towards an antiferromagnetic (AFM) Mott insulator. Using scanning tunneling microscopy and spectroscopy we will address the effect of individual Mn dopants on the local electronic density of states in lightly doped Sr3(Ru1-xMnx)2 O7 and investigate the evolution of its electronic states across the paramagnetic metal to AFM Mott insulating phase transition.

  9. Electronic Cigarette Use Among Working Adults - United States, 2014.

    PubMed

    Syamlal, Girija; Jamal, Ahmed; King, Brian A; Mazurek, Jacek M

    2016-01-01

    Electronic cigarettes (e-cigarettes) are battery-powered devices that deliver a heated aerosol, which typically contains nicotine, flavorings, and other additives, to the user. The e-cigarette marketplace is rapidly evolving, but the long-term health effects of these products are not known. Carcinogens and toxins such as diacetyl, acetaldehyde, and other harmful chemicals have been documented in the aerosol from some e-cigarettes (1-3). On May 5, 2016, the Food and Drug Administration (FDA) finalized a rule extending its authority to all tobacco products, including e-cigarettes.* The prevalence of e-cigarette use among U.S. adults has increased in recent years, particularly among current and former conventional cigarette smokers (4); in 2014, 3.7% of all U.S. adults, including 15.9% of current cigarette smokers, and 22.0% of former cigarette smokers, used e-cigarettes every day or some days (5). The extent of current e-cigarette use among U.S. working adults has not been assessed. Therefore, CDC analyzed 2014 National Health Interview Survey (NHIS) data for adults aged ≥18 years who were working during the week before the interview, to provide national estimates of current e-cigarette use among U.S. working adults by industry and occupation. Among the estimated 146 million working adults, 3.8% (5.5 million) were current (every day or some days) e-cigarette users; the highest prevalences were among males, non-Hispanic whites, persons aged 18-24 years, persons with annual household income <$35,000, persons with no health insurance, cigarette smokers, other combustible tobacco users, and smokeless tobacco users. By industry and occupation, workers in the accommodation and food services industry and in the food preparation and serving-related occupations had the highest prevalence of current e-cigarette use. Higher prevalences of e-cigarette use among specific groups and the effect of e-cigarette use on patterns of conventional tobacco use underscore the importance

  10. Cardiac damage induced by 2-amino-3-methyl-imidazo[4,5-f]quinoline in nonhuman primates.

    PubMed Central

    Thorgeirsson, U P; Farb, A; Virmani, R; Adamson, R H

    1994-01-01

    The heterocyclic aromatic amine 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) is a potent hepatocarcinogen in cynomolgus and rhesus monkeys. The finding of high cardiac IQ-DNA adduct levels prompted a histopathological study of perfusion-fixed hearts from 10 tumor-bearing monkeys chronically dosed with IQ at 10 mg/kg or 20 mg/kg 5 days per week for 48-80 months. Two monkeys dosed only with the vehicle for IQ, hydroxypropylcellulose, served as controls. All the monkeys had normal heart weights, and no abnormalities were observed upon gross inspection of the hearts. Microscopically, focal myocardial lesions were observed in 8 of 10 monkeys dosed with IQ. Light microscopic abnormalities included myocyte necrosis with or without chronic inflammatory infiltrates, interstitial fibrosis with myocyte hypertrophy or atrophy, and vasculitis. Electron microscopic findings included disruption of the mitochondrial architecture (i.e., mitochondrial swelling and clearing of matrix densities), myofibrillar loss, disorganization of the normal alignment of sarcomeres, and occasional myocytes showing nuclear hypertrophy or peripheral clumping of the nuclear chromatin. There was some correlation between the cumulative dose of IQ and the extent of the myocardial abnormalities. These findings suggest that chronic exposure to IQ can lead to myocardial damage in monkeys. Although focal and not associated with clinical evidence of heart failure, these abnormalities may represent the initial stages of IQ-induced toxic cardiomyopathy. Images Figure 1. A Figure 1. B Figure 1. C Figure 1. D Figure 2. A Figure 2. B Figure 3. A Figure 3. B Figure 3. C Figure 3. D Figure 4. A Figure 4. B Figure 5. A Figure 5. B PMID:8033851

  11. Oxidative Stress Type Influences the Properties of Antioxidants Containing Polyphenols in RINm5F Beta Cells

    PubMed Central

    Auberval, Nathalie; Dal, Stéphanie; Bietiger, William; Seyfritz, Elodie; Peluso, Jean; Muller, Christian; Zhao, Minjie; Marchioni, Eric; Pinget, Michel; Jeandidier, Nathalie; Maillard, Elisa; Schini-Kerth, Valérie; Sigrist, Séverine

    2015-01-01

    The in vitro methods currently used to screen bioactive compounds focus on the use of a single model of oxidative stress. However, this simplistic view may lead to conflicting results. The aim of this study was to evaluate the antioxidant properties of two natural extracts (a mix of red wine polyphenols (RWPs) and epigallocatechin gallate (EGCG)) with three models of oxidative stress induced with hydrogen peroxide (H2O2), a mixture of hypoxanthine and xanthine oxidase (HX/XO), or streptozotocin (STZ) in RINm5F beta cells. We employed multiple approaches to validate their potential as therapeutic treatment options, including cell viability, reactive oxygen species production, and antioxidant enzymes expression. All three oxidative stresses induced a decrease in cell viability and an increase in apoptosis, whereas the level of ROS production was variable depending on the type of stress. The highest level of ROS was found for the HX/XO-induced stress, an increase that was reflected by higher expression antioxidant enzymes. Further, both antioxidant compounds presented beneficial effects during oxidative stress, but EGCG appeared to be a more efficient antioxidant. These data indicate that the efficiency of natural antioxidants is dependent on both the nature of the compound and the type of oxidative stress generated. PMID:26508986

  12. Autoionization states in CO{sub 2} and CS{sub 2} studied by electron impact

    SciTech Connect

    Wen, A.T.; Tremblay, D.; Tremblay, B.; Gourier, C.; Roy, D.

    1993-12-01

    A multi-angle-detector electron scattering spectrometer has been adapted to electron ejection measurements. A study of autoionization from Rydberg states has been carried out for CO{sub 2} in the continuum region 15-19 eV by low-energy electron impact. Observations have been made of structure due to excitation of these states by slow electron scattering and their decay by ejection of electrons. A multi-angle parallel detection technique has been used and this has enabled some CO{sub 2} autoionizing states resulting from non-dipole transitions to be observed clearly. The major features appearing in the ejected electron spectra of CO{sub 2} have tentatively been classified and/or assigned, and the spectral behaviour (intensity, width, and shape) of these features has been addressed as a function of incident energy and angle of ejection. In addition to the features already known, new features have been observed, and they seem to be rather sensitive to electron impact energies employed. Studies of autoionizing states in CS{sub 2} in the energy region 11-14 eV are also presented.

  13. The Helium Field Effect Transistor (I): Storing Surface State Electrons on Helium Films

    NASA Astrophysics Data System (ADS)

    Ashari, M.; Rees, D. G.; Kono, K.; Scheer, E.; Leiderer, P.

    2012-04-01

    We present investigations of surface state electrons on liquid helium films in confined geometry, using a suitable substrate structure microfabricated on a silicon wafer, similar to a Field Effect Transistor (FET). The sample has a source and drain region, separated by a gate structure, which consists of two gold electrodes with a narrow gap (channel) through which the transport of the surface state electrons takes place. The sample is illuminated to provide a sufficient number of free carriers in the silicon substrate, such that a well-defined potential distribution is achieved. The eventual goal of these experiments is to study the electron transport through a narrow channel in the various states of the phase diagram of the 2D electron system. In the present work we focus on storing the electrons in the source area of the FET, and investigate the spatial distribution of these electrons. It is shown that under the influence of a potential gradient in the silicon substrate the electrons accumulate in front of the potential barrier of the gate. The electron distribution, governed by Coulomb repulsion and by the substrate potential, is determined experimentally. The result is found to be in good agreement with a parallel-plate capacitor model of the system, developed with the aid of a finite element calculation of the surface potential profile of the device.

  14. Entanglement Concentration of Partially Entangled Multi-electron Spin W States with CNOT Gates

    NASA Astrophysics Data System (ADS)

    Gu, Bin; Huang, Yugai; Fang, Xia; Wang, Haibin

    2014-04-01

    We propose a novel entanglement concentration protocol (ECP) for nonlocal N-electron systems in a partially entangled W state, resorting to an ancillary single electron and controlled-not gates. Compared with other ECPs for W states, our ECP has some illustrious advantages. First, each N-electron entangled system can be used to complete the entanglement concentration with only an ancillary electron. It does not require that there are two copies of N-electron entangled systems in each round of entanglement concentration. Second, only one of the users, say Charlie, needs to perform the protocol, while all parties should perform the same operations as Charlie in other ECPs for W-class states. Third, only Charlie asks other parities to retain or discard their electrons, and they do not need to check their measurement results, which greatly simplifies the complication of classical communication. Fourth, our ECP has a higher success probability than other ECPs for W-class states as its success probability equals to the limit value of an ECP for a W state in theory. These advantages maybe make our ECP more useful in practical applications.

  15. Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires

    NASA Astrophysics Data System (ADS)

    Beidenkopf, Haim; Reiner, Jonathan; Norris, Andrew; Nayak, Abhay Kumar; Avraham, Nurit; Shtrikman, Hadas

    One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions. Some of these may bear implications on the topological superconducting state and Majorana modes therein. The authors acknowledge support from the Israeli Science Foundation (ISF).

  16. Electronic structure of fluorides: general trends for ground and excited state properties

    NASA Astrophysics Data System (ADS)

    Cadelano, E.; Cappellini, G.

    2011-05-01

    The electronic structure of fluorite crystals are studied by means of density functional theory within the local density approximation for the exchange correlation energy. The ground-state electronic properties, which have been calculated for the cubic structures CaF2, SrF2, BaF2, CdF2, HgF2, β-PbF2, using a plane waves expansion of the wave functions, show good comparison with existing experimental data and previous theoretical results. The electronic density of states at the gap region for all the compounds and their energy-band structure have been calculated and compared with the existing data in the literature. General trends for the ground-state parameters, the electronic energy-bands and transition energies for all the fluorides considered are given and discussed in details. Moreover, for the first time results for HgF2 have been presented.

  17. On the entanglement of electronic states of impurity atoms in nanoparticles

    SciTech Connect

    Basharov, Askhat M; Znamenskiy, Nikolay V; Gorbachev, Valery N

    2006-08-31

    By using the derived master equations, it is shown that the decay of electronic impurities in a nanocrystal can be described as a collective relaxation of particles. A set of entangled states of impurity atoms is found, which have immunity to this relaxation. These states can be used for decoherence-free quantum processing. (quantum optics and information)

  18. Electronic interconnects and devices with topological surface states and methods for fabricating same

    DOEpatents

    Yazdani, Ali; Ong, N. Phuan; Cava, Robert J.

    2016-05-03

    An interconnect is disclosed with enhanced immunity of electrical conductivity to defects. The interconnect includes a material with charge carriers having topological surface states. Also disclosed is a method for fabricating such interconnects. Also disclosed is an integrated circuit including such interconnects. Also disclosed is a gated electronic device including a material with charge carriers having topological surface states.

  19. Chieffile: The Electronic Mail, News, and Information Service of the Council of Chief State School Officers.

    ERIC Educational Resources Information Center

    Rush, George

    1986-01-01

    Information services offered by the Council of Chief State School Officers (CCSSO) include "Chieffile," an electronic mail system, and "CHIEFLINE," a semiweekly news bulletin board. Chieffile provides information on federal legislation which is updated weekly, technology-related activities, a clearinghouse for information on state responses to the…

  20. Characterization of adsorption and electronic excited states of quercetin on titanium dioxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Zdyb, Agata; Krawczyk, Stanisław

    2016-03-01

    Adsorption of quercetin on colloidal titanium dioxide nanoparticles in ethanol and its excited-state electronic structure were investigated by means of electronic and vibrational spectroscopies. The changes in electronic charge redistribution as reflected by the dipole moment difference, ∆μ, between the ground and excited electronic states were measured with electroabsorption spectroscopy and analyzed using results of TD DFT computations. Adsorption of quercetin causes a red shift of its absorption spectrum. Raman spectra of quercetin analyzed with reference to analogous data for morin indicate binding of quercetin through the hydroxy groups of the catechol moiety. The difference dipole moment, which is 5.5 D in free quercetin, increases to 11.8 D in opposite direction in adsorbed quercetin, and is associated with charge-transfer to the Ti atom. The computed transition energy, intensity, vector Δμ and molecular orbitals involved in the electronic transition at different molecular configurations indicate a bidentate chelating mode of binding of quercetin.

  1. Fabrication and characterization of solid-state nanopores using a field emission scanning electron microscope

    SciTech Connect

    Chang Hung; Iqbal, Samir M.; Stach, Eric A.; King, Alexander H.; Zaluzec, Nestor J.; Bashir, Rashid

    2006-03-06

    The fabrication of solid-state nanopores using the electron beam of a transmission electron microscope (TEM) has been reported in the past. Here, we report a similar method to fabricate solid-state nanopores using the electron source of a conventional field-emission scanning electron microscope (FESEM) instead. Micromachining was used to create initial pore diameters between 50 nm and 200 nm, and controlled pore shrinking to sub 10 nm diameters was performed subsequently during in situ processing in the FESEM. Noticeably, different shrinking behavior was observed when using irradiation from the electron source of the FESEM than the TEM. Unlike previous reports of TEM mediated pore shrinkage, the mechanism of pore shrinkage when using the FESEM could be a result of surface defects generated by radiolysis and subsequent motion of silicon atoms to the pore periphery.

  2. Differential cross sections for intermediate-energy electron scattering from α-tetrahydrofurfuryl alcohol: Excitation of electronic-states

    SciTech Connect

    Chiari, L.; Jones, D. B.; Thorn, P. A.; Pettifer, Z.; Duque, H. V.; Silva, G. B. da; Limão-Vieira, P.; Duflot, D.; Hubin-Franskin, M.-J.; Delwiche, J.; Blanco, F.; García, G.; and others

    2014-07-14

    We report on measurements of differential cross sections (DCSs) for electron impact excitation of a series of Rydberg electronic-states in α-tetrahydrofurfuryl alcohol (THFA). The energy range of these experiments was 20–50 eV, while the scattered electron was detected in the 10°–90° angular range. There are currently no other experimental data or theoretical computations against which we can directly compare the present measured results. Nonetheless, we are able to compare our THFA DCSs with earlier cross section measurements for Rydberg-state electronic excitation for tetrahydrofuran, a similar cyclic ether, from Do et al. [J. Chem. Phys. 134, 144302 (2011)]. In addition, “rotationally averaged” elastic DCSs, calculated using our independent atom model with screened additivity rule correction approach are also reported. Those latter results give integral cross sections consistent with the optical theorem, and supercede those from the only previous study of Milosavljević et al. [Eur. Phys. J. D 40, 107 (2006)].

  3. Probing the electronic states and impurity effects in black phosphorus vertical heterostructures

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolong; Wang, Lin; Wu, Yingying; Gao, Heng; Wu, Yabei; Qin, Guanhua; Wu, Zefei; Han, Yu; Xu, Shuigang; Han, Tianyi; Ye, Weiguang; Lin, Jiangxiazi; Long, Gen; He, Yuheng; Cai, Yuan; Ren, Wei; Wang, Ning

    2016-03-01

    Atomically thin black phosphorus (BP) is a promising two-dimensional material for fabricating electronic and optoelectronic nano-devices with high mobility and tunable bandgap structures. However, the charge-carrier mobility in few-layer phosphorene (monolayer BP) is mainly limited by the presence of impurity and disorders. In this study, we demonstrate that vertical BP heterostructure devices offer great advantages in probing the electron states of monolayer and few-layer phosphorene at temperatures down to 2 K through capacitance spectroscopy. Electronic states in the conduction and valence bands of phosphorene are accessible over a wide range of temperature and frequency. Exponential band tails have been determined to be related to disorders. Unusual phenomena such as the large temperature-dependence of the electron state population in few-layer phosphorene have been observed and systematically studied. By combining the first-principles calculation, we identified that the thermal excitation of charge trap states and oxidation-induced defect states were the main reasons for this large temperature dependence of the electron state population and degradation of the on-off ratio in phosphorene field-effect transistors.

  4. Electronic states of Zn2 - Ab initio calculations of a prototype for Hg2

    NASA Technical Reports Server (NTRS)

    Hay, P. J.; Dunning, T. H., Jr.; Raffenetti, R. C.

    1976-01-01

    The electronic states of Zn2 are investigated by ab initio polarization configuration-interaction calculations. Molecular states dissociating to Zn(1S) + Zn(1S, 3P, 1P) and Zn(3P) + Zn(3P) are treated. Important effects from states arising from Zn(+)(25) + Zn(-)(2P) are found in the potential-energy curves and electronic-transition moments. A model calculation for Hg2 based on the Zn2 curves and including spin-orbit coupling leads to a new interpretation of the emission bands in Hg vapor.

  5. Detection of dark states in two-dimensional electronic photon-echo signals via ground-state coherence

    SciTech Connect

    Egorova, Dassia

    2015-06-07

    Several recent experiments report on possibility of dark-state detection by means of so called beating maps of two-dimensional photon-echo spectroscopy [Ostroumov et al., Science 340, 52 (2013); Bakulin et al., Ultrafast Phenomena XIX (Springer International Publishing, 2015)]. The main idea of this detection scheme is to use coherence induced upon the laser excitation as a very sensitive probe. In this study, we investigate the performance of ground-state coherence in the detection of dark electronic states. For this purpose, we simulate beating maps of several models where the excited-state coherence can be hardly detected and is assumed not to contribute to the beating maps. The models represent strongly coupled electron-nuclear dynamics involving avoided crossings and conical intersections. In all the models, the initially populated optically accessible excited state decays to a lower-lying dark state within few hundreds femtoseconds. We address the role of Raman modes and of interstate-coupling nature. Our findings suggest that the presence of low-frequency Raman active modes significantly increases the chances for detection of dark states populated via avoided crossings, whereas conical intersections represent a more challenging task.

