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Sample records for 5f electron states

  1. 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

  2. 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).

  3. Electronic Structure, Localization and 5f Occupancy in Pu Materials

    SciTech Connect

    Joyce, John J.; Beaux, Miles F.; Durakiewicz, Tomasz; Graham, Kevin S.; Bauer, Eric D.; Mitchell, Jeremy N.; Tobash, Paul H.; Richmond, Scott

    2012-05-03

    The electronic structure of delta plutonium ({delta}-Pu) and plutonium compounds is investigated using photoelectron spectroscopy (PES). Results for {delta}-Pu show a small component of the valence electronic structure which might reasonably be associated with a 5f{sup 6} configuration. PES results for PuTe are used as an indication for the 5f{sup 6} configuration due to the presence of atomic multiplet structure. Temperature dependent PES data on {delta}-Pu indicate a narrow peak centered 20 meV below the Fermi energy and 100 meV wide. The first PES data for PuCoIn5 indicate a 5f electronic structure more localized than the 5fs in the closely related PuCoGa{sub 5}. There is support from the PES data for a description of Pu materials with an electronic configuration of 5f{sup 5} with some admixture of 5f{sup 6} as well as a localized/delocalized 5f{sup 5} description.

  4. High-resolution angle-resolved photoemission study of UN and USb; Dual character of 5f electrons

    NASA Astrophysics Data System (ADS)

    Ito, T.; Kumigashira, H.; Souma, S.; Takahashi, T.; Suzuki, T.

    2001-05-01

    We have performed high-resolution angle-resolved photoemission spectroscopy on UN and USb to study the electronic structure near the Fermi level ( EF) and the nature of U 5f electrons. We found that the pnictogen (N and Sb) p bands are fully occupied in contrast with Ce monopnictides and shows a good qualitative agreement with the band calculation by treating the U 5f states as bands. On the other hand, we have not observed dispersive U 5f bands near EF predicted by the band calculation, instead we found two non-dispersive bands near EF, which are assigned as the 5f 2-final-state multiplet indicative of localized U 5f states. The intensity of multiplet structure is stronger in USb than in UN. These results indicate the dual character of U 5f electrons and its difference between USb and UN.

  5. 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.

  6. 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.

  7. Pump-probe reflectivity study of ultrafast dynamics of strongly correlated 5f electrons inUO2

    SciTech Connect

    Au, Yongqiang Q; Taylor, Antoinette J; Durakiewicz, Tomasz; Rodriguez, George

    2010-01-01

    5f electrons in the Mott insulator UO{sub 2} produce intriguing electronic states and dynamics, such as strong correlation and f-f excitations. We have performed femtosecond pump-probe reflectivity measurements on a single crystal UO{sub 2} at temperatures 5-300 K to study the ultrafast dynamics of photoexcited 5f electrons. The laser pulses at 400 nm pump 5 f electrons across the Mott gap, while those at 800 nm probe the pump-induced change of reflectivity. We find temperature-dependent excitation and relaxation processes and long-lived acoustic phonons, and extract picosecond risetimes and microsecond relaxation times at low temperatures. The observed slow relaxation is ascribed to the decay of Hubbard excitons formed by U{sup 3+}-U{sup 5+} pairs.

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

    PubMed

    Moore, K T; van der Laan, G; Tobin, J G; Chung, B W; Wall, M A; Schwartz, A J

    2006-03-01

    Spin-orbit interaction in the 5f states is believed to strongly influence exotic behaviors observed in actinide 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 edge 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 they 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. 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.

  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. Electron attachment and detachment, and the electron affinities of C5F5N and C5HF4N.

    PubMed

    Van Doren, Jane M; Kerr, Donna M; Miller, Thomas M; Viggiano, A A

    2005-09-15

    Rate constants have been measured for electron attachment to C5F5N (297-433 K) and to 2, 3, 5, 6-C5HF4N (303 K) using a flowing-afterglow Langmuir-probe apparatus (at a He gas pressure of 133 Pa). In both cases only the parent anion was formed in the attachment process. The attachment rate constants measured at room temperature are 1.8 +/- 0.5 X 10(-7) and 7 +/- 3 X 10(-10) cm(-3) s(-1), respectively. Rate constants were also measured for thermal electron detachment from the parent anions of these molecules. For C5F5N- detachment is negligible at room temperature, but increases to 2530 +/- 890 s(-1) at 433 K. For 2, 3, 5, 6-C5HF4N-, the detachment rate at 303 K was 520 +/- 180 s(-1). The attachment/detachment equilibrium yielded experimental electron affinities EA(C5F5N)=0.70 +/- 0.05 eV and EA(2, 3, 5, 6-C5HF4N)=0.40 +/- 0.08 eV. Electronic structure calculations were carried out for these molecules and related C5HxF5-xN using density-functional theory and the G3(MP2)//B3LYP compound method. The EAs are found to decrease by 0.25 eV, on average, with each F substitution by H. The calculated EAs are in good agreement with the present experimental results.

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

    PubMed

    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. 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

  16. 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.

  17. High-resolution solid-state oxygen-17 NMR of actinide-bearing compounds: an insight into the 5f chemistry.

    PubMed

    Martel, Laura; Magnani, Nicola; Vigier, Jean-Francois; Boshoven, Jacobus; Selfslag, Chris; Farnan, Ian; Griveau, Jean-Christophe; Somers, Joseph; Fanghänel, Thomas

    2014-07-01

    A massive interest has been generated lately by the improvement of solid-state magic-angle spinning (MAS) NMR methods for the study of a broad range of paramagnetic organic and inorganic materials. The open-shell cations at the origin of this paramagnetism can be metals, transition metals, or rare-earth elements. Actinide-bearing compounds and their 5f unpaired electrons remain elusive in this intensive research area due to their well-known high radiotoxicity. A dedicated effort enabling the handling of these highly radioactive materials now allows their analysis using high-resolution MAS NMR (>55 kHz). Here, the study of the local structure of a series of actinide dioxides, namely, ThO2, UO2, NpO2, PuO2, and AmO2, using solid-state (17)O MAS NMR is reported. An important increase of the spectral resolution is found due to the removal of the dipolar broadening proving the efficiency of this technique for structural analysis. The NMR parameters in these systems with numerous and unpaired 5f electrons were interpreted using an empirical approach. Single-ion model calculations were performed for the first time to determine the z component of electron spin on each of the actinide atoms, which is proportional to the shifts. A similar variation thereof was observed only for the heavier actinides of this study.

  18. 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.

  19. 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.

  20. 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.

  1. Gas-phase reactions of doubly charged actinide cations with alkanes and alkenes--probing the chemical activity of 5f electrons from Th to Cm.

    PubMed

    Marçalo, Joaquim; Santos, Marta; Gibson, John K

    2011-11-01

    Small alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) were used to probe the gas-phase reactivity of doubly charged actinide cations, An(2+) (An = Th, Pa, U, Np, Pu, Am, Cm), by means of Fourier transform ion cyclotron resonance mass spectrometry. Different combinations of doubly and singly charged ions were observed as reaction products, comprising species formed via metal-ion induced eliminations of small molecules, simple adducts and ions resulting from electron, hydride or methide transfer channels. Th(2+), Pa(2+), U(2+) and Np(2+) preferentially yielded doubly charged products of hydrocarbon activation, while Pu(2+), Am(2+) and Cm(2+) reacted mainly through transfer channels. Cm(2+) was also capable of forming doubly charged products with some of the hydrocarbons whereas Pu(2+) and Am(2+) were not, these latter two ions conversely being the only for which adduct formation was observed. The product distributions and the reaction efficiencies are discussed in relation to the electronic configurations of the metal ions, the energetics of the reactions and similar studies previously performed with doubly charged lanthanide and transition metal cations. The conditions for hydrocarbon activation to occur as related to the accessibility of electronic configurations with one or two 5f and/or 6d unpaired electrons are examined and the possible chemical activity of the 5f electrons in these early actinide ions, particularly Pa(2+), is considered.

  2. Effect of high-pressure annealing on the normal-state transport of LaO0.5F0.5BiS2

    NASA Astrophysics Data System (ADS)

    Pallecchi, I.; Lamura, G.; Putti, M.; Kajitani, J.; Mizuguchi, Y.; Miura, O.; Demura, S.; Deguchi, K.; Takano, Y.

    2014-06-01

    We study normal state electrical, thermoelectrical, and thermal transport in polycrystalline BiS2-based compounds, which become superconducting by F doping on the O site. In particular, we explore undoped LaOBiS2 and doped LaO0.5F0.5BiS2 samples, prepared either with or without high-pressure annealing, in order to evidence the roles of doping and preparation conditions. The high-pressure annealed sample exhibits room temperature values of resistivity ρ around 5 mΩcm, Seebeck coefficient S around -20μV /K, and thermal conductivity κ around 1.5 W/Km, while the Hall resistance RH is negative at all temperatures and its value is -10-8 m3/C at low temperature. The sample prepared at ambient pressure exhibits RH positive in sign and five times larger in magnitude, and S negative in sign and slightly smaller in magnitude. These results reveal a complex multiband evolution brought about by high-pressure annealing. In particular, the sign inversion and magnitude suppression of RH, indicating increased electron-type carrier density in the high-pressure sample, may be closely related to previous findings about change in lattice parameters and enhancement of superconducting Tc by high-pressure annealing. As for the undoped sample, it exhibits 10 times larger resistivity, 10 times larger |S|, and 10 times larger |RH| than its doped counterpart, consistent with its insulating nature. Our results point out the dramatic effect of preparation conditions in affecting charge carrier density as well as structural, band, and electronic parameters in these systems.

  3. 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.

  4. 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.

  5. 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.

  6. DFT insights into the electronic and optical properties of fluorine-doped monoclinic niobium pentoxide (B-Nb2O5:F)

    NASA Astrophysics Data System (ADS)

    El-Shazly, Tamer S.; Hassan, Walid M. I.; Rehim, Sayed S. Abdel; Allam, Nageh K.

    2016-09-01

    We report on the effect of fluorine doping on the electronic structure and optical properties of monoclinic niobium pentoxide (B-Nb2O5) as revealed by the first principles calculations. Density functional theory (DFT) along with generalized gradient approximation (GGA) at the revised Perdew-Burke-Ernzerhof (PBEsol) exchange-correlation functional was used in this study. The band calculations revealed that the studied materials are indirect bandgap semiconductors, with bandgap energies of 2.67 and 2.28 eV for the undoped and F-doped B-Nb2O5, respectively. Upon doping B-Nb2O5, the Fermi level shifts towards the conduction band, allowing optical absorption in the visible region with enhanced transmittance in the wavelength range 400-1000 nm. The calculated static refractive index of the undoped B-Nb2O5 is in good agreement with the reported experimental value, which is enhanced upon F-incorporation resulting in cladding properties for the F-doped B-Nb2O5. Also, the effective mass of free charge carriers increased upon F-doping. The enhanced properties were attributed to the effect of the excessive valent electron of the incorporated F atom.

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

    PubMed

    Fujimori, Shin-ichi

    2016-04-20

    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 eV) or high-energy synchrotron radiations (hν >/~ 400 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 CeMIn5(M = Rh, Ir, and Co) and YbRh2Si2 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 U5f compounds such as UFeGa5, their electronic structures can be well-described by the band-structure calculation assuming that all U5f electrons are itinerant. In contrast, the band structures of localized U5f compounds such as UPd3 and UO2 are essentially explained by the localized model that treats U5f electrons as localized core states. In regards to heavy fermion U-based compounds such as the hidden-order compound URu2Si2, their electronic structures exhibit complex behaviors. Their overall band structures are generally well-explained by the band-structure calculation, whereas the states in the vicinity of EF show some deviations due to electron correlation effects. Furthermore, the electronic structures of URu2Si2 in the paramagnetic and hidden-order phases are

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

    PubMed

    Fujimori, Shin-ichi

    2016-04-20

    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 eV) or high-energy synchrotron radiations (hν >/~ 400 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 CeMIn5(M = Rh, Ir, and Co) and YbRh2Si2 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 U5f compounds such as UFeGa5, their electronic structures can be well-described by the band-structure calculation assuming that all U5f electrons are itinerant. In contrast, the band structures of localized U5f compounds such as UPd3 and UO2 are essentially explained by the localized model that treats U5f electrons as localized core states. In regards to heavy fermion U-based compounds such as the hidden-order compound URu2Si2, their electronic structures exhibit complex behaviors. Their overall band structures are generally well-explained by the band-structure calculation, whereas the states in the vicinity of EF show some deviations due to electron correlation effects. Furthermore, the electronic structures of URu2Si2 in the paramagnetic and hidden-order phases are

  9. 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

  10. 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.

  11. 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.

  12. 5-F catheter in cerebral angiography

    SciTech Connect

    O'Reilly, G.V.; Naheedy, M.H.; Colucci, V.M.; Hammerschlag, S.B.

    1981-11-01

    Although the 5-F catheter is reputed to cause less vascular trauma than larger catheters, subintimal injections of contrast material have occurred following intimal damage by the catheter tip. Microscopic studies of the tips of two widely used 5-F polyethylene catheters have revealed a difference in configuration resulting in one of the catheters becoming markedly damaged during angiography. The authors make recommendations for finishing and protecting the catheter tip.

  13. 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

  14. Ground-state Electronic Structure of Actinide Monocarbides and Mononitrides

    SciTech Connect

    Petit, Leon; Svane, Axel; Szotek, Zdzislawa; Temmerman, Walter M; Stocks, George Malcolm

    2009-01-01

    The self-interaction corrected local spin-density approximation is used to investigate the ground-state valency configuration of the actinide ions in the actinide monocarbides, AC (A=U,Np,Pu,Am,Cm), and the actinide mononitrides, AN. The electronic structure is characterized by a gradually increasing degree of f electron localization from U to Cm, with the tendency toward localization being slightly stronger in the (more ionic) nitrides compared to the (more covalent) carbides. The itinerant band picture is found to be adequate for UC and acceptable for UN, while a more complex manifold of competing localized and delocalized f-electron configurations underlies the ground states of NpC, PuC, AmC, NpN, and PuN. The fully localized 5f-electron configuration is realized in CmC (f{sup 7}), CmN (f{sup 7}), and AmN (f{sup 6}). The observed sudden increase in lattice parameter from PuN to AmN is found to be related to the localization transition. The calculated valence electron densities of states are in good agreement with photoemission data.

  15. 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

  16. Electronic Defect States in Polyaniline.

    NASA Astrophysics Data System (ADS)

    Ginder, John Matthew

    The electronic defect states of the conducting polymer polyaniline are studied by a variety of magnetic and optical techniques. The insulating emeraldine base form (EB) of polyaniline can be converted to the conducting emeraldine salt form (ES) by treatment with aqueous acids such as HCl. This "protonic acid doping" process occurs via the bonding of protons to the polymer chain, without altering the number of chain electrons. Magnetic susceptibility studies reveal that a roughly linear growth of the Pauli paramagnetic susceptibility, and an increase in the density of Curie-like spins, accompanies this conversion. Consequently, the protonation-induced defects are mainly spin-1/2 polarons; further, the linear growth of the Pauli susceptibility suggests that fully protonated regions--metallic islands --grow with increasing doping level. The electronic structure of the metallic phase is proposed to be that of a polaron lattice with electronic bandwidth ~0.4 eV and polaron decay length ~2 A. The defects which accomodate excess charge in EB were also studied by near-steady-state photoinduced absorption experiments. Upon photoexcitation into the 2 eV absorption band in EB, several photoinduced features evolved. Induced bleachings of the existing transitions at 2.0 and 3.7 eV were observed; induced absorptions were found at 0.9, 1.4, and 3.0 eV. The 2.0 eV bleaching is consistent with the production of molecular charge-transfer excitons, which may relax to a different ring conformation causing long-lived bleaching, or to two separate charges on a single chain. Indeed, the induced absorptions at 1.4 and 3.0 eV are, by analogy with similar protonation -induced absorptions and by their bimolecular recombination kinetics, assigned to photoexcited polarons. Light-induced electron spin resonance experiments confirm the presence of photogenerated spins upon pumping into the excitonic absorption. Near-steady-state photoconductivity measurements on EB reveal a very small induced

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Louisiana State University Libraries' Electronic Imaging Laboratory.

    ERIC Educational Resources Information Center

    Phillips, Faye; Condrey, Richard

    1994-01-01

    Describes Louisiana State University Libraries' Electronic Imaging Laboratory for preservation. The project uses digital imaging technology to reformat rare book materials for access. This technology can exist with traditional conservation procedures. (JLB)

  4. 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.

  5. Unoccupied electronic states of Ru(0001)

    NASA Astrophysics Data System (ADS)

    del Campo, Valeria; Correa, Julián-David; Correa-Puerta, Jonathan; Kroeger, Daniel; Häberle, Patricio

    2016-11-01

    This report presents a combined theoretical and experimental description of the unoccupied electronic states of Ru(0001), along the Γ̅M̅ high symmetry direction of the Brillouin zone. A direct comparison between angle-resolved inverse photoemission spectroscopy and ab initio calculations of the 3-dimensional (3D) electronic structure of Ru(0001) have been used to determine the energy dispersion and the identification of different states and surface resonances. Both, measurements and calculations, complement previous reports regarding the electronic structure of Ru.

  6. 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.

  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. On the origin of POU5F1

    PubMed Central

    2013-01-01

    Background Pluripotency is a fundamental property of early mammalian development but it is currently unclear to what extent its cellular mechanisms are conserved in vertebrates or metazoans. POU5F1 and POU2 are the two principle members constituting the class V POU domain family of transcription factors, thought to have a conserved role in the regulation of pluripotency in vertebrates as well as germ cell maintenance and neural patterning. They have undergone a complex pattern of evolution which is poorly understood and controversial. Results By analyzing the sequences of POU5F1, POU2 and their flanking genes, we provide strong indirect evidence that POU5F1 originated at least as early as a common ancestor of gnathostomes but became extinct in a common ancestor of teleost fishes, while both POU5F1 and POU2 survived in the sarcopterygian lineage leading to tetrapods. Less divergent forms of POU5F1 and POU2 appear to have persisted among cartilaginous fishes. Conclusions Our study resolves the controversial evolutionary relationship between teleost pou2 and tetrapod POU2 and POU5F1, and shows that class V POU transcription factors have existed at least since the common ancestor of gnathostome vertebrates. It provides a framework for elucidating the basis for the lineage-specific extinctions of POU2 and POU5F1. PMID:23659605

  9. 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)

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Recoherence by squeezed states in electron interferometry

    SciTech Connect

    Hsiang, J.-T.; Ford, L. H.

    2008-09-15

    Coherent electrons coupled to the quantized electromagnetic field undergo decoherence which can be viewed as due either to fluctuations of the Aharonov-Bohm phase or to photon emission. When the electromagnetic field is in a squeezed vacuum state, it is possible for this decoherence to be reduced, leading to the phenomenon of recoherence. This recoherence effect requires electrons which are emitted at selected times during the cycle of the excited mode of the electromagnetic field. We show that there are bounds on the degree of recoherence which are analogous to quantum inequality restriction on negative energy densities in quantum field theory. We make some estimates of the degree of recoherence, and show that although small, it is in principle observable.

  16. 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.

  17. 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.

  18. 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.

  19. Nonadiabatic evolution of electronic states by electron nuclear dynamics theory

    NASA Astrophysics Data System (ADS)

    Hagelberg, Frank

    The problem of how to determine the nonadiabatic content of any given dynamic process involving molecular motion is addressed in the context of Electron Nuclear Dynamics (END) theory. Specifically, it is proposed to cast the dynamic END wave function into the language of static electronic configurations with time dependent complex-valued amplitudes. This is achieved by adiabatic transport of an electronic basis along the classical nuclear trajectories of the studied molecular system, as yielded by END simulation. Projecting the dynamic wave function on this basis yields a natural distinction between adiabatic and nonadiabatic components of the motion considered. Tracing the evolution of the leading configurations is shown to be a helpful device for clarifying the physical nature of electronic excitation processes. For illustration of these concepts, dynamic configuration analysis is applied to the scattering of a proton by a lithium atom.

  20. 45 CFR 265.6 - Must States file reports electronically?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false Must States file reports electronically? 265.6... (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...

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. Semiclassical analysis of perturbed two-electron states in barium

    NASA Astrophysics Data System (ADS)

    Bates, Kenneth A.

    Recent semiclassical studies of atomic spectra allow new insight into their electron dynamics. The semiclassical closed orbit theory demonstrates the influence of classical orbits in atomic photoabsorption spectra, and has been successfully used for one-electron alkali atoms. Atomic states with one highly-excited electron are known as Rydberg states. If an atom has two valence electrons, and the electrons are treated as independent of each other, then the atom will also have states with two excited electrons. The electrons are not actually independent, so these two different configurations will interact in an atom. If some of the "singly-excited" states occur near the energy of a "doubly-excited" state, then the resulting "perturbed states" are shifted from their hydrogenic positions and have several unusual properties not accounted for by closed orbit theory. We report the first use of closed orbit theory to describe the photoabsorption of perturbed two-electron atomic states. The experimental photoabsorption for two series of perturbed states in barium were measured as a function of electric field. A new extension of semiclassical closed orbit theory was found for perturbed states, using an energy-dependent quantum defect to account for the second valence electron. Scaled energy spectroscopy measurements, a successful analysis technique for one-electron atoms, proved unhelpful when studying perturbed barium states. This demonstrated that perturbed atoms have an important electron-electron interaction term in their Hamiltonian with non-alkali scaling. Our photoabsorption calculations for hydrogen, sodium and cesium verified our experimental calibration and our analysis of atomic core effects. We also show the mathematical equivalence of closed orbit theory and quantum defect theory for modeling the photoabsorption of perturbed atomic states in a field-free environment.

  6. 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

  7. First observation of intra-5f fluorescence from an actinyl center: Np(VI) near-IR emission in Cs[sub 2]U(Np)O[sub 2]CI[sub 4

    SciTech Connect

    Wilkerson, M. P.; Berg, J. M.; Dewey, H. J.; Hopkins, T. A.

    2004-01-01

    We have identified the first example of 5f-5f luminescence by an actinyl ion. NpO{sub 2}Cl{sub 4}{sup 2-} luminesces with reasonable intensity at both liquid nitrogen temperature, and more notably, it luminesces strongly at room temperature. Relaxation pathways from the second excited state is competitive with radiationless deactivation pathways to a large number of vibronic states accessible at room temperature. Excitation spectra show correlation with absorption spectra. We plan to investigate 5f-5f luminescence from other more complex (5f{sup n}, N > 1) actinyl molecular species.

  8. Electronic states in systems of reduced dimensionality

    SciTech Connect

    Ulloa, S.E.

    1992-04-15

    This report briefly discusses the following research: magnetically modulated systems, inelastic magnetotunneling, ballistic transport review, screening in reduced dimensions, raman and electron energy loss spectroscopy; and ballistic quantum interference effects. (LSP).

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Electron Temperature features of RFP DAX states

    NASA Astrophysics Data System (ADS)

    Fassina, Alessandro; Franz, Paolo; Ruzzon, Alberto; Alfier, Alberto; Gobbin, Marco; Marrelli, Lionello; Martines, Emilio; Momo, Barbara

    2011-10-01

    RFP states characterized by the presence of an hot helical structure in the plasma core have shown a significative improvement in the plasma performances. In this work we focused on DAX (Double AXis) states, in which the hot island is surrounded by a separatrix and does not cross the plasma centroid. These states, with respect to SHAx-or Single Helical Axis,-, show smaller thermal structures, but the ∇Te strength suggests a drastic local reduction of energy transport. The analysis relies on data obtained by the Main Thomson Scattering and by the multichord double filter SXR spectrometer. The general scaling properties of local ∇Te are presented and the results are compared with SHAx datasets; overall confinement changing is analyzed relying both on Te and ne data. Finally, being data remapping on helical coordinates a widely used tool in SHAx analysis, limits and possibilities of this technique for DAX states are discussed.

  14. 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.

  15. 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.

  16. 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

    2014-08-08

    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.

  17. 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.

  18. Creation of Electron Trap States in Silicon Dioxide By Local Electron Injection

    NASA Astrophysics Data System (ADS)

    Winslow, Dustin; Williams, Clayton

    2012-02-01

    Over a decade ago, the Scanning Tunneling Microscope was shown capable of desorbing single hydrogen atoms from the surface of hydrogen terminated silicon.ootnotetextT.C. Shen et. al. Science 268, 1590 (1995). The resultant dangling bonds can act as atomic scale quantum dots.ootnotetextM. B Haider et. al. PRL 102, 046805 (2009). Electrons trapped in such dangling bond states at the surface of crystalline silicon have short retention times at room temperature, due to the proximity of the occupied state energy level to the conduction band. Here we report on a method for creating electron trap states at the surface of a silicon dioxide film by electron injection from a metalized Atomic Force Microscope probe tip. Single Electron Tunneling Force measurementsootnotetextE. Bussmann, et. al. Appl. Phys. Lett., 85, 13 (2004). are employed to examine the existence of trap states in the silicon dioxide surface before and after the electron injection. Evidence for electron trap state creation, without topographic modification of the silicon dioxide surface, will be presented. The trap states created by this process have electron retention times which are greater than one second at room temperature. The methodology for trap state creation and detection will be presented.

  19. Adsorbates in a Box: Titration of Substrate Electronic States

    NASA Astrophysics Data System (ADS)

    Cheng, Zhihai; Wyrick, Jonathan; Luo, Miaomiao; Sun, Dezheng; Kim, Daeho; Zhu, Yeming; Lu, Wenhao; Kim, Kwangmoo; Einstein, T. L.; Bartels, Ludwig

    2010-08-01

    Nanoscale confinement of adsorbed CO molecules in an anthraquinone network on Cu(111) with a pore size of ≈4nm arranges the CO molecules in a shell structure that coincides with the distribution of substrate confined electronic states. Molecules occupy the states approximately in the sequence of rising electron energy. Despite the sixfold symmetry of the pore boundary itself, the adsorbate distribution adopts the threefold symmetry of the network-substrate system, highlighting the importance of the substrate even for such quasi-free-electron systems.

  20. Circularly polarized luminescence of curium: a new characterization of the 5f actinide complexes.

    PubMed

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

    2012-09-19

    A key distinction between the lanthanide (4f) and the 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, 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.

  1. Bis(imidazo[4,5-f][1,10]phenanthroline)dinitratolead(II)

    PubMed Central

    Li, Chun-Xiang; Zha, Xiao-Lin; Liu, Chun-Bo; Li, Xiu-Ying; Che, Guang-Bo

    2009-01-01

    In the title compound, [Pb(NO3)2(C13H8N4)2], the PbII atom (site symmetry 2) is hexa­coordinated by four N atoms from two N,N′-bidentate imidazo[4,5-f][1,10]phenanthroline (L) ligands and two O atoms from two weakly coordinated nitrate ions [Pb—O = 2.872 (5) Å] in an irregular arrangement, which may be ascribed to the stereochemically active lone pair of electrons on the metal ion. In the crystal, inter­molecular bifurcated N—H⋯(O,O) hydrogen bonds connect the mol­ecules into chains propagating along [100]. Adjacent chains inter­act by strong aromatic π–π stacking inter­actions, with a centroid–centroid distance of 3.483 (2) Å. PMID:21581524

  2. 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.

