Quantum mechanical calculation of electric fields and vibrational Stark shifts at active site of human aldose reductase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xianwei; State Key Laboratory of Precision Spectroscopy, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062; Zhang, John Z. H.

2015-11-14

Recent advance in biophysics has made it possible to directly measure site-specific electric field at internal sites of proteins using molecular probes with C = O or C≡N groups in the context of vibrational Stark effect. These measurements directly probe changes of electric field at specific protein sites due to, e.g., mutation and are very useful in protein design. Computational simulation of the Stark effect based on force fields such as AMBER and OPLS, while providing good insight, shows large errors in comparison to experimental measurement due to inherent difficulties associated with point charge based representation of force fields. Inmore » this study, quantum mechanical calculation of protein’s internal electrostatic properties and vibrational Stark shifts was carried out by using electrostatically embedded generalized molecular fractionation with conjugate caps method. Quantum calculated change of mutation-induced electric field and vibrational Stark shift is reported at the internal probing site of enzyme human aldose reductase. The quantum result is in much better agreement with experimental data than those predicted by force fields, underscoring the deficiency of traditional point charge models describing intra-protein electrostatic properties.« less

Phonon-Mediated Exciton Stark Effect Enhanced by a Static Electric Field

NASA Astrophysics Data System (ADS)

Ivanov, A. L.

1997-03-01

The optical properties of semiconductor QW's change in the presence of coherent pump light. The exciton (phonon-mediated, biexciton-mediated, etc.) optical Stark effect is an effective shift of the exciton level that follow dynamically the intensity I0 ~= 0.1 div 1 GW/cm^2 of the pump light. In the present work we develop a theory of a low-intensity electric-field enhanced phonon-mediated optical Stark effect in polar semiconductors and semiconductor microstructures. The main point is that the exciton - LO-phonon Fröhlich interaction can be strongly enhanced by a (quasi-) static electric field F which polarizes the exciton in the geometry F | k | p, where k and p are the wavevectors of the pump and probe light, respectively. The electric field enhancement of spontaneous Raman scattering has been already analyzed (E. Burstein et al., 1971). Even a moderate electric field F ~= 10^3 V/cm reduces the intensity of the pump light to I0 ~= 1 div 10 MW/cm^2. Moreover, the phonon-mediated Stark effect enhanced by a static electric field F allow us to realize the both red and blue dynamical shifts of the exciton level.

A photoelastic-modulator-based motional Stark effect polarimeter for ITER that is insensitive to polarized broadband background reflections.

PubMed

Thorman, A; Michael, C; De Bock, M; Howard, J

2016-07-01

A motional Stark effect polarimeter insensitive to polarized broadband light is proposed. Partially polarized background light is anticipated to be a significant source of systematic error for the ITER polarimeter. The proposed polarimeter is based on the standard dual photoelastic modulator approach, but with the introduction of a birefringent delay plate, it generates a sinusoidal spectral filter instead of the usual narrowband filter. The period of the filter is chosen to match the spacing of the orthogonally polarized Stark effect components, thereby increasing the effective signal level, but resulting in the destructive interference of the broadband polarized light. The theoretical response of the system to an ITER like spectrum is calculated and the broadband polarization tolerance is verified experimentally.

The Stark Effect in Linear Potentials

ERIC Educational Resources Information Center

Robinett, R. W.

2010-01-01

We examine the Stark effect (the second-order shifts in the energy spectrum due to an external constant force) for two one-dimensional model quantum mechanical systems described by linear potentials, the so-called quantum bouncer (defined by V(z) = Fz for z greater than 0 and V(z) = [infinity] for z less than 0) and the symmetric linear potential…

ac Stark-mediated quantum control with femtosecond two-color laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serrat, Carles

2005-11-15

A critical dependence of the quantum interference on the optical Stark spectral shift produced when two-color laser pulses interact with a two-level medium is observed. The four-wave mixing of two ultrashort phase-locked {omega}-3{omega} laser pulses propagating coherently in a two-level system depends on the pulses' relative phase. The phase dominating the efficiency of the coupling to the anti-Stokes Raman component is found to be determined by the sign of the total ac Stark shift induced in the system, in such a way that the phase sensitivity disappears precisely where the ac Stark effect due to both pulses is compensated. Amore » coherent control scheme based on this phenomenon can be contemplated as the basis for nonlinear optical spectroscopy techniques.« less

Higher order Stark effect and transition probabilities on hyperfine structure components of hydrogen like atoms

NASA Astrophysics Data System (ADS)

Pal'Chikov, V. G.

2000-08-01

A quantum-electrodynamical (QED) perturbation theory is developed for hydrogen and hydrogen-like atomic systems with interaction between bound electrons and radiative field being treated as the perturbation. The dependence of the perturbed energy of levels on hyperfine structure (hfs) effects and on the higher-order Stark effect is investigated. Numerical results have been obtained for the transition probability between the hfs components of hydrogen-like bismuth.

Influence of the dynamic Stark effect on long-term frequency stability of a self-oscillating magnetometer with laser-pumped alkali atoms

NASA Astrophysics Data System (ADS)

Baranov, A. A.; Ermak, S. V.; Kulachenkov, N. K.; Petrenko, M. V.; Sagitov, E. A.; Semenov, V. V.