  6. Effect of spin-orbit and on-site Coulomb interactions on the electronic structure and lattice dynamics of uranium monocarbide

    NASA Astrophysics Data System (ADS)

    Wdowik, U. D.; Piekarz, P.; Legut, D.; Jagło, G.

    2016-08-01

    Uranium monocarbide, a potential fuel material for the generation IV reactors, is investigated within density functional theory. Its electronic, magnetic, elastic, and phonon properties are analyzed and discussed in terms of spin-orbit interaction and localized versus itinerant behavior of the 5 f electrons. The localization of the 5 f states is tuned by varying the local Coulomb repulsion interaction parameter. We demonstrate that the theoretical electronic structure, elastic constants, phonon dispersions, and their densities of states can reproduce accurately the results of x-ray photoemission and bremsstrahlung isochromat measurements as well as inelastic neutron scattering experiments only when the 5 f states experience the spin-orbit interaction and simultaneously remain partially localized. The partial localization of the 5 f electrons could be represented by a moderate value of the on-site Coulomb interaction parameter of about 2 eV. The results of the present studies indicate that both strong electron correlations and spin-orbit effects are crucial for realistic theoretical description of the ground-state properties of uranium carbide.

  7. Chirality-assisted electronic cloaking of confined States in bilayer graphene.

    PubMed

    Gu, Nan; Rudner, Mark; Levitov, Leonid

    2011-10-01

    We show that the strong coupling of pseudospin orientation and charge carrier motion in bilayer graphene has a drastic effect on transport properties of ballistic p-n-p junctions. Electronic states with zero momentum parallel to the barrier are confined under it for one pseudospin orientation, whereas states with the opposite pseudospin tunnel through the junction totally uninfluenced by the presence of confined states. We demonstrate that the junction acts as a cloak for confined states, making them nearly invisible to electrons in the outer regions over a range of incidence angles. This behavior is manifested in the two-terminal conductance as transmission resonances with non-Lorentzian, singular peak shapes. The response of these phenomena to a weak magnetic field or electric-field-induced interlayer gap can serve as an experimental fingerprint of electronic cloaking. PMID:22107310

  8. Spin eigen-states of Dirac equation for quasi-two-dimensional electrons

    SciTech Connect

    Eremko, Alexander; Brizhik, Larissa; Loktev, Vadim

    2015-10-15

    Dirac equation for electrons in a potential created by quantum well is solved and the three sets of the eigen-functions are obtained. In each set the wavefunction is at the same time the eigen-function of one of the three spin operators, which do not commute with each other, but do commute with the Dirac Hamiltonian. This means that the eigen-functions of Dirac equation describe three independent spin eigen-states. The energy spectrum of electrons confined by the rectangular quantum well is calculated for each of these spin states at the values of energies relevant for solid state physics. It is shown that the standard Rashba spin splitting takes place in one of such states only. In another one, 2D electron subbands remain spin degenerate, and for the third one the spin splitting is anisotropic for different directions of 2D wave vector.

  9. Exact many-electron ground states on the diamond Hubbard chain

    NASA Astrophysics Data System (ADS)

    Gulacsi, Zsolt; Kampf, Arno; Vollhardt, Dieter

    2008-03-01

    Exact ground states of interacting electrons on the diamond Hubbard chain in a magnetic field are constructed which exhibit a wide range of properties such as flat-band ferromagnetism, correlation induced metallic, half-metallic, or insulating behavior [1]. The properties of these ground states can be tuned by changing the magnetic flux, local potentials, or electron density.The results show that the studied simple one-dimensional structure displays remarkably complex physical properties. The virtue of tuning different ground states through external parameters points to new possibilities for the design of electronic devices which can switch between insulating or conducting and nonmagnetic or (fully or partially spin polarized) ferromagnetic states, open new routes for the design of spin-valve devices and gate induced ferromagnetism. [1] Z. Gulacsi, A. Kampf, D. Vollhardt, Phys. Rev. Lett. 99, 026404(2007).

  10. Study on the steady operating state of a micro-pulse electron gun

    SciTech Connect

    Kui, Zhou; Xing, Luo; Xiangyang, Lu; Shengwen, Quan; Jifei, Zhao; Ziqin, Yang

    2014-09-15

    Micro-pulse electron gun (MPG) employs the basic concept of multipacting to produce high-current and short-pulse electron beams from a radio-frequency (RF) cavity. The concept of MPG has been proposed for more than two decades. However, the unstable operating state of MPG vastly obstructs its practical applications. This paper presents a study on the steady operating state of a micro-pulse electron gun with theory and experiments. The requirements for the steady operating state are proposed through the analysis of the interaction between the RF cavity and the beam load. Accordingly, a MPG cavity with the frequency of 2856 MHz has been designed, constructed, and tested. Some primary experiments have been finished. Both the unstable and stable operating states of the MPG have been observed. The stable output beam current has been detected at about 3.8 mA. Further experimental study is under way now.

  11. Chirality-Assisted Electronic Cloaking of Confined States in Bilayer Graphene

    NASA Astrophysics Data System (ADS)

    Gu, Nan; Rudner, Mark; Levitov, Leonid

    2011-10-01

    We show that the strong coupling of pseudospin orientation and charge carrier motion in bilayer graphene has a drastic effect on transport properties of ballistic p-n-p junctions. Electronic states with zero momentum parallel to the barrier are confined under it for one pseudospin orientation, whereas states with the opposite pseudospin tunnel through the junction totally uninfluenced by the presence of confined states. We demonstrate that the junction acts as a cloak for confined states, making them nearly invisible to electrons in the outer regions over a range of incidence angles. This behavior is manifested in the two-terminal conductance as transmission resonances with non-Lorentzian, singular peak shapes. The response of these phenomena to a weak magnetic field or electric-field-induced interlayer gap can serve as an experimental fingerprint of electronic cloaking.

  12. Explicit calculation of the excited electronic states of the photosystem II reaction centre.

    PubMed

    Frankcombe, Terry J

    2015-02-01

    The excited states of sets of the cofactors found in the photosystem II reaction centre have been calculated directly as a multi-monomer supermolecule for the first time. Time-dependent density functional theory was used with the CAM-B3LYP functional. Multiple excited states for each cofactor were found at lower energies than the lowest energy state corresponding to charge transfer states (in which an electron is shifted from one cofactor to another). The electrostatic environment was found to have a dramatic impact on the excited state energies, with the effect of a surrounding dielectric medium being less significant. PMID:25523136

  13. An ab initio study of the lowest electronic states of yttrium dicarbide, YC2

    NASA Astrophysics Data System (ADS)

    Puzzarini, Cristina; Peterson, Kirk A.

    2005-02-01

    The low-lying electronic states of yttrium dicarbide have been calculated using highly correlated wave functions and systematic sequences of correlation consistent basis sets. For the A12 ground electronic state, the near-equilibrium potential energy surface (PES) has been calculated using the coupled cluster method in conjunction with basis sets ranging in size from double to quintuple ζ. The relativistic effects have been taken into account by using pseudopotentials for the Y atom. After extrapolation to the complete basis set limit, additional corrections due to core-valence correlation and spin-orbit effects have also been included. The same approach has been followed for the B12,B22, and A22 states but only the C2V PESs have been considered in these cases. For the two A12 electronic excited states and, for comparison purposes, for the ground state, the multireference configuration interaction (MRCI) approach has been used in conjunction with double-ζ and triple-ζ basis sets for the construction of the PES. The molecular and spectroscopic properties predicted for the ground and excited states investigated in this work compare well with the available experimental data, particularly for the ground electronic state. The 0 K dissociation enthalpy of YC2,ΔHY-C2(0K ), and its atomization enthalpy, ΣD0, are predicted to be 148.4 and 291.5kcal /mol, respectively.

  14. Sulfur-Bridged Terthiophene Dimers: How Sulfur Oxidation State Controls Interchromophore Electronic Coupling.

    PubMed

    Cruz, Chad D; Christensen, Peter R; Chronister, Eric L; Casanova, David; Wolf, Michael O; Bardeen, Christopher J

    2015-10-01

    Symmetric dimers have the potential to optimize energy transfer and charge separation in optoelectronic devices. In this paper, a combination of optical spectroscopy (steady-state and time-resolved) and electronic structure theory is used to analyze the photophysics of sulfur-bridged terthiophene dimers. This class of dimers has the unique feature that the interchromophore (intradimer) electronic coupling can be modified by varying the oxidation state of the bridging sulfur from sulfide (S), to sulfoxide (SO), to sulfone (SO2). Photoexcitation leads to the formation of a delocalized charge resonance state (S1) that relaxes quickly (<10 ps) to a charge-transfer state (S1*). The amount of charge-transfer character in S1* can be enhanced by increasing the oxidation state of the bridging sulfur group as well as the solvent polarity. The S1* state has a decreased intersystem crossing rate when compared to monomeric terthiophene, leading to an enhanced photoluminescence quantum yield. Computational results indicate that electrostatic screening by the bridging sulfur electrons is the key parameter that controls the amount of charge-transfer character. Control of the sulfur bridge oxidation state provides the ability to tune interchromophore interactions in covalent assemblies without altering the molecular geometry or solvent polarity. This capability provides a new strategy for the design of functional supermolecules with applications in organic electronics. PMID:26331195

  15. Probing Interfacial Electronic States in CdSe Quantum Dots using Second Harmonic Generation Spectroscopy

    SciTech Connect

    Doughty, Benjamin L.; Ma, Yingzhong; Shaw, Robert W

    2015-01-07

    Understanding and rationally controlling the properties of nanomaterial surfaces is a rapidly expanding field of research due to the dramatic role they play on the optical and electronic properties vital to light harvesting, emitting and detection technologies. This information is essential to the continued development of synthetic approaches designed to tailor interfaces for optimal nanomaterial based device performance. In this work, closely spaced electronic excited states in model CdSe quantum dots (QDs) are resolved using second harmonic generation (SHG) spectroscopy, and the corresponding contributions from surface species to these states are assessed. Two distinct spectral features are observed in the SHG spectra, which are not readily identified in linear absorption and photoluminescence excitation spectra. These features include a weak band at 395 6 nm, which coincides with transitions to the 2S1/2 1Se state, and a much more pronounced band at 423 4 nm arising from electronic transitions to the 1P3/2 1Pe state. Chemical modification of the QD surfaces through oxidation resulted in disappearance of the SHG band corresponding to the 1P3/2 1Pe state, indicating prominent surface contributions. Signatures of deep trap states localized on the surfaces of the QDs are also observed. We further find that the SHG signal intensities depend strongly on the electronic states being probed and their relative surface contributions, thereby offering additional insight into the surface specificity of SHG signals from QDs.

  16. Probing Interfacial Electronic States in CdSe Quantum Dots using Second Harmonic Generation Spectroscopy

    DOE PAGESBeta

    Doughty, Benjamin L.; Ma, Yingzhong; Shaw, Robert W

    2015-01-07

    Understanding and rationally controlling the properties of nanomaterial surfaces is a rapidly expanding field of research due to the dramatic role they play on the optical and electronic properties vital to light harvesting, emitting and detection technologies. This information is essential to the continued development of synthetic approaches designed to tailor interfaces for optimal nanomaterial based device performance. In this work, closely spaced electronic excited states in model CdSe quantum dots (QDs) are resolved using second harmonic generation (SHG) spectroscopy, and the corresponding contributions from surface species to these states are assessed. Two distinct spectral features are observed in themore » SHG spectra, which are not readily identified in linear absorption and photoluminescence excitation spectra. These features include a weak band at 395 6 nm, which coincides with transitions to the 2S1/2 1Se state, and a much more pronounced band at 423 4 nm arising from electronic transitions to the 1P3/2 1Pe state. Chemical modification of the QD surfaces through oxidation resulted in disappearance of the SHG band corresponding to the 1P3/2 1Pe state, indicating prominent surface contributions. Signatures of deep trap states localized on the surfaces of the QDs are also observed. We further find that the SHG signal intensities depend strongly on the electronic states being probed and their relative surface contributions, thereby offering additional insight into the surface specificity of SHG signals from QDs.« less

  17. Electron impact excitation and assignment of the low-lying electronic states of N2O

    NASA Technical Reports Server (NTRS)

    Hall, R. I.; Chutjian, A.; Trajmar, S.

    1973-01-01

    Electron scattering spectra of nitrous oxide are reported in the 5- to 10-eV energy-loss range at scattering angles of 20, 30, 90, and 130 deg at a residual energy of 7.0 eV; and at residual energies of 10.0, 2.0, 1.0, 0.6, and 0.2 eV at a scattering angle of 90 deg. Several new distinct and overlapping continua are observed to lie in this energy-loss range. The experimental spectra are discussed in the light of semiempirical INDO calculations of Chutjian and Segal (1972) of the vertical transition energies of N2O. An assignment of the symmetries of the observed excitations consistent with the experimental and theoretical data is suggested.

  18. Excited-state evolution probed by convoy-electron emission in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Takabayashi, Y.; Ito, T.; Azuma, T.; Komaki, K.; Yamazaki, Y.; Tawara, H.; Takada, E.; Murakami, T.; Seliger, M.; Tökési, K.; O. Reinhold, C.; Burgdörfer, J.

    2003-10-01

    We present a joint experimental and theoretical study of convoy-electron emission resulting from highly-charged-ion transport through carbon foils at moderately relativistic speeds. Energy spectra of electrons ejected at 0° have been measured for 390 MeV/u hydrogen-like Ar17+ ions and 460 MeV/u (β=v/c=0.74,γ=1.49) Fe25+ (1s), Fe24+ (1s2), and Fe23+ (1s22s) incident on carbon foils with thicknesses from 25 to 8700 μg/cm2. Due to this unprecedented wide range of thicknesses, the sequential excitation and ionization of initially deeply bound electrons to highly excited states and continuum states can be followed in considerable detail. The analysis of the spectra is aided by simulations based on the classical transport theory which has been extended to relativistic energies and to multielectron projectiles. The motion of the projectile electron inside the solid target is calculated taking into account the Coulomb potential of the projectile ion and the multiple stochastic collisions with target cores and target electrons. Different phases of the convoy-electron emissions can be disentangled: direct ejection to the continuum, the transient buildup of an excited-state wave packet followed by ionization, and postionization modification of the continuum spectrum. We find good agreement between experiment and simulation for the evolution of charge states and the emission spectrum.

  19. Chaotic compound states in atomic processes: electron, photon and atom scattering, recombination, photoionization and radiation

    NASA Astrophysics Data System (ADS)

    Flambaum, Victor; Berengut, Julian; Dzuba, Vladimir; Gribakin, Gleb; Harabati, Celal; Kozlov, Michael

    2016-05-01

    Level density of many-body states exponentially increases with the number of excited particles. When residual interaction exceeds the interval between these levels, the eigenstates (compound states) become chaotic superpositions of of thousands, or even millions of Slater determinant basis states.This situation takes place in highly excited nuclei, rare-earth and actinide atoms, open f-shell ions excited by the electron recombination and in ultracold collisions of open f-shell atoms. We derived formulas for the resonant multi-electron recombination via di-electron doorway states leading to the many-electron compound resonances and performed numerical calculations for the electron recombination with gold (Au+25) and tungsten ions (W+1724). A recent experiment showed that the electron recombination of tungsten ion W20+exceeds the direct recombination by three order of magnitude. Our calculations agree with the experimental results for Au+25 and W20+. Other manifestation of chaos are enhancement of weak interactions and Raman photon scattering, and suppression of the photoionization.

  20. Single substitutional nitrogen defects revealed as electron acceptor states in diamond using ultrafast spectroscopy

    NASA Astrophysics Data System (ADS)

    Ulbricht, R.; van der Post, S. T.; Goss, J. P.; Briddon, P. R.; Jones, R.; Khan, R. U. A.; Bonn, M.

    2011-10-01

    We report on the carrier dynamics and recombination pathways of photogenerated electrons in type Ib synthetic diamond using ultrafast spectroscopic techniques. Samples with controlled amounts of nitrogen defects were grown using the high-pressure high-temperature (HPHT) method. Electrons were excited from single substitutional nitrogen defects into the conduction band via an ultrashort pulse from a frequency-doubled Ti-sapphire laser. Using time-resolved terahertz time-domain spectroscopy, we determined the mobility of the photoexcited electrons and monitored their recombination dynamics, at temperatures ranging from cryogenic temperatures to room temperature. The electron mobility was observed to be limited by scattering with neutral nitrogen impurity defects (Ns0). Electrons were observed to predominantly recombine into neutral nitrogen states rather than their original ionized nitrogen defects, thereby creating negatively charged nitrogen states (Ns-). The creation of Ns- states is confirmed experimentally by tracking the localized vibrational modes (LVM) of nitrogen defects during the electron recombination process using visible pump-infrared probe transient spectroscopy. We observe a transient infrared absorption feature at 1349 cm-1 that can be assigned to the LVM of Ns-. Density functional calculations are carried out to determine the LVMs of nitrogen in various charge states, and we find a ˜10 cm-1 upward shift of the mode on passing from Ns0 to Ns-, in agreement with experimental observations.

  1. Revised Model of the Steady-state Solar Wind Halo Electron Velocity Distribution Function

    NASA Astrophysics Data System (ADS)

    Yoon, Peter H.; Kim, Sunjung; Choe, G. S.; moon, Y.-J.

    2016-08-01

    A recent study discussed the steady-state model for solar wind electrons during quiet time conditions. The electrons emanating from the Sun are treated in a composite three-population model—the low-energy Maxwellian core with an energy range of tens of eV, the intermediate ∼102–103 eV energy-range (“halo”) electrons, and the high ∼103–105 eV energy-range (“super-halo”) electrons. In the model, the intermediate energy halo electrons are assumed to be in resonance with transverse EM fluctuations in the whistler frequency range (∼102 Hz), while the high-energy super-halo electrons are presumed to be in steady-state wave–particle resonance with higher-frequency electrostatic fluctuations in the Langmuir frequency range (∼105 Hz). A comparison with STEREO and WIND spacecraft data was also made. However, ignoring the influence of Langmuir fluctuations on the halo population turns out to be an unjustifiable assumption. The present paper rectifies the previous approach by including both Langmuir and whistler fluctuations in the construction of the steady-state velocity distribution function for the halo population, and demonstrates that the role of whistler-range fluctuation is minimal unless the fluctuation intensity is arbitrarily raised. This implies that the Langmuir-range fluctuations, known as the quasi thermal noise, are important for both halo and super-halo electron velocity distribution.