  3. Search for bound-state electron+positron pair decay

    NASA Astrophysics Data System (ADS)

    Bosch, F.; Hagmann, S.; Hillenbrand, P.-M.; Lane, G. J.; Litvinov, Yu. A.; Reed, M. W.; Sanjari, M. S.; Stöhlker, Th.; Torilov, S. Yu.; Tu, X. L.; Walke, P. M.

    2016-09-01

    The heavy ion storage rings coupled to in-flight radioactive-ion beam facilities, namely the ability to produce and store for extended periods of time radioactive nuclides in high atomic charge states, for the searchof yet unobserved decay mode - bound-state electron-positron pair decay.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. Pharmacology of Valinate and tert-Leucinate Synthetic Cannabinoids 5F-AMBICA, 5F-AMB, 5F-ADB, AMB-FUBINACA, MDMB-FUBINACA, MDMB-CHMICA, and Their Analogues.

    PubMed

    Banister, Samuel D; Longworth, Mitchell; Kevin, Richard; Sachdev, Shivani; Santiago, Marina; Stuart, Jordyn; Mack, James B C; Glass, Michelle; McGregor, Iain S; Connor, Mark; Kassiou, Michael

    2016-09-21

    Indole and indazole synthetic cannabinoids (SCs) featuring l-valinate or l-tert-leucinate pendant group have recently emerged as prevalent recreational drugs, and their use has been associated with serious adverse health effects. Due to the limited pharmacological data available for these compounds, 5F-AMBICA, 5F-AMB, 5F-ADB, AMB-FUBINACA, MDMB-FUBINACA, MDMB-CHMICA, and their analogues were synthesized and assessed for cannabimimetic activity in vitro and in vivo. All SCs acted as potent, highly efficacious agonists at CB1 (EC50 = 0.45-36 nM) and CB2 (EC50 = 4.6-128 nM) receptors in a fluorometric assay of membrane potential, with a general preference for CB1 activation. The cannabimimetic properties of two prevalent compounds with confirmed toxicity in humans, 5F-AMB and MDMB-FUBINACA, were demonstrated in vivo using biotelemetry in rats. Bradycardia and hypothermia were induced by 5F-AMB and MDMB-FUBINACA doses of 0.1-1 mg/kg (and 3 mg/kg for 5F-AMB), with MDMB-FUBINACA showing the most dramatic hypothermic response recorded in our laboratory for any SC (>3 °C at 0.3 mg/kg). Reversal of hypothermia by pretreatment with a CB1, but not CB2, antagonist was demonstrated for 5F-AMB and MDMB-FUBINACA, consistent with CB1-mediated effects in vivo. The in vitro and in vivo data indicate that these SCs act as highly efficacious CB receptor agonists with greater potency than Δ(9)-THC and earlier generations of SCs. PMID:27421060

  10. Pharmacology of Valinate and tert-Leucinate Synthetic Cannabinoids 5F-AMBICA, 5F-AMB, 5F-ADB, AMB-FUBINACA, MDMB-FUBINACA, MDMB-CHMICA, and Their Analogues.

    PubMed

    Banister, Samuel D; Longworth, Mitchell; Kevin, Richard; Sachdev, Shivani; Santiago, Marina; Stuart, Jordyn; Mack, James B C; Glass, Michelle; McGregor, Iain S; Connor, Mark; Kassiou, Michael

    2016-09-21

    Indole and indazole synthetic cannabinoids (SCs) featuring l-valinate or l-tert-leucinate pendant group have recently emerged as prevalent recreational drugs, and their use has been associated with serious adverse health effects. Due to the limited pharmacological data available for these compounds, 5F-AMBICA, 5F-AMB, 5F-ADB, AMB-FUBINACA, MDMB-FUBINACA, MDMB-CHMICA, and their analogues were synthesized and assessed for cannabimimetic activity in vitro and in vivo. All SCs acted as potent, highly efficacious agonists at CB1 (EC50 = 0.45-36 nM) and CB2 (EC50 = 4.6-128 nM) receptors in a fluorometric assay of membrane potential, with a general preference for CB1 activation. The cannabimimetic properties of two prevalent compounds with confirmed toxicity in humans, 5F-AMB and MDMB-FUBINACA, were demonstrated in vivo using biotelemetry in rats. Bradycardia and hypothermia were induced by 5F-AMB and MDMB-FUBINACA doses of 0.1-1 mg/kg (and 3 mg/kg for 5F-AMB), with MDMB-FUBINACA showing the most dramatic hypothermic response recorded in our laboratory for any SC (>3 °C at 0.3 mg/kg). Reversal of hypothermia by pretreatment with a CB1, but not CB2, antagonist was demonstrated for 5F-AMB and MDMB-FUBINACA, consistent with CB1-mediated effects in vivo. The in vitro and in vivo data indicate that these SCs act as highly efficacious CB receptor agonists with greater potency than Δ(9)-THC and earlier generations of SCs.

  11. 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

  12. STEADY-STATE MODEL OF SOLAR WIND ELECTRONS REVISITED

    SciTech Connect

    Yoon, Peter H.; Kim, Sunjung; Choe, G. S.

    2015-10-20

    In a recent paper, Kim et al. put forth a steady-state model for the solar wind electrons. The model assumed local equilibrium between the halo electrons, characterized by an intermediate energy range, and the whistler-range fluctuations. The basic wave–particle interaction is assumed to be the cyclotron resonance. Similarly, it was assumed that a dynamical steady state is established between the highly energetic superhalo electrons and high-frequency Langmuir fluctuations. Comparisons with the measured solar wind electron velocity distribution function (VDF) during quiet times were also made, and reasonable agreements were obtained. In such a model, however, only the steady-state solution for the Fokker–Planck type of electron particle kinetic equation was considered. The present paper complements the previous analysis by considering both the steady-state particle and wave kinetic equations. It is shown that the model halo and superhalo electron VDFs, as well as the assumed wave intensity spectra for the whistler and Langmuir fluctuations, approximately satisfy the quasi-linear wave kinetic equations in an approximate sense, thus further validating the local equilibrium model constructed in the paper by Kim et al.

  13. 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.

  14. 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.

  15. 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.

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

    PubMed

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

    2016-02-28

    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. PMID:26931702

  17. 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.

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

    DOE PAGESBeta

    Abriata, Luciano A.; Alvarez-Paggi, Damian; Ledesma, Gabirela N.; Blackburn, Ninian J.; Vila, Alejandro J.; Murgida, Daniel H.

    2012-10-10

    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 electronicmore » wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. In conclusion, 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.« less

  19. Determination of differential cross sections for electron-impact excitation of electronic states of molecular oxygen

    SciTech Connect

    Campbell, L.; Green, M. A.; Brunger, M. J.; Teubner, P. J. O.; Cartwright, D. C.

    2000-02-01

    The development and initial results of a method for the determination of differential cross sections for electron scattering by molecular oxygen are described. The method has been incorporated into an existing package of computer programs which, given spectroscopic factors, dissociation energies and an energy-loss spectrum for electron-impact excitation, determine the differential cross sections for each electronic state relative to that of the elastic peak. Enhancements of the original code were made to deal with particular aspects of electron scattering from O{sub 2}, such as the overlap of vibrational levels of the ground state with transitions to excited states, and transitions to levels close to and above the dissocation energy in the Herzberg and Schumann-Runge continua. The utility of the code is specifically demonstrated for the ''6-eV states'' of O{sub 2}, where we report absolute differential cross sections for their excitation by 15-eV electrons. In addition an integral cross section, derived from the differential cross section measurements, is also reported for this excitation process and compared against available theoretical results. The present differential and integral cross sections for excitation of the ''6-eV states'' of O{sub 2} are the first to be reported in the literature for electron-impact energies below 20 eV. (c) 2000 The American Physical Society.

  20. 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.

  1. 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.

  2. Attractive Correlated Electron-Pair Ground State of Resonant Bosons

    NASA Astrophysics Data System (ADS)

    Chakraverty, B. K.

    We consider a strictly one-band Hamiltonian of electrons with attractive interaction between them. We show that in the interesting intermediate density regime, where V ≤ ɛF, the system admits a mixed state of free fermions and dynamic correlated pairs or resonant bosons. The inevitable coupling between the two sub-system produces a superconducting ground state. This should be called Schafroth Condensation.

  3. 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

  4. 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.

  5. [Transfection efficiency of adenoviral vector AD5/F35 to malignant hematopoietic cells of different origins].

    PubMed

    Wabg, Kai; Peng, Jian-Qinag; Yuan, Zhen-Hua; Wu, Xiao-Bin

    2006-06-01

    This study was aimed to investigate the transfection efficiency of adenoviral vector AD5/F35 to hematopoietic malignant cells lines of various origins and AD5/F35 cytotoxicity. The hematologic malignant cell lines of various origins were transfected by AD5/F35-EGFP at different multiple of infection (MOI) and AD5-EGFP was used as control; the proportion of fluorescence positive cells was detected by flow cytometry; the killing effect of virus on infective target cells was assayed by MTT and observed by fluorescence microscopy. The results showed that the transfection efficiency of AD5/F35 vector to cell line of myeloid origin was > 99% at MOI = 30, the transfective efficiency of AD5 vector was 26.4% at MOI = 1,000; the transfection efficiency of AD5/F35 vector and AD5 vector to cell line of B cell origin were 11.7% and 5.7%, respectively, at MOI = 1,000. AD5/F35 and AD5 vectors could not effectively transfect cells of T cell origin, no fluorescence positive cells were detected at MOI = 1,000; no significant killing effect of AD5/F35 vector on infective target cells was observed at MOI = 1,000. It is concluded that AD5/F35 vector infection has definite selectivity to hematologic malignant cells of various origin, the infection ability of AD5/F35 vector to cells of myeloid origin is stronger than that to cells of B cell origin, the cytotoxicity of AD5/F35 vector to infective target cells is small. The AD5/F35 vector is preferable to AD5 vector in respect of infection ability and offers good prospects of application in gene therapy for myeloid leukemia cells as target cells.

  6. 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

  7. 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.

  8. Investigation of equation of states and electronic properties of Am and Cm metals in their gamma plutonium phase using GGA+SO+U method

    NASA Astrophysics Data System (ADS)

    Verma, Ashok K.; Modak, P.; Sharma, Surinder M.; Sikka, S. K.

    2013-06-01

    Pressure-volume equation of state for Am and Cm metals were studied in their gamma plutonium phase using GGA+SO+U method. Non-magnetic density functional theory with GGA exchange-correlation failed to estimate structural parameters and equation of states accurately. As expected, inclusion of onsite Hubbard interaction (U) between 5f electrons shows enormous effect on electronic and bulk properties. Nonmagnetic GGA+SO+U (=4.0 eV for Am and 5.5 eV for Cm) calculated EOS gives very good match with that of experimental data. Equally good match of EOS was found for spin-polarized GGA+SO+U calculations with much smaller Hubbard parameter.

  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. 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.

  11. Determining the Origins of Electronic States in Semiconductor Nanostructures

    SciTech Connect

    Goldman, Rachel S.; Johnson, H. T.

    2014-12-15

    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.

  12. 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

  13. 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...

  14. 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.

  15. Research on electronic states at silicon grain boundaries

    NASA Astrophysics Data System (ADS)

    Werner, J. H.

    1983-02-01

    Electronic states at grain boundaries in artificially grown, boron-doped silicon bicrystals are investigated. The dependence of conductivity and capacitance on temperature, photon energy and density, and frequency of the applied alternating voltage are discussed and quantitatively analyzed. The measurements show that the current transport though the grain boundary is controlled by thermal emission from holes over the grain boundary potential barrier. A formal expression is given for the occupation of interface states in stationary disequilibrium. Measurements of the photoconductivity and photocapacity as a function of light wavelength and intensity are analyzed, and a new spectroscopic method for determining the state density at the grain boundary is developed.

  16. Total Electron Scattering and Electronic State Excitations Cross Sections for O_2, CO, and CH_4

    NASA Technical Reports Server (NTRS)

    Kanik, I.; Trajmar, S.; Nickel, J. C.

    1993-01-01

    Available electron collision cross section data concerning total and elastic scattering, vibrationalexcitation, and ionization for O_2, CO, and CH_4 have been critically reviewed, and a set of crosssections for modeling of planetary atmospheric behavior is recommended. Utilizing theserecommended cross sections, we derived total electronic state excitation cross sections and upperlimits for dissociation cross sections, which in the case of CH_4 should very closely equal the actualdissociation cross section.

  17. Total electron scattering and electronic state excitations cross sections for O2, CO, and CH4

    NASA Technical Reports Server (NTRS)

    Kanik, I.; Trajmar, S.; Nickel, J. C.

    1993-01-01

    Available electron collision cross section data concerning total and elastic scattering, vibrational excitation, and ionization for O2, CO, and CH4 have been critically reviewed, and a set of cross sections for modeling of planetary atmospheric behavior is recommended. Utilizing these recommended cross sections, we derived total electronic state excitation cross sections and upper limits for dissociation cross sections, which in the case of CH4 should very closely equal the actual dissociation cross section.

  18. 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

  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. 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.

  1. 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.

  2. 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.

  3. Determining the electronic confinement of a subsurface metallic state.

    PubMed

    Mazzola, Federico; Edmonds, Mark T; Høydalsvik, Kristin; Carter, Damien John; Marks, Nigel A; Cowie, Bruce C C; Thomsen, Lars; Miwa, Jill; Simmons, Michelle Yvonne; Wells, Justin W

    2014-10-28

    Dopant profiles in semiconductors are important for understanding nanoscale electronics. Highly conductive and extremely confined phosphorus doping profiles in silicon, known as Si:P δ-layers, are of particular interest for quantum computer applications, yet a quantitative measure of their electronic profile has been lacking. Using resonantly enhanced photoemission spectroscopy, we reveal the real-space breadth of the Si:P δ-layer occupied states and gain a rare view into the nature of the confined orbitals. We find that the occupied valley-split states of the δ-layer, the so-called 1Γ and 2Γ, are exceptionally confined with an electronic profile of a mere 0.40 to 0.52 nm at full width at half-maximum, a result that is in excellent agreement with density functional theory calculations. Furthermore, the bulk-like Si 3pz orbital from which the occupied states are derived is sufficiently confined to lose most of its pz-like character, explaining the strikingly large valley splitting observed for the 1Γ and 2Γ states. PMID:25243326

  4. 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.

  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.

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

    PubMed

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

    2013-10-31

    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

  7. 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

  8. 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.

  9. Electronic excited States of polynucleotides: a study by electroabsorption spectroscopy.

    PubMed

    Krawczyk, Stanislaw; Luchowski, Rafal

    2007-02-01

    Electroabsorption spectra were obtained for single-stranded polynucleotides poly(U), poly(C), poly(A), and poly(G) in glycerol/water glass at low temperature, and the differences in permanent dipole moment (Deltamu) and polarizability (Deltaalpha) were estimated for several spectral ranges covering the lowest energy absorption band around 260 nm. In each spectral range, the electrooptical parameters associated with apparent features in the absorption spectrum exhibit distinct values representing either a dominant single transition or the resultant value for a group of a relatively narrow cluster of overlapping transitions. The estimated spacing in energy between electronic origins of these transitions is larger than the electronic coupling within the Coulombic interaction model which is usually adopted in computational studies. The electroabsorption data allow us to distinguish a weak electronic transition associated with a wing in polynucleotide absorption spectra, at an energy below the electronic origin in absorption spectra of monomeric nucleobases. In poly(C) and poly(G), these low-energy transitions are related to increased values of Deltamu and Deltaalpha, possibly indicating a weak involvement of charge resonance in the respective excited states. A model capable of explaining the origin of low-energy excited states, based on the interaction of pipi* and npi* transitions in neighboring bases, is introduced and briefly discussed on the grounds of point dipole interaction. PMID:17266277

  10. 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.

  11. Electronic spectrum of 17 electronic states of BN molecule: A theoretical study

    NASA Astrophysics Data System (ADS)

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

    The potential energy curves (PECs) of the X3Π, a1Σ+, b1Π, A3Σ+, B3Σ-, c1Δ, D3Π, 15Π, 31Σ+, 33Π, 21Π, 23Σ+, 13Δ, 15Σ+, 43Π, 23Σ- and 15Σ- 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 X3Π and D3Π electronic states. The vibrational level, inertial rotation and centrifugal distortion constants are calculated for each vibrational state of each electronic state. And those of the first 20 vibrational

  12. Theory of electron transfer and molecular state in DNA

    NASA Astrophysics Data System (ADS)

    Endres, Robert Gunter

    2002-09-01

    In this thesis, a mechanism for long-range electron transfer in DNA and a systematic search for high conductance DNA are developed. DNA is well known for containing the genetic code of all living species. On the other hand, there are some experimental indications that DNA can mediate effectively long-range electron transfer leading to the concept of chemistry at a distance. This can be important for DNA damage and healing. In the first part of the thesis, a possible mechanism for long-range electron transfer is introduced. The weak distance dependent electron transfer was experimentally observed using transition metal intercalators for donor and acceptor. In our model calculations, the transfer is mediated by the molecular analogue of a Kondo bound state well known from solid state physics of mixed-valence rare-earth compounds. We believe this is quite realistic, since localized d orbitals of the transition metal ions could function as an Anderson impurity embedded in a reservoir of rather delocalized molecular orbitals of the intercalator ligands and DNA pi orbitals. The effective Anderson model is solved with a physically intuitive variational ansatz as well as with the essentially exact DMRG method. The electronic transition matrix element, which is important because it contains the donor-acceptor distance dependence, is obtained with the Mulliken-Hush algorithm as well as from Born-Oppenheimer potential energy surfaces. Our possible explanation of long-range electron transfer is put in context to other more conventional mechanisms which also could lead to similar behavior. Another important issue of DNA is its possible use for nano-technology. Although DNA's mechanical properties are excellent, the question whether it can be conducting and be used for nano-wires is highly controversial. Experimentally, DNA shows conducting, semi-conducting and insulating properties. Motivated by these wide ranging experimental results on the conductivity of DNA, we have

  13. 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.

  14. 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...

  15. 75 FR 1617 - Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of New York

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-12

    ..., 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 New...'s approval, under regulations for Cross-Media Electronic Reporting, of the State of New...

  16. 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.

  17. 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.

  18. 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.

  19. Optimized dynamics of state to state transitions in 2-electron quantum dot molecules

    NASA Astrophysics Data System (ADS)

    Sælen, L.; Nepstad, R.; Degani, I.; Hansen, J. P.

    2009-11-01

    We investigate optimal control strategies for state to state transitions in a model of a quantum dot molecule containing two active strongly interacting electrons. The resulting optimized electric pulses are in the THz regime and can populate combinations of states with very short transition times. The speedup compared to intuitively constructed pulses is an order of magnitude. We furthermore make use of optimized pulse control in the simulation of an experimental preparation of the molecular quantum dot system. It is shown that exclusive population of certain excited states leads to a complete suppression of spin dephasing, as predicted in Nepstad et al. [1].

  20. High-energy spectroscopic study of the occupied and empty electronic levels in uranium metal and compounds

    NASA Astrophysics Data System (ADS)

    Baer, Y.

    1980-10-01

    X-ray photoemission spectroscopy (XPS) and bremsstrahlung isochromat spectroscopy (BIS) have been used to investigate the occupied and empty density of states (DOS) of α-uranium and of the compounds UO 2, US, and UAs. At the photon energy (1486.6 eV) used in both methods, the l = 3 projected DOS is bringing the dominant contribution to the experimental spectra. In the pure metal, the total 5f DOS appears as a 4 eV wide band showing a splitting. A completely different situation is encountered in the insulator UO 2 which contains two localized 5f electrons. Discrete XPS (5f 1) and BIS (5f 3) final states are observed on each side of EF, allowing the first determination of the Coulomb correlation energy for 5f electrons. In the occupied part of the band the p states are clearly separated from the 5f peak. The XPS spectra of US and UAs show similarly separated p and f structures but the metallic character of these compounds is recognized by the high DOS at EF. Their BIS spectra are formed by a dominant peak followed by an intense tail extending far above EF. This feature is attributed to strong many-body effects, as demonstrated by the line shape of the U core levels in these compounds. Satellites involving discrete excitations to empty 5f states are observed in the spectra of UO 2 and Th metal.

  1. Efficient numerical simulation of electron states in quantum wires

    NASA Technical Reports Server (NTRS)

    Kerkhoven, Thomas; Galick, Albert T.; Ravaioli, Umberto; Arends, John H.; Saad, Youcef

    1990-01-01

    A new algorithm is presented for the numerical simulation of electrons in a quantum wire as described by a two-dimensional eigenvalue problem for Schroedinger's equation coupled with Poisson's equation. Initially, the algorithm employs an underrelaxed fixed point iteration to generate an approximation which is reasonably close to the solution. Subsequently, this approximate solution is employed as an initial guess for a Jacobian-free implementation of an approximate Newton method. In this manner the nonlinearity in the model is dealt with effectively. The effectiveness of this approach is demonstrated in a set of numerical experiments which study the electron states on the cross section of a quantum wire structure based on III-V semiconductors at 4.2 and 77 K.

  2. 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.

  3. Spin states and electronic conduction in Ni oxides

    NASA Astrophysics Data System (ADS)

    Dionne, Gerald F.

    1990-05-01

    Magnetic and electronic properties of the mixed-valence semiconductor LixNi2+1-2xNi3+xO are reinterpreted in terms of low-spin states for both Ni ions. Anomalous decreases in hopping electron activation energies are discussed on the basis of (i) breakdown in antiferromagnetic ordering through spin canting of the Ni sublattices through exchange isolation caused by diamagnetic Li1+ ions that group with the low-spin Ni3+ (S= (1)/(2) ) to form polarons, and (ii) enhanced disruption of magnetic superexchange that results from a combination of Li1+ dilutants and S=0 states of surrounding Ni2+ ions induced at low temperatures by static Jahn-Teller tetragonal distortions of the oxygen octahedra around the Ni3+ polarons. Reported magnetic ordering and conduction anomalies in La2-xSrxNiO4 are then compared to the behavior of Cu in LixCu1-xO, and in the high-Tc superconducting La2-xSrxCuO4 system. Spontaneous conduction through molecular-orbital states involving zero-spin Ni and Cu ions is discussed, together with the role of S=0 polarons in other oxide superconductors.

  4. Dimensionality and Localization of Electron States in Conducting Polymers

    NASA Astrophysics Data System (ADS)

    Wang, Zhao Hui

    The electron localization and the dimensionality of conducting polymers are studied by a variety of transport and magnetic techniques. Two model conducting polymer systems, the emeraldine salt form of polyaniline (PAN-ES) and one of its derivatives (POT-ES), are employed in the studies. The electron localization is increased with increasing one-dimensionality of a quasi-one-dimensional disordered system (Quasi-1d-DS). This concept is tested by studying electron localization in polyaniline (PAN) and its methyl ring-substituted derivative poly(o-toluidine) (POT). The experimental results showed greater electron localization in the HCl salt of POT than that of PAN, reflected in much smaller sigma_{DC}, sigma_{MW} and epsilon, increased Curie susceptibility and decreased Pauli-like susceptibility. The localization is attributed to the reduced interchain diffusion rate caused by decreased interchain coherence and increased interchain separation, both of which result from the presence of CH_3 on the C_6 rings. The T-dependences of lnsigma ~ -T^{-1/2} and S(T) ~ S_0 + B/T are interpreted as quasi-1d variable range hopping (VRH) between the nearest neighboring chains. Within the model, electric field (F) dependence of sigma(F)~{cal K}F^{1/2} with { cal K}~ T^{-1/2} can be understood. Charging energy limited tunneling model for granular metals and three-dimensional VRH model with a Coulomb gap are not consistent with the experiment. Other possible mechanisms for electron localization and the general implications for control of dimensionality and conductivity are discussed. The interchain coupling may change the dimensionality of electron states of conducting polymers. It is an open question if "metallic" polymers have one dimensional or three dimensional conduction states. We investigate this issue by studying the oriented polyaniline system. The thermopower, microwave dielectric constant and EPR data suggest that the electrons are three-dimensionally delocalized while the

  5. 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

  6. Ab Initio Study of Electronic States of Astrophysically Important Molecules

    NASA Astrophysics Data System (ADS)

    Valiev, R. R.; Berezhnoy, A. A.; Minaev, B. F.; Chernov, V. E.; Cherepanov, V. N.

    2016-08-01

    A study of electronic states of LiO, NaO, KO, MgO, and CaO molecules has been performed. Potential energy curves of the investigated molecules have been constructed within the framework of the XMC-QDPT2 method. Lifetimes and efficiencies of photolysis mechanisms of these monoxides have been estimated within the framework of an analytical model of photolysis. The results obtained show that oxides of the considered elements in the exospheres of the Moon and Mercury are destroyed by solar photons during the first ballistic flight.

  7. 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.

  8. Detection of pulsed neutrons with solid-state electronics

    NASA Astrophysics Data System (ADS)

    Chatzakis, J.; Rigakis, I.; Hassan, S. M.; Clark, E. L.; Lee, P.

    2016-09-01

    Measurements of the spatial and time-resolved characteristics of pulsed neutron sources require large area detection materials and fast circuitry that can process the electronic pulses readout from the active region of the detector. In this paper, we present a solid-state detector based on the nuclear activation of materials by neutrons, and the detection of the secondary particle emission of the generated radionuclides’ decay. The detector utilizes a microcontroller that communicates using a modified SPI protocol. A solid-state, pulse shaping filter follows a charge amplifier, and it is designed as an inexpensive, low-noise solution for measuring pulses measured by a digital counter. An imaging detector can also be made by using an array of these detectors. The system can communicate with an interface unit and pass an image to a personal computer.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. Electronic spin state of iron in lower mantle perovskite

    SciTech Connect

    Li, J.; Struzhkin, V.; Mao, H.-k.; Shu, J.; Hemley, R.; Fei, Y.; Mysen, B.; Dera, P.; Parapenka, V.; Shen, G.

    2010-11-16

    The electronic spin state of iron in lower mantle perovskite is one of the fundamental parameters that governs the physics and chemistry of the most voluminous and massive shell in the Earth. We present experimental evidence for spin-pairing transition in aluminum-bearing silicate perovskite (Mg,Fe)(Si,Al)O{sub 3} under the lower mantle pressures. Our results demonstrate that as pressure increases, iron in perovskite transforms gradually from the initial high-spin state toward the final low-spin state. At 100 GPa, both aluminum-free and aluminum-bearing samples exhibit a mixed spin state. The residual magnetic moment in the aluminum-bearing perovskite is significantly higher than that in its aluminum-free counterpart. The observed spin evolution with pressure can be explained by the presence of multiple iron species and the occurrence of partial spin-paring transitions in the perovskite. Pressure-induced spin-pairing transitions in the perovskite would have important bearing on the magnetic, thermoelastic, and transport properties of the lower mantle, and on the distribution of iron in the Earth's interior. The lower mantle constitutes more than half of the Earth's interior by volume (1), and it is believed to consist predominantly (80-100%) of (Mg,Fe)(Si,Al)O{sub 3} perovskite (hereafter called perovskite), with up to 20% (Mg,Fe)O ferropericlase (2). The electronic spin state of iron has direct influence on the physical properties and chemical behavior of its host phase. Hence, knowledge on the spin state of iron is important for the interpretation of seismic observations, geochemical modeling, and geodynamic simulation of the Earth's deep interior (3, 4). Crystal field theory (4, 5) and band theory (6) predicted that a high-spin to low-spin transition would occur as a result of compression. To date, no experimental data exist on the spin sate of iron in Al-bearing perovskite. To detect possible spinpairing transition of iron in perovskite under the lower mantle

  15. 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.