2017-11-01

This paper presents the results of investigation Stark shift effect influence on the long-term stability of a dual scheme of quantum magnetometers. Such scheme allows suppressing Stark shift components when a certain pumping light polarization is applied. As a result, long-term stability of a quantum sensor increases. However, when low-frequency (LF) and microwave fields are attached to a single vapor cell a coherence circulation in hyperfine structure of alkali atoms takes place. Physical origin of this effect is associated with the so called “dressed” atom theory, when atom is “dressed” by LF field. It yields in multiphoton absorption and resonance frequency shift. First estimates for this shift based on density matrix evolution formalism are provided in the paper.

A Simultaneous Discovery: The Case of Johannes Stark and Antonino Lo Surdo

NASA Astrophysics Data System (ADS)

Leone, Matteo; Paoletti, Alessandro; Robotti, Nadia

2004-09-01

In 1913 the German physicist Johannes Stark (1874 1957) and the Italian physicist Antonino Lo Surdo (1880 1949)discovered virtually simultaneously and independently that hydrogen spectral lines are split into components by an external electric field. Both of their discoveries ensued from studies on the same phenomenon, the Doppler effect in canal rays, but they arose in different theoretical contexts. Stark had been working within the context of the emerging quantum theory, following a research program aimed at studying the effect of an electric field on spectral lines. Lo Surdo had been working within the context of the classical theory, and his was an accidental discovery. Both discoveries, however, played important roles in the history of physics: Stark’s discovery contributed to the establishment of both the old and the new quantum theories; Lo Surdo’s discovery led Antonio Garbasso (1871 1933)to introduce research on the quantum theory into Italian physics. Ironically, soon after their discoveries, both Stark and Lo Surdo rejected developments in modern physics and allied themselves with the political and racial programs of Hitler and Mussolini.

Heterostructure Quantum Confined Stark Effect Electrooptic Modulators Operating at 938 nm

DTIC Science & Technology

1993-12-01

type of modulator, suitable for use in optical interconnects, is an asymmetric Fabry-Perot reflection modulator (ARM). This type of an intensity ...calibrated spectrometer/diode array (Princeton Instruments Model ST-100) used in conjunction with an optical multichannel analyzer (OMA). The transmission...AD-A279 342 -" RL-TR-93-259 In -House Report December 1993N~I HETEROSTRUCTURE QUANTUM CONFINED STARK EFFECT ELECTRO- OPTIC MODULATORS OPERATING AT 938

Full color modulation of firefly luciferase through engineering with unified Stark effect.

PubMed

Cai, Duanjun; Marques, Miguel A L; Nogueira, Fernando

2013-11-07

The firefly luciferase has been a unique marking tool used in various bioimaging techniques. Extensive color modulation is strongly required to meet special marking demands; however, intentional and accurate wavelength tuning has yet to be achieved. Here, we demonstrate that the color shift of the firefly chromophore (OxyLH2-1) by internal and external fields can be described as a unified Stark shift. Electrostatic microenvironmental effects on fluorescent spectroscopy are modeled in vacuo through effective electric fields by using time-dependent density functional theory. A complete visible fluorescence spectrum of firefly chromophore is depicted, which enables one to control the emission in a specific color. As an application, the widely observed pH-correlated color shift is proved to be associated with the local Stark field generated by the trace water-ions (vicinal hydronium and hydroxide ions) at active sites close to the OxyLH2-1.

Developing Pairwise Preference-Based Personality Test and Experimental Investigation of Its Resistance to Faking Effect by Item Response Model

ERIC Educational Resources Information Center

Usami, Satoshi; Sakamoto, Asami; Naito, Jun; Abe, Yu

2016-01-01

Recent years have shown increased awareness of the importance of personality tests in educational, clinical, and occupational settings, and developing faking-resistant personality tests is a very pragmatic issue for achieving more precise measurement. Inspired by Stark (2002) and Stark, Chernyshenko, and Drasgow (2005), we develop a pairwise…

Investigations on the effects of the Stark splitting on the fluorescence behaviors in Yb3+-doped silicate, tellurite, germanate, and phosphate glasses

NASA Astrophysics Data System (ADS)

Zhang, Liaolin; Xia, Yu; Shen, Xiao; Yang, Runlan; Wei, Wei

2018-01-01

In this work, we systematically studied the spectroscopic characteristics of Yb3+ doped germanate, phosphate, silicate, and tellurite glasses. The emission peak beyond 976 nm showed irregular shift from 1001 nm to 1023 nm when Yb3+ in different glass matrices. It was associated with the Stark splitting of 2F7/2 and the emission intensities ratio between the transition from the lowest Stark splitting energy level of 2F5/2 to the Stark splitting energy levels of 2F7/2, e to b and that of e to d. Larger Stark splitting of 2F7/2 results in the red-shift of the near infrared emission band at room temperature and larger ratio results in the blue-shift of emission band. The fluorescence lifetimes of Yb3+ doped germanate, phosphate, silicate, and tellurite glasses were measured to be 0.94, 0.82, 1.51, and 0.66 ms, respectively. The fluorescence lifetime was associated with the reabsorption of Yb3+, which larger absorption cross section at the emission band results in larger reabsorption, then leads to the shorter near infrared fluorescence lifetime.

Orthogonal Electric Field Measurements near the Green Fluorescent Protein Fluorophore through Stark Effect Spectroscopy and pKa Shifts Provide a Unique Benchmark for Electrostatics Models.