  2. Revised Model of the Steady-state Solar Wind Halo Electron Velocity Distribution Function

    NASA Astrophysics Data System (ADS)

    Yoon, Peter H.; Kim, Sunjung; Choe, G. S.; moon, Y.-J.

    2016-08-01

    A recent study discussed the steady-state model for solar wind electrons during quiet time conditions. The electrons emanating from the Sun are treated in a composite three-population model—the low-energy Maxwellian core with an energy range of tens of eV, the intermediate ˜102–103 eV energy-range (“halo”) electrons, and the high ˜103–105 eV energy-range (“super-halo”) electrons. In the model, the intermediate energy halo electrons are assumed to be in resonance with transverse EM fluctuations in the whistler frequency range (˜102 Hz), while the high-energy super-halo electrons are presumed to be in steady-state wave–particle resonance with higher-frequency electrostatic fluctuations in the Langmuir frequency range (˜105 Hz). A comparison with STEREO and WIND spacecraft data was also made. However, ignoring the influence of Langmuir fluctuations on the halo population turns out to be an unjustifiable assumption. The present paper rectifies the previous approach by including both Langmuir and whistler fluctuations in the construction of the steady-state velocity distribution function for the halo population, and demonstrates that the role of whistler-range fluctuation is minimal unless the fluctuation intensity is arbitrarily raised. This implies that the Langmuir-range fluctuations, known as the quasi thermal noise, are important for both halo and super-halo electron velocity distribution.

  3. Solid-state electron transport via cytochrome c depends on electronic coupling to electrodes and across the protein

    PubMed Central

    Amdursky, Nadav; Ferber, Doron; Bortolotti, Carlo Augusto; Dolgikh, Dmitry A.; Chertkova, Rita V.; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2014-01-01

    Electronic coupling to electrodes, Γ, as well as that across the examined molecules, H, is critical for solid-state electron transport (ETp) across proteins. Assessing the importance of each of these couplings helps to understand the mechanism of electron flow across molecules. We provide here experimental evidence for the importance of both couplings for solid-state ETp across the electron-mediating protein cytochrome c (CytC), measured in a monolayer configuration. Currents via CytC are temperature-independent between 30 and ∼130 K, consistent with tunneling by superexchange, and thermally activated at higher temperatures, ascribed to steady-state hopping. Covalent protein–electrode binding significantly increases Γ, as currents across CytC mutants, bound covalently to the electrode via a cysteine thiolate, are higher than those through electrostatically adsorbed CytC. Covalent binding also reduces the thermal activation energy, Ea, of the ETp by more than a factor of two. The importance of H was examined by using a series of seven CytC mutants with cysteine residues at different surface positions, yielding distinct electrode–protein(–heme) orientations and separation distances. We find that, in general, mutants with electrode-proximal heme have lower Ea values (from high-temperature data) and higher conductance at low temperatures (in the temperature-independent regime) than those with a distal heme. We conclude that ETp across these mutants depends on the distance between the heme group and the top or bottom electrode, rather than on the total separation distance between electrodes (protein width). PMID:24706771

  4. Electronic Structure and Oxidation State Changes in the Mn4Ca Cluster of Photosystem II

    SciTech Connect

    Yano, Junko; Pushkar, Yulia; Messinger, Johannes; Bergmann, Uwe; Glatzel, Pieter; Yachandra, Vittal K

    2007-08-03

    Oxygen-evolving complex (Mn4Ca cluster) of Photosystem II cycles through five intermediate states (Si-states, i =0-4) before a molecule of dioxygen is released. During the S-state transitions, electrons are extracted from the OEC, either from Mn or alternatively from a Mn ligand. The oxidation state of Mn is widely accepted as Mn4(III2,IV2) and Mn4(III,IV3) for S1 and S2 states, while it is still controversial for the S0 and S3 states. We used resonant inelastic X-ray scattering (RIXS) to study the electronic structure of Mn4Ca complex in the OEC. The RIXS data yield two-dimensional plots that provide a significant advantage by obtaining both K-edge pre-edge and L-edge-like spectra (metal spin state) simultaneously. We have collected data from PSII samples in the each of the S-states and compared them with data from various inorganic Mncomplexes. The spectral changes in the Mn 1s2p3/2 RIXS spectra between the S-states were compared to those of the oxides of Mn and coordination complexes. The results indicate strong covalency for the electronic configuration in the OEC, and we conclude that the electron is transferred from a strongly delocalized orbital, compared to those in Mn oxides or coordination complexes. The magnitude for the S0 to S1, and S1 to S2 transitions is twice as large as that during the S2 to S3 transition, indicating that the electron for this transition is extracted from a highly delocalized orbital with little change in charge density at the Mn atoms.

  5. Electronic Structure and Oxidation State Changes in the Mn (4) Ca Cluster of Photosystem II

    SciTech Connect

    Yano, J.; Pushkar, Y.; Messinger, J.; Bergmann, U.; Glatzel, P.; Yachandra, V.K.; /SLAC

    2012-08-17

    Oxygen-evolving complex (Mn{sub 4}Ca cluster) of Photosystem II cycles through five intermediate states (S{sub i}-states, i = 0-4) before a molecule of dioxygen is released. During the S-state transitions, electrons are extracted from the OEC, either from Mn or alternatively from a Mn ligand. The oxidation state of Mn is widely accepted as Mn{sub 4}(III{sub 2},IV{sub 2}) and Mn{sub 4}(III,IV{sub 3}) for S{sub 1} and S{sub 2} states, while it is still controversial for the S{sub 0} and S{sub 3} states. We used resonant inelastic X-ray scattering (RIXS) to study the electronic structure of Mn{sub 4}Ca complex in the OEC. The RIXS data yield two-dimensional plots that provide a significant advantage by obtaining both K-edge pre-edge and L-edge-like spectra (metal spin state) simultaneously. We have collected data from PSII samples in the each of the S-states and compared them with data from various inorganic Mn complexes. The spectral changes in the Mn 1s2p{sub 3/2} RIXS spectra between the S-states were compared to those of the oxides of Mn and coordination complexes. The results indicate strong covalency for the electronic configuration in the OEC, and we conclude that the electron is transferred from a strongly delocalized orbital, compared to those in Mn oxides or coordination complexes. The magnitude for the S{sub 0} to S{sub 1}, and S{sub 1} to S{sub 2} transitions is twice as large as that during the S{sub 2} to S{sub 3} transition, indicating that the electron for this transition is extracted from a highly delocalized orbital with little change in charge density at the Mn atoms.

  6. Electron-energy-loss spectroscopy and X-ray absorption spectroscopy as complementary probes for complex f-electron metals: cerium and plutonium

    NASA Astrophysics Data System (ADS)

    Moore, K. T.; Wall, M. A.; Schwartz, A. J.; Chung, B. W.; Morton, S. A.; Tobin, J. G.; Lazar, S.; Tichelaar, F. D.; Zandbergen, H. W.; Söderlind, P.; van der Laan, G.

    2004-04-01

    In this paper, we demonstrate the power of electron-energy-loss spectroscopy (EELS) in a transmission electron microscope by investigating the electron structure of two f-electron metals: Ce and Pu. It is shown that EELS in a transmission electron microscope may be used to circumvent the difficulty of producing single-phase or single-crystal samples owing to its high spatial resolution, and that diffraction patterns and images can be acquired, providing unambiguous phase determination when acquiring spectra. EELS results are supported by synchrotron-radiation-based X-ray absorption, multielectron atomic spectral simulations, and local density approximation calculations based on density-functional theory with the generalized gradient approximation. For Ce, it is shown that changes in {111} stacking sequences can drive substantial modifications in the electronic structure of close-packed phases of Ce that have similar atomic volumes, contrary to previous assumptions in literature. For Pu, it is shown that Russell-Saunders (L-S) coupling fails for the 5f states and that either a j-j or an intermediate scheme must be used for the actinides because of the considerable spin-orbit interaction in the 5f states. We present a model showing how the 5f states behave along the light actinide series.

  7. Probing the ν =5/2 quantum Hall state with electronic Mach-Zehnder interferometry

    NASA Astrophysics Data System (ADS)

    Yang, Guang

    2015-03-01

    It was recently pointed out that Halperin's 113 topological order explains the transport experiments in the quantum Hall liquid at filling factor ν =5 /2 . The 113 order, however, cannot be easily distinguished from other likely topological orders at ν =5 /2 such as the non-Abelian Pfaffian and anti-Pfaffian states and the Abelian Halperin 331 state in Fabry-Pérot interferometry. We show that an electronic Mach-Zehnder interferometer provides a clear identification of these candidate ν =5 /2 states. Specifically, the I -V curve for the tunneling current through the interferometer is more asymmetric in the 113 state than in other ν =5 /2 states. Moreover, the Fano factor for the shot noise in the interferometer can reach 13.6 in the 113 state, much greater than the maximum Fano factors of 3.2 in the Pfaffian and anti-Pfaffian states and 2.3 in the 331 state.

  8. The superatom states of fullerenes and their hybridization into the nearly free electron bands of fullerites.

    PubMed

    Zhao, Jin; Feng, Min; Yang, Jinlong; Petek, Hrvoje

    2009-04-28

    Motivated by the discovery of the superatom states of C60 molecules, we investigate the factors that influence their energy and wave function hybridization into nearly free electron bands in molecular solids. As the n = 3 solutions of the radial Schrodinger equation of the central attractive potential consisting of the short-range C atom core and the long-range collective screening potentials, respectively, located on the icosahedral C60 molecule shell and within its hollow core, superatom states are distinguished by their atom-like orbitals corresponding to different orbital angular momentum states (l = 0, 1, 2,...). Because they are less tightly bound than the pi orbitals, that is, the n = 2 states, which are often exploited in the intermolecular electron transport in aromatic organic molecule semiconductors, superatom orbitals hybridize more extensively among aggregated molecules to form bands with nearly free electron dispersion. The prospect of exploiting the strong intermolecular coupling to achieve metal-like conduction in applications such as molecular electronics may be attained by lowering the energy of superatom states from 3.5 eV for single chemisorbed C60 molecules to below the Fermi level; therefore, we study how the superatom state energies depend on factors such as their aggregation into 1D-3D solids, cage size, and exo- and endohedral doping by metal atoms. We find, indeed, that if the ionization potential of endohedral atom, such as copper, is sufficiently large, superatom states can form the conduction band in the middle of the gap between the HOMO and LUMO of the parent C60 molecule. Through a plane-wave density functional theory study, we provide insights for a new paradigm for intermolecular electronic interaction beyond the conventional one among the sp(n) hybridized orbitals of the organic molecular solids that could lead to design of novel molecular materials and quantum structures with extraordinary optical and electronic properties. PMID

  9. The Superatom States of Fullerenes and Their Hybridization into the Nearly Free Electron Bands of Fullerites

    SciTech Connect

    Zhao, Jin; Feng, Min; Yang, Jinlong; Petek, Hrvoje

    2009-04-07

    Motivated by the discovery of the superatom states of C₆₀ molecules, we investigate the factors that influence their energy and wave function hybridization into nearly free electron bands in molecular solids. As the n = 3 solutions of the radial Schro¨dinger equation of the central attractive potential consisting of the shortrange C atom core and the long-range collective screening potentials, respectively, located on the icosahedral C60 molecule shell and within its hollow core, superatom states are distinguished by their atom-like orbitals corresponding to different orbital angular momentum states (l = 0, 1, 2,...). Because they are less tightly bound than the π orbitals, that is, the n = 2 states, which are often exploited in the intermolecular electron transport in aromatic organic molecule semiconductors, superatom orbitals hybridize more extensively among aggregated molecules to form bands with nearly free electron dispersion. The prospect of exploiting the strong intermolecular coupling to achieve metal-like conduction in applications such as molecular electronics may be attained by lowering the energy of superatom states from 3.5 eV for single chemisorbed C₆₀ molecules to below the Fermi level; therefore, we study how the superatom state energies depend on factors such as their aggregation into 1D - 3D solids, cage size, and exo- and endohedral doping by metal atoms. We find, indeed, that if the ionization potential of endohedral atom, such as copper, is sufficiently large, superatom states can form the conduction band in the middle of the gap between the HOMO and LUMO of the parent C₆₀ molecule. Through a plane-wave density functional theory study, we provide insights for a new paradigm for intermolecular electronic interaction beyond the conventional one among the spn hybridized orbitals of the organic molecular solids that could lead to design of novel molecular materials and quantum structures with extraordinary optical and

  10. Theoretical Study of Tautomerization Reactions for the Ground and First Excited Electronic States of Adenine

    NASA Technical Reports Server (NTRS)

    Salter, Latasha M.; Chaban, Galina M.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Geometrical structures and energetic properties for different tautomers of adenine are calculated in this study, using multi-configurational wave functions. Both the ground and the lowest singlet excited state potential energy surfaces are studied. Four tautomeric forms are considered, and their energetic order is found to be different on the ground and the excited state potential energy surfaces. Minimum energy reaction paths are obtained for hydrogen atom transfer (tautomerization) reactions in the ground and the lowest excited electronic states. It is found that the barrier heights and the shapes of the reaction paths are different for the ground and the excited electronic states, suggesting that the probability of such tautomerization reaction is higher on the excited state potential energy surface. This tautomerization process should become possible in the presence of water or other polar solvent molecules and should play an important role in the photochemistry of adenine.

  11. Coexistence of Midgap Antiferromagnetic and Mott States in Undoped, Hole- and Electron-Doped Ambipolar Cuprates.

    PubMed

    Yin, Xinmao; Zeng, Shengwei; Das, Tanmoy; Baskaran, G; Asmara, Teguh Citra; Santoso, Iman; Yu, Xiaojiang; Diao, Caozheng; Yang, Ping; Breese, Mark B H; Venkatesan, T; Lin, Hsin; Ariando; Rusydi, Andrivo

    2016-05-13

    We report the first observation of the coexistence of a distinct midgap state and a Mott state in undoped and their evolution in electron and hole-doped ambipolar Y_{0.38}La_{0.62}(Ba_{0.82}La_{0.18})_{2}Cu_{3}O_{y} films using spectroscopic ellipsometry and x-ray absorption spectroscopies at the O K and Cu L_{3,2} edges. Supported by theoretical calculations, the midgap state is shown to originate from antiferromagnetic correlation. Surprisingly, while the magnetic state collapses and its correlation strength weakens with dopings, the Mott state in contrast moves toward a higher energy and its correlation strength increases. Our result provides important clues to the mechanism of electronic correlation strengths and superconductivity in cuprates. PMID:27232036

  12. Coexistence of Midgap Antiferromagnetic and Mott States in Undoped, Hole- and Electron-Doped Ambipolar Cuprates

    NASA Astrophysics Data System (ADS)

    Yin, Xinmao; Zeng, Shengwei; Das, Tanmoy; Baskaran, G.; Asmara, Teguh Citra; Santoso, Iman; Yu, Xiaojiang; Diao, Caozheng; Yang, Ping; Breese, Mark B. H.; Venkatesan, T.; Lin, Hsin; Ariando; Rusydi, Andrivo

    2016-05-01

    We report the first observation of the coexistence of a distinct midgap state and a Mott state in undoped and their evolution in electron and hole-doped ambipolar Y0.38 La0.62 (Ba0.82 La0.18 )2Cu3 Oy films using spectroscopic ellipsometry and x-ray absorption spectroscopies at the O K and Cu L3 ,2 edges. Supported by theoretical calculations, the midgap state is shown to originate from antiferromagnetic correlation. Surprisingly, while the magnetic state collapses and its correlation strength weakens with dopings, the Mott state in contrast moves toward a higher energy and its correlation strength increases. Our result provides important clues to the mechanism of electronic correlation strengths and superconductivity in cuprates.

  13. Ultrafast interfacial electron transfer from the excited state of anchored molecules into a semiconductor

    NASA Astrophysics Data System (ADS)

    Gundlach, L.; Ernstorfer, R.; Willig, F.

    Ultrafast heterogeneous electron transfer (HET) from the excited singlet state of the large organic chromophore perylene into the inorganic semiconductor rutile TiO 2 was investigated with femtosecond time-resolved two-photon photoemission (TR-2PPE). The strength of the electronic interaction between the chromophore and the semiconductor was varied by inserting different anchor/bridge groups that functioned either as electronic wire or electronic tunnelling barrier. Both anchor groups, i.e. carboxylic and phosphonic acid, formed strong chemical bonds at the TiO 2 surface. The perylene chromophore with the different anchor/bridge groups was adsorbed from solution in a dedicated ultra-high-vacuum (UHV) chamber. The adsorption geometry of the chromophore perylene was determined from angle and polarization dependent two-photon photoemission (2PPE) signals and was found to be very different for the two different anchor/bridge groups. The measured adsorption geometries are compatible with recent DFT (density functional theory) calculations by P. Persson and co-workers [M. Nilsing, S. Lunell, P. Persson, L. Ojamäe, Phosphonic acid adsorption at the TiO 2 anatase (1 0 1) surface investigated by periodic hybrid HF-DFT computations, Surf. Sci. 582 (2005) 49-60]. Two different processes contributed to the TR-2PPE transients, firstly electron transfer from the chromophore to the electronic acceptor states on the surface and secondly escape of the electrons from the surface into the bulk of the semiconductor. The latter escape process was measured separately by making the interfacial electron injection process instantaneous when the chromophore catechol was employed in place of the perylene compounds. The thus measured electron escape behavior was governed by the same time constants that have recently been predicted by Prezhdo and coworkers from time dependent DFT calculations [W.R. Duncan, W.M. Stier, O.V. Prezhdo, Ab initio nonadiabatic molecular dynamics of the ultrafast

  14. On the ground electronic states of copper silicide and its ions

    NASA Astrophysics Data System (ADS)

    Boldyrev, Alexander I.; Simons, Jack; Scherer, J. J.; Paul, J. B.; Collier, C. P.; Saykally, R. J.