  16. Linear energy relationships in ground state proton transfer and excited state proton-coupled electron transfer.

    PubMed

    Gamiz-Hernandez, Ana P; Magomedov, Artiom; Hummer, Gerhard; Kaila, Ville R I

    2015-02-12

    Proton-coupled electron transfer (PCET) processes are elementary chemical reactions involved in a broad range of radical and redox reactions. Elucidating fundamental PCET reaction mechanisms are thus of central importance for chemical and biochemical research. Here we use quantum chemical density functional theory (DFT), time-dependent density functional theory (TDDFT), and the algebraic diagrammatic-construction through second-order (ADC(2)) to study the mechanism, thermodynamic driving force effects, and reaction barriers of both ground state proton transfer (pT) and photoinduced proton-coupled electron transfer (PCET) between nitrosylated phenyl-phenol compounds and hydrogen-bonded t-butylamine as an external base. We show that the obtained reaction barriers for the ground state pT reactions depend linearly on the thermodynamic driving force, with a Brønsted slope of 1 or 0. Photoexcitation leads to a PCET reaction, for which we find that the excited state reaction barrier depends on the thermodynamic driving force with a Brønsted slope of 1/2. To support the mechanistic picture arising from the static potential energy surfaces, we perform additional molecular dynamics simulations on the excited state energy surface, in which we observe a spontaneous PCET between the donor and the acceptor groups. Our findings suggest that a Brønsted analysis may distinguish the ground state pT and excited state PCET processes.

  17. Electronic States and Spectra of BiO

    NASA Astrophysics Data System (ADS)

    Shestakov, O.; Breidohr, R.; Demes, H.; Setzer, K. D.; Fink, E. H.

    1998-07-01

    The electronic spectrum of the BiO radical has been studied by Fourier transform emission spectroscopy, laser-induced fluorescence, and excimer laser photolysis techniques. Six new electronic states,A1(Ω = 3/2) (Te= 11 528.8 cm-1, ωe= 530.4 cm-1, ωexe= 2.42 cm-1),G(Ω = 3/2) (Te= 20 273 cm-1, ωe= 499 cm-1, ωexe= 2.6 cm-1),H(Ω = 1/2) (Te= 20 469.76(6) cm-1, ωe= 471.63(18) cm-1, ωexe= 2.153(35) cm-1),I(Ω = 1/2) (Te= 21 982.50(2) cm-1, ωe= 506.50(11) cm-1, ωexe= 3.263(34) cm-1),J(Ω = 3/2) (Te= 25 598.95(42) cm-1, ωe= 489.95(16) cm-1, ωexe= 2.309(45) cm-1), andK(Ω = 1/2) (Te= 26 744.7(2) cm-1, ωe= 420.6(4) cm-1, ωexe= 5.25(5) cm-1), and 14 new electronic transitions (A1← X1,G → X2,H ↔ X1,H → A2(A),I ↔ X1,I → A2,J ↔ X1,J ↔ X2,K ↔ X1,K ↔ X2,K → A2,B ↔ X2,B → A2,C ↔ X2) have been detected. Time-resolved measurements of the fluorescence decays have yielded the radiative lifetimes of thev= 0 levels of most states up to <30 500 cm-1energy (τX2= 480 ± 100 μs, τA2= 9.3 ± 1.5 μs, τH= 15 ± 3 μs, τI= 16 ± 3 μs, τJ= 4.9 ± 0.9 μs, τK= 2.6 ± 0.3 μs, τB= 0.55 ± 0.08 μs, τC= 0.84 ± 0.15 μs) and rate constants for quenching of the states by some rare gas atoms and simple molecules. The new electronic statesA1,G,H,I,J, andKand the previously known levelsX1,X2,A2(A),B,C, andDare assigned to spin-orbit states arising from low-energy valence configurations of BiO with the help of detailed theoretical data calculated by Alekseyevet al.(J. Chem. Phys.100,8956-8968 (1994)).

  18. 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.

  19. 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...

  20. 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...

  1. 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.

  2. 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

  3. Study of squeezed state on free electron lasers

    NASA Astrophysics Data System (ADS)

    Chen, Teng; Madey, J. M. J.

    1998-02-01

    Preliminary investigations on squeezed state of FEL have been undertaken at the Duke FEL lab by means of photon counting experiments. We report photon statistics for spontaneous undulator radiation from Duke Storage Ring. Photon counting measurements have also been constructed on the Mark III FEL to obtain the statistical behavior of the visible harmonics of the infrared radiation. The initial experimental data demonstrate that the squeezing of optical phase fluctuations in an FEL is directly associated with the phase regulation of the electron beam as a result of FEL bunching. Simulation results on phase fluctuations in FEL radiation are also presented which support the above viewpoint. Further measurements are in process in an attempt to obtain better understanding on the effect of quantum fluctuations on the FEL interaction.

  4. 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

  5. Electronic states of lead salt nanocrystal and nanocrystal assemblies

    NASA Astrophysics Data System (ADS)

    Yang, Jun

    With the development of new synthetic methods, semiconductor nanocrystals of various morphologies and dimensions have been created. This changes their electro-optical properties, and brings new questions in understanding. At the same time, more and more research is now focused on nanocrystal assemblies, in particular nanocrystal superlattices with atomically coherent lattices, with the potential for various optoelectronic device applications. This thesis examines, in both theory and experiment, a number of nanocrystal systems, with the stress on dimensionality and morphology. In particular, in 1D and 2D systems, due to the anisotropic quantum connenment, the electrons and holes will form a tightly bond excitons, even at room temperature, in contrast to 0D and 3D systems, where either quantum connenment or coulomb interaction completely dominates. We'll also look into nanocrystal assemblies, both amorphous and atomically coherent, and study the effect of the inherent disorder in the structure on their electronic properties, with the goal of charge transportation through delocalized states. Last, we'll examine the ne structure in these nanocrystals.

  6. High-lying electronic states of the rubidium dimer—Ab initio predictions and experimental observation of the 5 1 Σu + and 51Πu states of Rb2 by polarization labelling spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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 51Πu 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 51Πu and 5 1 Σu + states. Analysis was guided by ab initio calculations performed to describe the 1,3Λg,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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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}.

  15. 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...

  16. 26 CFR 5f.103-2 - Public approval of industrial development bonds.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 14 2014-04-01 2013-04-01 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...

  17. 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...

  18. 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

  19. 48 CFR 47.303-5 - F.o.b. origin, with differentials.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) Differentials for mode of... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false F.o.b. origin, with... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-5 F.o.b. origin,...

  20. 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

  1. 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,...

  2. 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,...

  3. 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,...

  4. 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,...

  5. 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.

  6. 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

  7. 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

    ... Privacy Act of 1974; Treasury/United States Mint .013--United States Mint National Electronic Incident Reporting System of Records AGENCY: United States Mint, Treasury. ACTION: Notice of Proposed New System of..., the Department of the Treasury (``Treasury'') and the United States Mint proposes to establish a...

  8. 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.

  9. 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.

  10. 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.

  11. 45 CFR 270.12 - Must States file the data electronically?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false Must States file the data electronically? 270.12... (ASSISTANCE PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES HIGH PERFORMANCE BONUS AWARDS § 270.12 Must States file the data electronically? Each State must submit the...

  12. Characterization of the POU5F1 Homologue in Nile Tilapia: From Expression Pattern to Biological Activity.

    PubMed

    Xiaohuan, Huang; Yang, Zhao; Linyan, Liu; Zhenhua, Fan; Linyan, Zhou; Zhijian, Wang; Ling, Wei; Deshou, Wang; Jing, Wei

    2016-09-15

    POU5F1 (OCT4) is a crucial transcription factor for induction and maintenance of cellular pluripotency, as well as survival of germ cells in mammals. However, the homologues of POU5F1 in teleost fish, including zebrafish and medaka, now named Pou5f3, exhibit considerable differences in expression pattern and pluripotency-maintaining activity. To what extent the POU5F1 homologues are conserved in vertebrates has been unclear. In this study, we report that the POU5F1 homologue from the Nile tilapia (Oreochromis niloticus), OnPou5f3, displays an expression pattern and biological activity somewhat different from those in zebrafish or medaka. The expression of Onpou5f3 at both mRNA and protein levels was abundant in early development embryos until blastula stages, barely detectable as proceeding, and then displayed a transiently strong expression domain in the brain region during neurula stages similar to zebrafish but not medaka. Afterward, OnPou5f3 appeared as germline-restricted (including primordial germ cells and female and male gonad germ cells) expression just like medaka. Notably, OnPou5f3 depletion through morpholino oligos caused blastula blockage or lethality and failure of survival and proliferation of blastula cell-derived cells. These findings indicate that equivalent POU5F1-like expression and activity of Pou5f3 might be conserved accompanying with species-specific expression pattern during evolution. Our study provides insight into the evolutionary conservation of the POU5F1 homologues across vertebrates. PMID:27473876

  13. 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.

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

    PubMed Central

    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

    2016-01-01

    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

  15. Sad State of Phage Electron Microscopy. Please Shoot the Messenger

    PubMed Central

    Ackermann, Hans-W.

    2013-01-01

    Two hundred and sixty publications from 2007 to 2012 were classified according to the quality of electron micrographs; namely as good (71); mediocre (21); or poor (168). Publications were from 37 countries; appeared in 77 journals; and included micrographs produced with about 60 models of electron microscopes. The quality of the micrographs was not linked to any country; journal; or electron microscope. Main problems were poor contrast; positive staining; low magnification; and small image size. Unsharp images were frequent. Many phage descriptions were silent on virus purification; magnification control; even the type of electron microscope and stain used. The deterioration in phage electron microscopy can be attributed to the absence of working instructions and electron microscopy courses; incompetent authors and reviewers; and lenient journals. All these factors are able to cause a gradual lowering of standards.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Electronic structure of solid uranium tetrafluoride UF4

    NASA Astrophysics Data System (ADS)

    Teterin, A. Yu.; Teterin, Yu. A.; Maslakov, K. I.; Panov, A. D.; Ryzhkov, M. V.; Vukcevic, L.

    2006-07-01

    X-ray photoelectron spectra (XPS) and conversion electron spectra of the outer (0-15eV) and inner (15-40eV) valence electrons for UF4 were measured. Relativistic Xα discrete variation ( RXα DV) calculation data for the UF84-(C4v) cluster reflecting uranium close environment in solid UF4 were used for the quantitative interpretation of the fine spectral structure. Quantitative agreement between the experimental and theoretical data was established. The U5f electrons ( ≈1 U5f electron) were shown to participate directly in the chemical bond formation. This U 5 f electron was shown to be delocalized within the outer valence molecular orbitals (OVMO) range (1-15eV) . The other U5f electrons were shown to be localized and to participate weakly in the chemical bond formation. The XPS line associated with these electrons was observed at 3.8eV . The vacant U5f states are generally delocalized in the range of the low positive energies (0-7 eV). The contribution of the U6p electronic density to the molecular orbitals of UF4 was experimentally and theoretically evaluated. The U6p electrons were experimentally shown to participate significantly ( 0.6U6p electrons) in the formation of the OVMO beside the formation of the inner valence molecular orbitals (IVMO). IVMO composition and sequence order in the binding energy range 15-40eV in UF4 were determined.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  8. 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.

  9. 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

  10. The low-lying electronic states of SiO

    NASA Astrophysics Data System (ADS)

    Bauschlicher, Charles W.

    2016-08-01

    The singlet states of SiO that correlate with ground state atoms have been studied. The computed spectroscopic constants are in good agreement with experiment. The lifetime of the E state has been calculated to be 10.9 ns; this is larger than the results of previous computations and is in excellent agreement with the experimental value of 10.5 ± 1.1 ns. The lifetime of the A state is about three times larger than found in experiment. We suggest that absorption from the X state to the (2)1 Π state is responsible for the unidentified lines in the experiment of Hormes et al.

  11. 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.

  12. 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.

  13. 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.

  14. Molecular Electron Microscopy: State of the Art and Current Challenges

    PubMed Central

    2008-01-01

    The objective of molecular electron microscopy (EM) is to use electron microscopes to visualize the structure of biological molecules. This Review provides a brief overview of the methods used in molecular EM, their respective strengths and successes, and current developments that promise an even more exciting future for molecular EM in the structural investigation of proteins and macromolecular complexes, studied in isolation or in the context of cells and tissues. PMID:18484707

  15. 77 FR 37039 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Delaware

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-20

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

  16. 77 FR 37038 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Illinois

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-20

    ... 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 Illinois...

  17. 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...

  18. CHARACTERIZATION OF TANK 5F VERTICAL COOLING COIL LEACHATES FOR SELECT RADIONUCLIDES 2011

    SciTech Connect

    Oji, L.; Diprete, D.

    2001-08-17

    Two twenty-four inch samples of vertical sections of the cooling coils from Tank 5F, taken from Riser 1, were made available to SRNL by SRR for leaching and characterization of the leachates for select radionuclide trapped in the corrosion layer on the exterior of the cooling coils. One piece of cooling coil sample was obtained from a section of a vertical cooling coil located above the 45-inch elevation from the tank floor and the other also from a vertical section of a cooling coil located below the 45-inch elevation from the tank floor of Tank 5F. Analysis results from both cooling coils show that the predominant radionuclides contributing to the activity in both coils are strontium-90 and cesium-137. The activities for strontium-90 and cesium-137 in the Tank 5F vertical cooling coil located above the 45-inch elevation of the tank and designated as sample 5-R1-A45 averaged 1.34E-02 {+-} 1.12E-03 and 7.27E-04 {+-} 4.46E-05 Ci/ft{sup 2}, respectively, while the activities for the vertical cooling coil located below the 45-inch elevation of the tank and designated as sample 5-R1-B45 averaged 8.93E-03 {+-} 8.25E-04 for Sr-90 and 8.10E-04 {+-} 6.36E-05 Ci/ft{sup 2} for Cs-137. Other significant activity contributing radionuclides are americium-241 and europium-154/155. With the exception of the analysis result for Pu-241 in the 5-R1-A45 cooling coils samples, the target detection limits for the other radionuclides were met in both cooling coil samples. The detection limits for Pu-241 analyses result in coil sample 5-R1-A45 were not met consistently because of possible background changes during counting.

  19. Donor acceptor electronic couplings in π-stacks: How many states must be accounted for?

    NASA Astrophysics Data System (ADS)

    Voityuk, Alexander A.

    2006-04-01

    Two-state model is commonly used to estimate the donor-acceptor electronic coupling Vda for electron transfer. However, in some important cases, e.g. for DNA π-stacks, this scheme fails to provide accurate values of Vda because of multistate effects. The Generalized Mulliken-Hush method enables a multistate treatment of Vda. In this Letter, we analyze the dependence of calculated electronic couplings on the number of the adiabatic states included in the model. We suggest a simple scheme to determine this number. The superexchange correction of the two-state approximation is shown to provide good estimates of the electronic coupling.

  20. 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...

  1. 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.

  2. Nonadiabatic Evolution of Electronic States by Electron Nuclear Dynamics Theory: Application to Atom-Molecule Scattering Problems.

    NASA Astrophysics Data System (ADS)

    Hagelberg, Frank

    2004-03-01

    In this contribution, we address the problem how to determine accurately the nonadiabatic content of any given dynamic process involving molecular motion. More specifically, we generate a dynamic electronic wave function using Electron Nuclear Dynamics (END) theory^2 and cast this wave function into the language of electronic excitations. This is achieved by adiabatic transport of an electronic basis along the classical nuclear trajectories of the studied molecular system. This basis is chosen as the static UHF molecular ground state determinant of the system in conjunction with all determinants that arise from the ground state by single, double and triple substitutions. Projecting the dynamic wave function into this basis, we arrive at a natural distinction between adiabatic and nonadiabatic components of the motion considered. We will discuss this concept by the examples of various scattering problems, among them the interaction of proton projectiles with methylene targets. ^2E. Deumens et al., Rev. Mod. Phys. 1994, 66, 917.

  3. Nature of Electronically Excited States of Organic Compounds and Processes of Nonradiative Conversion

    NASA Astrophysics Data System (ADS)

    Mayer, G. V.; Plotnikov, V. G.; Artyukhov, V. Ya.

    2016-08-01

    Models of quantum-chemical calculation of rate constants for internal processes and intersystem crossing in polyatomic molecules are considered. The influence of the nature of electronically excited states in organic compounds is investigated. It is shown that the explicit allowance for the nature of wave functions of electronic states for estimation of electronic matrix elements of nonadiabaticity operators and spin-orbit interaction allows photophysical processes in organic compounds to be considered in detail.

  4. 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}.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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…

  10. 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.

  11. Quantitative imaging reveals real-time Pou5f3–Nanog complexes driving dorsoventral mesendoderm patterning in zebrafish

    PubMed Central

    Perez-Camps, Mireia; Tian, Jing; Chng, Serene C; Sem, Kai Pin; Sudhaharan, Thankiah; Teh, Cathleen; Wachsmuth, Malte; Korzh, Vladimir; Ahmed, Sohail; Reversade, Bruno

    2016-01-01

    Formation of the three embryonic germ layers is a fundamental developmental process that initiates differentiation. How the zebrafish pluripotency factor Pou5f3 (homologous to mammalian Oct4) drives lineage commitment is unclear. Here, we introduce fluorescence lifetime imaging microscopy and fluorescence correlation spectroscopy to assess the formation of Pou5f3 complexes with other transcription factors in real-time in gastrulating zebrafish embryos. We show, at single-cell resolution in vivo, that Pou5f3 complexes with Nanog to pattern mesendoderm differentiation at the blastula stage. Later, during gastrulation, Sox32 restricts Pou5f3–Nanog complexes to the ventrolateral mesendoderm by binding Pou5f3 or Nanog in prospective dorsal endoderm. In the ventrolateral endoderm, the Elabela / Aplnr pathway limits Sox32 levels, allowing the formation of Pou5f3–Nanog complexes and the activation of downstream BMP signaling. This quantitative model shows that a balance in the spatiotemporal distribution of Pou5f3–Nanog complexes, modulated by Sox32, regulates mesendoderm specification along the dorsoventral axis. DOI: http://dx.doi.org/10.7554/eLife.11475.001 PMID:27684073

  12. Efficient gene transfer into normal human B lymphocytes with the chimeric adenoviral vector Ad5/F35.

    PubMed

    Jung, Daniel; Néron, Sonia; Drouin, Mathieu; Jacques, Annie

    2005-09-01

    The failure to efficiently introduce genes into normal cells such as human B lymphocytes limits the characterization of their function on cellular growth, differentiation and survival. Recent studies have shown that a new adenoviral vector Ad5/F35 can efficiently transduce human haematopoietic CD34+ progenitor cells. In this study, we compared the gene transfer efficiencies of the Ad5/F35 vector to that of the parental vector Ad5 in human B lymphocytes. Peripheral blood B cells obtained from healthy individuals were cultured in vitro using CD40-CD154 system. Normal B lymphocytes were infected with replication-defectives Ad5 and Ad5/F35, both containing the GFP reporter gene, and transduction efficiencies were monitored by flow cytometry. Ad5 was highly ineffective, infecting only about 5% of human B lymphocytes. In contrast, Ad5/F35 transduced up to 60% of human B lymphocytes and GFP expression could be detected for up to 5 days post infection. Importantly, physiology of B lymphocytes such as proliferation, viability and antibodies secretion were unaffected following Ad5/F35 transduction. Finally, we observed that memory B lymphocytes were more susceptible to Ad5/F35 infection than naïve B lymphocytes. Thus, our results demonstrate that the adenoviral vector Ad5/F35 is an efficient tool for the functional characterization of genes in B lymphopoiesis.

  13. Effect of the spin-orbit interaction and the electron phonon coupling on the electronic state in a silicon vacancy

    NASA Astrophysics Data System (ADS)

    Yamada, Takemi; Yamakawa, Youichi; Ōno, Yoshiaki

    2010-01-01

    The electronic state around a single vacancy in silicon crystal is investigated by using the Green's function approach. The triply degenerate charge states are found to be widely extended and account for extremely large elastic softening at low temperature as observed in recent ultrasonic experiments. When we include the LS coupling λSi on each Si atom, the 6-fold spin-orbital degeneracy for the V+ state with the valence +1 and spin 1/2 splits into Γ doublet groundstates and Γ8 quartet excited states with a reduced excited energy of O(λSi/10). We also consider the effect of couplings between electrons and Jahn-Teller phonons in the dangling bonds within the second order perturbation and find that the groundstate becomes Γ8 quartet which is responsible for the magnetic-field suppression of the softening in B-doped silicon.

  14. 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.

  15. A multi-state fragment charge difference approach for diabatic states in electron transfer: Extension and automation

    NASA Astrophysics Data System (ADS)

    Yang, Chou-Hsun; Hsu, Chao-Ping

    2013-10-01

    The electron transfer (ET) rate prediction requires the electronic coupling values. The Generalized Mulliken-Hush (GMH) and Fragment Charge Difference (FCD) schemes have been useful approaches to calculate ET coupling from an excited state calculation. In their typical form, both methods use two eigenstates in forming the target charge-localized diabatic states. For problems involve three or four states, a direct generalization is possible, but it is necessary to pick and assign the locally excited or charge-transfer states involved. In this work, we generalize the 3-state scheme for a multi-state FCD without the need of manual pick or assignment for the states. In this scheme, the diabatic states are obtained separately in the charge-transfer or neutral excited subspaces, defined by their eigenvalues in the fragment charge-difference matrix. In each subspace, the Hamiltonians are diagonalized, and there exist off-diagonal Hamiltonian matrix elements between different subspaces, particularly the charge-transfer and neutral excited diabatic states. The ET coupling values are obtained as the corresponding off-diagonal Hamiltonian matrix elements. A similar multi-state GMH scheme can also be developed. We test the new multi-state schemes for the performance in systems that have been studied using more than two states with FCD or GMH. We found that the multi-state approach yields much better charge-localized states in these systems. We further test for the dependence on the number of state included in the calculation of ET couplings. The final coupling values are converged when the number of state included is increased. In one system where experimental value is available, the multi-state FCD coupling value agrees better with the previous experimental result. We found that the multi-state GMH and FCD are useful when the original two-state approach fails.

  16. 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.

  17. 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.

  18. 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.

  19. Mapping unoccupied electronic states of freestanding graphene by angle-resolved low-energy electron transmission

    NASA Astrophysics Data System (ADS)

    Wicki, Flavio; Longchamp, Jean-Nicolas; Latychevskaia, Tatiana; Escher, Conrad; Fink, Hans-Werner

    2016-08-01

    We report angle-resolved electron transmission measurements through freestanding graphene sheets in the energy range of 18 to 30 eV above the Fermi level. The measurements are carried out in a low-energy electron point source microscope, which allows simultaneously probing the transmission for a large angular range. The characteristics of low-energy electron transmission through graphene depend on its electronic structure above the vacuum level. The experimental technique described here allows mapping of the unoccupied band structure of freestanding two-dimensional materials as a function of the energy and probing angle, respectively, in-plane momentum. Our experimental findings are consistent with theoretical predictions of a resonance in the band structure of graphene above the vacuum level [V. U. Nazarov, E. E. Krasovskii, and V. M. Silkin, Phys. Rev. B 87, 041405 (2013), 10.1103/PhysRevB.87.041405].

  20. 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.

  1. 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

  2. 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.

    2016-10-01

    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.

  3. 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.

  4. 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.

  5. 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

  6. Vibrationally resolved photoelectron spectroscopy of electronic excited states of DNA bases: application to the ã state of thymine cation.

    PubMed

    Hochlaf, Majdi; Pan, Yi; Lau, Kai-Chung; Majdi, Youssef; Poisson, Lionel; Garcia, Gustavo A; Nahon, Laurent; Al Mogren, Muneerah Mogren; Schwell, Martin

    2015-02-19

    For fully understanding the light-molecule interaction dynamics at short time scales, recent theoretical and experimental studies proved the importance of accurate characterizations not only of the ground (D0) but also of the electronic excited states (e.g., D1) of molecules. While ground state investigations are currently straightforward, those of electronic excited states are not. Here, we characterized the à electronic state of ionic thymine (T(+)) DNA base using explicitly correlated coupled cluster ab initio methods and state-of-the-art synchrotron-based electron/ion coincidence techniques. The experimental spectrum is composed of rich and long vibrational progressions corresponding to the population of the low frequency modes of T(+)(Ã). This work challenges previous numerous works carried out on DNA bases using common synchrotron and VUV-based photoelectron spectroscopies. We provide hence a powerful theoretical and experimental framework to study the electronic structure of ionized DNA bases that could be generalized to other medium-sized biologically relevant systems.

  7. 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.

  8. 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.

  9. Electronic states and spectra of BiS

    NASA Astrophysics Data System (ADS)

    Setzer, K. D.; Meinecke, F.; Fink, E. H.

    2009-11-01

    NIR/VIS emission spectra of BiS were measured in the 5800-25 000 cm -1 region with a Fourier-transform spectrometer. BiS was produced by reaction of bismuth and sulfur vapor and excited by energy transfer from metastable oxygen O 2( a1Δ g) in a fast-flow system. The spectrum of BiS was found to be closely related to that of the previously studied BiO radical [O. Shestakov et al., J. Mol. Spectrosc. 190 (1998) 28-77]. Five transitions connecting the Ω-components of the first three excited states, A4Π( A13/2, A21/2), B2Π( B11/2), and C4Σ -( C11/2, C23/2), with the components of the strongly split ground state, X2Π( X11/2, X23/2, have been observed and analyzed.

  10. Probing the electron states and metal-insulator transition mechanisms in molybdenum disulphide vertical heterostructures.

    PubMed

    Chen, Xiaolong; Wu, Zefei; Xu, Shuigang; Wang, Lin; Huang, Rui; Han, Yu; Ye, Weiguang; Xiong, Wei; Han, Tianyi; Long, Gen; Wang, Yang; He, Yuheng; Cai, Yuan; Sheng, Ping; Wang, Ning

    2015-01-01

    The metal-insulator transition is one of the remarkable electrical properties of atomically thin molybdenum disulphide. Although the theory of electron-electron interactions has been used in modelling the metal-insulator transition in molybdenum disulphide, the underlying mechanism and detailed transition process still remain largely unexplored. Here we demonstrate that the vertical metal-insulator-semiconductor heterostructures built from atomically thin molybdenum disulphide are ideal capacitor structures for probing the electron states. The vertical configuration offers the added advantage of eliminating the influence of large impedance at the band tails and allows the observation of fully excited electron states near the surface of molybdenum disulphide over a wide excitation frequency and temperature range. By combining capacitance and transport measurements, we have observed a percolation-type metal-insulator transition, driven by density inhomogeneities of electron states, in monolayer and multilayer molybdenum disulphide. In addition, the valence band of thin molybdenum disulphide layers and their intrinsic properties are accessed.

  11. 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.