PubMed

Slocum, Joshua D; First, Jeremy T; Webb, Lauren J

2017-07-20

Measurement of the magnitude, direction, and functional importance of electric fields in biomolecules has been a long-standing experimental challenge. pK a shifts of titratable residues have been the most widely implemented measurements of the local electrostatic environment around the labile proton, and experimental data sets of pK a shifts in a variety of systems have been used to test and refine computational prediction capabilities of protein electrostatic fields. A more direct and increasingly popular technique to measure electric fields in proteins is Stark effect spectroscopy, where the change in absorption energy of a chromophore relative to a reference state is related to the change in electric field felt by the chromophore. While there are merits to both of these methods and they are both reporters of local electrostatic environment, they are fundamentally different measurements, and to our knowledge there has been no direct comparison of these two approaches in a single protein. We have recently demonstrated that green fluorescent protein (GFP) is an ideal model system for measuring changes in electric fields in a protein interior caused by amino acid mutations using both electronic and vibrational Stark effect chromophores. Here we report the changes in pK a of the GFP fluorophore in response to the same mutations and show that they are in excellent agreement with Stark effect measurements. This agreement in the results of orthogonal experiments reinforces our confidence in the experimental results of both Stark effect and pK a measurements and provides an excellent target data set to benchmark diverse protein electrostatics calculations. We used this experimental data set to test the pK a prediction ability of the adaptive Poisson-Boltzmann solver (APBS) and found that a simple continuum dielectric model of the GFP interior is insufficient to accurately capture the measured pK a and Stark effect shifts. We discuss some of the limitations of this continuum-based model in this system and offer this experimentally self-consistent data set as a target benchmark for electrostatics models, which could allow for a more rigorous test of pK a prediction techniques due to the unique environment of the water-filled GFP barrel compared to traditional globular proteins.

A system for NMR stark spectroscopy of quadrupolar nuclei.

PubMed

Tarasek, Matthew R; Kempf, James G

2010-05-13

Electrostatic influences on NMR parameters are well accepted. Experimental and computational routes have been long pursued to understand and utilize such Stark effects. However, existing approaches are largely indirect informants on electric fields, and/or are complicated by multiple causal factors in spectroscopic change. We present a system to directly measure quadrupolar Stark effects from an applied electric (E) field. Our apparatus and applications are relevant in two contexts. Each uses a radiofrequency (rf) E field at twice the nuclear Larmor frequency (2omega(0)). The mechanism is a distortion of the E-field gradient tensor that is linear in the amplitude (E(0)) of the rf E field. The first uses 2omega(0) excitation of double-quantum transitions for times similar to T(1) (the longitudinal spin relaxation time). This perturbs the steady state distribution of spin population. Nonlinear analysis versus E(0) can be used to determine the Stark response rate. The second context uses POWER (perturbations observed with enhanced resolution) NMR. Here, coherent, short-time (

Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas.

PubMed

Dutra, E C; Koch, J A; Presura, R; Angermeier, W A; Darling, T; Haque, S; Mancini, R C; Covington, A M

2016-11-01

Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

Rydberg State Stark Spectroscopy and Applications to Plasma Diagnostics

DTIC Science & Technology

1990-03-01

Bayfield47 provides an excellent review of the AC Stark effect, in which the primary effect is Rabi splitting. Several authors48 , 49, 50 have...purity of the spectrum indicates that the field present is dominantly anisotropic . 53 n:26NEON LINE n=35 0 n= 40 p.- n=45 IL 0 31975 31950 31925 31900...applied (axial) electric field which is anisotropic , so pure polarization spectra can be recorded. The intensity profile of the Am = 0 polarization is

[Calculating the stark broadening of welding arc spectra by Fourier transform method].

PubMed

Pan, Cheng-Gang; Hua, Xue-Ming; Zhang, Wang; Li, Fang; Xiao, Xiao

2012-07-01

It's the most effective and accurate method to calculate the electronic density of plasma by using the Stark width of the plasma spectrum. However, it's difficult to separate Stark width from the composite spectrum linear produced by several mechanisms. In the present paper, Fourier transform was used to separate the Lorentz linear from the spectrum observed, thus to get the accurate Stark width. And we calculated the distribution of the TIG welding arc plasma. This method does not need to measure arc temperature accurately, to measure the width of the plasma spectrum broadened by instrument, and has the function to reject the noise data. The results show that, on the axis, the electron density of TIG welding arc decreases with the distance from tungsten increasing, and changes from 1.21 X 10(17) cm(-3) to 1.58 x 10(17) cm(-3); in the radial, the electron density decreases with the distance from axis increasing, and near the tungsten zone the biggest electronic density is off axis.

Measurements of the internal magnetic field on DIII-D using intensity and spacing of the motional Stark multiplet.

PubMed

Pablant, N A; Burrell, K H; Groebner, R J; Kaplan, D H; Holcomb, C T

2008-10-01

We describe a version of a motional Stark effect (MSE) diagnostic based on the relative line intensities and spacing of Stark split D(alpha) emission from the neutral beams. This system, named B-Stark, has been recently installed on the DIII-D tokamak. To find the magnetic pitch angle, we use the ratio of the intensities of the pi(3) and sigma(1) lines. These lines originate from the same upper level and so are not dependent on the level populations. In future devices, such as ITER, this technique may have advantages over diagnostics based on MSE polarimetry. We have done an optimization of the viewing direction for the available ports on DIII-D to choose the installation location. With this placement, we have a near optimal viewing angle of 59.6 degrees from the vertical direction. All hardware has been installed for one chord, and we have been routinely taking data since January 2007. We fit the spectra using a simple Stark model in which the upper level populations of the D(alpha) transition are treated as free variables. The magnitude and direction of the magnetic field obtained using this diagnostic technique compare well with measurements from MSE polarimetry and EFIT.