    1998-04-01

    The low-lying electronic states of SiCu, SiCu+, and SiCu- have been studied using a variety of high-level ab initio techniques. As expected on the basis of simple orbital occupancy and bond forming for Si(s2p2)+Cu(s1) species, 2Πr, 1Σ+, and 3Σ- states were found to be the ground electronic states for SiCu, SiCu+, and SiCu-, respectively; the 2Πr state is not that suggested in most recent experimental studies. All of these molecules were found to be quite strongly bound although the bond lengths, bond energies, and harmonic frequencies vary slightly among them, as a result of the nonbonding character of the 2π-MO (molecular orbital) [composed almost entirely of the Si 3p-AO (atomic orbital)], the occupation of which varies from 0 to 2 within the 1Σ+, 2Πr, and 3Σ- series. The neutral SiCu is found to have bound excited electronic states of 4Σ-, 2Δ, 2Σ+, and 2Πi symmetry lying 0.5, 1.2, 1.8, and 3.2 eV above the 2Πr ground state. It is possible but not yet certain that the 2Πi state is, in fact, the "B state" observed in the recent experimental studies by Scherer, Paul, Collier, and Saykally.

  15. Entanglement of electronic subbands and coherent superposition of spin states in a Rashba nanoloop

    NASA Astrophysics Data System (ADS)

    Safaiee, R.; Golshan, M. M.

    2011-10-01

    The present work is concerned with an analysis of the entanglement between the electronic coherent superpositions of spin states and subbands in a quasi-one-dimensional Rashba nanoloop acted upon by a strong perpendicular magnetic field. We explicitly include the confining potential and the Rashba spin-orbit coupling into the Hamiltonian and then proceed to calculate the von Neumann entropy, a measure of entanglement, as a function of time. An analysis of the von Neumann entropy demonstrates that, as expected, the dynamics of entanglement strongly depends upon the initial state and electronic subband excitations. When the initial state is a pure one formed by a subband excitation and the z-component of spin states, the entanglement exhibits periodic oscillations with local minima (dips). On the other hand, when the initial state is formed by the subband states and a coherent superposition of spin states, the entanglement still periodically oscillates, exhibiting stronger correlations, along with elimination of the dips. Moreover, in the long run, the entanglement for the latter case undergoes the phenomenon of collapse-revivals. This behaviour is absent for the first case of the initial states. We also show that the degree of entanglement strongly depends upon the electronic subband excitations in both cases.

  16. Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135.

    PubMed

    De Luca, Maria Antonietta; Castelli, M Paola; Loi, Barbara; Porcu, Alessandra; Martorelli, Mariella; Miliano, Cristina; Kellett, Kathryn; Davidson, Colin; Stair, Jacqueline L; Schifano, Fabrizio; Di Chiara, Gaetano

    2016-06-01

    In order to investigate the in vivo dopamine (DA) stimulant properties of selected 3rd generation Spice/K2 cannabinoids, BB-22, 5F-PB-22, 5F-AKB-48 and STS-135, their in vitro affinity and agonist potency at native rat and mice CB1 receptors was studied. The compounds bind with high affinity to CB1 receptors in rat cerebral cortex homogenates and stimulate CB1-induced [(35)S]GTPγS binding with high potency and efficacy. BB-22 and 5F-PB-22 showed the lowest Ki of binding to CB1 receptors (0.11 and 0.13 nM), i.e., 30 and 26 times lower respectively than that of JWH-018 (3.38 nM), and a potency (EC50, 2.9 and 3.7 nM, respectively) and efficacy (Emax, 217% and 203%, respectively) as CB1 agonists higher than JWH-018 (EC50, 20.2 nM; Emax, 163%). 5F-AKB-48 and STS-135 had higher Ki for CB1 binding, higher EC50 and lower Emax as CB1 agonists than BB-22 and 5F-PB-22 but still comparatively more favourable than JWH-018. The agonist properties of all the compounds were abolished or drastically reduced by the CB1 antagonist/inverse agonist AM251 (0.1 μM). No activation of G-protein was observed in CB1-KO mice. BB-22 (0.003-0.01 mg/kg i.v.) increased dialysate DA in the accumbens shell but not in the core or in the medial prefrontal cortex, with a bell shaped dose-response curve and an effect at 0.01 mg/kg and a biphasic time-course. Systemic AM251 (1.0 mg/kg i.p.) completely prevented the stimulant effect of BB-22 on dialysate DA in the NAc shell. All the other compounds increased dialysate DA in the NAc shell at doses consistent with their in vitro affinity for CB1 receptors (5F-PB-22, 0.01 mg/kg; 5F-AKB-48, 0.1 mg/kg; STS-135, 0.15 mg/kg i.v.). 3rd generation cannabinoids can be even more potent and super-high CB1 receptor agonists compared to JWH-018. Future research will try to establish if these properties can explain the high toxicity and lethality associated with these compounds. PMID:26686391

  17. Dispersive measurement of electron spin states in Coulomb-confined silicon double quantum dots

    NASA Astrophysics Data System (ADS)

    House, Matthew; Kobayashi, Takashi; Weber, Bent; Hile, Sam; Rogge, Sven; Simmons, Michelle

    2015-03-01

    We use radio frequency reflectometry with a resonant circuit to investigate a double quantum dot device patterned by the placement of phosphorus donors in silicon with scanning tunnelling microscope lithography. The circuit responds to electron tunnelling to and from the quantum dots, the complex admittance of which provides information about the tunnel coupling between the dots and the leads. With four electrons on two dots, the Pauli Exclusion Principle makes tunnelling of one electron between the two dots spin dependent, which we exploit to measure the electronic spin state. We map the ground state transition between singlet and triplet states as a function of electric and magnetic fields, which shows that the exchange energy can be tuned over an order of magnitude (about 10 to 100 μeV) or more in this device. We apply high frequency pulses to induce an excited spin state and observe that the dispersive measurement can detect the excited spin state in addition to the ground state.

  18. Femtosecond electron injection from optically populated donor states into the conduction band of semiconductors

    NASA Astrophysics Data System (ADS)

    Ernstorfer, Ralph; Toeben, Lars; Gundlach, Lars; Felber, Silke; Galoppini, Elena; Wei, Qian; Eichberger, Rainer; Storck, Winfried; Zimmermann, Carsten; Willig, Frank

    2003-12-01

    Unoccupied donor states can be populated via light absorption at the surface of semiconductor in the range of the conduction band levels. Hot electrons are injected from such donor states into the conduction band of a semiconductor on a femtosecond time scale. Such donor states can have rather different physical properties, e.g. unoccupied surface bands formed via reconstruction of the clean surface of a semiconductor in contact with ultra high vacuum or chromophores in molecules that are anchored at the surface of the semiconductor. The energy levels of the donor states with respect to the bands in the semiconductor can be determined with UPS and fs-2PPE. Experimental data on the energetics and dynamics of electron injection are presented for the two different cases of donor states mentioned above. The influence of vibrational wavepackets on electron injection is discussed for the case of a molecular donor state. Energy loss of the hot electrons injected into the semiconductor is measured with energy and time resolution employing femtosecond two-photon-photoemission.

  19. Ground state of a hydrogen ion molecule immersed in an inhomogeneous electron gas

    NASA Astrophysics Data System (ADS)

    Diaz-Valdes, J.; Gutierrez, F. A.; Matamala, A. R.; Denton, C. D.; Vargas, P.; Valdes, J. E.

    2007-01-01

    In this work we have calculated the ground state energy of the hydrogen molecule, H2+, immersed in the highly inhomogeneous electron gas around a metallic surface within the local density approximation. The molecule is perturbed by the electron density of a crystalline surface of Au <1 0 0> with the internuclear axis parallel to the surface. The surface spatial electron density is calculated through a linearized band structure method (LMTO-DFT). The ground state of the molecule-ion was calculated using the Born-Oppenheimer approximation for a fixed-ion while the screening effects of the inhomogeneous electron gas are depicted by a Thomas-Fermi like electrostatic potential. We found that within our model the molecular ion dissociates at the critical distance of 2.35 a.u. from the first atomic layer of the solid.

  20. Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures

    NASA Astrophysics Data System (ADS)

    Wallbank, J. R.; Ghazaryan, D.; Misra, A.; Cao, Y.; Tu, J. S.; Piot, B. A.; Potemski, M.; Pezzini, S.; Wiedmann, S.; Zeitler, U.; Lane, T. L. M.; Morozov, S. V.; Greenaway, M. T.; Eaves, L.; Geim, A. K.; Fal'ko, V. I.; Novoselov, K. S.; Mishchenko, A.

    2016-08-01

    Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays a crucial role in relativistic phenomena, such as Klein tunneling, but it is difficult to visualize directly. Here, we report the direct observation and manipulation of chirality and pseudospin polarization in the tunneling of electrons between two almost perfectly aligned graphene crystals. We use a strong in-plane magnetic field as a tool to resolve the contributions of the chiral electronic states that have a phase difference between the two components of their vector wave function. Our experiments not only shed light on chirality, but also demonstrate a technique for preparing graphene’s Dirac electrons in a particular quantum chiral state in a selected valley.

  1. Studying dissociative electron attachment through formation of heavy-Rydberg ion-pair states

    NASA Astrophysics Data System (ADS)

    Kelley, Michael; Buathong, Sitti; Dunning, F. Barry

    2016-05-01

    Following dissociative electron transfer in collisions between Rydberg atoms and electron-attaching targets, it is possible for the resulting pair of ions to remain electrostatically bound, forming heavy-Rydberg ion-pair states. Precise measurement of the velocity distributions of such ion-pair states provides information concerning the dissociation dynamics of the excited intermediates initially created by electron transfer. Here, electric-field-induced dissociation is used to detect the product ion pairs and observe their velocity distributions. These distributions are analyzed with the aid of a Monte Carlo collision code that models the electron transfer. Measurements with a number of different target species show that through this analysis, dissociation energetics, the branching ratios into different dissociation products, and the lifetimes of the excited intermediates can be examined. Research supported by the Robert A. Welch Foundation.

  2. A hybrid density functional study on the electron and hole trap states in anatase titanium dioxide.

    PubMed

    Yamamoto, Takenori; Ohno, Takahisa

    2012-01-14

    We present a theoretical study on electron and hole trap states in the bulk and (001) surface of anatase titanium dioxide using screened hybrid density functional calculations. In both the bulk and surface, calculations suggest that the neutral and ionized oxygen vacancies are possible electron traps. The doubly ionized oxygen vacancy is the most stable in the bulk, and is a candidate for a shallow donor in colorless anatase crystals. The hole trap states are localized at oxygen anions in both the bulk and surface. The self-trapped electron centered at a titanium cation cannot be produced in the bulk, but can be formed at the surface. The electron trap level at the surface oxygen vacancy is consistent with observations by photoelectron spectroscopy. The optical absorptions and luminescence in UV-irradiated anatase nanoparticles are found to come from the surface self-trapped hole and the surface oxygen vacancy. PMID:22127526

  3. Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures.

    PubMed

    Wallbank, J R; Ghazaryan, D; Misra, A; Cao, Y; Tu, J S; Piot, B A; Potemski, M; Pezzini, S; Wiedmann, S; Zeitler, U; Lane, T L M; Morozov, S V; Greenaway, M T; Eaves, L; Geim, A K; Fal'ko, V I; Novoselov, K S; Mishchenko, A

    2016-08-01

    Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays a crucial role in relativistic phenomena, such as Klein tunneling, but it is difficult to visualize directly. Here, we report the direct observation and manipulation of chirality and pseudospin polarization in the tunneling of electrons between two almost perfectly aligned graphene crystals. We use a strong in-plane magnetic field as a tool to resolve the contributions of the chiral electronic states that have a phase difference between the two components of their vector wave function. Our experiments not only shed light on chirality, but also demonstrate a technique for preparing graphene's Dirac electrons in a particular quantum chiral state in a selected valley. PMID:27493182

  4. Assessment of the accuracy of shape-consistent relativistic effective core potentials using multireference spin-orbit configuration interaction singles and doubles calculations of the ground and low-lying excited states of U(4+) and U(5+).

    PubMed

    Beck, Eric V; Brozell, Scott R; Blaudeau, Jean-Philippe; Burggraf, Larry W; Pitzer, Russell M

    2009-11-12

    Multireference spin-orbit configuration interaction calculations were used to determine the accuracy of 60-, 68-, and 78-electron shape-consistent relativistic effective core potentials (RECPs) for uranium V and VI ground and low-lying excited states. Both 5f(n) and (5f6d)(n), (n = 1, 2) reference spaces were investigated using correlation-consistent double-zeta quality basis sets. Accuracy was assessed against gas-phase experimental spectra. The 68-electron RECP calculations yielded low relative and rms errors and predicted the empirical ordering of states most consistently. PMID:19888778

  5. Electronic states of MgO: Spectroscopy, predissociation, and cold atomic Mg and O production

    SciTech Connect

    Maatouk, A.; Ben Houria, A.; Yazidi, O.; Jaidane, N.; Hochlaf, M.

    2010-10-14

    We used multiconfigurational methods and a large basis set to compute the potential energy curves of the valence and valence-Rydberg electronic states of MgO molecule. New bound electronic states are found. Using these highly correlated wave functions, we evaluated their mutual spin-orbit couplings and transition moment integrals. For the bound electronic states of MgO, we deduced an accurate set of spectroscopic constants that agree remarkably well with experimental results. Moreover, our potentials, transition moments, and spin-orbit coupling evolutions are incorporated into Fermi golden rule calculations to deduce the radiative lifetimes of MgO(B {sup 1}{Sigma}{sup +}) rovibrational levels and the natural lifetimes of MgO(A {sup 1}{Pi}) vibrational levels, where a good agreement is found with experimental values. Finally, we suggest new routes for the production of cold Mg and O atoms and cold MgO molecules.

  6. Time-of-Flight Measurements of Single-Electron Wave Packets in Quantum Hall Edge States

    NASA Astrophysics Data System (ADS)

    Kataoka, M.; Johnson, N.; Emary, C.; See, P.; Griffiths, J. P.; Jones, G. A. C.; Farrer, I.; Ritchie, D. A.; Pepper, M.; Janssen, T. J. B. M.

    2016-03-01

    We report time-of-flight measurements on electrons traveling in quantum Hall edge states. Hot-electron wave packets are emitted one per cycle into edge states formed along a depleted sample boundary. The electron arrival time is detected by driving a detector barrier with a square wave that acts as a shutter. By adding an extra path using a deflection barrier, we measure a delay in the arrival time, from which the edge-state velocity v is deduced. We find that v follows 1 /B dependence, in good agreement with the E →×B → drift. The edge potential is estimated from the energy dependence of v using a harmonic approximation.

  7. Electronic transport characterization of silicon wafers by spatially resolved steady-state photocarrier radiometric imaging

    SciTech Connect

    Wang, Qian; Li, Bincheng

    2015-09-28

    Spatially resolved steady-state photocarrier radiometric (PCR) imaging technique is developed to characterize the electronic transport properties of silicon wafers. Based on a nonlinear PCR theory, simulations are performed to investigate the effects of electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) on the steady-state PCR intensity profiles. The electronic transport parameters of an n-type silicon wafer are simultaneously determined by fitting the measured steady-state PCR intensity profiles to the three-dimensional nonlinear PCR model. The determined transport parameters are in good agreement with the results obtained by the conventional modulated PCR technique with multiple pump beam radii.

  8. Electron impact excitation of the 3s3p 1P1 state in magnesium

    NASA Astrophysics Data System (ADS)

    Predojević, Branko

    2006-12-01

    Differential cross sections (DCSs) for electron-impact excitation of the 3s3p 1P1 resonance state of magnesium have been measured at 10, 15, 20, 40, 60, 80 and 100 eV incident electron energies (Eo). Scattered-electron intensities were measured over wide range of scattering angles from 2° to 150°. The absolute DCS scale for the 1P1 state was determined through normalizations of its relative DCSs to optical oscillator strength using forward scattering function method, except at Eo ⩽ 15 eV where the excitation function of the 3s3p 1P1 state experimentally obtained by Leep and Gallagher (1976 Phys. Rev. A 13 148) was utilized for normalization. These absolute DCSs were extrapolated to 0° and 180° and numerically integrated to yield integral, momentum transfer and viscosity cross sections. Our results are compared with available experimental and theoretical data.

  9. Electronic state-lifetime interference in resonant Auger spectra: a tool to disentangle overlapping core-excited states.

    PubMed

    Goldsztejn, Gildas; Marchenko, Tatiana; Céolin, Denis; Journel, Loïc; Guillemin, Renaud; Rueff, Jean-Pascal; Kushawaha, Rajesh K; Püttner, Ralph; Piancastelli, Maria Novella; Simon, Marc

    2016-06-01

    We have measured resonant-Auger decay following Cl 1s(-1) excitations in HCl and CH3Cl molecules, and extracted the pseudo-cross sections of different Cl 2p(-2) final states. These cross sections show clear evidence of shake processes as well as contributions of electronic state-lifetime interference (ELI). To describe the spectra we developed a fit approach that takes into account ELI contributions and ultrafast nuclear dynamics in dissociative core-excited states. Using this approach we utilized the ELI contributions to obtain the intensity ratios of the overlapping states Cl 1s(-1)4pπ/1s(-1)4pσ in HCl and Cl 1s(-1)4pe/1s(-1)4pa1 in CH3Cl. The experimental value for HCl is compared with theoretical results showing satisfactory agreement. PMID:27199185

  10. Non-steady-state transport of superthermal electrons in the plasmasphere

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Liemohn, Michael W.; Gombosi, Tamas I.; Nagy, Andrew F.

    1993-01-01

    Numerical solutions to the time-dependent kinetic equation, which describes the transport of superthermal electrons in the splasmasphere between the two conjugate ionospheres, are presented. The model calculates the distribution function as a function of time, field-aligned distance, energy, and pitch-angle. The processes of refilling, depleting, and establishing steady-state conditions of superthermal electrons in the plasmasphere are discussed.