  12. Electron Impact Excitation of Xenon from the Ground State and the Metastable State to the 5p57p Levels

    NASA Astrophysics Data System (ADS)

    Chen, Zhan-Bin; Dong, Chen-Zhong; Xie, Lu-You; Jiang, Jun

    2014-03-01

    Electron impact excitation cross sections from the ground state and the lowest metastable state 5p56s J = 2 to the excited states of the 5p57p configuration of xenon are calculated systematically using the fully relativistic distorted wave method. Special attention is paid to the configuration interaction effects in the wave-function expansion of target states. The results are in good agreement with the recent experimental data by Jung et al. [Phys. Rev. A 80 (2009) 062708] over the measured energy range. These accurate theoretical results can be used in the modeling and diagnosis of plasmas containing xenon.

  13. The influence of nonthermal electron distributions on the charge state of heavy ions

    NASA Astrophysics Data System (ADS)

    Kartavykh, Yu.; Ostryakov, V.

    2001-08-01

    We investigate the influence of non-thermal electrons on the formation of ionic states of heavy elements in SEP events. The equilibrium mean charge of Mg, Si and Fe for several samples of non-Maxwellian populations (power law electron beam and bi-Maxwellian distribution) were calculated. According to our estimates the anomalously high density of non-thermal electrons is required to obtain substantial difference in the mean charge of heavy ions as compared with `pure' thermal dstribution.

  14. 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.

  15. General Organizational Classification: An Empirical Test Using the United States and Japanese Electronics Industries.

    ERIC Educational Resources Information Center

    Ulrich, Dave; McKelvey, Bill

    1990-01-01

    Tests for and identifies populations within a family of electronics industries. Data include 669 United States and 144 Japanese electronics firms. Demonstrates the relevance of a general organizational classification for explaining how different natural selection processes affect different populations. (75 references) (MLF)

  16. 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...

  17. 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...

  18. 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...

  19. 76 FR 25334 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Maryland

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    ... . 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 Maryland...

  20. 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...

  1. 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...

  2. 78 FR 49510 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Montana

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-14

    ... 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 establishes... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Montana...

  3. 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...

  4. 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...

  5. 77 FR 58131 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Mississippi

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-19

    ... . 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...

  6. 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...

  7. 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...

  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 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...

  10. 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...

  11. 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...

  12. 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…

  13. Engineering the electronic state of a perovskite electrocatalyst for synergistically enhanced oxygen evolution reaction.

    PubMed

    Guo, Yuqiao; Tong, Yun; Chen, Pengzuo; Xu, Kun; Zhao, Jiyin; Lin, Yue; Chu, Wangsheng; Peng, Zhenmeng; Wu, Changzheng; Xie, Yi

    2015-10-21

    A surface hydrogen effect to modulate the pure electronic-state transition in perovskite Ca0.9 Yb0.1 MnO3 synergistically generates a more suitable eg electron filling status and better conductivity. This achieves 100 times higher catalytic activity compared to that of a pristine sample. PMID:26316037

  14. Configuring Electronic States in an Atomically Precise Array of Quantum Boxes.

    PubMed

    Nowakowska, Sylwia; Wäckerlin, Aneliia; Piquero-Zulaica, Ignacio; Nowakowski, Jan; Kawai, Shigeki; Wäckerlin, Christian; Matena, Manfred; Nijs, Thomas; Fatayer, Shadi; Popova, Olha; Ahsan, Aisha; Mousavi, S Fatemeh; Ivas, Toni; Meyer, Ernst; Stöhr, Meike; Ortega, J Enrique; Björk, Jonas; Gade, Lutz H; Lobo-Checa, Jorge; Jung, Thomas A

    2016-07-01

    A 2D array of electronically coupled quantum boxes is fabricated by means of on-surface self-assembly assuring ultimate precision of each box. The quantum states embedded in the boxes are configured by adsorbates, whose occupancy is controlled with atomic precision. The electronic interbox coupling can be maintained or significantly reduced by proper arrangement of empty and filled boxes.

  15. Teleportation of electronic many-qubit states encoded in the electron spin of quantum dots via single photons.

    PubMed

    Leuenberger, Michael N; Flatté, Michael E; Awschalom, D D

    2005-03-18

    We propose a teleportation scheme that relies only on single-photon measurements and Faraday rotation, for teleportation of many-qubit entangled states stored in the electron spins of a quantum dot system. The interaction between a photon and the two electron spins, via Faraday rotation in microcavities, establishes Greenberger-Horne-Zeilinger entanglement in the spin-photon-spin system. The appropriate single-qubit measurements, and the communication of two classical bits, produce teleportation. This scheme provides the essential link between spintronic and photonic quantum information devices by permitting quantum information to be exchanged between them.

  16. Improved Detection of Fast Neutrons with Solid-State Electronics

    NASA Astrophysics Data System (ADS)

    Chatzakis, J.; Hassan, S. M.; Clark, E. L.; Talebitaher, A.; Lee, P.

    2014-02-01

    There is an increasing requirement for alternative and improved detection of fast neutrons due to the renewed interest in neutron diagnostics applications. Some applications require heavily shielded neutron sources that emit a substantial proportion of their emission as fast neutrons and so require high performance fast neutron detectors. In some applications, the detection of neutron bursts from pulsed neutron sources has to be synchronized to the repetition rate of the source. Typical fast neutron detectors incorporate scintillators that are sensitive to all kinds of ionizing radiations as well as neutrons, and their efficiency is low. In this paper, we present a device based on the principle of neutron activation coupled to solid-state p-i-n diodes connected to a charge amplifier. The charge amplifier is specially developed to operate with high capacitance detectors and has been optimized by the aid of the SPICE program. A solid-state pulse shaping filter follows the charge amplifier, as an inexpensive solution, capable to provide pulses that can be counted by a digital counter.

  17. Multicentered valence electron effective potentials: a solution to the link atom problem for ground and excited electronic states.

    PubMed

    Slavícek, Petr; Martínez, Todd J

    2006-02-28

    We introduce a multicentered valence electron effective potential (MC-VEEP) description of functional groups which succeeds even in the context of excited electronic states. The MC-VEEP is formulated within the ansatz which is familiar for effective core potentials in quantum chemistry, and so can be easily incorporated in any quantum chemical calculation. By demanding that both occupied and virtual orbitals are described correctly on the MC-VEEP, we are able to ensure correct behavior even when the MC-VEEP borders an electronically excited region. However, the present formulation does require that the electrons represented by the MC-VEEP are primarily spectators and not directly participating in the electronic excitation. We point out the importance of separating the electrostatic and exchange-repulsion components of the MC-VEEP in order that interactions between the effective potential and other nuclei can be modeled correctly. We present a MC-VEEP for methyl radical with one active electron which is tested in several conjugated molecules. We discuss the use of the MC-VEEP as a solution to the "link atom" problem in hybrid quantum mechanical/molecular mechanical methods. We also discuss the limitations and further development of this approach.

  18. 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

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

    PubMed

    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

    2015-05-18

    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.

  20. 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

  1. 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.

  2. Nonadiabatic excited-state molecular dynamics: treatment of electronic decoherence.

    PubMed

    Nelson, Tammie; Fernandez-Alberti, Sebastian; Roitberg, Adrian E; Tretiak, Sergei

    2013-06-14

    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. 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)

  4. 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

  5. Electronic states and spectra of BiTe

    NASA Astrophysics Data System (ADS)

    Setzer, K. D.; Laufs, S.; Fink, E. H.

    2010-09-01

    NIR/VIS emission spectra of the bismuth telluride radical, BiTe, were measured in the 3600-20 000 cm -1 region with a Fourier-transform spectrometer. BiTe was produced by reaction of bismuth and tellurium vapors and excited by energy transfer from metastable oxygen O 2( a1Δ g) in a fast-flow system. The spectrum of BiTe was found to be markedly different from those of the previously studied BiO, BiS and BiSe radicals. The A24Π 1/2 → X12Π 1/2 transition which forms the most prominent and extended band system in these molecules was not observed for BiTe, and the X22Π 3/2 → X12Π 1/2 fine structure transition shows up with a different structure and at much lower wavenumbers than in the spectra of the lighter bismuth chalcogenides. The only common feature is the C14Σ -1/2 → X12Π 1/2 system which is found in the range 16 500-19 000 cm -1 similar to the three other molecules. Besides the X2 → X1 and C1 → X1 systems, seven other transitions show up by short Δ ν = 0 sequences only. With help of the data derived from the analyses of the X2 → X1 and C1 → X1 systems and theoretical predictions of electronic and vibrational energies and transition probabilities of the strongest transitions of BiTe by Lingott et al. [7] the spectra were assigned to the transitions C14Σ -1/2 → X22Π 3/2, C14Σ -1/2 → A24Π 1/2, A44Π 1/2 → A24Π 1/2, A44Π 1/2 → X22Π 3/2, B12Π 1/2 → A24Π 1/2, B12Π 1/2 → A14Π 3/2, and B22Π 3/2 → X22Π 3/2.

  6. 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

  7. Electronic Cigarette Use Among Working Adults - United States, 2014.

    PubMed

    Syamlal, Girija; Jamal, Ahmed; King, Brian A; Mazurek, Jacek M

    2016-06-10

    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

  8. Satellites and solid state electronics test concrete pressure water pipelines

    NASA Astrophysics Data System (ADS)

    Fumo, John; Worthington, Will

    2000-06-01

    Like all structures, water pressure pipelines have a finite life. Pipelines will eventually begin to fail, leaving the pipeline owner to deal with the quandary: what caused this to happen, can we prevent future failures, must we replace this structure now? The causes for pipeline failure include defects and anomalies which may occur in any phase of a pipeline's life: during the engineering, the manufacture, the construction, or the operation. Failure may simply be the result of environmental conditions or old age. In the past five years, passive acoustic emission detection technology has been adapted to concrete pressure pipelines. This method of inspection is based on the caustic emissions made by the prestressed reinforcing wire as it releases its energy. A recently patented method of using this technology relies on a series of remote, independent test stations to detect, record and time-stamp these acoustic emissions. A low-powered, high- performance embedded processor system makes use of global positioning system time signals to synchronize multiple stations. These methods are re-defining the standard of care of water pressure pipelines. This paper describes pipeline failure mechanisms and a state-of-the-art data sampling system which has been developed to evaluate pipeline structural integrity.

  9. Dressed projectile charge state dependence of differential electron emission from Ne atom

    NASA Astrophysics Data System (ADS)

    Biswas, S.; Monti, J. M.; Rivarola, R. D.; Tribedi, L. C.

    2015-01-01

    We study the projectile charge state dependence of doubly differential electron emission cross section (DDCS) in ionization of Ne under the impact of dressed and bare oxygen ions. Experimental DDCS results measured at different angles are compared with the calculations based on a CDW-EIS approximation using the GSZ model potential to describe projectile active-electron interaction. This prescription gives an overall very good agreement. In general a deviation from the q2-law was observed in the DDCS. The observations crudely identify the dominance of different projectile electron loss mechanisms at certain electron energy range.

  10. Steady-state hollow electron temperature profiles in the Rijnhuizen Tokamak Project

    SciTech Connect

    Hogeweij, G.M.; Oomens, A.A.; Barth, C.J.; Beurskens, M.N.; Chu, C.C.; van Gelder, J.F.; Lok, J.; Lopes Cardozo, N.J.; Pijper, F.J.; Polman, R.W.; Rommers, J.H.

    1996-01-01

    In the Rijnhuizen Tokamak Project steady-state hollow electron temperature ({ital T}{sub {ital e}}) profiles have been sustained with strong off-axis electron cyclotron heating, creating a region of reversed magnetic shear. In this region the effective electron thermal diffusivity ({chi}{sub {ital e}}{sup {ital pb}}) is close to neoclassical in high density plasmas. For medium density, {chi}{sub {ital e}}{sup {ital pb}} is lower than neoclassical and may even be negative, indicating that off-diagonal elements in the transport matrix drive an electron heat flux up the {ital T}{sub {ital e}} gradient. {copyright} {ital 1996 The American Physical Society.}

  11. 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)].

  12. 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.

  13. 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.

  14. Steady-State Model of Solar Wind Electrons and Implications for Kappa Distribution

    NASA Astrophysics Data System (ADS)

    Kim, S.; Yoon, P. H.; Choe, G. S.

    2015-12-01

    The solar wind electrons are made of three or four distinct components, which are core Maxwellian background, isotropic halo, and super-halo (and sometimes, highly field-aligned strahl component which can be considered as a fourth element). A recent paper [Kim et al., ApJ, 806, 32 (2015)] puts forth a steady-state model for the solar wind electrons. The halo electrons are assumed to be in dynamical steady state with the whistler fluctuations, while the super-halo electrons maintain dynamical steady-state equilibrium with the Langmuir fluctuations, known as the quasi-thermal noise. However, the model was based upon the consideration of steady-state electron particle kinetic equation. The present paper completes the analysis by considering both the steady-state particle and wave kinetic equations. It is shown that the coupled equations enjoy two exact solutions, the Maxwellian and inverse power-law velocity distribution functions (VDFs). Kim et al. (2015) had modeled both halo and super-halo electrons by kappa VDFs. Since the kappa VDF matches the Maxwellian model for low energy and an inverse power-law for high-energy tail, the fact that exact solutions represent both aspects provides the plasma physical justification for the kappa VDF.

  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. Electron energy-loss spectroscopy of excited states of the pyridine molecules

    NASA Astrophysics Data System (ADS)

    Linert, Ireneusz; Zubek, Mariusz

    2016-04-01

    Electron energy-loss spectra of the pyridine, C5H5N, molecules in the gas phase have been measured to investigate electronic excitation in the energy range 3.5-10 eV. The applied wide range of residual electron energy and the scattering angle range from 10° to 180° enabled to differentiate between optically-allowed and -forbidden transitions. These measurements have allowed vertical excitation energies of the triplet excited states of pyridine to be determined and tentative assignments of these states to be proposed. Some of these states have not been identified in the previous works. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  17. 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…

  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. 45 CFR 270.12 - Must States file the data electronically?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (ASSISTANCE PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES HIGH PERFORMANCE BONUS AWARDS § 270.12 Must States file the data electronically? Each State must submit the data required to compete for the high performance bonus work measures and the Medicaid/SCHIP...

  20. 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)

  1. 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

  2. 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

  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. Study on the steady operating state of a micro-pulse electron gun.

    PubMed

    Kui, Zhou; Xiangyang, Lu; Shengwen, Quan; Jifei, Zhao; Xing, Luo; Ziqin, Yang

    2014-09-01

    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.

  6. 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.

  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. 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.

  9. Study on the steady operating state of a micro-pulse electron gun.

    PubMed

    Kui, Zhou; Xiangyang, Lu; Shengwen, Quan; Jifei, Zhao; Xing, Luo; Ziqin, Yang

    2014-09-01

    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. PMID:25273716

  10. Some useful odds and ends from the n-electron valence state perturbation theory.

    PubMed

    Angeli, Celestino; Cimiraglia, Renzo

    2014-08-21

    The n-electron valence state perturbation theory makes use of zero-order wave functions whose energies are endowed with a direct physical interest, describing various processes occurring in the active space (removal/addition of one or two electrons, electronic excitations). It is shown that the zero-order energies related to the process of removal of an electron from the active space provide a reasonable and cheap approximation to the vertical ionization potentials. The zero-order energies referring to the process of an electronic excitation within the active space can also provide a first approximation to electronic transition energies, provided that a careful choice of the active molecular orbitals is performed. Test calculations have been carried out on the molecules N2 and H2CO.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Spectroscopy and applications of the 3 3Σ+ electronic state of 39K85Rb

    NASA Astrophysics Data System (ADS)

    Banerjee, Jayita; Rahmlow, David; Carollo, Ryan; Bellos, Michael; Eyler, Edward E.; Gould, Phillip L.; Stwalley, William C.

    2013-11-01

    We report new results on the spectroscopy of the 3 3Σ+ electronic state of 39K85Rb. The observations are based on resonance-enhanced multiphoton ionization of ultracold KRb molecules starting in vibrational levels v'' = 18-23 of the a 3Σ+ state and ionized via the intermediate 3 3Σ+ state. The a-state ultracold molecules are formed by photoassociation of ultracold 39K and 85Rb atoms to the 3(0+) state of KRb followed by spontaneous emission. We discuss the potential applications of this state to future experiments, as a pathway for populating the lowest vibrational levels of the a state as well as the X state.

  1. Pou5f1/Oct4 Promotes Cell Survival via Direct Activation of mych Expression during Zebrafish Gastrulation

    PubMed Central

    Wendik, Björn; Polok, Bożena K.; Ben-Dor, Shifra; Onichtchouk, Daria; Driever, Wolfgang

    2014-01-01

    Myc proteins control cell proliferation, cell cycle progression, and apoptosis, and play important roles in cancer as well in establishment of pluripotency. Here we investigated the control of myc gene expression by the Pou5f1/Oct4 pluripotency factor in the early zebrafish embryo. We analyzed the expression of all known zebrafish Myc family members, myca, mycb, mych, mycl1a, mycl1b, and mycn, by whole mount in situ hybridization during blastula and gastrula stages in wildtype and maternal plus zygotic pou5f1 mutant (MZspg) embryos, as well as by quantitative PCR and in time series microarray data. We found that the broad blastula and gastrula stage mych expression, as well as late gastrula stage mycl1b expression, both depend on Pou5f1 activity. We analyzed ChIP-Seq data and found that both Pou5f1 and Sox2 bind to mych and mycl1b control regions. The regulation of mych by Pou5f1 appears to be direct transcriptional activation, as overexpression of a Pou5f1 activator fusion protein in MZspg embryos induced strong mych expression even when translation of zygotically expressed mRNAs was suppressed. We further showed that MZspg embryos develop enhanced apoptosis already during early gastrula stages, when apoptosis was not be detected in wildtype embryos. However, Mych knockdown alone did not induce early apoptosis, suggesting potentially redundant action of several early expressed myc genes, or combination of several pathways affected in MZspg. Experimental mych overexpression in MZspg embryos did significantly, but not completely suppress the apoptosis phenotype. Similarly, p53 knockdown only partially suppressed apoptosis in MZspg gastrula embryos. However, combined knockdown of p53 and overexpression of Mych completely rescued the MZspg apoptosis phenotype. These results reveal that Mych has anti-apoptotic activity in the early zebrafish embryo, and that p53-dependent and Myc pathways are likely to act in parallel to control apoptosis at these stages. PMID:24643012

  2. Pou5f1/Oct4 promotes cell survival via direct activation of mych expression during zebrafish gastrulation.

    PubMed

    Kotkamp, Kay; Kur, Esther; Wendik, Björn; Polok, Bożena K; Ben-Dor, Shifra; Onichtchouk, Daria; Driever, Wolfgang

    2014-01-01

    Myc proteins control cell proliferation, cell cycle progression, and apoptosis, and play important roles in cancer as well in establishment of pluripotency. Here we investigated the control of myc gene expression by the Pou5f1/Oct4 pluripotency factor in the early zebrafish embryo. We analyzed the expression of all known zebrafish Myc family members, myca, mycb, mych, mycl1a, mycl1b, and mycn, by whole mount in situ hybridization during blastula and gastrula stages in wildtype and maternal plus zygotic pou5f1 mutant (MZspg) embryos, as well as by quantitative PCR and in time series microarray data. We found that the broad blastula and gastrula stage mych expression, as well as late gastrula stage mycl1b expression, both depend on Pou5f1 activity. We analyzed ChIP-Seq data and found that both Pou5f1 and Sox2 bind to mych and mycl1b control regions. The regulation of mych by Pou5f1 appears to be direct transcriptional activation, as overexpression of a Pou5f1 activator fusion protein in MZspg embryos induced strong mych expression even when translation of zygotically expressed mRNAs was suppressed. We further showed that MZspg embryos develop enhanced apoptosis already during early gastrula stages, when apoptosis was not be detected in wildtype embryos. However, Mych knockdown alone did not induce early apoptosis, suggesting potentially redundant action of several early expressed myc genes, or combination of several pathways affected in MZspg. Experimental mych overexpression in MZspg embryos did significantly, but not completely suppress the apoptosis phenotype. Similarly, p53 knockdown only partially suppressed apoptosis in MZspg gastrula embryos. However, combined knockdown of p53 and overexpression of Mych completely rescued the MZspg apoptosis phenotype. These results reveal that Mych has anti-apoptotic activity in the early zebrafish embryo, and that p53-dependent and Myc pathways are likely to act in parallel to control apoptosis at these stages.

  3. Ultrafast imaging of electronic relaxation in n-propylbenzene: Direct observation of intermediate state

    NASA Astrophysics Data System (ADS)

    Liu, Yuzhu; Gerber, Thomas; Radi, Peter; Knopp, Gregor

    2015-10-01

    The ultrafast dynamics of the second singlet electronically excited state (S2) in n-propylbenzene has been investigated by femtosecond time-resolved photoelectron imaging coupled with photofragmentation spectroscopy. The intermediate state for the deactivation of the S2 state is observed by transient photoelectron kinetic energy distributions and photoelectron angular distributions. An ultrafast electronic relaxation process on timescale of the fitted ∼50 fs was observed in the S2 state by time-resolved photoelectron imaging and it is attributed to the S1 ← S2 internal conversion (IC). The time constant of 1.23 (±0.2) ps is determined for the further deactivation of the intermediate S1 state.

  4. 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.

  5. 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

  6. Excited state X-ray absorption spectroscopy: Probing both electronic and structural dynamics

    NASA Astrophysics Data System (ADS)

    Neville, Simon P.; Averbukh, Vitali; Ruberti, Marco; Yun, Renjie; Patchkovskii, Serguei; Chergui, Majed; Stolow, Albert; Schuurman, Michael S.

    2016-10-01

    We investigate the sensitivity of X-ray absorption spectra, simulated using a general method, to properties of molecular excited states. Recently, Averbukh and co-workers [M. Ruberti et al., J. Chem. Phys. 140, 184107 (2014)] introduced an efficient and accurate L 2 method for the calculation of excited state valence photoionization cross-sections based on the application of Stieltjes imaging to the Lanczos pseudo-spectrum of the algebraic diagrammatic construction (ADC) representation of the electronic Hamiltonian. In this paper, we report an extension of this method to the calculation of excited state core photoionization cross-sections. We demonstrate that, at the ADC(2)x level of theory, ground state X-ray absorption spectra may be accurately reproduced, validating the method. Significantly, the calculated X-ray absorption spectra of the excited states are found to be sensitive to both geometric distortions (structural dynamics) and the electronic character (electronic dynamics) of the initial state, suggesting that core excitation spectroscopies will be useful probes of excited state non-adiabatic dynamics. We anticipate that the method presented here can be combined with ab initio molecular dynamics calculations to simulate the time-resolved X-ray spectroscopy of excited state molecular wavepacket dynamics.

  7. 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.

  8. 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.

  9. Manifestation of topological surface electron states in the photoelectromagnetic effect induced by terahertz laser radiation

    NASA Astrophysics Data System (ADS)

    Galeeva, A. V.; Egorova, S. G.; Chernichkin, V. I.; Tamm, M. E.; Yashina, L. V.; Rumyantsev, V. V.; Morozov, S. V.; Plank, H.; Danilov, S. N.; Ryabova, L. I.; Khokhlov, D. R.

    2016-09-01

    We demonstrate that measurements of the photoelectromagnetic effect using terahertz laser radiation may provide a unique opportunity to discriminate between the topological surface states and other highly conductive surface electron states. We performed a case study of mixed (Bi{}1-xIn x )2Se3 crystals undergoing a topological phase transformation due to the transition from the inverse to the direct electron energy spectrum in the crystal bulk at variation of the composition x. We show that for the topological insulator phase, the photoelectromagnetic effect amplitude is defined by the number of incident radiation quanta, whereas for the trivial insulator phase, it depends on the power in a laser pulse irrespective of its wavelength. We assume that such behavior is attributed to a strong damping of the electron-electron interaction in the topological insulator phase compared to the trivial insulator.

  10. 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.

  11. 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

  12. Renormalization of spin polarised itinerant electron bands in the normal state of a model ferromagnetic superconductor

    NASA Astrophysics Data System (ADS)

    Ma, Lei; Huang, Ai-Qun; Li, Jun

    2011-03-01

    This paper studies the normal state properties of itinerant electrons in a toy model, which is constructed according to the model for coexisting ferromagnetism and superconductivity proposed by Suhl [Suhl H 2001 Phys. Rev. Lett. 87 167007]. In this theory with ferromagnetic ordering based on localized spins, the exchange interaction J between conduction electrons and localized spin is taken as the pairing glue for s-wave superconductivity. It shows that this J term will first renormalize the normal state single conduction electron structures substantially. It finds dramatically enhanced or suppressed magnetization of itinerant electrons for positive or negative J. Singlet Cooper pairing can be ruled out due to strong spin polarisation in the J > 0 case while a narrow window for s-wave superconductivity is opened around some ferromagnetic J. Project supported by the National Natural Science Foundation of China (Grant No. 10574063).

  13. 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.

  14. Spatially inhomogeneous electron state deep in the extreme quantum limit of strontium titanate

    PubMed Central

    Bhattacharya, Anand; Skinner, Brian; Khalsa, Guru; Suslov, Alexey V.

    2016-01-01

    When an electronic system is subjected to a sufficiently strong magnetic field that the cyclotron energy is much larger than the Fermi energy, the system enters the extreme quantum limit (EQL) and becomes susceptible to a number of instabilities. Bringing a three-dimensional electronic system deeply into the EQL can be difficult however, since it requires a small Fermi energy, large magnetic field, and low disorder. Here we present an experimental study of the EQL in lightly-doped single crystals of strontium titanate. Our experiments probe deeply into the regime where theory has long predicted an interaction-driven charge density wave or Wigner crystal state. A number of interesting features arise in the transport in this regime, including a striking re-entrant nonlinearity in the current–voltage characteristics. We discuss these features in the context of possible correlated electron states, and present an alternative picture based on magnetic-field induced puddling of electrons. PMID:27680386

  15. Lattice relaxation in many-electron states of the diamond vacancy

    NASA Astrophysics Data System (ADS)

    Heidari Saani, M.; Vesaghi, M. A.; Esfarjani, K.; Ghods Elahi, T.; Sayari, M.; Hashemi, H.; Gorjizadeh, N.

    2005-01-01

    Symmetric lattice relaxation around a vacancy in diamond and its effect on many electron states of the defect have been investigated. A molecular approach is used to evaluate accurately electron-electron (e-e) interaction via a semiempirical formalism which is based on a generalized Hubbard Hamiltonian. Coupling of the defect molecule to surrounding bulk is also considered using an improved Stillinger-Weber potential for diamond. Strong dependence of the electronic energy levels to the relaxation size of the nearest neighbor (NN) atoms indicates that in order to obtain quantitative results the effect of lattice relaxation should be considered. Except for the high spin state of the defect A25 , the order of other lowest levels, particularly the ground state of the vacancy E1 does not change by the relaxation. At 12% outward relaxation, there is a level crossing between A25 and the excited state of the well-known GR1 transition T21 . The reported level crossing confirms the predicted relative energies of these states in the band gap that was speculated by monitoring the temperature dependence of the electron paramagnetic resonance (EPR) signal. By considering the outward relaxation effect, we obtained midgap position for the A25 state in agreement with the suggestion made by EPR. The position of the low lying T13 level varies from 100to400meV with increasing outward relaxation. When the ion-ion interaction of the NN atoms is included the outward relaxation lowers the energies of all electronic states. The relaxing force is different for investigated electronic states. By considering the interaction of the first and second shell neighbors of the vacancy, the calculated elastic barrier restricts outward relaxation of the vacancy to 12% for the ground and 18% for the A25 excited state. The calculated equilibrium bond lengths are in very good agreement with ab initio density functional theory and EPR measurement data. Electronic configurations in the unrelaxed and

  16. Computation of energy states of hydrogenic quantum dot with two-electrons

    NASA Astrophysics Data System (ADS)

    Yakar, Y.; Özmen, A.; ćakır, B.