Dielectric waveguide gas-filled stark shift modulator

DOEpatents

Hutchinson, Donald P.; Richards, Roger K.

2003-07-22

An optical modulator includes a dielectric waveguide for receiving an optical beam and coupling energy of the optical beam into the waveguide. At least one Stark material is provided in the waveguide. A bias circuit generates a bias signal to produce an electrical field across the Stark material to shift at least one of the Stark absorption frequencies towards the frequency of the optical beam. A circuit for producing a time varying electric field across the Stark material modulates the optical beam. At least a portion of the bias field can be generated by an alternating bias signal, such as a square wave. A method of modulating optical signals includes the steps of providing a dielectric waveguide for receiving an optical beam and coupling energy of the optical beam into the waveguide, the waveguide having at least one Stark material disposed therein, and varying an electric field imposed across the Stark material.

Initial operation of a newly developed multichord motional Stark effect diagnostic in KSTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, J., E-mail: jinil@nfri.re.kr; Ko, J.; Wi, H.

2016-11-15

A photo-elastic modulator based 25-chord motional Stark effect (MSE) diagnostic has been successfully developed and commissioned in Korea Superconducting Tokamak Advanced Research. The diagnostic measures the radial magnetic pitch angle profile of the Stark splitting of a D-alpha line at 656.1 nm by the electric field associated with the neutral deuterium heating beam. A tangential view of the neutral beam provides a good spatial resolution of 1–3 cm for covering the major radius from 1.74 m to 2.28 m, and the time resolution is achieved at 10 ms. An in-vessel calibration before the vacuum closing as well as an inmore » situ calibration during the tokamak operation was performed by means of specially designed polarized lighting sources. In this work, we present the final design of the installed MSE diagnostic and the first results of the commissioning.« less

Stark parameter dependence of the rest core charge of the emitters for multiply charged ions spectral lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Šćepanović, M., E-mail: mara.scepanovic@gmail.com; Purić, J.

2016-03-25

Stark width and shift simultaneous dependence on the upper level ionization potential and rest core charge of the emitter has been evaluated and discussed. It has been verified that the found relations, connecting Stark broadening parameters with upper level ionization potential and rest core charge of the emitters for particular electron temperature and density, can be used for prediction of Stark line width and shift data in case of ions for which observed data, or more detailed calculations, are not yet available. Stark widths and shifts published data are used to demonstrate the existence of other kinds of regularities withinmore » similar spectra of different elements and their ionization stages. The emphasis is on the Stark parameter dependence on the upper level ionization potential and on the rest core charge for the lines from similar spectra of multiply charged ions. The found relations connecting Stark widths and shift parameters with upper level ionization potential, rest core charge and electron temperature were used for a prediction of new Stark broadening data, thus avoiding much more complicated procedures.« less

Stark broadening parameters and transition probabilities of persistent lines of Tl II

NASA Astrophysics Data System (ADS)

de Andrés-García, I.; Colón, C.; Fernández-Martínez, F.

2018-05-01

The presence of singly ionized thallium in the stellar atmosphere of the chemically peculiar star χ Lupi was reported by Leckrone et al. in 1999 by analysis of its stellar spectrum obtained with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. Atomic data about the spectral line of 1307.50 Å and about the hyperfine components of the spectral lines of 1321.71 Å and 1908.64 Å were taken from different sources and used to analyse the isotopic abundance of thallium II in the star χ Lupi. From their results the authors concluded that the photosphere of the star presents an anomalous isotopic composition of Tl II. A study of the atomic parameters of Tl II and of the broadening by the Stark effect of its spectral lines (and therefore of the possible overlaps of these lines) can help to clarify the conclusions about the spectral abundance of Tl II in different stars. In this paper we present calculated values of the atomic transition probabilities and Stark broadening parameters for 49 spectral lines of Tl II obtained by using the Cowan code including core polarization effects and the Griem semiempirical approach. Theoretical values of radiative lifetimes for 11 levels (eight with experimental values in the bibliography) are calculated and compared with the experimental values in order to test the quality of our results. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed. Trends of our calculated Stark width for the isoelectronic sequence Tl II-Pb III-Bi IV are also displayed.

A model of magnetic and relaxation properties of the mononuclear [Pc2Tb](-)TBA+ complex.

PubMed

Reu, O S; Palii, A V; Ostrovsky, S M; Tregenna-Piggott, P L W; Klokishner, S I

2012-10-15

The present work is aimed at the elaboration of the model of magnetic properties and magnetic relaxation in the mononuclear [Pc(2)Tb](-)TBA(+) complex that displays single-molecule magnet properties. We calculate the Stark structure of the ground (7)F(6) term of the Tb(3+) ion in the exchange charge model of the crystal field, taking account for covalence effects. The ground Stark level of the complex possesses the maximum value of the total angular momentum projection, while the energies of the excited Stark levels increase with decreasing |M(J)| values, thus giving rise to a barrier for the reversal of magnetization. The one-phonon transitions between the Stark levels of the Tb(3+) ion induced by electron-vibrational interaction are shown to lead to magnetization relaxation in the [Pc(2)Tb](-)TBA(+) complex. The rates of all possible transitions between the low-lying Stark levels are calculated in the temperature range 14 K

Stark widths regularities within spectral series of sodium isoelectronic sequence

NASA Astrophysics Data System (ADS)

Trklja, Nora; Tapalaga, Irinel; Dojčinović, Ivan P.; Purić, Jagoš

2018-02-01

Stark widths within spectral series of sodium isoelectronic sequence have been studied. This is a unique approach that includes both neutrals and ions. Two levels of problem are considered: if the required atomic parameters are known, Stark widths can be calculated by some of the known methods (in present paper modified semiempirical formula has been used), but if there is a lack of parameters, regularities enable determination of Stark broadening data. In the framework of regularity research, Stark broadening dependence on environmental conditions and certain atomic parameters has been investigated. The aim of this work is to give a simple model, with minimum of required parameters, which can be used for calculation of Stark broadening data for any chosen transitions within sodium like emitters. Obtained relations were used for predictions of Stark widths for transitions that have not been measured or calculated yet. This system enables fast data processing by using of proposed theoretical model and it provides quality control and verification of obtained results.