  11. State laws prohibiting sales to minors and indoor use of electronic nicotine delivery systems--United States, November 2014.

    PubMed

    Marynak, Kristy; Holmes, Carissa Baker; King, Brian A; Promoff, Gabbi; Bunnell, Rebecca; McAfee, Timothy

    2014-12-12

    Electronic nicotine delivery systems (ENDS), including electronic cigarettes (e-cigarettes) and other devices such as electronic hookahs, electronic cigars, and vape pens, are battery-powered devices capable of delivering aerosolized nicotine and additives to the user. Experimentation with and current use of e-cigarettes has risen sharply among youths and adults in the United States. Youth access to and use of ENDS is of particular concern given the potential adverse effects of nicotine on adolescent brain development. Additionally, ENDS use in public indoor areas might passively expose bystanders (e.g., children, pregnant women, and other nontobacco users) to nicotine and other potentially harmful constituents. ENDS use could have the potential to renormalize tobacco use and complicate enforcement of smoke-free policies. State governments can regulate the sales of ENDS and their use in indoor areas where nonusers might be involuntarily exposed to secondhand aerosol. To learn the current status of state laws regulating the sales and use of ENDS, CDC assessed state laws that prohibit ENDS sales to minors and laws that include ENDS use in conventional smoking prohibitions in indoor areas of private worksites, restaurants, and bars. Findings indicate that as of November 30, 2014, 40 states prohibited ENDS sales to minors, but only three states prohibited ENDS use in private worksites, restaurants, and bars. Of the 40 states that prohibited ENDS sales to minors, 21 did not prohibit ENDS use or conventional smoking in private worksites, restaurants, and bars. Three states had no statewide laws prohibiting ENDS sales to minors and no statewide laws prohibiting ENDS use or conventional smoking in private worksites, restaurants, and bars. According to the Surgeon General, ENDS have the potential for public health harm or public health benefit. The possibility of public health benefit from ENDS could arise only if 1) current smokers use these devices to switch completely

  12. The double ionization of H{sub 2} by fast electron impact: Influence of the final state electron-electron correlation

    SciTech Connect

    Chuluunbaatar, O. Gusev, A. A.; Joulakian, B. B.

    2013-02-15

    We have determined fully differential cross sections of the (e, 3e) double ionization of H{sub 2} by employing correlated initial- and final-state wave functions. We have constructed for the description of the two slow ejected electrons a symmetrized product of a correlation function and two-center continuum wave functions, which fulfill the correct boundary conditions asymptotically up to the order O((kr){sup -2}). We have shown that the introduction of the correlated part of the final-state wave function improves the results on the (e, 3-1e) of H{sub 2}.

  13. Ab initio study on electronically excited states of lithium isocyanide, LiNC

    NASA Astrophysics Data System (ADS)

    Yasumatsu, Hisato; Jeung, Gwang-Hi

    2014-01-01

    The electronically excited states of the lithium isocyanide molecule, LiNC, were studied by means of ab initio calculations. The bonding nature of LiNC up to ˜10 eV is discussed on the basis of the potential energy surfaces according to the interaction between the ion-pair and covalent states. The ion-pair states are described by Coulomb attractive interaction in the long distance range, while the covalent ones are almost repulsive or bound with a very shallow potential dent. These two states interact each other to form adiabatic potential energy surfaces with non-monotonic change in the potential energy with the internuclear distance.

  14. Electronic structure of multiquantum giant vortex states in mesoscopic superconducting disks

    PubMed Central

    Tanaka, Kaori; Robel, István; Jankó, Boldizsár

    2002-01-01

    We report self-consistent calculations of the microscopic electronic structure of the so-called giant vortex states. These multiquantum vortex states, detected by recent magnetization measurements on submicron disks, are qualitatively different from the Abrikosov vortices in the bulk. We find that, in addition to multiple branches of bound states in the core region, the local tunneling density of states exhibits Tomasch oscillations caused by the single-particle interference arising from quantum confinement. These features should be directly observable by scanning tunneling spectroscopy. PMID:16578872

  15. Surface hopping with a manifold of electronic states. I. Incorporating surface-leaking to capture lifetimes

    SciTech Connect

    Ouyang, Wenjun; Dou, Wenjie; Subotnik, Joseph E.

    2015-02-28

    We investigate the incorporation of the surface-leaking (SL) algorithm into Tully’s fewest-switches surface hopping (FSSH) algorithm to simulate some electronic relaxation induced by an electronic bath in conjunction with some electronic transitions between discrete states. The resulting SL-FSSH algorithm is benchmarked against exact quantum scattering calculations for three one-dimensional model problems. The results show excellent agreement between SL-FSSH and exact quantum dynamics in the wide band limit, suggesting the potential for a SL-FSSH algorithm. Discrepancies and failures are investigated in detail to understand the factors that will limit the reliability of SL-FSSH, especially the wide band approximation. Considering the easiness of implementation and the low computational cost, we expect this method to be useful in studying processes involving both a continuum of electronic states (where electronic dynamics are probabilistic) and processes involving only a few electronic states (where non-adiabatic processes cannot ignore short-time coherence)

  16. Pressure-induced phase transition in La1–xSmxO0.5F0.5BiS2

    DOE PAGESBeta

    Fang, Y.; Yazici, D.; White, B. D.; Maple, M. B.

    2015-09-15

    Electrical resistivity measurements on La1–xSmxO0.5F0.5BiS2 (x = 0.1, 0.3, 0.6, 0.8) have been performed under applied pressures up to 2.6 GPa from 2 K to room temperature. The superconducting transition temperature Tc of each sample significantly increases at a Sm-concentration dependent pressure Pt, indicating a pressure-induced phase transition from a low-Tc to a high-Tc phase. At ambient pressure, Tc increases dramatically from 2.8 K at x = 0.1 to 5.4 K at x = 0.8; however, the Tc values at P > Pt decrease slightly with x and Pt shifts to higher pressures with Sm substitution. In the normal state,more » semiconducting-like behavior is suppressed and metallic conduction is induced with increasing pressure in all of the samples. Furthermore, these results suggest that the pressure dependence of Tc for the BiS2-based superconductors is related to the lattice parameters at ambient pressure and enable us to estimate the evolution of Tc for SmO0.5F0.5BiS2 under pressure.« less

  17. Pressure-induced phase transition in La1 -xSmxO0.5F0.5BiS2

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Yazici, D.; White, B. D.; Maple, M. B.

    2015-09-01

    Electrical resistivity measurements on La1 -xSmxO0.5F0.5BiS2 (x =0.1 ,0.3 ,0.6 ,0.8 ) have been performed under applied pressures up to 2.6 GPa from 2 K to room temperature. The superconducting transition temperature Tc of each sample significantly increases at a Sm-concentration-dependent pressure Pt, indicating a pressure-induced phase transition from a low-Tc to a high-Tc phase. At ambient pressure, Tc increases dramatically from 2.8 K at x =0.1 to 5.4 K at x =0.8 ; however, the Tc values at P >Pt decrease slightly with x , and Pt shifts to higher pressures with Sm substitution. In the normal state, semiconducting-like behavior is suppressed, and metallic conduction is induced with increasing pressure in all of the samples. These results suggest that the pressure dependence of Tc for the BiS2-based superconductors is related to the lattice parameters at ambient pressure and enable us to estimate the evolution of Tc for SmO0.5F0.5BiS2 under pressure.

  18. On bound state computations in three- and four-electron atomic systems

    SciTech Connect

    Frolov, A. M. Wardlaw, D. M.

    2010-07-15

    A variational approach is developed for bound state calculations in three- and four-electron atomic systems. This approach can be applied to determine, in principle, an arbitrary bound state in three- and four-electron ions and atoms. Our variational wave functions are constructed from four- and five-body Gaussoids that respectively depend on six (r{sub 12}, r{sub 13}, r{sub 14}, r{sub 23}, r{sub 24}, r{sub 34}) and ten (r{sub 12}, r{sub 13}, r{sub 14}, r{sub 15}, r{sub 23}, r{sub 24}, r{sub 25}, r{sub 34}, r{sub 35} and r{sub 45}) relative coordinates. The approach allows operating with the more than one electron spin functions. In particular, the trial wave functions for the {sup 1}S states in four-electron atomic systems include the two independent spin functions {chi}{sub 1} = {alpha}{beta}{alpha}{beta} + {beta}{alpha}{beta}{alpha} - {beta}{alpha}{alpha}{beta} - {alpha}{beta}{beta}{alpha} and {chi}{sub 2} = 2{alpha}{alpha}{beta}{beta} + 2{beta}{beta}{alpha}{alpha} - {beta}{alpha}{alpha}{beta} - {alpha}{beta}{beta}{alpha} - {beta}{alpha}{beta}{alpha} - {alpha}{beta}{alpha}{beta}. We also discuss the construction of variational wave functions for the excited 2{sup 3}S states in four- electron atomic systems.

  19. Spectral exhibition of electron-vibrational relaxation in P* state of Rhodobacter sphaeroides reaction centers.

    PubMed

    Yakovlev, Andrei G; Shuvalov, Vladimir A

    2015-08-01

    Electron-vibrational relaxation in the excited state of the primary electron donor, bacteriochlorophyll dimer P, in the reaction centers (RCs) of purple photosynthetic bacteria Rhodobacter sphaeroides is modeled. A multimode model of three states (i.e., the ground state Pg, initially excited P1*, and relaxed excited P2*) is used to calculate the incoherent dynamics of the difference (ΔA) spectra on a femtosecond timescale for the YM210 W mutant RCs. The relaxation processes are described by the step-ladder model. The model shows that the electron-vibrational relaxation in the excited state of P is visualized by the transient red shift of the stimulated emission from P*. The dynamics of this shift is observed as a change in the ΔA spectrum shape in its red-most part, within a few hundreds of femtoseconds after excitation. As a result, an initial rise in the red-side ΔA kinetics is delayed with respect to the blue-side kinetics. The time constant of the P1* → P2* electronic relaxation (54 fs) and the Pg, P1*, and P2* vibrational relaxations (120 fs), used in the model, provided the best fit of the experimental time-resolved ΔA spectra and kinetics at 90 and 293 K. The possible nature of the P1* → P2* electronic relaxation is discussed. PMID:25240681

  20. Statistical theory of relaxation of high-energy electrons in quantum Hall edge states

    NASA Astrophysics Data System (ADS)

    Lunde, Anders Mathias; Nigg, Simon E.

    2016-07-01

    We investigate theoretically the energy exchange between the electrons of two copropagating, out-of-equilibrium edge states with opposite spin polarization in the integer quantum Hall regime. A quantum dot tunnel coupled to one of the edge states locally injects electrons at high energy. Thereby a narrow peak in the energy distribution is created at high energy above the Fermi level. A second downstream quantum dot performs an energy-resolved measurement of the electronic distribution function. By varying the distance between the two dots, we are able to follow every step of the energy exchange and relaxation between the edge states, even analytically under certain conditions. In the absence of translational invariance along the edge, e.g., due to the presence of disorder, energy can be exchanged by non-momentum-conserving two-particle collisions. For weakly broken translational invariance, we show that the relaxation is described by coupled Fokker-Planck equations. From these we find that relaxation of the injected electrons can be understood statistically as a generalized drift-diffusion process in energy space for which we determine the drift velocity and the dynamical diffusion parameter. Finally, we provide a physically appealing picture in terms of individual edge-state heating as a result of the relaxation of the injected electrons.

  1. Anisotropic Nature of Anatase TiO2 and Its Intrinsic (001) Surface Electronic States

    NASA Astrophysics Data System (ADS)

    Chen, Hungru; Dawson, James A.; Umezawa, Naoto

    2015-07-01

    Anatase TiO2 attracts considerable interest for a range of technological applications such as photocatalysis and electronic memory devices. Recent studies have shown that the (001) surface plays a crucial role in its photocatalytic activity and this has been attributed to its higher surface energy and its ability to adsorb water dissociatively. However, a fundamental understanding of why this surface is so unique is still lacking. In this study, the anatase TiO2 (001) and (101) surfaces, both present in its equilibrium crystal shape, are studied using state-of-the-art ab initio hybrid density-functional-theory calculations. It is found that the electronic states at the (001) surface strongly deviate from the bulk, while the electronic states at the (101) surface do not. We illustrate the role of anisotropy in the crystal on the electronic structures of anatase TiO2 and demonstrate how the formation of the (001) surface disrupts local orbital interactions and gives rise to distinctive surface electronic states, which give the (001) surface its unique properties.

  2. Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating

    PubMed Central

    Jin, Kui; Hu, Wei; Zhu, Beiyi; Kim, Dohun; Yuan, Jie; Sun, Yujie; Xiang, Tao; Fuhrer, Michael S.; Takeuchi, Ichiro; Greene, Richard. L.

    2016-01-01

    The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2−xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of −2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected. PMID:27221198

  3. Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating

    NASA Astrophysics Data System (ADS)

    Jin, Kui; Hu, Wei; Zhu, Beiyi; Kim, Dohun; Yuan, Jie; Sun, Yujie; Xiang, Tao; Fuhrer, Michael S.; Takeuchi, Ichiro; Greene, Richard. L.

    2016-05-01

    The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2‑xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of ‑2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected.

  4. Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating.

    PubMed

    Jin, Kui; Hu, Wei; Zhu, Beiyi; Kim, Dohun; Yuan, Jie; Sun, Yujie; Xiang, Tao; Fuhrer, Michael S; Takeuchi, Ichiro; Greene, Richard L

    2016-01-01

    The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2-xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of -2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected. PMID:27221198

  5. Ring Puckering Potentials of Three Fluorinated Cyclopentenes: C_5F_8, C_5HF_7, and C_5H_2F_6

    NASA Astrophysics Data System (ADS)

    Arsenault, E. A.; Long, B. E.; Pringle, Wallace C.; Choi, Yoon Jeong; Cooke, S. A.; Ocola, Esther J.; Laane, Jaan

    2015-06-01

    A systematic study on the ring puckering potentials of three fluorinated cyclopentenes has been performed using Fourier transform microwave spectroscopy in tandem with quantum chemical calculations. Spectra between 8 GHz and 16 GHz have been measured for octafluorocyclopentene, 1H-heptafluorocyclopentene, and 1H,2H-hexafluorocyclopentene, where the hydrogens sequentially replace the fluorines on the sp^2 hybridized carbons. Rotational constants and centrifugal distortion constants have been determined for the parent species and all 13C isotopologues. In regards to the ring puckering, double minimum potential, both cross state and intra-state transitions were observed for all molecules except the 1H,2H-hexafluorocyclopentene. Experimental Coriolis coupling constants and ΔE01 values will be presented and discussed. The ring puckering barrier heights for C_5F_8, C_5HF_7, and C_5H_2F_6, have been calculated to be 222 wn, 302 wn, and 367 wn, respectively.

  6. Observation of surface states on gold films by electron tunneling spectroscopy

    NASA Technical Reports Server (NTRS)

    Lambe, J.; Thakoor, A. P.; Khanna, S. K.

    1984-01-01

    It is pointed out that inelastic electron tunneling spectroscopy (IETS) is a useful technique for the study of vibrational modes of molecules adsorbed on the surface of the insulating layer in a metal-insulator-metal tunnel junction. A detailed study of electron tunneling in aluminum-aluminum oxide-gold (Al-Al2O3-Au) tunnel junctions has been conducted with an overall goal of exploring possible mechanisms in such a thin film device useful for chemical sensing. For an understanding of the electronic effects in the presence of chemicals in a junction, the electronic surface properties of the metallic films in a clean tunnel junction must be established. The present investigation is concerned with room temperature observations of electronic states on the surface of highly oriented gold film in Al-Al2O3-Au junctions.

  7. Adsorption and electronic states of morin on TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zdyb, Agata; Krawczyk, Stanisław

    2014-10-01

    Low temperature Stark effect spectroscopy has been used to investigate the changes in the electronic charge distribution in the flavonoid morin caused by adsorption to colloidal TiO2 nanoparticles in ethanol. The differences in the permanent dipole moment, Δμ, and in polarizability, Δα, between the ground and excited state were determined. Adsorption causes an increase in both Δμ and Δα of morin but the vector Δμ remains nearly perpendicular to the Ti-dye direction, like in the free molecule. This picture of electron movement on electronic excitation is supported by semiempirical calculations. In contrast to other dyes adsorbed on TiO2, it indicates the indirect effect of chelated Ti atom on morin electronic structure which does not involve the atomic orbitals of the metal, and the electronic structure of adsorbed morin similar to that of the anion.

  8. Numerical bound state electron dynamics of carbon dioxide in the strong-field regime.

    PubMed

    Smith, Stanley M; Romanov, Dmitri A; Li, Xiaosong; Sonk, Jason A; Schlegel, H Bernhard; Levis, Robert J

    2010-02-25

    Time-dependent Hartree-Fock simulations for a linear triatomic molecule (CO(2)) interacting with a short IR (1.63 eV) three-cycle pulse reveal that the carrier-envelope shape and phase are the essential field parameters determining the bound state electron dynamics during and after the laser-molecule interaction. Analysis of the induced dipole oscillation reveals that the envelope shape (Gaussian or trapezoidal) controls the excited state population distribution. Varying the carrier envelope phase for each of the two pulse envelope shapes considerably changes the excited state populations. Increasing the electric field amplitude alters the relative populations of the excited states, generally exciting higher states. A windowed Fourier transform analysis of the dipole evolution during the laser pulse reveals the dynamics of state excitation and in particular state coupling as the laser intensity increases. PMID:20113001

  9. State-averaged Monte Carlo configuration interaction applied to electronically excited states

    NASA Astrophysics Data System (ADS)

    Coe, J. P.; Paterson, M. J.