    2016-03-01

    In this study we have investigated the electronic structure of the hydrogenic quantum dot with two electrons inside an impenetrable potential surface. The energy eigenvalues and wavefunctions of the ground and excited states of spherical quantum dot have been calculated by using the Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothaan (HFR) method, and the energies are investigated as a function of dot radius. The results show that as dot radius increases, the energy of quantum dot decreases.

  17. 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}.

  18. 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.

  19. Decoherence of high-energy electrons in weakly disordered quantum Hall edge states

    NASA Astrophysics Data System (ADS)

    Nigg, Simon E.; Lunde, Anders Mathias

    2016-07-01

    We investigate theoretically the phase coherence of electron transport in edge states of the integer quantum Hall effect at filling factor ν =2 , in the presence of disorder and inter edge state Coulomb interaction. Within a Fokker-Planck approach, we calculate analytically the visibility of the Aharonov-Bohm oscillations of the current through an electronic Mach-Zehnder interferometer. In agreement with recent experiments, we find that the visibility is independent of the energy of the current-carrying electrons injected high above the Fermi sea. Instead, it is the amount of disorder at the edge that sets the phase space available for inter edge state energy exchange and thereby controls the visibility suppression.

  20. 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.

  1. Excited state intramolecular proton transfer in electron-rich and electron-poor derivatives of 10-hydroxybenzo[h]quinoline.

    PubMed

    Piechowska, Joanna; Huttunen, Kirsi; Wróbel, Zbigniew; Lemmetyinen, Helge; Tkachenko, Nikolai V; Gryko, Daniel T

    2012-10-01

    Eight previously inaccessible derivatives of 10-hydroxybenzo[h]quinoline were prepared via a straightforward strategy comprising formation of the benzo[h]quinoline skeleton followed by C-H acetoxylation at position 10. The occurrence of excited state intramolecular proton transfer (ESIPT) was detected in all cases since emission was observed only from the excited keto-tautomer. Studies on derivatives bearing both electron-donating and electron-withdrawing groups adjacent to the pyridine ring allowed us to identify some design patterns giving rise to NIR emission and large Stokes shifts. For a derivative of 10-hydroxybenzo[c]acridine, emission at 745 nm was observed, one of the lowest energy fluorescence ever reported for ESIPT system. On the basis of time-resolved measurements, proton transfer was found to be extremely fast with time constants in the range (0.08-0.45 ps). PMID:22946783

  2. Influence of variations in the electron-electron interaction on the ground state metric space "band structure" of a two-electron magnetic system

    NASA Astrophysics Data System (ADS)

    Sharp, P. M.; D'Amico, I.

    2016-02-01

    We consider a model system of two electrons confined in a two-dimensional harmonic oscillator potential, with the electrons interacting via an α / r2 potential, and subject to a magnetic field applied perpendicular to the plane of confinement. Our results show that variations in the strength of the electron-electron interaction generate a "band structure" in ground state metric spaces, which shares many characteristics with those generated as a result of varying the confinement potential. In particular, the metric spaces for wavefunctions, particle densities, and paramagnetic current densities all exhibit distinct "bands" and "gaps". The behavior of the polar angle of the bands also shares traits with that obtained by varying the confinement potential, but the behavior of the arc lengths of the bands on the metric space spheres can be seen to be different for the two cases and opposite for a large range of angular momentum values. The findings here and in Refs. [1,2] demonstrate that the "band structure" that arises in ground state metric spaces when a magnetic field is applied is a robust feature.

  3. An extended multireference study of the electronic states of para-benzyne

    NASA Astrophysics Data System (ADS)

    Wang, Evan B.; Parish, Carol A.; Lischka, Hans

    2008-07-01

    A state-averaged, multireference complete active space (CAS) approach was used for the determination of the vertical excitation energies of valence and Rydberg states of para-benzyne. Orbitals were generated with a 10- and 32-state averaged multiconfigurational self-consistent field approach. Electron correlation was included using multireference configuration interaction with singles and doubles, including the Pople correction for size extensivity, multireference averaged quadratic coupled cluster (MR-AQCC), and MR-AQCC based on linear response theory. There is a very high density of electronic states in this diradical system-there are more than 17 states within 7 eV of the ground state including two 3s Rydberg states. All excitations, except 2 1Ag, are from the π system to the σσ* system. Of the 32 states characterized, 15 were multiconfigurational, including the ground 1Ag state, providing further evidence for the necessity of a multireference approach for p-benzyne. The vertical singlet-triplet splitting was also characterized using a two-state averaged approach. A CAS(2,2) calculation was shown to be inadequate due to interaction with the π orbitals.

  4. An extended multireference study of the electronic states of para-benzyne.

    PubMed

    Wang, Evan B; Parish, Carol A; Lischka, Hans

    2008-07-28

    A state-averaged, multireference complete active space (CAS) approach was used for the determination of the vertical excitation energies of valence and Rydberg states of para-benzyne. Orbitals were generated with a 10- and 32-state averaged multiconfigurational self-consistent field approach. Electron correlation was included using multireference configuration interaction with singles and doubles, including the Pople correction for size extensivity, multireference averaged quadratic coupled cluster (MR-AQCC), and MR-AQCC based on linear response theory. There is a very high density of electronic states in this diradical system-there are more than 17 states within 7 eV of the ground state including two 3s Rydberg states. All excitations, except 2 (1)A(g), are from the pi system to the sigmasigma(*) system. Of the 32 states characterized, 15 were multiconfigurational, including the ground (1)A(g) state, providing further evidence for the necessity of a multireference approach for p-benzyne. The vertical singlet-triplet splitting was also characterized using a two-state averaged approach. A CAS(2,2) calculation was shown to be inadequate due to interaction with the pi orbitals.

  5. 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)

  6. Electron

    NASA Astrophysics Data System (ADS)

    Springford, Michael

    1997-03-01

    1. J. J. Thomson and the discovery of the electron A. B. P. Pippard; 2. The isolated electron W. N. Cottingham; 3. The relativistic electron D. I. Olive; 4. The electron glue B. L. Gyorffy; 5. The electron fluid P. Coleman; 6. The magnetic electron G. G. Lonzarich; 7. The paired electron A. J. Leggett; 8. The heavy electron M. Springford; 9. The coherent electron Y. Imry and M. Peskin; 10. The composite electron R. Nicholas; 11. The electron in the cosmos M. S. Longair.

  7. Electron

    NASA Astrophysics Data System (ADS)

    Springford, Michael

    2008-12-01

    1. J. J. Thomson and the discovery of the electron A. B. P. Pippard; 2. The isolated electron W. N. Cottingham; 3. The relativistic electron D. I. Olive; 4. The electron glue B. L. Gyorffy; 5. The electron fluid P. Coleman; 6. The magnetic electron G. G. Lonzarich; 7. The paired electron A. J. Leggett; 8. The heavy electron M. Springford; 9. The coherent electron Y. Imry and M. Peskin; 10. The composite electron R. Nicholas; 11. The electron in the cosmos M. S. Longair.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. Energetics and structure of the bound states in a lithium complex: The (LiH 2) + electronic ground state

    NASA Astrophysics Data System (ADS)

    Sanz, Cristina; Bodo, Enrico; Gianturco, Franco A.

    2005-07-01

    The ionic complex formed by the lithium cation and the hydrogen molecule is analyzed in its electronic ground state and the region of the interaction potential that leads to an asymptotic fragmentation with the H 2 molecule in its v = 0 level is described. The corresponding potential energy surface is employed to obtain the J = 0 bound states of the complex. The computed wavefunctions are analyzed in terms of local modes of the full system and qualitative correspondence is found between their spatial shapes and the locally active vibrational coordinates up to the highest excited states near dissociation threshold, where mode-mixing effects defy such a simple analysis. The case of vibrationally excited H 2, and some of the corresponding resonances, are also presented and the resonant states discussed.

  18. 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.

  19. Spectral and thermodynamic properties of electrons in mobility gap states of covalent glasses

    NASA Astrophysics Data System (ADS)

    Klinger, M. I.; Karpov, V. G.

    1981-07-01

    Spectral and thermodynamic properties of electrons (holes) in covalent semiconducting glasses are considered in which self-trapping of electron (hole) pairs is realized with negative effective correlation energy U -. Unlike the Anderson model, electron (hole) pairing is restricted to a small part of the glass bonds. Ranges of the U - values are found in which either pair effects (suppression of paramagnetism etc.) or single-particle effects predominate; the concentration of the pair states and of the occupied ones can roughly be estimated and can be fairly high. The problem of the coexistence of the Fermi level pinning and effective diamagnetism in glasses is discussed. Some related effects are briefly considered.

  20. 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.

  1. Rydberg state, metastable, and electron dynamics in the low-pressure argon afterglow

    NASA Astrophysics Data System (ADS)

    Tsankov, Tsanko V.; Johnsen, Rainer; Czarnetzki, Uwe

    2015-12-01

    In this work a time-dependent collisional-radiative model for recombining plasmas is developed. It tracks the collisional and radiative capture of electrons into highly-excited (Rydberg) states and their consecutive deexcitation through collisions and radiation to the ground or the metastable state. The model allows the calculation of the net recombination rate and the electron energy gain by recombination. It is coupled to the volume-averaged balance equations for the electron density and temperature. The numerical solution of these equations includes a model for the diffusion cooling of the electrons (Celik et al 2012 Phys. Rev. E 85 046407) and a simplified model for the gas cooling. Using as only input the experimentally determined initial values of the electron density and temperature, gas temperature and metastable density, the temporal evolution of all parameters in the afterglow is calculated and compared with measurements. The results reproduce very well the measured quantities (electron density, light emission and metastable density) without the need to invoke adjustable parameters. This gives confidence in the validity of the model that allows it to be used not only to deepen the understanding of afterglow plasmas but also to tailor their properties as required for applications. The analysis of the model results further shows that gas heating and cooling must be explicitly taken into account to reproduce experimental observations. The electron heating by recombination is another process that is important for the good agreement. Both of these effects were largely ignored in previous works on afterglows.

  2. 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.

  3. Initial-state dependence of coupled electronic and nuclear fluxes in molecules

    NASA Astrophysics Data System (ADS)

    Kenfack, A.; Marquardt, F.; Paramonov, G. K.; Barth, I.; Lasser, C.; Paulus, B.

    2010-05-01

    We demonstrate that coupled electronic and nuclear fluxes in molecules can strongly depend on the initial state preparation. Starting the dynamics of an aligned D2+ molecule at two different initial conditions, the inner and the outer turning points, we observe qualitatively different oscillation patterns of the nuclear fluxes developing after 30 fs. This corresponds to different orders of magnitude bridged by the time evolution of the nuclear dispersion. Moreover, there are attosecond time intervals within which the electronic fluxes do not adapt to the nuclei motion depending on the initial state. These results are inferred from two different approaches for the numerical flux simulation, which are both in good agreement.

  4. 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.

  5. Identification of electronic state in perovskite CaCr O3 by high-pressure studies

    NASA Astrophysics Data System (ADS)

    Zhou, J.-S.; Alonso, J. A.; Sanchez-Benitez, J.; Fernandez-Diaz, M. T.; Martinez-Coronado, R.; Cao, L.-P.; Li, X.; Marshall, L. G.; Jin, C.-Q.; Goodenough, J. B.

    2015-10-01

    CaCr O3 is at the crossover from localized to itinerant electronic behavior, and interpretation of its electronic state has remained controversial. It is a metal from an optical study. However, the collinear type-C antiferromagnetic spin ordering below TN≈90 K is characteristic of localized electron magnetism. We have performed many runs of high-pressure synthesis. CaCr O3 crystals can be found in some batches. We have used specific-heat measurement as a diagnostic tool to probe the electronic states near the Fermi energy. An electronic bandwidth is broadened by applying high pressure. The magnetization measurement under pressure reveals a d TN/d P <0 . The crystal structural change corresponding to the pressure-induced electron structural change has been monitored by in situ neutron diffraction under high pressure. The t22 d-electron configuration on octahedral site C r4 + is orbitally threefold degenerate. Local site distortions are argued to show that in CaCr O3 the crossover from localized to itinerant 3d electrons does not result in a charge-density wave in which segregation of the interatomic interactions results in the stabilization of molecular clusters, but in an intraatomic orbital ordering that stabilizes a half-filled localized-electron x y orbital and a 1 /4 -filled c -axis π* band. Local structural changes under pressure reveal a weakening of long-range magnetic order is associated with a smooth Mott-Hubbard transition of the x y electrons.

  6. 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

  7. 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

  8. An ab initio study of the low-lying electronic states of S3

    NASA Astrophysics Data System (ADS)

    Peterson, Kirk A.; Lyons, James R.; Francisco, Joseph S.

    2006-08-01

    Accurate calculations of the low-lying singlet and triplet electronic states of thiozone, S3, have been carried out using large multireference configuration interaction wave functions. Cuts of the full potential energy surfaces along the stretching and bending coordinates have been presented, together with the vertical excitation spectra. The strong experimentally observed absorption around 395nm is assigned to the 1B21 state, which correlates to ground state products. Absorption at wavelengths shorter than 260nm is predicted to lead to singlet excited state products, S2 (aΔg1)+S(D1). The spectroscopic properties of the XΣg -3, aΔg1, and bΣg +1 electronic states of the S2 radical have also been accurately characterized in this work. The investigations of the low-lying electronic states were accompanied by accurate ground state coupled cluster calculations of the thermochemistry of both S2 and S3 using large correlation consistent basis sets with corrections for core-valence correlation, scalar relativity, and atomic spin-orbit effects. Resulting values for D0(S2+S) and ∑D0 for S3 are predicted to be 61.3 and 162.7kcal/mol, respectively, with conservative uncertainties of ±1kcal/mol. Analogous calculations predict the C2v-D3h (open-cyclic) isomerization energy of S3 to be 4.4±0.5kcal/mol.

  9. Charge-Transfer State Dynamics Following Hole and Electron Transfer in Organic Photovoltaic Devices.

    PubMed

    Bakulin, Artem A; Dimitrov, Stoichko D; Rao, Akshay; Chow, Philip C Y; Nielsen, Christian B; Schroeder, Bob C; McCulloch, Iain; Bakker, Huib J; Durrant, James R; Friend, Richard H

    2013-01-01

    The formation of bound electron-hole pairs, also called charge-transfer (CT) states, in organic-based photovoltaic devices is one of the dominant loss mechanisms hindering performance. Whereas CT state dynamics following electron transfer from donor to acceptor have been widely studied, there is not much known about the dynamics of bound CT states produced by hole transfer from the acceptor to the donor. In this letter, we compare the dynamics of CT states formed in the different charge-transfer pathways in a range of model systems. We show that the nature and dynamics of the generated CT states are similar in the case of electron and hole transfer. However the yield of bound and free charges is observed to be strongly dependent on the HOMOD-HOMOA and LUMOD-LUMOA energy differences of the material system. We propose a qualitative model in which the effects of static disorder and sampling of states during the relaxation determine the probability of accessing CT states favorable for charge separation.

  10. 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

  11. 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

  12. 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

  13. Electronic states of alkali metal-NTCDA complexes: A DFT study

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Kawabata, Hiroshi

    2015-10-01

    Structures and electronic states of organic-inorganic compound of 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) with alkali metals, Mn(NTCDA) (Mdbnd Li and Na, n = 0-2), have been investigated by means of hybrid density functional theory (DFT) calculations. From the DFT calculations, it was found that the electronic state of the complex at the ground state is characterized by a charge-transfer state expressed by (M)+(NTCDA)-. The alkali metals were bound equivalently to the carbonyl oxygen and ether oxygen atoms of NTCDA. The Cdbnd O double bond character of NTCDA was changed to a C-O single bond like character by the strong interaction of M to the Cdbnd O and O sites. This change was the origin of the red-shift of the IR spectrum. The UV-vis absorption spectra of Mn(NTCDA) were theoretically predicted on the basis of theoretical results.

  14. 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.

  15. 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

  16. Materials Data on Al6B5(O5F)3 (SG:176) 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

  17. Materials Data on Ba3In2O5F2 (SG:139) by Materials Project

    DOE Data Explorer

    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

  18. 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

  19. Materials Data on BaSb2Xe5F22 (SG:69) 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 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

  1. Materials Data on CdP2Xe5F22 (SG:33) by Materials Project

    DOE Data Explorer

    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

  2. Materials Data on LiV2O5F (SG:18) by Materials Project

    DOE Data Explorer

    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

  3. 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

  4. Characterization of NOBOX DNA binding specificity and its regulation of Gdf9 and Pou5f1 promoters.

    PubMed

    Choi, Youngsok; Rajkovic, Aleksandar

    2006-11-24

    Nobox (newborn ovary homeobox gene) deficiency disrupts early folliculogenesis and the expression of oocyte-specific genes in mice. Here, we identified several cis-acting sites, TAATTG, TAGTTG, and TAATTA as NOBOX DNA binding elements (NBEs) using a library of randomly generated oligonucleotides by cyclic amplification of sequence target assay and mutation analyses. We show that NOBOX preferentially binds to the NOBOX binding elements with high affinity. In addition, we found that promoter regions of mouse Pou5f1 and Gdf9 contain one (-426) and three NOBOX binding elements (-786, -967, and -1259), respectively. NOBOX binds to these putative NOBOX binding elements with high affinity and augmented transcriptional activity of luciferase reporter driven by mouse Pou5f1 and Gdf9 promoters containing the NOBOX binding elements. In chromatin immunoprecipitation assays, DNA sequences from Pou5f1 and Gdf9 promoters co-precipitated with anti-NOBOX antibody. These results suggest that NOBOX directly regulates the transcription of Pou5f1 and Gdf9 in oocytes during early folliculogenesis.

  5. Gallic acid protects RINm5F beta-cells from glucolipotoxicity by its antiapoptotic and insulin-secretagogue actions.

    PubMed

    Sameermahmood, Zaheer; Raji, Lenin; Saravanan, Thangavel; Vaidya, Ashok; Mohan, Viswanathan; Balasubramanyam, Muthuswamy

    2010-01-01

    Gallic acid is claimed to possess antioxidant, antiinflammatory and cytoprotective effects. Since pancreatic islets from Type 2 diabetic patients have functional defects, it was hypothesized that glucolipotoxicity might induce apoptosis in beta-cells and gallic acid could offer protection. To test this, RINm5F beta-cells were exposed to high glucose (25 microM) or palmitate (500 microM) or a combination of both for 24 h in the presence and absence of gallic acid. Cells subjected to glucolipotoxicity in the absence and presence of gallic acid were assessed for DNA damage by comet assay. Apoptosis was inferred by caspase-3 protein expression and caspase-3 activity and changes in Bcl-2 mRNA. RT-PCR was used to analyse PDX-1, insulin and UCP-2 mRNA expression in RINm5F beta-cells and insulin levels were quantified from the cell culture supernatant. NFkappaB signal was studied by EMSA, immunofluorescence and Western blot analysis. While RINm5F beta-cells subjected to glucolipotoxicity exhibited increased DNA damage, apoptotic markers and NFkappaB signals, all these apoptotic perturbations were resisted by gallic acid. Gallic acid dose-dependently increased insulin secretion in RINm5F beta-cells and upregulated mRNA of PDX-1 and insulin. It is suggested that the insulin-secretagogue and transcriptional regulatory action of gallic acid is a newly identified mechanism in our study.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Electronic Transition Dipole Moment and Radiative Lifetime Calculations of Lithium Dimer Ion-Pair States

    NASA Astrophysics Data System (ADS)

    Sanli, Aydin; Beecher, David; Lyyra, Marjatta; Magnier, Sylvie; Ahmed, Ergin

    2016-05-01

    Lithium dimer molecular electronic states exhibit double wells and shoulders due to the interaction with the Li+ + Li- ion-pair configuration. The double well behavior is predominantly observed for higher lying electronic states of 1Σg+ symmetry at larger internuclear distance. The ion-pair character of these potential energy curves makes their lifetimes also interesting because of the unusual behavior of their transition dipole moments which exhibit rapid changes around potential curve shoulders and double wells. In this work we present a computational study of lifetimes and transition dipole moment matrix elements for the lithium dimer ion-pair states. We report here the ab initio calculated electronic transition dipole moments between the n1Σg+ states and the A1Σu+ state, that vary strongly as a function of internuclear distance. In addition, we have calculated the radiative lifetimes, τ, of these ion-pair states and compare them with experimental results from literature when available.

  13. Doubly excited states of ammonia by scattered electron-ion coincidence measurements

    NASA Astrophysics Data System (ADS)

    Yamamoto, Karin; Sakai, Yasuhiro

    2012-03-01

    To obtain information on the optically forbidden doubly excited states of ammonia (NH3), we performed scattered electron-ion coincidence measurements. First, we observed scattered electrons using electron energy-loss spectroscopy and determined the generalized oscillator strength distribution (GOSD) under 200 eV incident electron energy at a scattering angle of 8°. Ionic GOSDs were also determined by combination with the coincidence signal, which was observed by the time-of-flight mass spectrometer at each energy-loss value, for each ion. The total and partial ionic GOSDs were compared with the experimental results of both photon and fast electron impact. Moreover, the neutral GOSD determined by subtracting the total ionic GOSD from the total was compared with previous results. In addition to the optically forbidden doubly excited states, which were identified by Kato et al (2003 J. Phys. B: At. Mol. Opt. Phys. 36 3541) and Ishikawa et al (2008 J. Phys. B: At. Mol. Opt. Phys. 41 195204), we found a new optically forbidden doubly excited state at around 35 eV.

  14. 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

  15. Towards native-state imaging in biological context in the electron microscope

    PubMed Central

    Weston, Anne E.; Armer, Hannah E. J.

    2009-01-01

    Modern cell biology is reliant on light and fluorescence microscopy for analysis of cells, tissues and protein localisation. However, these powerful techniques are ultimately limited in resolution by the wavelength of light. Electron microscopes offer much greater resolution due to the shorter effective wavelength of electrons, allowing direct imaging of sub-cellular architecture. The harsh environment of the electron microscope chamber and the properties of the electron beam have led to complex chemical and mechanical preparation techniques, which distance biological samples from their native state and complicate data interpretation. Here we describe recent advances in sample preparation and instrumentation, which push the boundaries of high-resolution imaging. Cryopreparation, cryoelectron microscopy and environmental scanning electron microscopy strive to image samples in near native state. Advances in correlative microscopy and markers enable high-resolution localisation of proteins. Innovation in microscope design has pushed the boundaries of resolution to atomic scale, whilst automatic acquisition of high-resolution electron microscopy data through large volumes is finally able to place ultrastructure in biological context. PMID:19916039

  16. 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

  17. 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.

  18. From Russia with Love: Unique Sources of Electronic Information on the Commonwealth of Independent States.

    ERIC Educational Resources Information Center

    Schoenbrun, Cynthia

    1993-01-01

    Discusses the recent increase in information access to Russia and other members of the Commonwealth of Independent States. Russia, the area's only English language database, Internet resources, discussion groups, bulletin boards, electronic mail, and other information resources are described; and information on how to connect to network resources…

  19. 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)

  20. Equalizing Access to Electronic Networked Resources: A Model for Rural Libraries in the United States.

    ERIC Educational Resources Information Center

    Senkevitch, Judith J.; Wolfram, Dietmar

    1994-01-01

    Provides an overview of the current state of networking technology in rural libraries and describes a model for educating rural librarians in accessing electronic networks. Topics discussed include information needs in rural libraries; telecommunications technology access in rural areas; and examples of services to enhance information access.…

  1. 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.

  2. 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…

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Manifestation of topological surface electron states in the photoelectromagnetic effect induced by terahertz laser radiation

    NASA Astrophysics Data System (ADS)

    Galeeva, A. V.; Egorova, S. G.; Chernichkin, V. I.; Tamm, M. E.; Yashina, L. V.; Rumyantsev, V. V.; Morozov, S. V.; Plank, H.; Danilov, S. N.; Ryabova, L. I.; Khokhlov, D. R.

    2016-09-01

    We demonstrate that measurements of the photoelectromagnetic effect using terahertz laser radiation may provide a unique opportunity to discriminate between the topological surface states and other highly conductive surface electron states. We performed a case study of mixed (Bi{}1-xIn x )2Se3 crystals undergoing a topological phase transformation due to the transition from the inverse to the direct electron energy spectrum in the crystal bulk at variation of the composition x. We show that for the topological insulator phase, the photoelectromagnetic effect amplitude is defined by the number of incident radiation quanta, whereas for the trivial insulator phase, it depends on the power in a laser pulse irrespective of its wavelength. We assume that such behavior is attributed to a strong damping of the electron–electron interaction in the topological insulator phase compared to the trivial insulator.

  10. 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

  11. Atomistic simulation of the electronic states of adatoms in monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Chang, Jiwon; Larentis, Stefano; Tutuc, Emanuel; Register, Leonard F.; Banerjee, Sanjay K.

    2014-04-01

    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 (MoS2). 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 MoS2 are examined as starting points to search for the most energetically stable configuration for each adatom-monolayer MoS2 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.

  12. 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.

  13. 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.

  14. First observation of intra-5f fluorescence from an actinyl center: Np(VI) near-IR emission in Cs{sub 2}U(Np)O{sub 2}Cl{sub 4}

    SciTech Connect

    Wilkerson, Marianne P. . E-mail: mpw@lanl.gov; Berg, John M. . E-mail: jberg@lanl.gov; Hopkins, Todd A.; Dewey, Harry J. . E-mail: hd@lanl.gov

    2005-02-15

    Fluorescence from an excited 5f state of Np(VI) has been observed in the doped impurity system Cs{sub 2}U(Np)O{sub 2}Cl{sub 4}. This is the first intra-5f fluorescence transition that has been detected at room temperature in a condensed-phase system with an actinyl (An(VI)O{sub 2}{sup 2+}) core, and it is a rare example of fluorescence of any kind from non-uranyl ions of this type. The emission originates from an excited state approximately 6890cm{sup -1} above the ground state. Its emission spectrum and fluorescence lifetime at 295K will be discussed. Vibronic structure in the emission spectrum is assigned based on comparison with the detailed analysis of the absorption spectra published by Denning et al.

  15. 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

  16. 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.