Sensitivity of equilibrium profile reconstruction to motional Stark effect measurements

NASA Astrophysics Data System (ADS)

Batha, S. H.; Levinton, F. M.; Hirshman, S. P.; Bell, M. G.; Wieland, R. M.

1996-09-01

The magnetic-field pitch-angle profile, gamma p(R) identical to tan-1(Bpol/Btor), is measured on TFTR using a motional Stark effect (MSE) polarimeter. Measured pitch angle profiles, along with kinetic profiles and external magnetic measurements, are used to compute a self-consistent equilibrium using the free-boundary variational moments equilibrium code VMEC. Uncertainties in the q profile due to uncertainties in gamma P(R), magnetic measurements and kinetic measurements are found to be small. Subsequent uncertainties in the VMEC-calculated current density and shear profiles are also small

Stark cell optoacoustic detection of constituent gases in sample

NASA Technical Reports Server (NTRS)

Margolis, J. S.; Shumate, M. S. (Inventor)

1980-01-01

An optoacoustic detector for gas analysis is implemented with Stark effect cell modulation for switching a beam in and out of coincidence with a spectral line of a constituent gas in order to eliminate the heating effect of laser energy in the cell as a source of background noise. By using a multiline laser, and linearly sweeping the DC bias voltage while exciting the cell with a multiline laser, it is possible to obtain a spectrum from which to determine the combinations of excited constituents and determine their concentrations in parts per million.

Stark effect of Ar I lines for electric field strength diagnostics in the cathode sheath of glow discharge

NASA Astrophysics Data System (ADS)

Vasiljević, Milica M.; Spasojević, Djordje; Šišović, Nikola M.; Konjević, Nikola

2017-09-01

We present a study of argon glow discharge which shows that measured wavenumber DC Stark shifts Δ ν of two neutral argon lines, Ar I 518.75 nm and Ar I 522.127 nm, can be used for reliable determination of the electric field strength F distribution in the cathode sheath region of the discharge. In order to experimentally determine the coefficient c in quadratic correlation Δ ν =cF2 , manifested in a low field range (up to 15 kV/cm), the discharge is seeded with a small admixture of hydrogen, and the values of F are measured via Stark polarization spectroscopy of the hydrogen Balmer beta line. Once known, this can be used for the determination of F by a simple and inexpensive spectroscopic Stark shift measurement in discharges with other argon admixtures or pure argon. Reported shift results are in good agreement with data extrapolated from measurements performed at high electric fields (over 100 kV/cm) by Windholz (Phys. Scr., 21 (1980) 67).

Dynamic-Stark-effect-induced coherent mixture of virtual paths in laser-dressed helium: energetic electron impact excitation

NASA Astrophysics Data System (ADS)

Agueny, Hicham; Makhoute, Abdelkader; Dubois, Alain

2017-06-01

We theoretically investigate quantum virtual path interference caused by the dynamic Stark effect in bound-bound electronic transitions. The effect is studied in an intermediate resonant region and in connection with the energetic electron impact excitation of a helium atom embedded in a weak low-frequency laser field. The process under investigation is dealt with via a Born-Floquet approach. Numerical calculations show a resonant feature in laser-assisted cross sections. The latter is found to be sensitive to the intensity of the laser field dressing. We show that this feature is a signature of quantum beats which result from the coherent mixture of different quantum virtual pathways, and that excitation may follow in order to end up with a common final channel. This mixture arises from the dynamic Stark effect, which produces a set of avoided crossings in laser-dressed states. The effect allows one to coherently control quantum virtual path interference by varying the intensity of the laser field dressing. Our findings suggest that the combination of an energetic electron and a weak laser field is a useful tool for the coherent control of nonadiabatic transitions in an intermediate resonant region.

Dynamic Stark broadening as the Dicke narrowing effect

NASA Astrophysics Data System (ADS)

Calisti, A.; Mossé, C.; Ferri, S.; Talin, B.; Rosmej, F.; Bureyeva, L. A.; Lisitsa, V. S.

2010-01-01

A very fast method to account for charged particle dynamics effects in calculations of spectral line shape emitted by plasmas is presented. This method is based on a formulation of the frequency fluctuation model (FFM), which provides an expression of the dynamic line shape as a functional of the static distribution of frequencies. Thus, the main numerical work rests on the calculation of the quasistatic Stark profile. This method for taking into account ion dynamics allows a very fast and accurate calculation of Stark broadening of atomic hydrogen high- n series emission lines. It is not limited to hydrogen spectra. Results on helium- β and Lyman- α lines emitted by argon in microballoon implosion experiment conditions compared with experimental data and simulation results are also presented. The present approach reduces the computer time by more than 2 orders of magnitude as compared with the original FFM with an improvement of the calculation precision, and it opens broad possibilities for its application in spectral line-shape codes.