    2013-10-01

    We introduce state-averaging into the method of Monte Carlo configuration interaction (SA-MCCI) to allow the stable and efficient calculation of excited states. We show that excited potential curves for H3, including a crossing with the ground state, can be accurately reproduced using a small fraction of the full configuration interaction (FCI) space. A recently introduced error measure for potential curves [J. P. Coe and M. J. Paterson, J. Chem. Phys. 137, 204108 (2012)] is also shown to be a fair approach when considering potential curves for multiple states. We demonstrate that potential curves for LiF using SA-MCCI agree well with the FCI results and the avoided crossing occurs correctly. The seam of conical intersections for CH2 found by Yarkony [J. Chem. Phys. 104, 2932 (1996)] is used as a test for SA-MCCI and we compare potential curves from SA-MCCI with FCI results for this system for the first three triplet states. We then demonstrate the improvement from using SA-MCCI on the dipole of the 2 1A1 state of carbon monoxide. We then look at vertical excitations for small organic molecules up to the size of butadiene where the SA-MCCI energies and oscillator strengths are compared with CASPT2 values [M. Schreiber, M. R. Silva-Junior, S. P. A. Sauer, and W. Thiel, J. Chem. Phys. 128, 134110 (2008)]. We finally see if the SA-MCCI results for these excitation energies can be improved by using MCCIPT2 with approximate natural orbitals when the PT2 space is not onerously large.

  10. Potentially Functional Polymorphisms in POU5F1 Gene Are Associated with the Risk of Lung Cancer in Han Chinese

    PubMed Central

    Niu, Rui; Wang, Yuzhuo; Zhu, Meng; Wen, Yifan; Sun, Jie; Shen, Wei; Cheng, Yang; Zhang, Jiahui; Jin, Guangfu; Ma, Hongxia; Hu, Zhibin; Shen, Hongbing; Dai, Juncheng

    2015-01-01

    POU5F1 is a key regulator of self-renewal and differentiation in embryonic stem cells and may be associated with initiation, promotion, and progression in cancer. We hypothesized that functional polymorphisms in POU5F1 may play an important role in modifying the lung cancer risk. To test this hypothesis, we conducted a case-control study to explore the association between 17 potentially functional SNPs in POU5F1 gene and the lung cancer risk in 1,341 incident lung cancer cases and 1,982 healthy controls in a Chinese population. We found that variant alleles of rs887468 and rs3130457 were significantly associated with increased risk of lung cancer after multiple comparison (OR = 1.29, 95% CI: 1.11–1.51, Pfdr = 0.017 for rs887468; OR = 1.29, 95% CI: 1.10–1.51, Pfdr = 0.034 for rs3130457, resp.). In addition, we detected a significant interaction between rs887468 genotypes and smoking status on lung cancer risk (P = 0.017). Combined analysis of these 2 SNPs showed a significant allele-dosage association between the number of risk alleles and increased risk of lung cancer (Ptrend < 0.001). These findings indicate that potentially functional polymorphisms in POU5F1 gene may contribute to lung cancer susceptibility in a Chinese population. PMID:26824036

  11. The role of electron equation of state in heating partition of protons in a collisionless plasma

    SciTech Connect

    Parashar, Tulasi N.; Vasquez, Bernard J.; Markovskii, Sergei A.

    2014-02-15

    One of the outstanding questions related to the solar wind is the heating of solar wind plasma. Addressing this question requires a self consistent treatment of the kinetic physics of a collisionless plasma. A hybrid code (with particle ions and fluid electrons) is one of the most convenient computational tools, which allows us to explore self consistent ion kinetics, while saving us computational time as compared to the full particle in cell codes. A common assumption used in hybrid codes is that of isothermal electrons. In this paper, we discuss the role that the equation of state for electrons could potentially play in determining the ion kinetics.

  12. Clean Ir(111) and Pt(111) electronic surface states: A first-principle fully relativistic investigation

    NASA Astrophysics Data System (ADS)

    Dal Corso, Andrea

    2015-07-01

    We present a first-principle investigation of the fully relativistic electronic surface states and resonances of clean Pt(111) and Ir(111) and compare them with those of Au(111). Our calculations are based on a recently introduced fully relativistic projector augmented-wave (PAW) approach that includes spin-orbit coupling and allows us to access both the relativistic energy splittings and the spin polarization of the surface states. The maps of the electronic structure of the two surfaces are critically discussed in comparison with previous calculations and with some of the available angle-resolved photoelectron spectroscopy data.

  13. Density Functional Theory Studies of the Electronic Structure of Solid State Actinide Oxides

    SciTech Connect

    Wen, Xiaodong; Martin, Richard L.; Henderson, Thomas M.; Scuseria, Gustavo E.

    2013-02-13

    The actinide oxides have been extensively studied in the context of the nuclear fuel cycle. They are also of fundamental interest as members of a class of strongly correlated materials, the Mott insulators. Their complex physical and chemical properties make them challenging systems to characterize, both experimentally and theoretically. Chiefly, this is because actinide oxides can exhibit both electronic localization and electronic delocalization and have partially occupied f orbitals, which can lead to multiple possibilities for ground states. Of particular concern for theoretical work is that the large number of competing states display strong correlations which are dffcult to capture with computationally tractable methods.

  14. Localized electronic states at grain boundaries on the surface of graphene and graphite

    NASA Astrophysics Data System (ADS)

    Luican-Mayer, Adina; Barrios-Vargas, Jose E.; Toft Falkenberg, Jesper; Autès, Gabriel; Cummings, Aron W.; Soriano, David; Li, Guohong; Brandbyge, Mads; Yazyev, Oleg V.; Roche, Stephan; Andrei, Eva Y.

    2016-09-01

    Recent advances in large-scale synthesis of graphene and other 2D materials have underscored the importance of local defects such as dislocations and grain boundaries (GBs), and especially their tendency to alter the electronic properties of the material. Understanding how the polycrystalline morphology affects the electronic properties is crucial for the development of applications such as flexible electronics, energy harvesting devices or sensors. We here report on atomic scale characterization of several GBs and on the structural-dependence of the localized electronic states in their vicinity. Using low temperature scanning tunneling microscopy and spectroscopy, together with tight binding and ab initio numerical simulations we explore GBs on the surface of graphite and elucidate the interconnection between the local density of states and their atomic structure. We show that the electronic fingerprints of these GBs consist of pronounced resonances which, depending on the relative orientation of the adjacent crystallites, appear either on the electron side of the spectrum or as an electron-hole symmetric doublet close to the charge neutrality point. These two types of spectral features will impact very differently the transport properties allowing, in the asymmetric case to introduce transport anisotropy which could be utilized to design novel growth and fabrication strategies to control device performance.

  15. Effects of Electronic-State-Dependent Solute Polarizability: Application to Solute-Pump/Solvent-Probe Spectra.

    PubMed

    Sun, Xiang; Ladanyi, Branka M; Stratt, Richard M

    2015-07-23

    Experimental studies of solvation dynamics in liquids invariably ask how changing a solute from its electronic ground state to an electronically excited state affects a solution's dynamics. With traditional time-dependent-fluorescence experiments, that means looking for the dynamical consequences of the concomitant change in solute-solvent potential energy. But if one follows the shift in the dynamics through its effects on the macroscopic polarizability, as recent solute-pump/solvent-probe spectra do, there is another effect of the electronic excitation that should be considered: the jump in the solute's own polarizability. We examine the spectroscopic consequences of this solute polarizability change in the classic example of the solvation dye coumarin 153 dissolved in acetonitrile. After demonstrating that standard quantum chemical methods can be used to construct accurate multisite models for the polarizabilities of ground- and excited-state solvation dyes, we show via simulation that this polarizability change acts as a contrast agent, significantly enhancing the observable differences in optical-Kerr spectra between ground- and excited-state solutions. A comparison of our results with experimental solute-pump/solvent-probe spectra supports our interpretation and modeling of this spectroscopy. We predict, in particular, that solute-pump/solvent-probe spectra should be sensitive to changes in both the solvent dynamics near the solute and the electronic-state-dependence of the solute's own rotational dynamics. PMID:25299940

  16. Pair density related to one-electron information for the ground state of spin-compensated two-electron systems

    NASA Astrophysics Data System (ADS)

    Amovilli, C.; March, N. H.

    The recent study by Joubert on effects of Coulomb repulsions in a many-electron system has focused attention on an integral identity involving the pair density. This has motivated the derivation presented here of a vectorial differential form related to this integral result. Our differential identity is then illustrated explicitly by using (i) an exact ground-state wave function for the so-called Hookean atom having external potential energy (1/2)kr2, with k = 1/4, and (ii) Moshinsky's model in which both the interparticle interaction and the external potential are of harmonic type.

  17. Electron correlations in single-electron capture into any state of fast projectiles from heliumlike atomic systems

    NASA Astrophysics Data System (ADS)

    Mančev, Ivan; Milojević, Nenad; Belkić, Dževad

    2013-11-01

    State-selective and total single-electron capture cross sections in fast collisions of a bare projectile with a heliumlike target are examined in the four-body formalism. A special emphasis is given to a proper inclusion of dynamic electron-electron correlation effects. For this purpose, the post form of the four-body boundary-corrected first Born approximation (CB1-4B) is utilized. With regard to our related previous study, where the prior version has been considered, in the present work an extensive analytical study of the post-transition amplitude for electron capture into the arbitrary final states nflfmf of the projectile is carried out. The post-transition amplitude for single charge exchange encompassing symmetric and asymmetric collisions is derived in terms of five-dimensional integrals over real variables. The dielectronic interaction V12=1/r12≡1/|r⃗1-r⃗2| explicitly appears in the perturbation potential Vf of the post-transition probability amplitude Tif+, such that the CB1-4B method can provide information about the relative significance of the dynamic interelectron correlation in the collisions under study. An illustrative computation is performed involving state-selective and total single capture cross sections for the p-He collisions at intermediate and high impact energies. The so-called post-prior discrepancy, which plagues almost all the existing distorted wave approximations, is presently shown to be practically nonexistent in the CB1-4B method. The validity of our findings is critically assessed in comparisons with the available experimental data for both state-selective and total cross sections summed over all the discrete energy levels of the hydrogenlike atom formed with the projectile. Overall, excellent performance of the CB1-4B method is recorded, thus robustly establishing this formalism as the leading first-order description of high-energy single charge exchange, which is a collision of paramount theoretical and practical

  18. Influence of a polarizable surrounding on the electronically excited states of aggregated perylene materials.

    PubMed

    Bellinger, Daniel; Settels, Volker; Liu, Wenlan; Fink, Reinhold F; Engels, Bernd

    2016-06-30

    To tune the efficiency of organic semiconductor devices it is important to understand limiting factors as trapping mechanisms for excitons or charges. An understanding of such mechanisms deserves an accurate description of the involved electronical states in the given environment. In this study, we investigate how a polarizable surrounding influences the relative positions of electronically excited states of dimers of different perylene dyes. Polarization effects are particularly interesting for these systems, because gas phase computations predict that the CT states lie slightly above the corresponding Frenkel states. A polarizable environment may change this energy order because CT states are thought to be more sensitive to a polarizable surrounding than Frenkel states. A first insight we got via a TD-HF approach in combination with a polarizable continuum model (PCM). These give limited insights because TD-HF overestimates excitation energies of CT states. However, SCS-CC2 approaches, which are sufficiently accurate, cannot easily be used in combination with continuum solvent models. Hence, we developed two approaches to combine gas phase SCS-CC2 results with solvent effects based on TD-HF computations. Their accuracies were finally checked via ADC(2)//COSMO computations. The results show that for perylene dyes a polarizable surrounding alone does not influence the energetic ordering of CT and Frenkel states. Variations in the energy order of the states only result from nuclear relaxation effects after the excitation process. © 2016 Wiley Periodicals, Inc. PMID:27030658

  19. Materials Data on PRu5C16(O5F)3 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on C4O5F6 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on B5F6 (SG:88) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Materials Data on AsI5F6 (SG:15) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on K3Fe5F15 (SG:127) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Materials Data on AsBr5F6 (SG:15) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on Nd2As6Xe5F46 (SG:12) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Materials Data on Nd2Au5F21 (SG:92) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Materials Data on Nd2Pb5F16 (SG:8) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  8. Materials Data on S4N5F (SG:2) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  9. Materials Data on La2Au5F21 (SG:92) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Materials Data on Y2Au5F21 (SG:13) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  11. Materials Data on Y6O5F8 (SG:1) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Materials Data on CaP2Xe5F22 (SG:33) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on CdP2Xe5F22 (SG:33) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Materials Data on Na3Sb5F18 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Electronic states at the interface between indium tin oxide and silicon

    SciTech Connect

    Malmbekk, H.; Vines, L.; Monakhov, E. V.; Svensson, B. G.

    2011-10-01

    Electronic properties and thermal stability of interfacial states between indium tin oxide (ITO) and monocrystalline silicon (Si) have been investigated. ITO films with thicknesses of about 300 nm were deposited by dc magnetron sputtering on n- and p-type (100) Si at room temperature. The samples were then annealed for 30 min at different temperatures in the range 100-600 deg. C, and the ITO-Si junction was found to exhibit rectifying behavior. Current-voltage (IV), capacitance-voltage (CV), and deep-level transient spectroscopy (DLTS) measurements have been used to electrically characterize the ITO-Si interface. DLTS measurements on p-type Si samples reveal a dominant hole trap at around 0.37 eV above the valence band edge. In the n-type samples, a broad band of electron traps occur in the range 0.1-0.2 eV below the conduction band edge. These electron traps display wide DLTS peaks, indicating a band of electronic energy levels rather than well-defined states originating from isolated point defects. All the traps in both the p- and n-type samples are found to be located near the ITO-Si interface. Investigations of the thermal stability of the observed electronic states show that the dominant hole trap anneal out after 30 min at 250 deg. C, while the dominant electron traps can be stable up to 500 deg. C. IV and DLTS measurements demonstrate a clear correlation between the annealing of the dominant electronic states and increase in the junction rectification.

  16. Temperature Dependence of Electron Drift Velocity and Electron Collision Cross Section Sets for Ground State and Vibrationally Excited State of the CO2 Molecule

    NASA Astrophysics Data System (ADS)

    Hayashi, M.; Nakamura, Y.

    1998-10-01

    The electron drift velocity in carbon dioxide was calculated at gas temperatures ranging from 193 to 573 K and at E/N values up to 100 Td, assuming that the gas was a mixture of ground state and vibrationally excited molecules and that the mix-ratio was determined by the gas temperature. The elastic momentum cross sections for the ground and the vibrationally excited molecules used in the present calculation were based on the compilation of Hayashi (1990) and recent experiments of Nakamura (1995) and Strakeljahn (1998). We also assumed that all other inelastic cross sections for the ground and the vibrationally excited molecules were the same (Schulz 1969, Srivastava 1983). The calculated electron drift velocity showed marked temperature dependence which agreed fairly well with the measurement of Elford (1980).

  17. State-of-the-art eigensolvers for electronic structure calculations of large scale nano-systems

    NASA Astrophysics Data System (ADS)

    Vömel, Christof; Tomov, Stanimire Z.; Marques, Osni A.; Canning, A.; Wang, Lin-Wang; Dongarra, Jack J.

    2008-07-01

    The band edge states determine optical and electronic properties of semiconductor nano-structures which can be computed from an interior eigenproblem. We study the reliability and performance of state-of-the-art iterative eigensolvers on large quantum dots and wires, focusing on variants of preconditioned CG, Lanczos, and Davidson methods. One Davidson variant, the GD + k (Olsen) method, is identified to be as reliable as the commonly used preconditioned CG while consistently being between two and three times faster.

  18. Multi-Center Electronic Structure Calculations for Plasma Equation of State

    SciTech Connect

    Wilson, B G; Johnson, D D; Alam, A

    2010-12-14

    We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.

  19. A Prototype System for Electronic Data Interchange among Registrar's Offices of Different States

    NASA Astrophysics Data System (ADS)

    Metz, Igor; Blöchlinger, Adrian; Varveris, Alexandros

    This work presents a prototype system that enables electronic integration of civil status records of the International Commission on Civil Status (ICCS) member states; the pursued issues are involving civil status matters for citizens of member states through their respective Registrars' Offices organization. Phase 1 of the prototype system is presented together with the technical feasibility securely to exchange messages among civil status offices as well as to assure message integrity, authenticity, confidentiality and non-repudiation.

  20. Measurement of the lifetime of excited-state electron bubbles in superfluid helium

    SciTech Connect

    Ghosh, Ambarish; Maris, Humphrey J.

    2005-08-01

    We report on the measurement of the lifetime of bubbles in superfluid helium that contain an electron in the 1P state. The 1P bubbles are produced by laser excitation of ground-state bubbles, and are detected by ultrasonic cavitation. Our measurements show that the lifetime of these excited bubbles is much less than the calculated lifetime for radiative decay and, hence, is determined by a nonradiative mechanism.

  1. Extensive ab initio study of the electronic states of BSe radical including spin-orbit coupling.

    PubMed

    Liu, Siyuan; Zhai, Hongsheng; Liu, Yufang

    2016-06-01

    The internally contracted multi-reference configuration interaction method (MRCI) with Davidson modification and the Douglas-Kroll scalar relativistic correction has been used to calculate the BSe molecule at the level of aug-cc-pV5Z basis set. The calculated electronic states, including 9 doublet and 6 quartet Λ-S states, are correlated to the dissociation limit of B((2)P(u))+Se((3)P(g)) and B((2)P(u))+Se((1)D(g)). The Spin-orbit coupling (SOC) interaction is taken into account via the state interaction approach with the full Breit-Pauli Hamiltonian operator, which causes the entire 15 Λ-S states to split into 32Ω states. This is the first time that the spin-orbit coupling calculation has been carried out on BSe. The potential energy curves of the Λ-S and Ω electronic states are depicted with the aid of the avoided crossing rule between electronic states of the same symmetry. The spectroscopic constants of the bound Λ-S and Ω states were determined, which are in good agreement with the experimental data. The transition dipole moments (TDMs) and the Franck-Condon factors (FCs) of the transitions from the low-lying bound Ω states A(2)Π(I)3/2, B(2)Π(I)1/2 and C(2)Δ(I)3/2 to the ground state X(2)Σ(+)1/2 have also been presented. Based on the previous calculations, the radiative lifetimes of the A(2)Π(I)3/2, B(2)Π(I)1/2 and C(2)Δ(I)3/2 were evaluated. PMID:26999315

  2. Extensive ab initio study of the electronic states of BSe radical including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Liu, Siyuan; Zhai, Hongsheng; Liu, Yufang

    2016-06-01

    The internally contracted multi-reference configuration interaction method (MRCI) with Davidson modification and the Douglas-Kroll scalar relativistic correction has been used to calculate the BSe molecule at the level of aug-cc-pV5Z basis set. The calculated electronic states, including 9 doublet and 6 quartet Λ-S states, are correlated to the dissociation limit of B(2Pu) + Se(3Pg) and B(2Pu) + Se(1Dg). The Spin-orbit coupling (SOC) interaction is taken into account via the state interaction approach with the full Breit-Pauli Hamiltonian operator, which causes the entire 15 Λ-S states to split into 32 Ω states. This is the first time that the spin-orbit coupling calculation has been carried out on BSe. The potential energy curves of the Λ-S and Ω electronic states are depicted with the aid of the avoided crossing rule between electronic states of the same symmetry. The spectroscopic constants of the bound Λ-S and Ω states were determined, which are in good agreement with the experimental data. The transition dipole moments (TDMs) and the Franck-Condon factors (FCs) of the transitions from the low-lying bound Ω states A2Π(I)3/2, B2Π(I)1/2 and C2Δ(I)3/2 to the ground state X2Σ+1/2 have also been presented. Based on the previous calculations, the radiative lifetimes of the A2Π(I)3/2, B2Π(I)1/2 and C2Δ(I)3/2 were evaluated.