  17. Solid state effects on the electronic structure of H2OEP.

    PubMed

    Marsili, M; Umari, P; Di Santo, G; Caputo, M; Panighel, M; Goldoni, A; Kumar, M; Pedio, M

    2014-12-28

    We present the results of a joint experimental and theoretical investigation concerning the effect of crystal packing on the electronic properties of the H2OEP molecule. Thin films, deposited in ultra high vacuum on metal surfaces, are investigated by combining valence band photoemission, inverse photoemission, and X-ray absorption spectroscopy. The spectra of the films are compared, when possible, with those measured in the gas phase. Once many-body effects are included in the calculations through the GW method, the electronic structure of H2OEP in the film and gas phase are accurately reproduced for both valence and conduction states. Upon going from an isolated molecule to the film phase, the electronic gap shrinks significantly and the lowest unoccupied molecular orbital (LUMO) and LUMO + 1 degeneracy is removed. The calculations show that the reduction of the transport gap in the film is entirely addressable to the enhancement of the electronic screening. PMID:25388091

  18. Resonance States of Two-Electron Ions in Dense Quantum Plasmas

    NASA Astrophysics Data System (ADS)

    Jiang, Pinghui; Jiang, Zishi; Kar, Sabyasachi

    2016-10-01

    Plasma screening effects on S-wave resonance states of two-electron systems, starting from Be^{2+} to Ne^{8+} , are investigated in a quantum plasma medium using highly correlated Hylleraas-type wave functions in the framework of the stabilization method. Resonance parameters (resonance position and width) for the 2s2 1Se and 2p2 1Se states along with the ground state energies are reported for the first time as functions of screening parameter. The 2p2 1Se resonance parameters for He and Li+ embedded in quantum plasma environments are also reported.

  19. 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

  20. 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.

  1. Tunable Plasmonic Reflection by Bound 1D Electron States in a 2D Dirac Metal

    NASA Astrophysics Data System (ADS)

    Jiang, B.-Y.; Ni, G. X.; Pan, C.; Fei, Z.; Cheng, B.; Lau, C. N.; Bockrath, M.; Basov, D. N.; Fogler, M. M.

    2016-08-01

    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.

  2. Broadband 2D electronic spectroscopy reveals a carotenoid dark state in purple bacteria.

    PubMed

    Ostroumov, Evgeny E; Mulvaney, Rachel M; Cogdell, Richard J; Scholes, Gregory D

    2013-04-01

    Although the energy transfer processes in natural light-harvesting systems have been intensively studied for the past 60 years, certain details of the underlying mechanisms remain controversial. We performed broadband two-dimensional (2D) electronic spectroscopy measurements on light-harvesting proteins from purple bacteria and isolated carotenoids in order to characterize in more detail the excited-state manifold of carotenoids, which channel energy to bacteriochlorophyll molecules. The data revealed a well-resolved signal consistent with a previously postulated carotenoid dark state, the presence of which was confirmed by global kinetic analysis. The results point to this state's role in mediating energy flow from carotenoid to bacteriochlorophyll.

  3. 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.

  4. 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.

  5. 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.

  6. Experimental Studies of the 43 Π Electronic State of NaCs

    NASA Astrophysics Data System (ADS)

    Steely, Andrew; Whipp, Ciara; Faust, Carl; Kortyna, Andrew; Richter, Kara; Huennekens, John

    2016-05-01

    We present results from experimental studies of the 43 Π electronic state of the NaCs molecule. This electronic state is interesting in that its potential energy curve likely exhibits a double minimum. As a result, interference effects are observed in the resolved bound-free fluorescence spectra. The optical-optical double resonance method was used to obtain Doppler-free excitation spectra for the 43 Π state. This dataset of measured level energies was expanded largely by observing fluorescence from levels populated by collisions. Simulations of resolved bound-free fluorescence spectra were calculated using the BCONT program (R. J. Le Roy, University of Waterloo). Spectroscopic constants are presented as a preliminary step toward an experimental potential energy curve. Work supported by NSF and Susquehanna University.

  7. Imaging electronic trap states in perovskite thin films with combined fluorescence and femtosecond transient absorption microscopy

    DOE PAGESBeta

    Xiao, Kai; Ma, Ying -Zhong; Simpson, Mary Jane; Doughty, Benjamin; Yang, Bin

    2016-04-22

    Charge carrier trapping degrades the performance of organometallic halide perovskite solar cells. To characterize the locations of electronic trap states in a heterogeneous photoactive layer, a spatially resolved approach is essential. Here, we report a comparative study on methylammonium lead tri-iodide perovskite thin films subject to different thermal annealing times using a combined photoluminescence (PL) and femtosecond transient absorption microscopy (TAM) approach to spatially map trap states. This approach coregisters the initially populated electronic excited states with the regions that recombine radiatively. Although the TAM images are relatively homogeneous for both samples, the corresponding PL images are highly structured. Themore » remarkable variation in the PL intensities as compared to transient absorption signal amplitude suggests spatially dependent PL quantum efficiency, indicative of trapping events. Furthermore, detailed analysis enables identification of two trapping regimes: a densely packed trapping region and a sparse trapping area that appear as unique spatial features in scaled PL maps.« less

  8. Both electron and hole Dirac cone states in Ba(FeAs)2 confirmed by magnetoresistance.

    PubMed

    Huynh, Khuong K; Tanabe, Yoichi; Tanigaki, Katsumi

    2011-05-27

    Quantum transport of Dirac cone states in the iron pnictide Ba(FeAs)(2) with a d-multiband system is studied by using single crystal samples. Transverse magnetoresistance develops linearly against the magnetic field at low temperatures. The transport phenomena are interpreted in terms of the zeroth Landau level by applying the theory predicted by Abrikosov. The results of the semiclassical analyses of a two carrier system in a low magnetic field limit show that both the electron and hole reside as the high mobility states. Our results show that pairs of electron and hole Dirac cone states must be taken into account for an accurate interpretation in iron pnictides, which is in contrast with previous studies.

  9. Towards producing ultracold CaNa+ molecular ions in the ground electronic state

    NASA Astrophysics Data System (ADS)

    Gacesa, Marko; Montgomery, John A.; Michels, Harvey H.; Côté, Robin

    2015-05-01

    We present a theoretical analysis of optical pathways for the formation of cold Ca(1S)Na+(1S) molecular ions, based on accurate potential energy curves and transition dipole moments calculated using effective-core-potential methods of quantum chemistry. In the proposed approach, starting from a mixture of trapped laser-cooled Ca+ ions immersed into an ultracold gas of Na atoms, the (NaCa)+ are photoassociated in the excited E1Σ+ electronic state, followed by spontaneous radiative charge transfer and emission through an intermediate state. We find the optimal formation pathway and report radiative charge-exchange cross sections and vibrational distributions of participating electronic states. This work is partially supported by ARO.

  10. Cavity quantum electrodynamics with many-body states of a two-dimensional electron gas.

    PubMed

    Smolka, Stephan; Wuester, Wolf; Haupt, Florian; Faelt, Stefan; Wegscheider, Werner; Imamoglu, Ataç

    2014-10-17

    Light-matter interaction has played a central role in understanding as well as engineering new states of matter. Reversible coupling of excitons and photons enabled groundbreaking results in condensation and superfluidity of nonequilibrium quasiparticles with a photonic component. We investigated such cavity-polaritons in the presence of a high-mobility two-dimensional electron gas, exhibiting strongly correlated phases. When the cavity was on resonance with the Fermi level, we observed previously unknown many-body physics associated with a dynamical hole-scattering potential. In finite magnetic fields, polaritons show distinct signatures of integer and fractional quantum Hall ground states. Our results lay the groundwork for probing nonequilibrium dynamics of quantum Hall states and exploiting the electron density dependence of polariton splitting so as to obtain ultrastrong optical nonlinearities.

  11. Cavity quantum electrodynamics with many-body states of a two-dimensional electron gas.

    PubMed

    Smolka, Stephan; Wuester, Wolf; Haupt, Florian; Faelt, Stefan; Wegscheider, Werner; Imamoglu, Ataç

    2014-10-17

    Light-matter interaction has played a central role in understanding as well as engineering new states of matter. Reversible coupling of excitons and photons enabled groundbreaking results in condensation and superfluidity of nonequilibrium quasiparticles with a photonic component. We investigated such cavity-polaritons in the presence of a high-mobility two-dimensional electron gas, exhibiting strongly correlated phases. When the cavity was on resonance with the Fermi level, we observed previously unknown many-body physics associated with a dynamical hole-scattering potential. In finite magnetic fields, polaritons show distinct signatures of integer and fractional quantum Hall ground states. Our results lay the groundwork for probing nonequilibrium dynamics of quantum Hall states and exploiting the electron density dependence of polariton splitting so as to obtain ultrastrong optical nonlinearities. PMID:25278508

  12. The electronic structure of VO in its ground and electronically excited states: A combined matrix isolation and quantum chemical (MRCI) study

    SciTech Connect

    Hübner, Olaf; Hornung, Julius; Himmel, Hans-Jörg

    2015-07-14

    The electronic ground and excited states of the vanadium monoxide (VO) molecule were studied in detail. Electronic absorption spectra for the molecule isolated in Ne matrices complement the previous gas-phase spectra. A thorough quantum chemical (multi-reference configuration interaction) study essentially confirms the assignment and characterization of the electronic excitations observed for VO in the gas-phase and in Ne matrices and allows the clarification of open issues. It provides a complete overview over the electronically excited states up to about 3 eV of this archetypical compound.

  13. Vibronic structure and coupling of higher excited electronic states in carotenoids

    NASA Astrophysics Data System (ADS)

    Krawczyk, Stanisław; Luchowski, Rafał

    2013-03-01

    Absorption spectra of all-trans carotenoids (lycopene, violaxanthin, ζ-carotene) at low temperature exhibit peculiar features in the UV range. The transition to the 11Ag+ state ('cis-band') weakens on cooling, indicating that it is induced by thermal deformations of the conjugated chain. The higher energy band has unique vibrational structure indicating the vibronic coupling of nBu with another electronic state. The electroabsorption spectra point to the electric field-induced mixing of the nBu state with the vibrational continuum of a lower-lying excited state (Fano effect). These observations widen the basis for elucidation of the vibronic coupling effects in the lower excited states.

  14. Experimental investigation of chimera states with quiescent and synchronous domains in coupled electronic oscillators.

    PubMed

    Gambuzza, Lucia Valentina; Buscarino, Arturo; Chessari, Sergio; Fortuna, Luigi; Meucci, Riccardo; Frasca, Mattia

    2014-09-01

    Chimera states, that is, dynamical regimes characterized by the existence of a symmetry-broken solution where a coherent domain and an incoherent one coexist, have been theoretically demonstrated and numerically found in networks of homogeneously coupled identical oscillators. In this work we experimentally investigate the behavior of a closed and an open chain of electronic circuits with neuron-like spiking dynamics and first neighbor connections. Experimental results show the onset of a regime that we call chimera states with quiescent and synchronous domains, where synchronization coexists with spatially patterned oscillation death. The whole experimental bifurcation scenario, showing how disordered states, synchronization, chimera states with quiescent and synchronous domains, and oscillatory death states emerge as coupling is varied, is presented.

  15. Creation of Ultracold Sr2 Molecules in the Electronic Ground State

    NASA Astrophysics Data System (ADS)

    Stellmer, Simon; Pasquiou, Benjamin; Grimm, Rudolf; Schreck, Florian

    2012-09-01

    We report on the creation of ultracold Sr284 molecules in the electronic ground state. The molecules are formed from atom pairs on sites of an optical lattice using stimulated Raman adiabatic passage (STIRAP). We achieve a transfer efficiency of 30% and obtain 4×104 molecules with full control over the external and internal quantum state. STIRAP is performed near the narrow S01-P13 intercombination transition, using a vibrational level of the 1(0u+) potential as an intermediate state. In preparation of our molecule association scheme, we have determined the binding energies of the last vibrational levels of the 1(0u+), 1(1u) excited-state and the XΣg+1 ground-state potentials. Our work overcomes the previous limitation of STIRAP schemes to systems with magnetic Feshbach resonances, thereby establishing a route that is applicable to many systems beyond alkali-metal dimers.

  16. Standoff Trace Chemical Sensing via Manipulation of Excited Electronic State Lifetimes

    SciTech Connect

    Rudakov, Fedor M

    2013-01-01

    We present a technique for standoff trace chemical sensing that is based on the dependence of excited electronic state lifetimes on the amount of internal vibrational energy. Time resolved photoionization measurements show that the lifetime of the S1 state in N,N-dimethylisopropylamine (DMIPA) decreases exponentially with the amount of energy deposited into vibrational degrees of freedom. This property is employed to acquire spectral signatures of the molecule. Two nanosecond laser pulses are used, one (266 nm) to ionize the molecule through the S1 state and another, with tunable wavelength, to alter the lifetime of the S1 state by depositing energy into vibrations. Reduction of the S1 state lifetime results in a dip in ionization efficiency that is observed by remotely probing the laser-induced plasma with microwave radiation.

  17. Mapping Dimensionality and Directionality of Electronic Behavior in CeCoIn5: the Normal State

    NASA Astrophysics Data System (ADS)

    Gyenis, Andras; Feldman, Benjamin E.; Randeria, Mallika T.; Peterson, Gabriel A.; Aynajian, Pegor; Bauer, Eric D.; Yazdani, Ali

    Materials made from alternating layers of different constituents can exhibit dramatic variability in their electronic properties depending on which layer is probed. This is evident in the heavy fermion compound CeCoIn5, where scanning tunneling microscopy (STM) has revealed preferential coupling to either light or heavy electron states depending on the surface termination. Here we report STM measurements of CeCoIn5 cleaved perpendicular to its basal plane that clearly shows the quasi-two-dimensional nature of the electronic behavior on a single (100) surface. We observe atomic scale modulation of tunneling into the light and heavy electron bands in the c-axis direction, with no variation visible along the basal planes in the b-axis direction. In addition, conductance maps reveal preferential scattering along the two-dimensional basal planes. Our measurements highlight the reduced effective dimensionality of electronic states in CeCoIn5, and underscore the potential insight that can be gained by imaging layered materials perpendicular to their c-axis.

  18. Excited state electron transfer from aminopyrene to graphene: a combined experimental and theoretical study.

    PubMed

    Chakraborti, Himadri; Bramhaiah, Kommula; John, Neena Susan; Pal, Suman Kalyan

    2013-12-01

    The quenching of the fluorescence of 1-aminopyrene (1-Ap) by reduced graphene oxide (rGO) has been investigated using spectroscopic techniques. In spite of the upward curvature in the Stern-Volmer plot, the unchanged spectral signature of the absorption of 1-Ap in the presence of rGO and the decrease in fluorescence lifetime with increasing rGO concentration point toward the dynamic nature of the quenching. Detailed analysis of steady state and time-resolved spectroscopic data has shown that the quenching arises due to the photoinduced electron transfer from 1-Ap to rGO. This is again supported by estimating the Gibb's free energy change for the ground as well as excited state electron transfer. Ab initio calculations under the density functional theory (DFT) formalism reveal that the possibility of π-π stacking is very slim in the 1-Ap-rGO system and the electron density resides completely on 1-Ap in the highest occupied molecular orbital (HOMO) and on graphene in the lowest unoccupied molecular orbital (LUMO), supporting the experimental findings of the intermolecular electron transfer between 1-Ap and rGO in the excited state.

  19. SUPRATHERMAL ELECTRONS IN THE SOLAR CORONA: CAN NONLOCAL TRANSPORT EXPLAIN HELIOSPHERIC CHARGE STATES?

    SciTech Connect

    Cranmer, Steven R.

    2014-08-20

    There have been several ideas proposed to explain how the Sun's corona is heated and how the solar wind is accelerated. Some models assume that open magnetic field lines are heated by Alfvén waves driven by photospheric motions and dissipated after undergoing a turbulent cascade. Other models posit that much of the solar wind's mass and energy is injected via magnetic reconnection from closed coronal loops. The latter idea is motivated by observations of reconnecting jets and also by similarities of ion composition between closed loops and the slow wind. Wave/turbulence models have also succeeded in reproducing observed trends in ion composition signatures versus wind speed. However, the absolute values of the charge-state ratios predicted by those models tended to be too low in comparison with observations. This Letter refines these predictions by taking better account of weak Coulomb collisions for coronal electrons, whose thermodynamic properties determine the ion charge states in the low corona. A perturbative description of nonlocal electron transport is applied to an existing set of wave/turbulence models. The resulting electron velocity distributions in the low corona exhibit mild suprathermal tails characterized by ''kappa'' exponents between 10 and 25. These suprathermal electrons are found to be sufficiently energetic to enhance the charge states of oxygen ions, while maintaining the same relative trend with wind speed that was found when the distribution was assumed to be Maxwellian. The updated wave/turbulence models are in excellent agreement with solar wind ion composition measurements.

  20. Effect of size on electronic states in a strained pyramidal InAs-GaAs quantum dot system

    SciTech Connect

    Ripan, G. H.; Woon, C. Y.; Gopir, G.

    2015-09-25

    The effect of size on electronic states in a strained pyramidal InAs-GaAs quantum dot system was studied. A comparison was made between two InAs quantum pyramids of different sizes embedded inside a cubic GaAs susbtrate material. Strain relaxation was carried out via the Metropolis Monte Carlo method and the calculated local strain tensors were then included to solve the energy values and the wave functions of the electronic states inside the two simulation cube. The 3D finite difference scheme was employed to solve the time independent Schrödinger equation based on the decoupled electron-hole model. Calculated energy values of the four lowest electronic states showed that the transitions between the electron and hole states widen as the size of the dot becomes smaller especially between the ground states. The confinement of electrons and holes become weaker as the size of the dot reduces.

  1. Probing electronic state at atomic scale on the surface of SrVO3 film

    NASA Astrophysics Data System (ADS)

    Okada, Yoshinori; Shimizu, Ryota; Shiraki, Susumu; Hitosugi, Taro

    2014-03-01

    Probing electronic structure of atomically well controlled surface of Perovskite-type 3d transition-metal oxides have been attracting much interest because of their intriguing emergent physical properties by heterostructure engineering. In this study, we have especially focused on SrVO3, where importance of correlation effects has been considered. We successfully obtained atomically flat surfaces of SrVO3, which gave us the great opportunity to visualize correlated electronic state at atomic scale by means of spectroscopic imaging scanning tunneling spectroscopy. Based on the experimental data, we discuss spectroscopic signature of many body effects on the surface of SrVO3 system.

  2. Quantum-chemical study of electronically excited states of protolytic forms of vanillic acid

    NASA Astrophysics Data System (ADS)

    Vusovich, O. V.; Tchaikovskaya, O. N.; Sokolova, I. V.; Vasil'eva, N. Y.

    2015-12-01

    The paper describes an analysis of possible ways of deactivation of electronically excited states of 4-hydroxy- 3-methoxy-benzoic acid (vanillic acid) and its protolytic forms with the use of quantum-chemical methods INDO/S (intermediate neglect of differential overlap with a spectroscopic parameterization) and MEP (molecular electrostatic potential). The ratio of radiative and non-radiative deactivation channels of the electronic excitation energy is established. The rate constants of photophysical processes (internal and intercombination conversions) occurring after the absorption of light in these forms are evaluated.

  3. Nonequilibrium Pump–Probe Photoexcitation as a Tool for Analyzing Unoccupied Equilibrium States of Correlated Electrons

    NASA Astrophysics Data System (ADS)

    Yamaji, Youhei; Imada, Masatoshi

    2016-09-01

    Relaxation of electrons in a Hubbard ring coupled to a dissipative bosonic bath is studied to simulate the pump-probe photoemission measurement. From this insight, we propose an experimental method of eliciting the unoccupied part of single-particle spectra at the equilibrium of doped Mott insulators. We reveal first that the effective temperatures of distribution functions and electronic spectra are different during the relaxation, which makes the frequently employed thermalization picture inappropriate. Contrary to the conventional analysis, we show that the unoccupied spectra at equilibrium can be detected as the states that relax faster.

  4. Nonequilibrium Pump-Probe Photoexcitation as a Tool for Analyzing Unoccupied Equilibrium States of Correlated Electrons

    NASA Astrophysics Data System (ADS)

    Yamaji, Youhei; Imada, Masatoshi

    2016-09-01

    Relaxation of electrons in a Hubbard ring coupled to a dissipative bosonic bath is studied to simulate the pump-probe photoemission measurement. From this insight, we propose an experimental method of eliciting the unoccupied part of single-particle spectra at the equilibrium of doped Mott insulators. We reveal first that the effective temperatures of distribution functions and electronic spectra are different during the relaxation, which makes the frequently employed thermalization picture inappropriate. Contrary to the conventional analysis, we show that the unoccupied spectra at equilibrium can be detected as the states that relax faster.

  5. Excitations of {sup 1}P levels of zinc by electron impact on the ground state

    SciTech Connect

    Fursa, Dmitry V.; Bray, Igor; Panajotovic, R.; Sevic, D.; Pejcev, V.; Marinkovic, B.P.; Filipovic, D.M.

    2005-07-15

    We present results of a joint theoretical and experimental investigation of electron scattering from the 4s{sup 2} {sup 1}S ground state of zinc. The 4s4p {sup 1}P{sup o} and 4s5p {sup 1}P{sup o} differential cross sections were measured at scattering angles between 10 degree sign and 150 degree sign and electron-energies of 15, 20, 25, 40, and 60 eV. Corresponding convergent close-coupling calculations have been performed and are compared with experiment.

  6. Dynamics of nonequilibrium electrons on neutral center states of interstitial magnesium donors in silicon

    NASA Astrophysics Data System (ADS)

    Pavlov, S. G.; Deßmann, N.; Pohl, A.; Shuman, V. B.; Portsel, L. M.; Lodygin, A. N.; Astrov, Yu. A.; Winnerl, S.; Schneider, H.; Stavrias, N.; van der Meer, A. F. G.; Tsyplenkov, V. V.; Kovalevsky, K. A.; Zhukavin, R. Kh.; Shastin, V. N.; Abrosimov, N. V.; Hübers, H.-W.

    2016-08-01

    Subnanosecond dynamics of optically excited electrons bound to excited states of neutral magnesium donor centers in silicon has been investigated. Lifetimes of nonequilibrium electrons have been derived from the decay of the differential transmission at photon energies matching the intracenter and the impurity-to-conduction band transitions. In contrast to hydrogenlike shallow donors in silicon, significantly longer lifetimes have been observed. This indicates weaker two-phonon and off-resonant interactions dominate the relaxation processes in contrast to the single-intervalley-phonon-assisted impurity-phonon interactions in the case of shallow donors in silicon.

  7. Ultrafast dynamics in photo-induced correlated electronic states in ladder cuprates

    NASA Astrophysics Data System (ADS)

    Ishihara, Sumio; Hashimoto, Hiroshi

    2014-03-01

    Ultrafast photo-induced dynamics in correlated electron systems, in particular, photon irradiation effects in half filled Mott insulators have been studied intensively from theoretical and experimental sides, and photo-induced Mott insulator to metal transition has been observed. On the other side, in recent ultrafast pump-probe experiments in ladder cuprates away from half filling, photo-irradiation weakens initial metallic state. We study ultrafast dynamics in photo-induced states in a ladder system. Real time dynamics in a ladder-type Hubbard model are analyzed by the numerical exact diagonalization method. Optical conductivity spectra and density of states show that the initial metallic state is changed into a bad metallic state by photo irradiation, in contrast to the photo-doped effect in half-filled Mott insulators. Through the calculation of the carrier pair correlation functions, we find that coherent motion of carrier pairs in initial states are reduced by pump photon irradiation. We further simulate a double pulse irradiation. Our simulations as well as the experimental results suggest an optical control of pair coherence in correlated electron system.

  8. Normal-state nodal electronic structure in underdoped high-Tc copper oxides.

    PubMed

    Sebastian, Suchitra E; Harrison, N; Balakirev, F F; Altarawneh, M M; Goddard, P A; Liang, Ruixing; Bonn, D A; Hardy, W N; Lonzarich, G G

    2014-07-01

    An outstanding problem in the field of high-transition-temperature (high-Tc) superconductivity is the identification of the normal state out of which superconductivity emerges in the mysterious underdoped regime. The normal state uncomplicated by thermal fluctuations can be studied using applied magnetic fields that are sufficiently strong to suppress long-range superconductivity at low temperatures. Proposals in which the normal ground state is characterized by small Fermi surface pockets that exist in the absence of symmetry breaking have been superseded by models based on the existence of a superlattice that breaks the translational symmetry of the underlying lattice. Recently, a charge superlattice model that positions a small electron-like Fermi pocket in the vicinity of the nodes (where the superconducting gap is minimum) has been proposed as a replacement for the prevalent superlattice models that position the Fermi pocket in the vicinity of the pseudogap at the antinodes (where the superconducting gap is maximum). Although some ingredients of symmetry breaking have been recently revealed by crystallographic studies, their relevance to the electronic structure remains unresolved. Here we report angle-resolved quantum oscillation measurements in the underdoped copper oxide YBa2Cu3O6 + x. These measurements reveal a normal ground state comprising electron-like Fermi surface pockets located in the vicinity of the nodes, and also point to an underlying superlattice structure of low frequency and long wavelength with features in common with the charge order identified recently by complementary spectroscopic techniques. PMID:24930767

  9. Infrared/ultraviolet quadruple resonance spectroscopy to investigate structures of electronically excited states

    SciTech Connect

    Weiler, M.; Bartl, K.; Gerhards, M.

    2012-03-21

    Molecular beam investigations in combination with IR/UV spectroscopy offer the possibility to obtain structural information on isolated molecules and clusters. One of the demanding tasks is the discrimination of different isomers, e.g., by the use of isomer specific UV excitations. If this discrimination fails due to overlaying UV spectra of different isomers, IR/IR methods offer another possibility. Here, we present a new IR/UV/IR/UV quadruple resonance technique to distinguish between different isomers especially in the electronically excited state. Due to the IR spectra, structural changes and photochemical pathways in excited states can be assigned and identified. The method is applied to the dihydrated cluster of 3-hydroxyflavone which has been investigated as photochemically relevant system and proton wire model in the S{sub 1} state. By applying the new IR/UV/IR/UV technique, we are able to show experimentally that both in the electronic ground (S{sub 0}) and the electronically excited state (S{sub 1}) two isomers have to be assigned.

  10. Potential energy surfaces of the electronic states of Li2F and Li2F-

    NASA Astrophysics Data System (ADS)

    Bhowmick, Somnath; Hagebaum-Reignier, Denis; Jeung, Gwang-Hi

    2016-07-01

    The potential energy surfaces of the ground and low-lying excited states for the insertion reaction of atomic fluorine (F) and fluoride (F-) into the dilithium (Li2) molecule have been investigated. We have carried out explicitly correlated multi-reference configuration interaction (MRCI-F12) calculations using Dunning's augmented correlation-consistent basis sets. For the neutral system, the insertion of F into Li2 proceeds via a harpoon-type mechanism on the ground state surface, involving a covalent state and an ionic state which avoid each other at long distance. A detailed analysis of the changes in the dipole moment along the reaction coordinate reveals multiple avoided crossings among the excited states and shows that the charge-transfer processes play a pivotal role for the stabilization of the low-lying electronic states of Li2F. For the anionic system, which is studied for the first time, the insertion of F- is barrierless for many states and there is a gradual charge transfer from F- to Li2 along the reaction path. We also report the optimized parameters and the spectroscopic properties of the five lowest states of the neutral and seven lowest states of the anionic systems, which are strongly stabilized with respect to their respective Li2 + F/F- asymptotes. The observed barrierless insertion mechanisms for both systems make them good candidates for investigation under the ultracold regime.