Quadratic stark effect in the fullerene C60 at low symmetry orientation in the field

NASA Astrophysics Data System (ADS)

Tuchin, A. V.; Bityutskaya, L. A.; Bormontov, E. N.

2014-08-01

Results of numeric simulation of the influence of the electric field E = 0 - 1 V/Å on the electronic structure of the neutral fullerene C60 taking into account orientational deformation of its carbon cage at arbitrary orientations in the electric field including low symmetry orientations are presented. Splitting of the frontier t 1 u - and h u -levels of the molecule due to the quadratic Stark effect has been investigated. Dependencies of the effective electron work function and the energy gap between the lowest unoccupied and highest occupied molecular orbitals on the strengths of the electric field have been determined.

Supersonic Molecular Beam Optical Stark Spectroscopy of MnH.

NASA Astrophysics Data System (ADS)

Gengler, Jamie; Ma, Tongmei; Harrison, Jeremy; Steimle, Timothy

2006-03-01

The large moment of inertia, large magnetic moment, and possible large permanent electric dipole moment of manganese monohydride, MnH, makes it a prime candidate for ultra-cold molecule production via Stark deceleration and magnetic trapping. Here we report the first molecular beam production of MnH and the analysis of the Stark effect in the (0,0) A^7 π -- X^ 7σ^+ band. The sample was prepared by laser ablation of solid Mn in an H2 supersonic expansion. The low rotational temperature (<50 K) and near natural linewidth resolution (˜50 MHz) facilitated analysis of the ^55Mn (I=5/2) and ^1H (I=1/2) hyperfine structure. A comparison of the derived field-free parameters with those obtained from sub- Doppler optical measurements will be made. Progress on the analysis of the Stark effect will be given. J.R. Bochinski, E.R. Hudson, H.J. Lewandowski, and J. Ye, Phys. Rev. A 70, 043410 (2004). S.Y.T. van de Meerakker, R.T. Jongma, H.L. Bethlem, and G. Meijer, Phys. Rev. A 64, 041401(R) (2001) report the first molecular beam production of MnH and the analysis of T.D. Varberg, J.A. Gray, R.W. Field, and A.J. Merer, J. Mol. Spec. 156, 296-318 (1992). I.E. Gordon, D.R.T. Appadoo, A. Shayesteh, K.A. Walker, and P.F. Bernath, J. Mol. Spec., 229, 145-149 (2005).

Stark-shift of impurity fundamental state in a lens shaped quantum dot

NASA Astrophysics Data System (ADS)

Aderras, L.; Bah, A.; Feddi, E.; Dujardin, F.; Duque, C. A.

2017-05-01

We calculate the Stark effect and the polarisability of shallow-donor impurity located in the centre of lens shaped quantum dot by a variational method and in the effective-mass approximation. Our theoretical model assumes an infinite confinement to describe the barriers at the dot boundaries and the electric field is considered to be applied in the z-direction. The systematic theoretical investigation contains results with the quantum dot size and the strength of the external field. Our calculations reveal that the interval wherein the polarisability varies depends strongly on the dot size.

On the Stark broadening of Cr VI spectral lines in astrophysical plasma

NASA Astrophysics Data System (ADS)

Dimitrijević, M. S.; Simić, Z.; Sahal-Bréchot, S.

2017-02-01

Stark broadening parameters for Cr VI lines have been calculated using semiclassical perturbation method for conditions of interest for stellar plasma. Here are presented, as an example of obtained results, Stark broadening parameters for electron- and proton-impact broadening for Cr VI 4s 2S-4p 2P° λ = 1430 Å and Cr VI 4p 2P°-5s 2S λ = 611.8 Å multiplets. The obtained results are used to demonstrate the importance of Stark broadening of Cr VI in DO white dwarf atmospheres. Also the obtained results will enter in STARK-B database which is included in Virtual Atomic and Molecula Data Center - VAMDC.

High-pressure and stark hole-burning studies of chlorosome antennas from Chlorobium tepidum.

PubMed

Wu, H M; Rätsep, M; Young, C S; Jankowiak, R; Blankenship, R E; Small, G J

2000-09-01

Results from high-pressure and Stark hole-burning experiments on isolated chlorosomes from the green sulfur bacterium Chlorobium tepidum are presented, as well as Stark hole-burning data for bacteriochlorophyll c (BChl c) monomers in a poly(vinyl butyral) copolymer film. Large linear pressure shift rates of -0.44 and -0.54 cm(-1)/MPa were observed for the chlorosome BChl c Q(y)-band at 100 K and the lowest Q(y)-exciton level at 12 K, respectively. It is argued that approximately half of the latter shift rate is due to electron exchange coupling between BChl c molecules. The similarity between the above shift rates and those observed for the B875 and B850 BChl a rings of the light-harvesting complexes of purple bacteria is emphasized. For BChl c monomer, fDeltamu++ = 0.35 D, where Deltamu+ is the dipole moment change for the Q(y) transition and f is the local field correction factor. The data establish that Deltamu+ is dominated by the matrix-induced contribution. The change in polarizability (Deltaalpha) for the Q(y) transition of the BChl c monomer is estimated at 19 A(3), which is essentially identical to that of the Chl a monomer. Interestingly, no Stark effects were observed for the lowest exciton level of the chlorosomes (maximum Stark field of 10(5) V/cm). Possible explanations for this are given, and these include consideration of structural models for the chlorosome BChl c aggregates.