  3. Extraction of a steady state electron beam from HCD plasmas for EBIS applications

    SciTech Connect

    Hershcovitch, A.; Kovarik, V.; Prelec, K.

    1988-01-01

    Experiments to extract high brightness electron beams from hollow cathode discharge plasmas are now in progress. A unique feature of these plasmas, which in principle can facilitate the extraction of large current low emittance electron beams, is the existence of a relatively high energy electron population with a very narrow energy spread. This electron population was identified in a self-extraction experiment, which yielded a 35 eV, 600 mA electron beam with parallel energy spread of less than 0.5 eV. Application of a very modest extraction voltage yielded a steady state extracted electron beam current of 6.5 A of which 5.7 had a preacceleration parallel energy spread of no more than 0.25 eV. The end result of this endeavor would be an electron beam current to 6 A even though, preliminary results strongly suggest that much larger electron beam currents can be produced. 6 refs., 4 figs.

  4. Photodissociation of carbon dioxide in singlet valence electronic states. II. Five state absorption spectrum and vibronic assignment

    NASA Astrophysics Data System (ADS)

    Grebenshchikov, Sergy Yu.

    2013-06-01

    The absorption spectrum of CO2 in the wavelength range 120-160 nm is analyzed by means of quantum mechanical calculations performed using vibronically coupled potential energy surfaces of five singlet valence electronic states and the coordinate dependent transition dipole moment vectors. The thermally averaged spectrum, calculated for T = 190 K via Boltzmann averaging of optical transitions from many initial rotational states, accurately reproduces the experimental spectral envelope, consisting of a low and a high energy band, the positions of the absorption maxima, their FWHMs, peak intensities, and frequencies of diffuse structures in each band. Contributions of the vibronic interactions due to Renner-Teller coupling, conical intersections, and the Herzberg-Teller effect are isolated and the calculated bands are assigned in terms of adiabatic electronic states. Finally, diffuse structures in the calculated bands are vibronically assigned using wave functions of the underlying resonance states. It is demonstrated that the main progressions in the high energy band correspond to consecutive excitations of the pseudorotational motion along the closed loop of the CI seam, and progressions differ in the number of nodes along the radial mode perpendicular to the closed seam. Irregularity of the diffuse peaks in the low energy band is interpreted as a manifestation of the carbene-type "cyclic" OCO minimum.

  5. First-principles equation of state and electronic properties of warm dense oxygen

    SciTech Connect

    Driver, K. P. Soubiran, F.; Zhang, Shuai; Militzer, B.

    2015-10-28

    We perform all-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of oxygen. Our simulations cover a wide density-temperature range of 1–100 g cm{sup −3} and 10{sup 4}–10{sup 9} K. By combining results from PIMC and DFT-MD, we are able to compute pressures and internal energies from first-principles at all temperatures and provide a coherent equation of state. We compare our first-principles calculations with analytic equations of state, which tend to agree for temperatures above 8 × 10{sup 6} K. Pair-correlation functions and the electronic density of states reveal an evolving plasma structure and ionization process that is driven by temperature and density. As we increase the density at constant temperature, we find that the ionization fraction of the 1s state decreases while the other electronic states move towards the continuum. Finally, the computed shock Hugoniot curves show an increase in compression as the first and second shells are ionized.

  6. Vibrational states of the triplet electronic state of H3+. The role of non-adiabatic Jahn-Teller coupling

    NASA Astrophysics Data System (ADS)

    Alijah, Alexander; Kokoouline, Viatcheslav

    2015-10-01

    Vibrational energies and wave functions of the triplet state of the H3+ ion have been determined. In the calculations, the ground and first excited triplet electronic states are included as well as the most important part of the non-Born-Oppenheimer coupling between them. The diabatization procedure proposed by Longuet-Higgins is then applied to transform the two adiabatic ab initio potential energy surfaces of the triplet-H3+ state into a 2 × 2 diabatic matrix. The diabatization takes into account the effect of the geometrical phase due to the conical intersection between the two adiabatic potential surfaces. The results are compared to the calculation involving only the lowest adiabatic potential energy surface of the triplet-H3+ ion and neglecting the geometrical phase. The energy difference between results with and without the non-adiabatic coupling and the geometrical phase is about one wave number for the lowest vibrational levels.

  7. ab Initio Diabatic energies and dipole moments of the electronic states of RbLi molecule.

    PubMed

    Dardouri, Riadh; Habli, Héla; Oujia, Brahim; Gadéa, Florent Xavier

    2013-09-15

    For all states dissociating below the ionic limit Li(-) Rb(+) , we perform a diabatic study for (1) Σ(+) electronic states dissociating into Rb (5s, 5p, 4d, 6s, 6p, 5d, 7s, 4f) + Li (2s, 2p, 3s). Furthermore, we present the diabatic results for the 1-11 (3) σ, 1-8 (1,3) Π, and 1-4 (1,3) Δ states. The present calculations on the RbLi molecule are complementary to previous theoretical work on this system, including recently observed electronic states that had not been calculated previously. The calculations rely on ab-initio pseudopotential, core polarization potential operators for the core-valence correlation and full valence configuration interaction approaches, combined to an efficient diabatization procedure. For the low-lying states, diabatic potentials and permanent dipole moments are analyzed, revealing the strong imprint of the ionic state in the (1) Σ(+) adiabatic states. The transition dipole moment is used to evaluate the radiative lifetimes of the vibrational levels trapped in the 2 (1) Σ(+) excited states for the first time. In addition to the bound-bound contribution, the bound-free term has been evaluated using the Franck-Condon approximation and also exactly added to the total radiative lifetime. PMID:23804208

  8. Semiempirical Quantum-Chemical Orthogonalization-Corrected Methods: Benchmarks of Electronically Excited States.

    PubMed

    Tuna, Deniz; Lu, You; Koslowski, Axel; Thiel, Walter

    2016-09-13

    The semiempirical orthogonalization-corrected OMx methods have recently been shown to perform well in extensive ground-state benchmarks. They can also be applied to the computation of electronically excited states when combined with a suitable multireference configuration interaction (MRCI) treatment. We report on a comprehensive evaluation of the performance of the OMx/MRCI methods for electronically excited states. The present benchmarks cover vertical excitation energies, excited-state equilibrium geometries (including an analysis of significant changes between ground- and excited-state geometries), minimum-energy conical intersections, ground- and excited-state zero-point vibrational energies, and 0-0 transition energies for a total of 520 molecular structures and 412 excited states. For comparison, we evaluate the TDDFT/B3LYP method for all benchmark sets, and the CC2, MRCISD, and CASPT2 methods for some of them. We find that the current OMx/MRCI methods perform reasonably well for many of the excited-state properties. However, in comparison to the first-principles methods, there are also a number of shortcomings that should be addressed in future developments. PMID:27380455

  9. Electronic States in Gallium Arsenide Quantum Wells Probed by Optically Pumped NMR

    NASA Astrophysics Data System (ADS)

    Tycko, R.; Barrett, S. E.; Dabbagh, G.; Pfeiffer, L. N.; West, K. W.

    1995-06-01

    An optical pumping technique was used to enhance and localize nuclear magnetic resonance (NMR) signals from an n-doped GaAs/Al0.1Ga0.9As multiple quantum well structure, permitting direct radio-frequency measurements of gallium-71 NMR spectra and nuclear spin-lattice relaxation rates (1/T_1) as functions of temperature (1.6 K < T < 4.2 K) and the Landau level filling factor (0.66 < ν < 1.76). The measurements reveal effects of electron-electron interactions on the energy levels and spin states of the two-dimensional electron system confined in the GaAs wells. Minima in 1/T_1 at ν≈ 1 and ν≈ 2/3 indicate energy gaps for electronic excitations in both integer and fractional quantum Hall states. Rapid, temperature-independent relaxation at intermediate ν values indicates a manifold of low-lying electronic states with mixed spin polarizations.

  10. Molecular electronic excitations calculated from a solid-state approach: Methodology and numerics

    NASA Astrophysics Data System (ADS)

    Hahn, P. H.; Schmidt, W. G.; Bechstedt, F.

    2005-12-01

    We investigate the applicability and accuracy of a solid-state approach, which was developed originally for the relatively homogeneous electron gas, to describe electronic single-particle and electron-hole pair excitations in molecules. Thereby we start from the determination of the molecular ground state within the local density functional theory using repeated supercells and pseudopotentials for the electron-ion interaction. The electronic spectra are obtained from the Green’s function formalism. The exchange-correlation self-energy Σ is linearly expanded in the screened Coulomb interaction, i.e., the GW approximation is used. Optical spectra are obtained from the Bethe-Salpeter equation for the irreducible polarization propagator. The numerical implementation and possible pitfalls of this methodology are discussed using silane, disilane, and water molecules as examples. In particular the influence of the dynamics of the screening, the supercell size, and the number of empty states are studied. The resulting single- and two-particle excitation energies are compared with experiment and previous theoretical work.

  11. Theoretical studies of electronic band-tail states, Anderson transition and surfaces of amorphous semiconductors

    NASA Astrophysics Data System (ADS)

    Dong, Jianjun

    In this dissertation, we study the Anderson transition within the electronic band tail states, and amorphous surfaces. The disorder induced band tail states is one of the unique character of amorphous semiconductors. Because of the proximity to the Fermi level, the nature of these band tail states is of obvious interest to theory of doping and transport. The study of amorphous solid surface is also an interesting area for theory. It is possible to have some major rearrangements near surfaces of amorphous solids (the amorphous analog of surface reconstruction), and the local bonding environment could be dramatically different from that of bulk. The study of the surfaces can also help people toward understanding the growth mechanism. First, electronic band tail states of amorphous silicon and amorphous diamond were studied based on the large (4096 atom) and realistic structural models. To solve the large tight-binding Hamiltonian matrices, we used two order N methods: the maximum entropy method for computing the total densities of states, and the modified Lanczos techniques for computing the individual energy eigenstates in the band gap regions. The DC conductivity was estimated with the Kubo formula. Next, the structural and electronic properties of the surfaces of tetrahedral amorphous carbon (ta-C) were also studied with a first-principles, local basis LDA technique. We reported two structural models made under different conditions, and examined the transition of the local bonding environment from the bulk to the surface. In the study of band tail states, we observe that Anderson (local-to-extended) transition within the band states proceeds by "cluster proliferation". We interpret the nature of band tail states in terms of a "resonant cluster model" through which one can qualitatively understand the evolution of the states from midgap toward the mobility edges. In the study of ta-C surfaces, we observe that nearly 50% surface atoms are threefold coordinated and

  12. Spectroscopy of molecular states in a few-electron double quantum dot

    NASA Astrophysics Data System (ADS)

    Hüttel, A. K.; Ludwig, S.; Eberl, K.; Kotthaus, J. P.

    2006-12-01

    Semiconductor quantum dots, so-called artificial atoms, have attracted considerable interest as mesoscopic model systems and prospective building blocks of the “quantum computer”. Electrons are trapped locally in quantum dots, forming controllable and coherent mesoscopic atom- and moleculelike systems. Electrostatic definition of quantum dots by use of top gates on a GaAs/AlGaAs heterostructure allows wide variation of the potential in the underlying two-dimensional electron gas. By distorting the trapping potential of a single quantum dot, a strongly tunnel-coupled double quantum dot can be defined. Transport spectroscopy measurements on such a system charged with N=0,1,2,… electrons are presented. In particular, the tunnel splitting of the double well potential for up to one trapped electron is unambiguously identified. It becomes visible as a pronounced level anticrossing at finite source drain voltage. A magnetic field perpendicular to the two-dimensional electron gas also modulates the orbital excitation energies in each individual dot. By tuning the asymmetry of the double well potential at finite magnetic field the chemical potentials of an excited state of one of the quantum dots and the ground state of the other quantum dot can be aligned, resulting in a second level anticrossing with a larger tunnel splitting. In addition, data on the two-electron transport spectrum are presented.

  13. Update on progress in electronic reporting of laboratory results to public health agencies - United States, 2014.

    PubMed

    Lamb, Emilie; Satre, John; Hurd-Kundeti, Glorietta; Liscek, Bonnie; Hall, C Jason; Pinner, Robert W; Conn, Laura; Zajac, Julie; Smallwood, Megan; Smith, Kaley

    2015-04-01

    Since 2010, CDC has provided resources from the Prevention and Public Health Fund of the Affordable Care Act to 57 state, local, and territorial health departments through the Epidemiology and Laboratory Capacity for Infectious Diseases cooperative agreement to assist with implementation of electronic laboratory reporting (ELR)* from clinical and public health laboratories to public health agencies. To update information from a previous report about the progress in implementing ELR in the United States, CDC examined regular communications between the agency and the 57 health departments during 2012-2014. The results indicated that, as of July 2014, 67% of the approximately 20 million laboratory reports received annually for notifiable conditions were received electronically, compared with 62% in July 2013. These electronic reports were received by 55 of the 57 jurisdictions and came from 3,269 (up from nearly 2,900 in July 2013) of approximately 10,600 reporting laboratories. The proportion of laboratory reports received electronically varied by jurisdiction. In 2014, compared with 2013, the number of jurisdictions receiving >75% of laboratory reports electronically was higher (21 versus 14), and the number of jurisdictions receiving <25% of reports electronically was lower (seven versus nine). National implementation of ELR continues to increase and appears it might reach 80% of total laboratory report volume by 2016. PMID:25837244

  14. Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

    ERIC Educational Resources Information Center

    Downey, Kay

    2012-01-01

    Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

  15. Excitation of the a {sup 3{Pi}} state of CO by electron impact

    SciTech Connect

    Ristic, M. M.; Poparic, G. B.; Belic, D. S.

    2011-04-15

    Electron impact excitation of the a {sup 3{Pi}} valence state of the carbon-monoxide molecule has been studied in the energy region from threshold to 10 eV. Excitation functions for spin forbidden transitions from the {nu}=0 level of the ground X {sup 1}{Sigma}{sup +} state of CO to the {nu}{sup '}=0, 1, 2, 3, 4, and 5 levels of the a {sup 3{Pi}} state are measured. A crossed beam double trochoidal electron spectrometer is used. Forward and backward scattered electrons from the {nu}{sup '}=0 excitation channel are separated by electron beam modulation and a time-of-flight detection technique. The present results are normalized to the ground state {sup 2{Pi}} resonance vibrational excitation cross sections and absolute values of the differential cross sections at the border angles of 0 deg. and 180 deg. are determined. In this way the differential cross section measurements are completed in the full angular range from 0 deg. to 180 deg. The present results are compared to the existing literature data.

  16. Quantification of electronic band gap and surface states on FeS2(100)

    NASA Astrophysics Data System (ADS)

    Herbert, F. W.; Krishnamoorthy, A.; Van Vliet, K. J.; Yildiz, B.

    2013-12-01

    The interfacial electronic properties and charge transfer characteristics of pyrite, FeS2, are greatly influenced by the presence of electronic states at the crystal free surface. We investigate the surface electronic structure of FeS2 (100) using scanning tunneling spectroscopy (STS) and interpret the results using tunneling current simulations informed by density functional theory. Intrinsic, dangling bond surface states located at the band edges reduce the fundamental band gap Eg from 0.95 eV in bulk FeS2 to 0.4 ± 0.1 eV at the surface. Extrinsic surface states from sulfur and iron defects contribute to Fermi level pinning but, due to their relatively low density of states, no detectable tunneling current was measured at energies within the intrinsic surface Eg. These findings help elucidate the nature of energy alignment for electron transfer processes at pyrite surfaces, which are relevant to evaluation of electrochemical processes including corrosion and solar energy conversion.

  17. Charge density stabilised local electron spin pair states in insulating polymers

    SciTech Connect

    Serra, S.; Dissado, L. A.

    2014-12-14

    A model is presented that addresses the energy stability of localized electron states in insulating polymers with respect to delocalized free electron-like states at variable charge densities. The model was derived using an effective Hamiltonian for the total energy of electrons trapped in large polarons and spin-paired bipolarons, which includes the electrostatic interaction between charges that occurs when the charge density exceeds the infinite dilution limit. The phase diagram of the various electronic states with respect to the charge density is derived using parameters determined from experimental data for polyethylene, and it is found that a phase transition from excess charge in the form of stable polarons to a stable state of bipolarons with charge = 2 and spin number S = 0 is predicted for a charge density between 0.2 C/m{sup 3} and ∼2 C/m{sup 3}. This transition is consistent with a change from low mobility charge transport to charge transport in the form of pulses with a mobility orders of magnitude higher that has been observed in several insulating polymers.