  11. Growth and diode-pumped laser operation of Pr3+:β-(Y0.5,Gd0.5)F3 at various transitions.

    PubMed

    Werner Metz, Philip; Marzahl, Daniel-Timo; Guguschev, Christo; Bertram, Rainer; Kränkel, Christian; Huber, Günter

    2015-06-15

    We report on the crystal growth of the orthorhombic low-temperature β-phase of (Y0.5,Gd0.5)F3 (YGF) single crystals. The crystals were activated with trivalent praseodymium (Pr3+) and characterized with respect to their ground state absorption and stimulated emission properties. Under InGaN-laser-diode pumping, laser oscillation was obtained at more than ten wavelengths in the green, orange, red, and dark red spectral regions. In these initial experiments, output powers exceeding 100 mW and slope efficiencies between 10% and 30% were obtained. To the best of our knowledge, these results represent the first application of YGF crystals as laser host material for any active ion. PMID:26076240

  12. Business pluralism of electronic prescriptions: state of development in Europe and the USA.

    PubMed

    Salmivalli, Lauri; Hilmola, Olli-Pekka

    2006-01-01

    In this paper, we analyse the current state of the development of electronic prescriptions in Europe and the USA. These two places have different approaches to the healthcare sector, since in the former one national social insurance usually provides treatment for all of the people (most often only with friction from total costs), but in the latter one the healthcare sector is under free market forces. As our analysis shows in this paper, electronic prescriptions in both of the places have developed in recent years quite favourably, but this development has not produced consistent results, whether electronic prescriptions should be provided by for-profit companies or should they be under strict control of governmental authorities. We base this finding in two empirical observations: (1) in Europe saving potential from electronic prescriptions is estimated to be high, and contains many abstract national economy accounts and (2) leading US companies (providing electronic prescription services) have went been able to increase their revenues significantly, but still their profitability is questionable. We argue that the situation of electronic prescriptions is similar with airline or credit card industry. Both of these are vital for international and local economies, but the business models have developed well after the initial idea. PMID:18048240

  13. Density functional investigation of the electronic structure and charge transfer excited states of a multichromophoric antenna

    NASA Astrophysics Data System (ADS)

    Basurto, Luis; Zope, Rajendra R.; Baruah, Tunna

    2016-05-01

    We report an electronic structure study of a multichromophoric molecular complex containing two of each borondipyrromethane dye, Zn-tetraphenyl-porphyrin, bisphenyl anthracene and a fullerene. The snowflake shaped molecule behaves like an antenna capturing photon at different frequencies and transferring the photon energy to the porphyrin where electron transfer occurs from the porphyrin to the fullerene. The study is performed within density functional formalism using large polarized Guassian basis sets (12,478 basis functions in total). The energies of the HOMO and LUMO states in the complex, as adjudged by the ionization potential and the electron affinity values, show significant differences with respect to their values in participating subunits in isolation. These differences are also larger than the variations of the ionization potential and electron affinity values observed in non-bonded C60-ZnTPP complexes in co-facial arrangement or end-on orientations. An understanding of the origin of these differences is obtained by a systematic study of the effect of structural strain, the presence of ligands, the effect of orbital delocalization on the ionization energy and the electron affinity. Finally, a few lowest charge transfer energies involving electronic transitions from the porphyrin component to the fullerene subunit of the complex are predicted.

  14. Taming the low-lying electronic states of FeH.

    PubMed

    DeYonker, Nathan J; Allen, Wesley D

    2012-12-21

    The low-lying electronic states (X (4)Δ, A (4)Π, a (6)Δ, b (6)Π) of the iron monohydride radical, which are especially troublesome for electronic structure theory, have been successfully described using a focal point analysis (FPA) approach that conjoined a correlation-consistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through hextuple (CCSDTQPH) excitations. Adiabatic excitation energies (T(0)) and spectroscopic constants (r(e), r(0), B(e), B(0), D(e), ω(e), v(0), α(e), ω(e)x(e)) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pwCV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, spin-orbit coupling, and the diagonal Born-Oppenheimer correction. The purely ab initio FPA approach yields the following T(0) results (in eV) for the lowest spin-orbit components of each electronic state: 0 (X (4)Δ) < 0.132 (A (4)Π) < 0.190 (a (6)Δ) < 0.444 (b (6)Π). The computed anharmonic fundamental vibrational frequencies (v(0)) for the (4,6)Δ electronic states are within 3 cm(-1) of experiment and provide reliable predictions for the (4,6)Π states. With the cc-pVDZ basis set, even CCSDTQPH energies give an incorrect ground state of FeH, highlighting the importance of combining high-order electron correlation treatments with robust basis sets when studying transition-metal radicals. The FPA computations provide D(0) = 1.86 eV (42.9 kcal mol(-1)) for the 0 K dissociation energy of FeH and Δ(f)H(298) (∘) [FeH((g))] = 107.7 kcal mol(-1) for the enthalpy of formation at room temperature. Despite sizable multireference character in the quartet states, high-order single-reference coupled cluster computations improve the spectroscopic parameters over previous multireference theoretical studies; for example, the X (4)Δ → A (4)Π and a (6)Δ → b (6)Π transition energies are reproduced to 0

  15. Taming the low-lying electronic states of FeH

    NASA Astrophysics Data System (ADS)

    DeYonker, Nathan J.; Allen, Wesley D.

    2012-12-01

    The low-lying electronic states (X 4Δ, A 4Π, a 6Δ, b 6Π) of the iron monohydride radical, which are especially troublesome for electronic structure theory, have been successfully described using a focal point analysis (FPA) approach that conjoined a correlation-consistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through hextuple (CCSDTQPH) excitations. Adiabatic excitation energies (T0) and spectroscopic constants (re, r0, Be, B0, overline De, ωe, v0, αe, ωexe) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pwCV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, spin-orbit coupling, and the diagonal Born-Oppenheimer correction. The purely ab initio FPA approach yields the following T0 results (in eV) for the lowest spin-orbit components of each electronic state: 0 (X 4Δ) < 0.132 (A 4Π) < 0.190 (a 6Δ) < 0.444 (b 6Π). The computed anharmonic fundamental vibrational frequencies (v0) for the 4,6Δ electronic states are within 3 cm-1 of experiment and provide reliable predictions for the 4,6Π states. With the cc-pVDZ basis set, even CCSDTQPH energies give an incorrect ground state of FeH, highlighting the importance of combining high-order electron correlation treatments with robust basis sets when studying transition-metal radicals. The FPA computations provide D0 = 1.86 eV (42.9 kcal mol-1) for the 0 K dissociation energy of FeH and Δ _f H_{298}° [FeH(g)] = 107.7 kcal mol-1 for the enthalpy of formation at room temperature. Despite sizable multireference character in the quartet states, high-order single-reference coupled cluster computations improve the spectroscopic parameters over previous multireference theoretical studies; for example, the X 4Δ → A 4Π and a 6Δ → b 6Π transition energies are reproduced to 0.012 and 0.002 eV, respectively, while the error for the problematic X 4Δ → a 6

  16. Cocrystallization of certain 4f and 5f elements in the bivalent state with alkali metal halides

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.M.; Veleshko, I.E.; Kulyukhin, S.A.

    1987-01-01

    The cocrystallization of Fm/sup 2 +/, Es/sup 2 +/, Cf/sup 2 +/, Am/sup 2 +/, Yb/sup 2 +/, Eu/sup 2 +/ and Sr/sup 2 +/ with NaCl, KCl and KBr in tetrahydrofuran (THF), hexamethylphosphorotriamide (HMPA), and ethanol has been studied. It is shown that in water-ethanol medium An/sup 2 +/ cocrystallize with KCl by the formation of anomalous mixed crystals and Ln/sup 2 +/ do not cocrystallize. In HMPA neither Ln/sup 2 +/ nor An/sup 2 +/ are observed to transfer into the KBr solid phase, while in THF both Ln/sup 2 +/ and An/sup 2 +/ cocrystallize with NaCl. The change in the behavior on Ln/sup 2 +/ and An/sup 2 +/ cocrystallize with a change from one solvent to another is caused by the difference in the effective ionic radii of these elements, which arises from the large nephelauxetic effect for An/sup 2 +/ as well as by the different solvating power of these solvents.

  17. Up-conversion routines of Er{sup 3+}–Yb{sup 3+} doped Y{sub 6}O{sub 5}F{sub 8} and YOF phosphors

    SciTech Connect

    Park, Sangmoon; Yang, Wonseok; Park, Chu-Young; Noh, Minhee; Choi, Seulki; Park, Dahye; Jang, Ho Seong; Cho, So-Hye

    2015-11-15

    Highlights: • Single-phase optical materials of Y{sub 6}O{sub 5}F{sub 8}:Er and YOF:Er were prepared. • Effective spectral converting properties were observed in Y{sub 6}O{sub 5}F{sub 8}:Er,Yb. • 980 nm diode laser was irradiated for up-converting analysis. • A multi-photon process in the phosphors was investigated. - Abstract: Optical materials composed of a Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} (p = 0.001–0.1, q = 0.005–0.1) solid solution with Y{sub 0.99}Er{sub 0.01}OF were prepared via a solid-state reaction using excess NH{sub 4}F flux at 950 °C for 30 min. X-ray diffraction patterns of Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} and Y{sub 0.99}Er{sub 0.01}OF were compared upon altering the synthesis temperature and the molar ratio of the NH{sub 4}F flux to the Y{sup 3+} (Er{sup 3+}, Yb{sup 3+}) ions. The effective spectral-conversion properties of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} ions in Y{sub 6}O{sub 5}F{sub 8} phosphors were monitored during excitation with a 980 nm wavelength diode-laser. Selection of appropriate Er{sup 3+} and/or Yb{sup 3+} concentrations in the Y{sub 6}O{sub 5}F{sub 8} structure led to achievement of the desired up-conversion emission, from the green to the red regions of the spectra. Furthermore, the mechanism of up-conversion in the phosphors was described by an energy-level schematic. Up-conversion emission spectra and the dependence of the emission intensity on pump power (between 193 and 310 mW) in the Y{sub 6(0.995−q)}Er{sub 0.03}Yb{sub 6q}O{sub 5}F{sub 8} phosphors were also investigated.

  18. Exchange and Inelastic OH(+) + H Collisions on the Doublet and Quartet Electronic States.

    PubMed

    Bulut, Niyazi; Lique, François; Roncero, Octavio

    2015-12-17

    The exchange and inelastic state-to-state cross sections for the OH(+) + H collisions are computed from wave packet calculations using the doublet and quartet ground electronic potential energy surface (PES) correlating to the open shell reactants, for collision energies in the range of 1 meV to 0.7 eV. The doublet PES presents a deep insertion well, of ≈6 eV, but the exchange reaction has a rather low probability, showing that the mechanism is not statistical. This well is also responsible of a rather high rotational energy transfer, which makes the rigid-rotor approach overestimate the cross section for low Δj transitions and for high collisonal energies. The quartet PES, with a much shallower well, also presents a low exchange reaction cross section, but the inelastic state-to-state cross sections are very well reproduced by rigid-rotor calculations. When the electronic partition is used to obtain the total state-to-state cross section, the contribution of the doublet state becomes small, and the resulting total cross sections become close to those obtained for the quartet state. Thus, the total (quartet and doublet) cross sections for this open shell system can be reproduced rather satisfactorily by those obtained with the rigid-rotor approximation on the quartet state. Finally, we compare the new OH(+)-H cross sections with OH(+)-He ones recently computed. We found significant differences, especially for transitions with large Δj showing that specific OH(+)-H calculations had to be performed to accurately analyze the OH(+) emission from interstellar molecular clouds.

  19. High thermal sensitivity and the selectable upconversion color of Ln, Yb:Y6O5F8 nanotubes.

    PubMed

    Zaldo, Carlos; Cascales, Concepción

    2014-11-14

    Yb(3+)-sensitized, Ln(3+)(Er(3+), Pr(3+))-doped Y6O5F8 micron-sized bundles of highly crystalline individual nanotubes have been prepared through hydrothermal syntheses at 185 °C. The inhomogeneous broadening observed in their optical spectra is associated with the large distribution of crystal fields around Y(3+)(Ln(3+)) sites in the orthorhombic Pbcm Vernier-type Y6O5F8 host. Based on ratiometric analyses of the thermal evolution of intensities of near-infrared NIR (∼978 nm)-excited green upconversion emissions corresponding to (2)H11/2, (4)S3/2 → (4)I15/2 Er(3+) transitions, the temperature sensing behaviour of Er, Yb:Y6O5F8 was studied. This thermal sensor exhibits a very high sensitivity S = 0.0060 K(-1) at physiological temperatures (22-50 °C), which surpasses the S value found for Er, Yb:β-NaYF4 at these temperatures, and a maximum S = 0.0082 K(-1) at ∼225 °C. Also under NIR diode laser excitation, the color of the upconverted light from codoped Pr, Er, Yb:Y6O5F8 nanotubes can be selected by the control of the Pr(3+) concentration and by the excitation regime and power density. Samples with low Pr(3+) concentration emit green light, and the selection between bluish-green light and white light has been demonstrated with high Pr(3+) concentration (2 mol%), under pulsed or continuous wave excitation, respectively.

  20. High thermal sensitivity and the selectable upconversion color of Ln, Yb:Y6O5F8 nanotubes.

    PubMed

    Zaldo, Carlos; Cascales, Concepción

    2014-11-14

    Yb(3+)-sensitized, Ln(3+)(Er(3+), Pr(3+))-doped Y6O5F8 micron-sized bundles of highly crystalline individual nanotubes have been prepared through hydrothermal syntheses at 185 °C. The inhomogeneous broadening observed in their optical spectra is associated with the large distribution of crystal fields around Y(3+)(Ln(3+)) sites in the orthorhombic Pbcm Vernier-type Y6O5F8 host. Based on ratiometric analyses of the thermal evolution of intensities of near-infrared NIR (∼978 nm)-excited green upconversion emissions corresponding to (2)H11/2, (4)S3/2 → (4)I15/2 Er(3+) transitions, the temperature sensing behaviour of Er, Yb:Y6O5F8 was studied. This thermal sensor exhibits a very high sensitivity S = 0.0060 K(-1) at physiological temperatures (22-50 °C), which surpasses the S value found for Er, Yb:β-NaYF4 at these temperatures, and a maximum S = 0.0082 K(-1) at ∼225 °C. Also under NIR diode laser excitation, the color of the upconverted light from codoped Pr, Er, Yb:Y6O5F8 nanotubes can be selected by the control of the Pr(3+) concentration and by the excitation regime and power density. Samples with low Pr(3+) concentration emit green light, and the selection between bluish-green light and white light has been demonstrated with high Pr(3+) concentration (2 mol%), under pulsed or continuous wave excitation, respectively. PMID:25255864

  1. Ab Initio Investigations of the Excited Electronic States of CaOCa

    NASA Astrophysics Data System (ADS)

    Fawzy, Wafaa M.; Heaven, Michael

    2016-06-01

    Chemical bonding in alkaline earth hypermetalic oxides is of fundamental interest. Previous Ab initio studies of CaOCa predicted a centrosymmetric linear geometry for both the 1Σg^+ ground state and the low lying triplet 3Σu^+ state. However, there have been no reports concerning the higher energy singlet and triplet states. The present work is focused on characterization of the potential energy surface (PES) of the excited 1Σu^+ state (assuming a centrosymmetric linear geometry) and obtaining predictions for the 1Σu^+←1Σg^+ vibronic transitions. We employed the multireference configuration interaction (MRCISD) method with state-averaged, full-valence complete active space self-consistent field (SA-FV-CASSCF) wavefunctions. In these calculations, the active space consisted of ten valence electrons in twelve orbitals, where all the valence electrons were correlated. Contributions of higher excitation and relativistic effects were taken into account using the Davidson correction and the Douglas-Kroll (DK) Hamiltonian, respectively. The correlation-consistent polarized weighed core-valence quadruple zeta basis set (cc-pwCVQZ-DK) was used for all three atoms. The full level of theory is abbreviated as SA-FV-CASSCF (10,12)-MRCISD-Q/cc-pwCVQZ-DK. The calculations were carried out using the MOLPRO2012 suite of programs. For the centrosymmetric linear geometry in all states, initial investigations of one-dimensional radial cuts provided equilibrium bond distances of 2.034 {Å}, 2.034 {Å}, and 1.999 {Å} for the 1Σg^+ , 3Σu^+ , and 1Σu^+ states, respectively. The vertical excitation frequency of the 1Σu^+←1Σg^+ optical transition was calculated to occur at 14801 wn. These predictions were followed by spectroscopic searches by Heaven et al. Indeed, rotationally resolved vibronic progressions were recorded in the vicinity of the predicted electronic band origin. Calculation of the three-dimensional PES showed that the potential minimum in the 1Σu^+ corresponds

  2. Electronic spectra and excited state dynamics of pentafluorophenol: Effects of low-lying πσ{sup ∗} states

    SciTech Connect

    Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas

    2015-05-14

    Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S{sub 1}←S{sub 0} absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S{sub 1} origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of πσ{sup ∗} character in the vicinity of the lowest valence ππ{sup ∗} state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ππ{sup ∗} and a nearby dissociative πσ{sup ∗} state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H{sub 2}O){sub n} clusters (n = 1-11), intensities of a number of πσ{sup ∗} states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the

  3. Evaluation of regulatory genetic variants in POU5F1 and risk of congenital heart disease in Han Chinese

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Ding, Chenyue; Zhang, Kai; Ni, Bixian; da, Min; Hu, Liang; Hu, Yuanli; Xu, Jing; Wang, Xiaowei; Chen, Yijiang; Mo, Xuming; Cui, Yugui; Shen, Hongbing; Sha, Jiahao; Liu, Jiayin; Hu, Zhibin

    2015-10-01

    OCT4 is a transcription factor of the POU family, which plays a key role in embryonic development and stem cell pluripotency. Previous studies have shown that Oct4 is required for cardiomyocyte differentiation in mice and its depletion could result in cardiac morphogenesis in embryo. However, whether the genetic variations in OCT4 coding gene, POU5F1, confer the predisposition to congenital heart disease (CHD) is unclear. This study sought to investigate the associations between low-frequency (defined here as having minor allele frequency (MAF) between 0.1%-5%) and rare (MAF below 0.1%) variants with potential function in POU5F1 and risk of CHD. We conducted association analysis in a two-stage case-control study with a total of 2,720 CHD cases and 3,331 controls in Chinese. The low-frequency variant rs3130933 was observed to be associated with a significantly increased risk of CHD [additive model: adjusted odds ratio (OR) = 2.15, adjusted P = 3.37 × 10-6]. Furthermore, luciferase activity assay showed that the variant A allele led to significantly lower expression levels as compared to the G allele. These findings indicate for the first time that low-frequency functional variant in POU5F1 may contribute to the risk of congenital heart malformations.

  4. Evaluation of regulatory genetic variants in POU5F1 and risk of congenital heart disease in Han Chinese.

    PubMed

    Lin, Yuan; Ding, Chenyue; Zhang, Kai; Ni, Bixian; Da, Min; Hu, Liang; Hu, Yuanli; Xu, Jing; Wang, Xiaowei; Chen, Yijiang; Mo, Xuming; Cui, Yugui; Shen, Hongbing; Sha, Jiahao; Liu, Jiayin; Hu, Zhibin

    2015-10-28

    OCT4 is a transcription factor of the POU family, which plays a key role in embryonic development and stem cell pluripotency. Previous studies have shown that Oct4 is required for cardiomyocyte differentiation in mice and its depletion could result in cardiac morphogenesis in embryo. However, whether the genetic variations in OCT4 coding gene, POU5F1, confer the predisposition to congenital heart disease (CHD) is unclear. This study sought to investigate the associations between low-frequency (defined here as having minor allele frequency (MAF) between 0.1%-5%) and rare (MAF below 0.1%) variants with potential function in POU5F1 and risk of CHD. We conducted association analysis in a two-stage case-control study with a total of 2,720 CHD cases and 3,331 controls in Chinese. The low-frequency variant rs3130933 was observed to be associated with a significantly increased risk of CHD [additive model: adjusted odds ratio (OR) = 2.15, adjusted P = 3.37 × 10(-6)]. Furthermore, luciferase activity assay showed that the variant A allele led to significantly lower expression levels as compared to the G allele. These findings indicate for the first time that low-frequency functional variant in POU5F1 may contribute to the risk of congenital heart malformations.

  5. Evaluation of regulatory genetic variants in POU5F1 and risk of congenital heart disease in Han Chinese

    PubMed Central

    Lin, Yuan; Ding, Chenyue; Zhang, Kai; Ni, Bixian; Da, Min; Hu, Liang; Hu, Yuanli; Xu, Jing; Wang, Xiaowei; Chen, Yijiang; Mo, Xuming; Cui, Yugui; Shen, Hongbing; Sha, Jiahao; Liu, Jiayin; Hu, Zhibin

    2015-01-01

    OCT4 is a transcription factor of the POU family, which plays a key role in embryonic development and stem cell pluripotency. Previous studies have shown that Oct4 is required for cardiomyocyte differentiation in mice and its depletion could result in cardiac morphogenesis in embryo. However, whether the genetic variations in OCT4 coding gene, POU5F1, confer the predisposition to congenital heart disease (CHD) is unclear. This study sought to investigate the associations between low-frequency (defined here as having minor allele frequency (MAF) between 0.1%–5%) and rare (MAF below 0.1%) variants with potential function in POU5F1 and risk of CHD. We conducted association analysis in a two-stage case-control study with a total of 2,720 CHD cases and 3,331 controls in Chinese. The low-frequency variant rs3130933 was observed to be associated with a significantly increased risk of CHD [additive model: adjusted odds ratio (OR) = 2.15, adjusted P = 3.37 × 10−6]. Furthermore, luciferase activity assay showed that the variant A allele led to significantly lower expression levels as compared to the G allele. These findings indicate for the first time that low-frequency functional variant in POU5F1 may contribute to the risk of congenital heart malformations. PMID:26507003

  6. Direct observations of local electronic states in an Al-based quasicrystal by STEM-EELS.

    PubMed

    Seki, Takehito; Abe, Eiji

    2014-11-01

    Most quasicrystals (QCs) reveal pseudogaps in their density of states around Fermi level, and hence the stability of QCs have been discussed in terms of energetic gains in electron systems. In fact, many QCs have been discovered by tuning valence electron density based on Hume-Rothery rule. Therefore, understanding electronic structures in QCs may provide an important clue for their stabilization mechanism. Generally, it has been frequently discussed based on an interaction between Fermi surface and Brillouin zone boundary within the framework of nearly free electron model, which is believed to be an underlying physics of a Hume-Rothery's empirical criteria. However the hybridization effect also stabilize electron system, particularly in Al-transition metal system, in which a lot of quasicrystalline phases were discovered. Therefore, the electronic structures of QCs have not yet been fully understood, whereas their atomic structures have been studied well in terms of configuration entropy by scanning transmission electron microscopy (STEM) [1]. In the present work, we investigate local electronic states in Al-based QCs using electron energy loss spectroscopy (EELS) combined with STEM, by which EELS spectra with sub-Å probe and atomic structure can be obtained simultaneously. We report STEM-EELS results on AlCuIr decagonal phases [2].jmicro;63/suppl_1/i17-a/DFU069F1F1DFU069F1Fig. 1.Core-loss edges obtained from cluster-centers and cluster-edges. Al L1 (left) Ir O23, Ir N67 (center) and Cu L23 (right). Principal components analysis clearly shows up the atomic-site dependence of plasmon loss spectra in a two-dimensional map. Qualitatively, there seems to be certain correlations between the plasmon peaks and the core-loss edges, Al L1, Ir O23, Ir N67 and Cu L23, all of which reveal different behaviors at the cluster centers and the edges (Fig. 1). All results indicate the cluster centers have metallic states and the cluster edges have covalent states in comparison

  7. Electronic excitation of ground state atoms by collision with heavy gas particles

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1993-01-01

    Most of the important chemical reactions which occur in the very high temperature air produced around space vehicles as they enter the atmosphere were investigated both experimentally and theoretically, to some extent at least. One remaining reaction about which little is known, and which could be quite important at the extremely high temperatures that will be produced by the class of space vehicles now contemplated - such as the AOTV - is the excitation of bound electron states due to collisions between heavy gas particles. Rates of electronic excitation due to free electron collisions are known to be very rapid, but because these collisions quickly equilibrate the free and bound electron energy, the approach to full equilibrium with the heavy particle kinetic energy will depend primarily on the much slower process of bound electron excitation in heavy particle collisions and the subsequent rapid transfer to free electron energy. This may be the dominant mechanism leading to full equilibrium in the gas once the dissociation process has depleted the molecular states so the transfer between molecular vibrational energy and free electron energy is no longer available as a channel for equilibration of free electron and heavy particle kinetic energies. Two mechanisms seem probable in electronic excitation by heavy particle impact. One of these is the collision excitation and deexcitation of higher electronic states which are Rydberg like. A report, entitled 'Semi-Classical Theory of Electronic Excitation Rates', was submitted previously. This presented analytic expressions for the transition probabilities, assuming that the interaction potential is an exponential repulsion with a perturbation ripple due to the dipole-induced dipole effect in the case of neutral-neutral collisions, and to the ion-dipole interaction in the case of ion-neutral collisions. However the above may be, there is little doubt that excitation of ground state species by collision occurs at the

  8. Probing the spinor nature of electronic states in nanosize non-collinear magnets

    NASA Astrophysics Data System (ADS)

    Fischer, Jeison A.; Sandratskii, Leonid M.; Phark, Soo-Hyon; Ouazi, Safia; Pasa, André A.; Sander, Dirk; Parkin, Stuart S. P.

    2016-10-01

    Non-collinear magnetization textures provide a route to novel device concepts in spintronics. These applications require laterally confined non-collinear magnets (NCM). A crucial aspect for potential applications is how the spatial proximity between the NCM and vacuum or another material impacts the magnetization texture on the nanoscale. We focus on a prototypical exchange-driven NCM given by the helical spin order of bilayer Fe on Cu(111). Spin-polarized scanning tunnelling spectroscopy and density functional theory reveal a nanosize- and proximity-driven modification of the electronic and magnetic structure of the NCM in interfacial contact with a ferromagnet or with vacuum. An intriguing non-collinearity between the local magnetization in the sample and the electronic magnetization probed above its surface results. It is a direct consequence of the spinor nature of electronic states in NCM. Our findings provide a possible route for advanced control of nanoscale spin textures by confinement.

  9. Probing the spinor nature of electronic states in nanosize non-collinear magnets

    PubMed Central

    Fischer, Jeison A.; Sandratskii, Leonid M.; Phark, Soo-Hyon; Ouazi, Safia; Pasa, André A.; Sander, Dirk; Parkin, Stuart S. P.