Contour shape analysis of hollow ion x-ray emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosmej, F. B.; Angelo, P.; Ecole Polytechnique, Laboratoire pour Utilisation des Lasers Intenses, Physique Atomique dans les Plasmas Denses, 91128 Palaiseau Cedex

2008-10-22

Hollow ion x-ray transitions originating from the configurations K{sup 0}L{sup N} have been studied via relativistic atomic structure and Stark broadening calculations. The broadening of the total contour is largely influenced by the oscillator strengths distribution over wavelengths rather than by Stark broadening alone. Interference effects between the upper and lower levels are shown to result in a considerable contour narrowing as well as in a shift of the total contour which could be either red or blue.

Stark width regularities within spectral series of the lithium isoelectronic sequence

NASA Astrophysics Data System (ADS)

Tapalaga, Irinel; Trklja, Nora; Dojčinović, Ivan P.; Purić, Jagoš

2018-03-01

Stark width regularities within spectral series of the lithium isoelectronic sequence have been studied in an approach that includes both neutrals and ions. The influence of environmental conditions and certain atomic parameters on the Stark widths of spectral lines has been investigated. This study gives a simple model for the calculation of Stark broadening data for spectral lines within the lithium isoelectronic sequence. The proposed model requires fewer parameters than any other model. The obtained relations were used for predictions of Stark widths for transitions that have not yet been measured or calculated. In the framework of the present research, three algorithms for fast data processing have been made and they enable quality control and provide verification of the theoretically calculated results.

Overflow of a dipolar exciton trap at high magnetic fields

NASA Astrophysics Data System (ADS)

Dietl, Sebastian; Kowalik-Seidl, Katarzyna; Hammer, Lukas; Schuh, Dieter; Wegscheider, Werner; Holleitner, Alexander; Wurstbauer, Ursula

We study the photoluminescence of trapped dipolar excitons (IX) in coupled double GaAs quantum wells at low temperatures and high magnetic fields. A voltage-tunable electrode geometry controls the strength of the quantum confined Stark effect and defines the lateral trapping potential. Furthermore, it enhances the IX lifetime, enabling them to cool down to lattice temperature. We show that a magnetic field in Faraday configuration effectively prevents the escape of unbound photogenerated charge carriers from the trap area, thus increasing the density of dipolar excitons. For large magnetic fields, we observe an overflow of the IX trap and an effectively suppressed quantum confined Stark effect. We acknowledge financial support by the German Excellence Initiative via the Nanosystems Initiative Munich (NIM).

Uncertainty propagation in q and current profiles derived from motional Stark effect polarimetry on TFTR (abstract)a)

NASA Astrophysics Data System (ADS)

Batha, S. H.; Levinton, F. M.; Bell, M. G.; Wieland, R. M.; Hirschman, S. P.

1995-01-01

The magnetic-field pitch-angle profile, γp(R)≡arctan(Bpol/Btor), is measured on the TFTR tokamak using a motional Stark effect (MSE) polarimeter. Measured profiles are converted to q profiles with the equilibrium code vmec. Uncertainties in the q profile due to uncertainties in the γp(R), magnetics, and kinetic measurements are quantified. Subsequent uncertainties in the vmec-calculated profiles of current density and shear, both of which are important for stability and transport analyses, are also quantified. Examples of circular plasmas under various confinement modes, including the supershot and L mode, will be given.

Imaging motional Stark effect measurements at ASDEX Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, O. P.; Burckhart, A.; McDermott, R.

2016-11-15

This paper presents an overview of results from the Imaging Motional Stark Effect (IMSE) diagnostic obtained during its first measurement campaign at ASDEX Upgrade since installation as a permanent diagnostic. A brief overview of the IMSE technique is given, followed by measurements of a standard H-mode discharge, which are compared to equilibrium reconstructions showing good agreement where expected. The development of special discharges for the calibration of pitch angle is reported and safety factor profile changes during sawteeth crashes are shown, which can be resolved to a few percent due to the high sensitivity at good time resolution of themore » new IMSE system.« less

The Stark truth: what your physician clients should know about Stark Law and the Anti-Kickback Statute.

PubMed

Taormina, Melissa

2013-01-01

This article summarizes key features of Stark Law and the Anti-Kickback Statute, statutes used to fight health care fraud and abuse within Medicare and Medicaid, and explains how attorneys can help health care providers comply with these laws.

Quantum confined Stark effect in organic fluorophores.

NASA Astrophysics Data System (ADS)

Peng, Xihong; Anderson, John; Tepper, Gary; Bandyopadhyay, Supriyo; Nayak, Saroj

2008-03-01

Fluorescent molecules have widely been used to detect and visualize structure and processes in biological samples due to its extraordinary sensitivity. However, the emission spectra of flurophores are usually broad and the accurate identification is difficult. Recently, experiments show that energy shifts by Stark effect can be used to aid the identification of organic molecules [1]. Stark effect originates from the shifting/splitting of energy levels when a molecule is under an external electric field, which shows a shift/splitting of a peak in absorption/emission spectra. The size of the shift depends on the magnitude of the external field and the molecular structure. In this talk we will show our theoretical study of the peak shifts on emission spectra for a series of organic fluorophores such as tyrosine, tryptophan, rhodamine123 and coumarin314 using density functional theory. We find that a particular peak shift is determined by the local dipole moments of molecular orbitals rather than the global dipole moment of the molecule. These molecular-specific shifts in emission spectra may enable to improve molecular identification in biosensors. Our results will be compared with experimental data. [1]Unpublished, S. Sarkar, B. Kanchibotla, S. Bandyopadhyay, G. Tepper, J. Edwards, J. Anderson, and R. Kessick.