  18. Direct evaluation via forced oscillation method of the electronic state density of sizable clusters.

    PubMed

    Conte, R; Arrighini, G P; Guidotti, C

    2007-01-30

    Metal clusters described in the framework of a simple tight binding model have been studied. Application of a dynamical approach (FOM), jointly with efficient storage of the sparse Hamiltonian matrix involved, is shown to allow direct evaluation of the electronic state density of sizable cubic-symmetry aggregates. PMID:17186475

  19. Study of intermediates from transition metal excited-state electron- transfer reactions

    SciTech Connect

    Hoffman, M.Z.

    1993-03-31

    Progress on 6 projects is reported: excited state absorption spectrum of Ru(bpy)[sub 3][sup 2+], solvent cage model for electron transfer quenching, reductive quenching of [sup *]Cr(III) complexes, solution medium effects in oxidative quenching of [sup *]Ru(II) complexes, photosensitized oxidation of phenol in aqueous solution, and quenching of Ru(II) complexes by oxygen.

  20. Theory of the electronic and structural properties of solid state oxides

    SciTech Connect

    Chelikowsky, J.R.

    1990-01-01

    Studies on electronic and structural properties of solid state oxides continued. This quarter, studies have concentrated on silica. Progress is discussed in the following sections: interatomic potentials and the structural properties of silica; chemical reactivity and covalent/metallic bonding on Si clusters; and surface and thermodynamic interatomic forces fields for silicon. 64 refs., 20 figs., 5 tabs. (CBS)

  1. Atomistic simulation of the electronic states of adatoms in monolayer MoS{sub 2}

    SciTech Connect

    Chang, Jiwon; Larentis, Stefano; Tutuc, Emanuel; Register, Leonard F.; Banerjee, Sanjay K.

    2014-04-07

    Using an ab initio density functional theory based electronic structure method, we study the effects of adatoms on the electronic properties of monolayer transition metal dichalcogenide Molybdenum-disulfide (MoS{sub 2}). We consider the 1st (Li, Na, K) and 7th (F, Cl, Br) column atoms and metals (Sc, Ti, Ta, Mo, Pd, Pt, Ag, Au). Three high symmetry sites for the adatom on the surface of monolayer MoS{sub 2} are examined as starting points to search for the most energetically stable configuration for each adatom-monolayer MoS{sub 2} system, as well as the type of associated bonding. For the most stable adatom positions, we characterize the emergence of adatom-induced electronic states including any dopant states.

  2. Study of intermediates from transition metal excited-state electron-transfer reactions

    SciTech Connect

    Hoffman, M.Z.

    1991-12-31

    During this period, conventional and fast-kinetics techniques of photochemistry, photophysics, radiation chemistry, and electrochemistry were used for the characterization of the intermediates that are involved in transition metal excited-state electron-transfer reactions. The intermediates of interest were the excited states of Ru(II) and Cr(III) photosensitizers, their reduced forms, and the species formed in the reactions of redox quenchers and electron-transfer agents. Of particular concern has been the back electron-transfer reaction between the geminate pair formed in the redox quenching of the photosensitizers, and the dependence of its rate on solution medium and temperature in competition with transformation and cage escape processes.

  3. Dynamic tunneling force microscopy for characterizing electronic trap states in non-conductive surfaces

    NASA Astrophysics Data System (ADS)

    Wang, R.; Williams, C. C.

    2015-09-01

    Dynamic tunneling force microscopy (DTFM) is a scanning probe technique for real space mapping and characterization of individual electronic trap states in non-conductive films with atomic scale spatial resolution. The method is based upon the quantum mechanical tunneling of a single electron back and forth between a metallic atomic force microscopy tip and individual trap states in completely non-conducting surface. This single electron shuttling is measured by detecting the electrostatic force induced on the probe tip at the shuttling frequency. In this paper, the physical basis for the DTFM method is unfolded through a physical model and a derivation of the dynamic tunneling signal as a function of several experimental parameters is shown. Experimental data are compared with the theoretical simulations, showing quantitative consistency and verifying the physical model used. The experimental system is described and representative imaging results are shown.

  4. Theoretical study on the ground electronic state of FO(+) and FO(-).

    PubMed

    Li, Song; Zheng, Rui; Chen, Shan-Jun; Zhu, De-Sheng; Fan, Qun-Chao

    2014-12-10

    The equilibrium structures of the ground electronic states for molecular ions FO(+) and FO(-) have been calculated by using the multi-reference configuration interaction method in combination with the augmented correlation-consistent basis sets up through sextuple zeta quality. The equilibrium parameters, potential energy curves and spectroscopic constants are derived for both species. The extrapolation schemes are adopted to estimate the complete basis set limit. The corrections of core-valence correlation and relativistic effect are included to improve the accuracy of the calculations. The vibrational energy levels as well as rotational and centrifugal distortion constants of the ground electronic states for both systems are obtained by solving the radial Schrödinger equation of nuclear motion. The computations on neutral FO radical are also carried out to investigate the ionization potentials and the electron affinities. PMID:24996216

  5. Active-Space Coupled-Cluster Study of Electronic States of Be₃

    SciTech Connect

    Kowalski, Karol; Hirata, So; Wloch, M W.; Piecuch, Piotr; Windus, Theresa L.

    2005-08-15

    An automated implementation of the active-space coupled-cluster (CC) and equation-of-motion (EOM) CC methods with all singles and doubles, and triples defined via active orbitals (CCSDt, EOMCCSDt) employing Tensor Contraction Engine (TCE), is reported. The TCE-generated CCSDt/ codes are parallel and applicable to closed-and open-shell references. The effectiveness of the new code in describing electronic quasi-degeneracies is illustrated by the CCSDt / EOMCCSDt) calculations for the challenging Be₃system, which is characterized by a large number of low-lying excited states dominated by two-electron transitions and significant high order correlation effects in the ground electronic state. Different strategies for defining triple excitation s within the CCSDt / EOMCCSDt) approach are discussed.

  6. Dynamic tunneling force microscopy for characterizing electronic trap states in non-conductive surfaces

    SciTech Connect

    Wang, R.; Williams, C. C.

    2015-09-15

    Dynamic tunneling force microscopy (DTFM) is a scanning probe technique for real space mapping and characterization of individual electronic trap states in non-conductive films with atomic scale spatial resolution. The method is based upon the quantum mechanical tunneling of a single electron back and forth between a metallic atomic force microscopy tip and individual trap states in completely non-conducting surface. This single electron shuttling is measured by detecting the electrostatic force induced on the probe tip at the shuttling frequency. In this paper, the physical basis for the DTFM method is unfolded through a physical model and a derivation of the dynamic tunneling signal as a function of several experimental parameters is shown. Experimental data are compared with the theoretical simulations, showing quantitative consistency and verifying the physical model used. The experimental system is described and representative imaging results are shown.

  7. The repopulation of electronic states upon vibrational excitation of niobium carbide clusters.

    PubMed

    Chernyy, V; Logemann, R; Bakker, J M; Kirilyuk, A

    2016-07-14

    We study the infrared (IR) resonant heating of neutral niobium carbide clusters probed through ultraviolet photoionization spectroscopy. The IR excitation not only changes the photoionization spectra for the photon energies above the ionization threshold, but also modulates ion yield for energies significantly below it. An attempt to describe the experimental spectra using either Fowler's theory or thermally populated vibrational states was not successful. However, the data can be fully modeled by vibrationally and rotationally broadened discrete electronic levels obtained from Density Functional Theory (DFT) calculations. The application of this method to spectra with different IR pulse energies not only yields information about the excited electronic states in the vicinity of the HOMO level, populated by manipulation of the vibrational coordinates of a cluster, but also can serve as an extra indicator for the cluster isomeric structure and corresponding DFT-calculated electronic levels. PMID:27421411

  8. Electronic States of Half-Metallic Chromium Oxides Probed by 53Cr NMR

    NASA Astrophysics Data System (ADS)

    Takeda, Hikaru; Shimizu, Yasuhiro; Itoh, Masayuki; Isobe, Masahiko; Ueda, Yutaka

    2012-12-01

    We have performed 53Cr NMR measurements to investigate local electronic states of K2Cr8O16 and CrO2 which are ferromagnetic half-metals with high valent chromium ions. In the ferromagnetic metallic phases of both oxides, we observed at least two 53Cr NMR spectra which are inconsistent with crystallographically inequivalent one chromium site on a tetragonal lattice, the hollandite structure (symmetry I4/m) of K2Cr8O16 and the rutile structure (P42mnm) of CrO2. The origin of this anomalous electronic state may be associated with an electronic phase separation in double exchange systems with the mixed valence.

  9. Parametrized equation of state for electron liquids in the Singwi-Tosi-Land-Sjolander aproximation

    NASA Technical Reports Server (NTRS)

    Tanaka, S.; Mitake, S.; Ichimaru, S.

    1985-01-01

    Results are reported of a theoretical study of an equation of state for electron liquids (one-component plasmas of electrons embedded in a uniform neutralizing background of positive charges), where there is an interplay between the strong Coulomb-coupling effect and the degrees of Fermi degeneracy. Calculations are based on the Singwi-Tosi-Land-Sjolander approximation (1968). The calculated results are parametrized in the form of analytic formulas for the interaction and excess free energies, which are applicable over a wide range of parameters as long as the electrons are in a paramagnetic fluid state. Unlike the present study, earlier studies concentrated on plasmas where the Fermi degeneracy parameter tended either to zero or to infinity, thus excluding many actual plasmas (stellar interiors, heavy planets such as Jupiter, plasmas in projected inertial confinement fusion experiments, and the liquid metals).

  10. Electronic states of lithium passivated germanium nanowires: An ab-initio study

    SciTech Connect

    Trejo, A.; Carvajal, E.; Vázquez-Medina, R.; Cruz-Irisson, M.

    2014-05-15

    A study of the electronic and structural properties of germanium nanowires (GeNWs) was performed using the ab-initio Density Functional Theory within the generalized gradient approximation where electron-ion interactions are described by ultrasoft pseudopotentials. To study the effects of the lithium in the surface of the GeNWs we compare the electronic band structures of Hydrogen passivated GeNWs with those of partial and totally Li passivated GeNWs. The nanowires were constructed in the [001], [111] and [110] directions, using the supercell model to create different wire diameters. The results show that in the case of partial Li passivation there are localized orbitals near the valence band maximum, which would create a p-doped-kind of state. The total Li passivation created metallic states for all the wires.

  11. Control of Triboelectrification by Engineering Surface Dipole and Surface Electronic State.

    PubMed

    Byun, Kyung-Eun; Cho, Yeonchoo; Seol, Minsu; Kim, Seongsu; Kim, Sang-Woo; Shin, Hyeon-Jin; Park, Seongjun; Hwang, Sungwoo

    2016-07-20

    Although triboelectrification is a well-known phenomenon, fundamental understanding of its principle on a material surface has not been studied systematically. Here, we demonstrated that the surface potential, especially the surface dipoles and surface electronic states, governed the triboelectrification by controlling the surface with various electron-donating and -withdrawing functional groups. The functional groups critically affected the surface dipoles and surface electronic states followed by controlling the amount of and even the polarity of triboelectric charges. As a result, only one monolayer with a thickness of less than 1 nm significantly changed the conventional triboelectric series. First-principles simulations confirmed the atomistic origins of triboelectric charges and helped elucidate the triboelectrification mechanism. The simulation also revealed for the first time where charges are retained after triboelectrification. This study provides new insights to understand triboelectrification. PMID:27337938

  12. The repopulation of electronic states upon vibrational excitation of niobium carbide clusters

    NASA Astrophysics Data System (ADS)

    Chernyy, V.; Logemann, R.; Bakker, J. M.; Kirilyuk, A.

    2016-07-01

    We study the infrared (IR) resonant heating of neutral niobium carbide clusters probed through ultraviolet photoionization spectroscopy. The IR excitation not only changes the photoionization spectra for the photon energies above the ionization threshold, but also modulates ion yield for energies significantly below it. An attempt to describe the experimental spectra using either Fowler's theory or thermally populated vibrational states was not successful. However, the data can be fully modeled by vibrationally and rotationally broadened discrete electronic levels obtained from Density Functional Theory (DFT) calculations. The application of this method to spectra with different IR pulse energies not only yields information about the excited electronic states in the vicinity of the HOMO level, populated by manipulation of the vibrational coordinates of a cluster, but also can serve as an extra indicator for the cluster isomeric structure and corresponding DFT-calculated electronic levels.

  13. The electronic states of a double carbon vacancy defect in pyrene: a model study for graphene.

    PubMed

    Machado, Francisco B C; Aquino, Adélia J A; Lischka, Hans

    2015-05-21

    The electronic states occurring in a double vacancy defect for graphene nanoribbons have been calculated in detail based on a pyrene model. Extended ab initio calculations using the MR configuration interaction (MRCI) method have been performed to describe in a balanced way the manifold of electronic states derived from the dangling bonds created by initial removal of two neighboring carbon atoms from the graphene network. In total, this study took into account the characterization of 16 electronic states (eight singlets and eight triplets) considering unrelaxed and relaxed defect structures. The ground state was found to be of (1)Ag character with around 50% closed shell character. The geometry optimization process leads to the formation of two five-membered rings in a pentagon-octagon-pentagon (5-8-5) structure. The closed shell character increases thereby to ∼70%; the analysis of unpaired density shows only small contributions confirming the chemical stability of that entity. For the unrelaxed structure the first five excited states ((3)B3g, (3)B2u, (3)B1u, (3)Au and (1)Au) are separated from the ground state by less than 2.5 eV. For comparison, unrestricted density functional theory (DFT) calculations using several types of functionals have been performed within different symmetry subspaces defined by the open shell orbitals. Comparison with the MRCI results gave good agreement in terms of finding the (1)Ag state as a ground state and in assigning the lowest excited states. Linear interpolation curves between the unrelaxed and relaxed defect structures also showed good agreement between the two classes of methods opening up the possibilities of using extended nanoflakes for multistate investigations at the DFT level. PMID:25905682

  14. The relation of the energy of electronic state with the interior periodic potential in quantum dot given by matrix method

    NASA Astrophysics Data System (ADS)

    Luo, Q. J.; Feng, S. M.; Gu, L. H.; Liu, J. X.; Tang, X. F.

    2016-01-01

    In this paper, we mainly investigate the effect of the interior periodic potential and the surface potential on the energy of electronic state in quantum dot. Based on Chebyshev polynomials of the second kind and matrix theory, we deduced one expression, which can clearly describe the relation of energy of electronic state with the surface and interior periodic potential. The theoretical analysis shows that the energy of electronic state in quantum dot strongly depend on surface potential and the interior periodic potential. For the same quantum dot with different surface potential, the energy of electronic state with the determined quantum number is different. For the quantum dot of same size with different interior periodic potential, the energy of electronic state with the determined quantum number is also different. The further study indicates that there are two different energy of electronic state in quantum dot for the decided quantum number.

  15. Controllable Quantum State Transfer Between a Josephson Charge Qubit and an Electronic Spin Ensemble

    NASA Astrophysics Data System (ADS)

    Yan, Run-Ying; Wang, Hong-Ling; Feng, Zhi-Bo

    2016-01-01

    We propose a theoretical scheme to implement controllable quantum state transfer between a superconducting charge qubit and an electronic spin ensemble of nitrogen-vacancy centers. By an electro-mechanical resonator acting as a quantum data bus, an effective interaction between the charge qubit and the spin ensemble can be achieved in the dispersive regime, by which state transfers are switchable due to the adjustable electrical coupling. With the accessible experimental parameters, we further numerically analyze the feasibility and robustness. The present scheme could provide a potential approach for transferring quantum states controllably with the hybrid system.

  16. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    DOEpatents

    Schwartz, Michael; White, James H.; Sammels, Anthony F.

    2000-01-01

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  17. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    DOEpatents

    Schwartz, Michael; White, James H.; Sammells, Anthony F.

    2005-09-27

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  18. Diamond-nitrogen-vacancy electronic and nuclear spin-state anticrossings under weak transverse magnetic fields

    NASA Astrophysics Data System (ADS)

    Clevenson, Hannah; Chen, Edward H.; Dolde, Florian; Teale, Carson; Englund, Dirk; Braje, Danielle

    2016-08-01

    We report on detailed studies of electronic and nuclear spin states in the diamond-nitrogen-vacancy (NV) center under weak transverse magnetic fields. We numerically predict and experimentally verify a previously unobserved NV hyperfine level anticrossing (LAC) occurring at bias fields of tens of gauss—two orders of magnitude lower than previously reported LACs at ˜500 and ˜1000 G axial magnetic fields. We then discuss how the NV ground-state Hamiltonian can be manipulated in this regime to tailor the NV's sensitivity to environmental factors and to map into the nuclear spin state.

  19. New electronic states of NH and ND observed by resonance enhanced multiphoton ionization spectroscopy

    NASA Technical Reports Server (NTRS)

    Johnson, Russell D., III; Hudgens, Jeffrey W.

    1990-01-01

    Resonance Enhanced MultiPhoton Ionization (REMPI) spectra of NH and ND, which reveal four new electronic states are presented. Transitions from NH a 1 delta to 3s and 3p Rydberg states in both NH and ND have been observed and rotationally analyzed. The transitions were observed in the wavelength range of 258 to 288 nm. The state assignments are: e 1 pi (3s sigma) at 82857/cm, f 1 pi (3p sigma) at 86378/cm, g 1 delta (3p pi) at 88141/cm and h 1 sigma (3p pi) at 89151/cm.

  20. Tunable Plasmonic Reflection by Bound 1D Electron States in a 2D Dirac Metal.

    PubMed

    Jiang, B-Y; Ni, G X; Pan, C; Fei, Z; Cheng, B; Lau, C N; Bockrath, M; Basov, D N; Fogler, M M

    2016-08-19

    We show that the surface plasmons of a two-dimensional Dirac metal such as graphene can be reflected by linelike perturbations hosting one-dimensional electron states. The reflection originates from a strong enhancement of the local optical conductivity caused by optical transitions involving these bound states. We propose that the bound states can be systematically created, controlled, and liquidated by an ultranarrow electrostatic gate. Using infrared nanoimaging, we obtain experimental evidence for the locally enhanced conductivity of graphene induced by a carbon nanotube gate, which supports this theoretical concept. PMID:27588873