    2016-01-01

    Non-collinear magnetization textures provide a route to novel device concepts in spintronics. These applications require laterally confined non-collinear magnets (NCM). A crucial aspect for potential applications is how the spatial proximity between the NCM and vacuum or another material impacts the magnetization texture on the nanoscale. We focus on a prototypical exchange-driven NCM given by the helical spin order of bilayer Fe on Cu(111). Spin-polarized scanning tunnelling spectroscopy and density functional theory reveal a nanosize- and proximity-driven modification of the electronic and magnetic structure of the NCM in interfacial contact with a ferromagnet or with vacuum. An intriguing non-collinearity between the local magnetization in the sample and the electronic magnetization probed above its surface results. It is a direct consequence of the spinor nature of electronic states in NCM. Our findings provide a possible route for advanced control of nanoscale spin textures by confinement. PMID:27721384

  10. Single-molecule spectroscopy exposes hidden states in an enzymatic electron relay

    NASA Astrophysics Data System (ADS)

    Grossman, Iris; Yuval Aviram, Haim; Armony, Gad; Horovitz, Amnon; Hofmann, Hagen; Haran, Gilad; Fass, Deborah

    2015-10-01

    The ability to query enzyme molecules individually is transforming our view of catalytic mechanisms. Quiescin sulfhydryl oxidase (QSOX) is a multidomain catalyst of disulfide-bond formation that relays electrons from substrate cysteines through two redox-active sites to molecular oxygen. The chemical steps in electron transfer have been delineated, but the conformational changes accompanying these steps are poorly characterized. Here we use single-molecule Förster resonance energy transfer (smFRET) to probe QSOX conformation in resting and cycling enzyme populations. We report the discovery of unanticipated roles for conformational changes in QSOX beyond mediating electron transfer between redox-active sites. In particular, a state of the enzyme not previously postulated or experimentally detected is shown to gate, via a conformational transition, the entrance into a sub-cycle within an expanded QSOX kinetic scheme. By tightly constraining mechanistic models, smFRET data can reveal the coupling between conformational and chemical transitions in complex enzymatic cycles.

  11. First-principles study of electronic states in Mg2C

    NASA Astrophysics Data System (ADS)

    Trivedi, D. K.; Galav, K. L.; Paliwal, U.; Joshi, K. B.

    2016-05-01

    The electronic properties of magnesium methanide Mg2C are reported. Investigations are carried out applying the linear combination of atomic orbitals method. After settling ground state of the antifluorite structure the electronic band structure calculations are undertaken using PBE-GGA exchange and correlation functional and PBE0 hybrid functional. All calculations show that Mg2C has indirect band gap with conduction band minimum at Γ and valence band maximum at the X point. The values of band gap from PBE and the PBE0 are 2.05 and 3.46 eV respectively. In comparison to beryllium methanide the electronic bands are flat suggesting ionic nature of bonding.

  12. Excited-state dynamics of oxazole: A combined electronic structure calculations and dynamic simulations study

    NASA Astrophysics Data System (ADS)

    Cao, Jun; Xie, Zhi-Zhong; Yu, Xiaodong

    2016-08-01

    In the present work, the combined electronic structure calculations and surface hopping simulations have been performed to investigate the excited-state decay of the parent oxazole in the gas phase. Our calculations show that the S2 state decay of oxazole is an ultrafast process characterized by the ring-opening and ring-closure of the five-membered oxazole ring, in which the triplet contribution is minor. The ring-opening involves the Osbnd C bond cleavage affording the nitrile ylide and airine intermediates, while the ring-closure gives rise to a bicyclic species through a 2sbnd 5 bond formation. The azirine and bicyclic intermediates in the S0 state are very likely involved in the phototranspositions of oxazoles. This is different from the previous mechanism in which these intermediates in the T1 state have been proposed for these phototranspositions.

  13. Electron-impact excitation and ionization cross sections for ground state and excited helium atoms

    SciTech Connect

    Ralchenko, Yu. Janev, R.K.; Kato, T.; Fursa, D.V.; Bray, I.; Heer, F.J. de

    2008-07-15

    Comprehensive and critically assessed cross sections for the electron-impact excitation and ionization of ground state and excited helium atoms are presented. All states (atomic terms) with n{<=}4 are treated individually, while the states with n{>=}5 are considered degenerate. For the processes involving transitions to and from n{>=}5 levels, suitable cross section scaling relations are presented. For a large number of transitions, from both ground and excited states, convergent close coupling calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions, which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in graphical form.

  14. Identification of unavoided crossings in nonadiabatic photoexcited dynamics involving multiple electronic states in polyatomic conjugated molecules.

    PubMed

    Fernandez-Alberti, Sebastian; Roitberg, Adrian E; Nelson, Tammie; Tretiak, Sergei

    2012-07-01

    Radiationless transitions between electronic excited states in polyatomic molecules take place through unavoided crossings of the potential energy surfaces with substantial non-adiabatic coupling between the respective adiabatic states. While the extent in time of these couplings are large enough, these transitions can be reasonably well simulated through quantum transitions using trajectory surface hopping-like methods. In addition, complex molecular systems may have multiple "trivial" unavoided crossings between noninteracting states. In these cases, the non-adiabatic couplings are described as sharp peaks strongly localized in time. Therefore, their modeling is commonly subjected to the identification of regions close to the particular instantaneous nuclear configurations for which the energy surfaces actually cross each other. Here, we present a novel procedure to identify and treat these regions of unavoided crossings between non-interacting states using the so-called Min-Cost algorithm. The method differentiates between unavoided crossings between interacting states (simulated by quantum hops), and trivial unavoided crossings between non-interacting states (detected by tracking the states in time with Min-Cost procedure). We discuss its implementation within our recently developed non-adiabatic excited state molecular dynamics framework. Fragments of two- and four-ring linear polyphenylene ethynylene chromophore units at various separations have been used as a representative molecular system to test the algorithm. Our results enable us to distinguish and analyze the main features of these different types of radiationless transitions the molecular system undertakes during internal conversion. PMID:22779670

  15. UV-induced DNA Damage: The Role of Electronic Excited States.

    PubMed

    Markovitsi, Dimitra

    2016-01-01

    The knowledge of the fundamental processes induced by the direct absorption of UV radiation by DNA allows extrapolating conclusions drawn from in vitro studies to the in-vivo DNA photoreactivity. In this respect, the characterization of the DNA electronic excited states plays a key role. For a long time, the mechanisms of DNA lesion formation were discussed in terms of generic "singlet" and "triplet" excited state reactivity. However, since the beginning of the 21(st) century, both experimental and theoretical studies revealed the existence of "collective" excited states, i.e. excited states delocalized over at least two bases. Two limiting cases are distinguished: Frenkel excitons (delocalized ππ* states) and charge-transfer states in which positive and negative charges are located on different bases. The importance of collective excited states in photon absorption (in particular in the UVA spectral domain), the redistribution of the excitation energy within DNA, and the formation of dimeric pyrimidine photoproducts is discussed. The dependence of the behavior of the collective excited states on conformational motions of the nucleic acids is highlighted.

  16. Collisional destruction of circular Rydberg states by atoms with small electron affinities

    NASA Astrophysics Data System (ADS)

    Mironchuk, Elena S.; Narits, Alexander A.; Lebedev, Vladimir S.

    2014-12-01

    The results of theoretical studies of interaction between neutral targets with small electron affinities and Rydberg atoms in circular states are reported. The cross sections of collisional destruction of such states due to the resonant quenching mechanism are calculated on the basis of the semiclassical theory of nonadiabatic transitions between the ionic and Rydberg covalent terms of a quasimolecule combined with recently developed technique for exact evaluation of matrix elements. We obtain the basic formula for the square of the coupling parameter involving Rydberg nlm-state with the given values of the principal, orbital, and magnetic quantum numbers. It is employed for the derivation of explicit expressions for transitions from circular states applicable in cases of s- and p-states of negative ion temporarily formed during a collision of atoms. Numerical calculations are carried out for thermal collisions of Li∗ and Na∗ atoms with Ca(4s2) and Sr(5s2). We explore n-, l-, m-, and velocity-dependences of the cross sections and analyze orientation effects in such collisions. Cross sections of resonant quenching for circular states (l = | m | = n - 1) are shown to be much smaller than those for states with small l values and typically two times lower than for nearly-circular states (l = n - 1) averaged over m.

  17. Pictures of unbound molecular electrons, including shape-resonant states. Eigenchannel contour maps

    SciTech Connect

    Loomba, Dinesh; Wallace, Scott; Dill, Dan; Dehmer, Joseph L.

    1981-01-01

    Eigenchannel wave functions are identified as the continuum analog of discrete-state eigenfunctions familiar from molecular structure calculations. As examples, eigenchannel wave functions are plotted for shape-resonant and nonresonant eigenchannels of N₂. Both types of functions show characteristic nodal patterns. The penetration over a narrow energy range of the resonantwave function through a potential barrier into the molecular interior, the key feature of shape-resonant states, is clearly seen for the example of the N₂ f-wave-dominated σu shape resonance at 1.2 Ry electron kinetic energy. This visualization of continuum electronic amplitudes should prove to be a significant new tool in the study of continuum electron–molecule dynamics.

  18. Electronic states of alkyl-radical-functionalized C20 fullerene using density functional theory

    NASA Astrophysics Data System (ADS)

    Abe, Shigeaki; Kawano, Shimpei; Toida, Yu; Nakamura, Mariko; Inoue, Satoshi; Sano, Hidehiko; Yoshida, Yasuhiro; Kawabata, Hiroshi; Tachikawa, Hiroto

    2016-03-01

    The structures and electronic states of alkyl-radical-functionalized C20 fullerenes (denoted by C20-R) have been investigated using density functional theory (DFT). The different alkyl radicals investigated were methyl, ethyl, propyl, and butyl radicals. The DFT calculation indicated that the alkyl radical binds to the carbon atom of C20 in the on-top site, thus forming a strong C-C single bond. The binding energies of the alkyl radicals to C20 were calculated to be 83.9-86.6 kcal/mol at the CAM-B3LYP/6-311G(d,p) level. The electronic states of the C20-R complex are discussed on the basis of the theoretical results.

  19. Lateral quantization of two-dimensional electron states by embedded Ag nanocrystals.

    PubMed

    Schouteden, K; Van Haesendonck, C

    2012-02-17

    We show that quantization of image-potential state (IS) electrons above the surface of nanostructures can be experimentally achieved by Ag nanocrystals that appear as stacking-fault tetrahedrons (SFTs) at Ag(111) surfaces. By means of cryogenic scanning tunneling spectroscopy, the n=1 IS of the Ag(111) surface is revealed to split up in discrete energy levels, which is accompanied by the formation of pronounced standing wave patterns that directly reflect the eigenstates of the SFT surface. The IS confinement behavior is compared to that of the surface state electrons in the SFT surface and can be directly linked to the particle-in-a-box model. ISs provide a novel playground for investigating quantum size effects and defect-induced scattering above nanostructured surfaces.

  20. Lateral quantization of two-dimensional electron states by embedded Ag nanocrystals

    NASA Astrophysics Data System (ADS)

    Van Haesendonck, Chris; Schouteden, Koen

    2013-03-01

    We show that quantization of image-potential state (IS)electrons above the surface of nanostructures can be experimentally achieved by Ag nanocrystals that appear as stacking fault tetrahedrons (SFTs) at Ag(111) surfaces. By means of cryogenic scanning tunneling spectroscopy the n = 1 IS of the Ag(111) surface is revealed to split up in discrete energy levels, which is accompanied by the formation of pronounced standing wave patterns that directly reflect the eigenstates of the SFT surface. The IS confinement behavior is compared to that of the surface state electrons in the SFT surface and can be directly linked to the particle-in-a-box model. ISs provide a novel playground for investigating quantum size effects and defect induced scattering above nanostructured surfaces. This work has been supported by the Research Foundation - Flanders (FWO, Belgium). K.S. is a postdoctoral researcher of the FWO.

  1. Lateral Quantization of Two-Dimensional Electron States by Embedded Ag Nanocrystals

    NASA Astrophysics Data System (ADS)

    Schouteden, K.; Van Haesendonck, C.

    2012-02-01

    We show that quantization of image-potential state (IS) electrons above the surface of nanostructures can be experimentally achieved by Ag nanocrystals that appear as stacking-fault tetrahedrons (SFTs) at Ag(111) surfaces. By means of cryogenic scanning tunneling spectroscopy, the n=1 IS of the Ag(111) surface is revealed to split up in discrete energy levels, which is accompanied by the formation of pronounced standing wave patterns that directly reflect the eigenstates of the SFT surface. The IS confinement behavior is compared to that of the surface state electrons in the SFT surface and can be directly linked to the particle-in-a-box model. ISs provide a novel playground for investigating quantum size effects and defect-induced scattering above nanostructured surfaces.

  2. Electron-impact ionization of moderately charged atomic ions in excited states

    SciTech Connect

    Pindzola, M. S.; Ballance, C. P.; Loch, S. D.

    2011-06-15

    Nonperturbative R-matrix and perturbative distorted-wave methods are used to calculate electron-impact ionization cross sections for C{sup 3+} in excited states. Convergence studies for the cross sections of the 1s{sup 2}5s excited configuration reveal that both the R-matrix and distorted-wave methods need fairly high ejected electron angular momenta. Reasonable agreement is found between the converged R-matrix and distorted-wave cross sections. Thus, the use of the computationally less demanding distorted-wave method as a tool for the n scaling of excited-state ionization cross sections appears to be reasonable for atomic ions with charge q{>=}3.

  3. Nature of electronic states and optical functions of sodium oxyanionic compounds

    NASA Astrophysics Data System (ADS)

    Zhuravlev, Yu. N.; Korabel'Nikov, D. V.

    2009-01-01

    The band structure, the density of states, the partial electron densities, and optical functions (such as permittivity, refraction index, reflection and absorption coefficients) of sodium nitrite, nitrate, carbonate, chlorate, sulfite, perchlorate, and sulfate are calculated in a local approximation of the density-functional theory using the Troullier-Martins pseudopotentials in the basis of numerical pseudoatomic orbitals. The nature of the upper valence bands and the lower empty bands is established. It is shown that the specific features of the optical functions at energies of up to 8 eV and at E> 8 eV are due to the excitation of electrons into a localized anionic conduction band and into the bands of anion-cation states, respectively. The results are compared to experimental photoelectron spectra and reflection and absorption spectra.

  4. Ultrafast Coherent Photoelectron Spectroscopy of Electronic States on a Cu (111) Surface

    NASA Astrophysics Data System (ADS)

    Carr, Adra; Chen, Cong; Tao, Zhensheng; Murnane, Margaret; Kapteyn, Henry; Matyba, Piotr; Emmerich, Sebastian; Aeschlimann, Martin; Hoefer, Ulrich

    2015-03-01

    We use laser-assisted high-harmonic time- and angle-resolved photoemission to directly observe coherent photoemission from a Cu(111) metal surface and the interferences between the emitted photoelectron wavepackets. A comb of high harmonics in combination with interferometrically timed infrared pulses enable a powerful combination of attosecond time resolution and high energy resolution, making it possible to extract phase information about the emitted photoelectron wavepackets and the distinct electronic states from which they emerge. By comparing photoemission from the well-known Shockley surface state to the sp and d bulk bands of Cu(111), we can observe non-negligible phase shifts in the emitted wavepackets, which cannot be attributed to time delays resulting from classical electron transport to the surface. Rather, we interpret these phase shifts as due to an intrinsic photoemission phase that is different for the sp and d band wavefunctions, thus providing a physical interpretation of temporal delays observed in photoemission from surfaces.

  5. Electronic states of zigzag graphene nanoribbons with edges reconstructed with topological defects

    NASA Astrophysics Data System (ADS)

    Pincak, R.; Smotlacha, J.; Osipov, V. A.

    2015-10-01

    The energy spectrum and electronic density of states (DOS) of zigzag graphene nanoribbons with edges reconstructed with topological defects are investigated within the tight-binding method. In case of the Stone-Wales zz(57) edge the low-energy spectrum is markedly changed in comparison to the pristine zz edge. We found that the electronic DOS at the Fermi level is different from zero at any width of graphene nanoribbons. In contrast, for ribbons with heptagons only at one side and pentagons at another one the energy gap at the Fermi level is open and the DOS is equal to zero. The reason is the influence of uncompensated topological charges on the localized edge states, which are topological in nature. This behavior is similar to that found for the structured external electric potentials along the edges.

  6. Hot-electron-mediated desorption rates calculated from excited-state potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob

    2009-01-01

    We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various transition-metal surfaces and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system with parameters obtained from the excited-state potential energy surface and show that this model can describe desorption dynamics in both the DIET and DIMET regimes and reproduce the power-law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong.

  7. Nonlinear optical response of noble gases via the metastable electronic state approach

    NASA Astrophysics Data System (ADS)

    Bahl, A.; Wright, E. M.; Kolesik, M.

    2016-08-01

    The goal of this paper is to elucidate the theoretical underpinnings of the metastable electronic state approach (MESA) and demonstrate its utility for the evaluation of the nonlinear optical response of noble-gas atoms with emphasis on the application of the method to the propagation of multicolor optical fields in large-scale, spatially resolved simulations. More specifically, single-active-electron models of various atoms are employed to calculate their nonlinear properties both within the adiabatic approximation, involving a single metastable state and beyond, capturing inertial effects, and wavelength-dependent ionization. Simulations for excitation pulses at different center wavelengths as well as ionization in two-color pulses are presented and compared with numerical solutions of the time-dependent Schrödinger equation. Illustrative examples of the numerical simulation of high-power pulse propagation incorporating MESA data are also presented and showcase the successful application to optical filamentation in the midinfrared region.

  8. 76 FR 82279 - Electronic Delivery of Search Results From the United States Patent and Trademark Office to the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... United States Patent and Trademark Office Electronic Delivery of Search Results From the United States Patent and Trademark Office to the European Patent Office AGENCY: United States Patent and Trademark Office, Commerce. ACTION: Notice. SUMMARY: The United States Patent and Trademark Office (USPTO)...

  9. Electronic Structure and Ground State Properties of Non-Magnetic NiPt Systems

    NASA Astrophysics Data System (ADS)

    PAUDYAL, DURGA; MOOKERJEE, ABHIJIT

    We have studied the electronic properties like density of states and band structures and also the ground state properties like formation energy, cohesive energy, bulk modulus and structural energy of NiPt system using the linearized muffin-tin orbital method introduced by Andersen.1,2 In an earlier communication we had argued that both charge neutrality and scalar relativistic corrections are very important for the high concentration of Pt alloys. The calculations here, were, therefore, carried out with charge neutrality as well as with and without scalar relativistic correction for comparison.

  10. Fluctuation of the electronic coupling in DNA: Multistate versus two-state model

    NASA Astrophysics Data System (ADS)

    Voityuk, Alexander A.

    2007-05-01

    The electronic coupling for hole transfer between guanine bases G in the DNA duplex (GT) 6GTG(TG) 6 is studied using a QM/MD approach. The coupling V is calculated for 10 thousand snapshots within the two- and multistate state Generalized Mulliken-Hush model. We find that the two-state scheme considerably underestimates the rate of the hole transfer within the π stack. Moreover, the probability distributions computed with the two- and multistate schemes are quite different. It has been found that large fluctuations of V2, which are at least an order of magnitude larger than its average value, occur roughly every 1 ps.

  11. Obstacles and opportunities in the commercialization of the solid-state-electronic fluorescent-lighting ballast

    SciTech Connect

    Johnson, D.R.; Marcus, A.A.; Campbell, R.S.; Sommers, P.; Skumatz, L.; Berk, B.; Petty, P.; Eschbach, C.

    1981-10-01

    The Solid State Ballast (SSB) Program, aimed at improving the efficiency of fluorescent lights, is described. The first generation of solid state electronic ballasts has been developed and the technology has been transferred to the private sector. This report examines the opportunities for rapid dissemination of this technology into the marketplace. It includes a description of product characteristics and their influence on the commercialization of the SSB, a description of the technology delivery system presently used by the ballast industry, an analysis of the market for SSB, and identification of some high-leverage opportunities to accelerate the commercialization process. (MCW)

  12. Charge-transfer photodissociation of adsorbed molecules via electron image states

    SciTech Connect

    Jensen, E. T.

    2008-01-28

    The 248 and 193 nm photodissociations of submonolayer quantities of CH{sub 3}Br and CH{sub 3}I adsorbed on thin layers of n-hexane indicate that the dissociation is caused by dissociative electron attachment from subvacuum level photoelectrons created in the copper substrate. The characteristics of this photodissociation-translation energy distributions and coverage dependences show that the dissociation is mediated by an image potential state which temporarily traps the photoelectrons near the n-hexane-vacuum interface, and then the charge transfers from this image state to the affinity level of a coadsorbed halomethane which then dissociates.

  13. Inelastic electron scattering to negative parity states of /sup 24/Mg

    SciTech Connect

    Zarek, H.; Yen, S.; Pich, B.O.; Drake, T.E.; Williamson, C.F.; Kowalski, S.; Sargent, C.P.

    1984-05-01

    The electromagnetic form factors for the stronger transitions to negative parity states in /sup 24/Mg were measured for electron energies 90--280 MeV and scattering angles of 90/sup 0/ and 160/sup 0/. The isoscalar K/sup ..pi../ = 0/sup -/ and 3/sup -/ bands show form factors in agreement with open-shell random-phase approximation calculations, even though the parentages of these two bands are radically different. For the isovector negative parity states, a quenching of magnetic strength is observed; its origins are discussed.

  14. Obstacles and opportunities in the commercialization of the solid state electronic fluorescent lighting ballast

    NASA Astrophysics Data System (ADS)

    Johnson, D. R.; Marcus, A. A.; Campbell, R. S.; Sommers, P.; Skumatz, L.; Berk, B.; Petty, P.; Eschbach, C.

    1981-10-01

    A solid state ballast (SSB), which improves the efficiency of fluorescent lights, is described. The first generation of solid state electronic ballasts was developed and the technology was transferred to the private sector. The opportunities for rapid dissemination of this technology into the marketplace is examined. Product characteristics and their influence on the commercialization of the SSB, a description of the technology delivery system presently used by the ballast industry, an analysis of the market for SSB, and identification of some high leverage opportunities to accelerate the commercialization process are included.

  15. Electronic State Interferences in Resonant X-Ray Emission after K-Shell Excitation in HCl

    SciTech Connect

    Kavcic, M.; Zitnik, M.; Bucar, K.; Mihelic, A.; Carniato, S.; Journel, L.; Guillemin, R.; Simon, M.

    2010-09-10

    We have measured a series of high-resolution x-ray spectra emitted upon resonant photoexcitation of HCl. The photon energy was tuned across the dissociative 1s{yields}6{sigma}* resonance and the Rydberg states converging to the Cl 1s{sup -1} threshold, and inelastic photon scattering was observed in the region of KL emission lines. Excellent agreement is found between fully ab initio calculated and measured spectra if interferences between different excitation-emission paths are taken into account. The effect of electronic state interferences is enhanced due to dynamical broadening of the 6{sigma}* resonance in HCl.

  16. Phase boundary of spin-polarized-current state of electrons in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Yan, Xin-Zhong; Ma, Yinfeng; Ting, C. S.

    2016-06-01

    Using a four-band Hamiltonian, we study the phase boundary of spin-polarized-current state (SPCS) of interacting electrons in bilayer graphene. The model of spin-polarized-current state has previously been shown to resolve a number of experimental puzzles in bilayer graphene. The phase boundaries of the SPCS with and without the external voltage between the two layers are obtained in this work. An unusual phase boundary where there are two transition temperatures for a given carrier concentration is found at finite external voltage. The physics of this phenomenon is explained.

  17. Quantum Electronic Transport of Topological Surface States in β-Ag2Se Nanowire.

    PubMed

    Kim, Jihwan; Hwang, Ahreum; Lee, Sang-Hoon; Jhi, Seung-Hoon; Lee, Sunghun; Park, Yun Chang; Kim, Si-In; Kim, Hong-Seok; Doh, Yong-Joo; Kim, Jinhee; Kim, Bongsoo

    2016-04-26

    Single-crystalline β-Ag2Se nanostructures, a new class of 3D topological insulators (TIs), were synthesized using the chemical vapor transport method. The topological surface states were verified by measuring electronic transport properties including the weak antilocalization effect, Aharonov-Bohm oscillations, and Shubnikov-de Haas oscillations. First-principles band calculations revealed that the band inversion in β-Ag2Se is caused by strong spin-orbit coupling and Ag-Se bonding hybridization. These investigations provide evidence of nontrivial surface state about β-Ag2Se TIs that have anisotropic Dirac cones.

  18. Spin-state blockade in Te6+-substituted electron-doped LaCoO3

    NASA Astrophysics Data System (ADS)

    Tomiyasu, Keisuke; Koyama, Shun-Ichi; Watahiki, Masanori; Sato, Mika; Nishihara, Kazuki; Onodera, Mitsugi; Iwasa, Kazuaki; Nojima, Tsutomu; Yamasaki, Yuuichi; Nakao, Hironori; Murakami, Youichi

    2015-03-01

    Perovskite-type LaCoO3 (Co3+: d6) is a rare inorganic material with sensitive and characteristic responses among low, intermediate, and high spin states. For example, in insulating nonmagnetic low-spin states below about 20 K, light hole doping (Ni substitution) induces much larger magnetization than expected; over net 10μB/hole (5μB/Ni) for 1μB/hole (1μB/Ni), in which the nearly isolated dopants locally change the surrounding Co low-spin states to magnetic ones and form spin molecules with larger total spin. Further, the former is isotropic, whereas the latter exhibits characteristic anisotropy probably because of Jahn-Teller distortion. In contrast, for electron doping, relatively insensitive spin-state responses were reported, as in LaCo(Ti4+) O3, but are not clarified, and are somewhat controversial. Here, we present macroscopic measurement data of another electron-doped system LaCo(Te6+) O3 and discuss the spin-state responses. This study was financially supported by Grants-in-Aid for Young Scientists (B) (No. 22740209 and 26800174) from the MEXT of Japan.

  19. Real-Space Mapping of Surface Trap States in CIGSe Nanocrystals Using 4D Electron Microscopy.

    PubMed

    Bose, Riya; Bera, Ashok; Parida, Manas R; Adhikari, Aniruddha; Shaheen, Basamat S; Alarousu, Erkki; Sun, Jingya; Wu, Tom; Bakr, Osman M; Mohammed, Omar F

    2016-07-13

    Surface trap states in copper indium gallium selenide semiconductor nanocrystals (NCs), which serve as undesirable channels for nonradiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with subpicosecond temporal and nanometer spatial resolutions. Here, we precisely map the collective surface charge carrier dynamics of copper indium gallium selenide NCs as a function of the surface trap states before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, the removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs. PMID:27228321

  20. On the bonding nature of electron states for the Fe-Mo double perovskite

    SciTech Connect

    Carvajal, E.; Cruz-Irisson, M.; Oviedo-Roa, R.; Navarro, O.

    2014-05-15

    The electronic transport as well as the effect of an external magnetic field has been investigated on manganese-based materials, spinels and perovskites. Potential applications of double perovskites go from magnetic sensors to electrodes in solid-oxide fuel cells; besides the practical interests, it is known that small changes in composition modify radically the physical properties of double perovskites. We have studied the Sr{sub 2}FeMoO{sub 6} double perovskite compound (SFMO) using first-principles density functional theory. The calculations were done within the generalized gradient approximation (GGA) scheme with the Perdew-Burke-Ernzerhof (PBE) functional. We have made a detailed analysis of each electronic state and the charge density maps around the Fermi level. For the electronic properties of SFMO it was used a primitive cell, for which we found the characteristic half-metallic behavior density of states composed by e{sub g} and t{sub 2g} electrons from Fe and Mo atoms. Those peaks were tagged as bonding or antibonding around the Fermi level at both, valence and conduction bands.