The paradox of progress: translating Evan Stark's Coercive Control into legal doctrine for abused women.

PubMed

Hanna, Cheryl

2009-12-01

This article examines Evan Stark's model of coercive control and what this paradigm shift might mean for the law. Coercive control can help redefine both criminal offenses involving domestic violence and defenses available to women who kill their abusers. This redefinition would shift the law away from incident-based violence and toward a more comprehensive and accurate paradigm that accounts for the deprivation of a woman's autonomy within the context of an abusive relationship. Such a change would likely provide more effective state intervention into what were once considered private relationships. Yet, this approach may also have some unintended consequences, including refocusing the law on a victim's mental state and complicity in her own abuse rather than on the harm caused by abusive men. Thus, although the law should more fully account for coercive control, lawyers must be cautiously optimistic in implementing Stark's proposed reforms.

Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch

DOE PAGES

Vogman, G. V.; Shumlak, U.

2011-10-13

Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian functionmore » associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. As a result, these measurements are used to gain a better understanding of Z-pinch equilibria.« less

Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogman, G. V.; Shumlak, U.

2011-10-15

Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian functionmore » associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. These measurements are used to gain a better understanding of Z-pinch equilibria.« less

Vibrational Stark Effects of Carbonyl Probes Applied to Reinterpret IR and Raman Data for Enzyme Inhibitors in Terms of Electric Fields at the Active Site.

PubMed

Schneider, Samuel H; Boxer, Steven G

2016-09-15

IR and Raman frequency shifts have been reported for numerous probes of enzyme transition states, leading to diverse interpretations. In the case of the model enzyme ketosteroid isomerase (KSI), we have argued that IR spectral shifts for a carbonyl probe at the active site can provide a connection between the active site electric field and the activation free energy (Fried et al. Science 2014, 346, 1510-1514). Here we generalize this approach to a much broader set of carbonyl probes (e.g., oxoesters, thioesters, and amides), first establishing the sensitivity of each probe to an electric field using vibrational Stark spectroscopy, vibrational solvatochromism, and MD simulations, and then applying these results to reinterpret data already in the literature for enzymes such as 4-chlorobenzoyl-CoA dehalogenase and serine proteases. These results demonstrate that the vibrational Stark effect provides a general framework for estimating the electrostatic contribution to the catalytic rate and may provide a metric for the design or modification of enzymes. Opportunities and limitations of the approach are also described.

Interface induced spin-orbit interaction in silicon quantum dots and prospects of scalability

NASA Astrophysics Data System (ADS)

Ferdous, Rifat; Wai, Kok; Veldhorst, Menno; Hwang, Jason; Yang, Henry; Klimeck, Gerhard; Dzurak, Andrew; Rahman, Rajib

A scalable quantum computing architecture requires reproducibility over key qubit properties, like resonance frequency, coherence time etc. Randomness in these properties would necessitate individual knowledge of each qubit in a quantum computer. Spin qubits hosted in Silicon (Si) quantum dots (QD) is promising as a potential building block for a large-scale quantum computer, because of their longer coherence times. The Stark shift of the electron g-factor in these QDs has been used to selectively address multiple qubits. From atomistic tight-binding studies we investigated the effect of interface non-ideality on the Stark shift of the g-factor in a Si QD. We find that based on the location of a monoatomic step at the interface with respect to the dot center both the sign and magnitude of the Stark shift change. Thus the presence of interface steps in these devices will cause variability in electron g-factor and its Stark shift based on the location of the qubit. This behavior will also cause varying sensitivity to charge noise from one qubit to another, which will randomize the dephasing times T2*. This predicted device-to-device variability is experimentally observed recently in three qubits fabricated at a Si/Si02 interface, which validates the issues discussed.

Influence of F- on stark splitting of Yb3+ and the thermal expansion of silica glass

NASA Astrophysics Data System (ADS)

Cao, Yabin; Chen, Si; Shao, Chongyun; Yu, Chunlei

2018-06-01

A local phosphate/fluoride environment of Yb3+ was created in silica glass using a multi-step method. The influence of F- on the Stark splitting of Yb3+ in Al3+/P5+/F- co-doped silica glass was studied at room-temperature, in addition to its effect on the thermal expansion performance of the glass matrix. The results indicate that Yb3+ ions in Al3+/P5+/F- co-doped silica glass have a larger Stark splitting energy of 2F7/2 compared to Al3+/P5+ co-doped silica glass. Moreover, a larger integrated absorption cross-section (34.58 pm2 × nm), stimulated emission cross-section (0.63 pm2), and better thermal expansion performance (1.3062 × 10-6 K- at 100 °C) are achieved in Al3+/P5+/F- co-doped silica glass. Finally, different function mechanisms of F- in silica and phosphate glasses were analyzed and the F-Si bond was used to explain the results in silica glass. The combination of low refractive index, large Stark splitting energy of 2F7/2, and small thermal expansion makes Al3+/P5+/F- co-doped silica glass a preferred material for large mode area fibers for high-power laser applications.

Demonstration of an all-optical feed-forward delay line buffer using the quadratic Stark effect and two-photon absorption in an SOA.

PubMed

Soto, Horacio; Tong, Miriam A; Domínguez, Juan C; Muraoka, Ramón

2017-09-04

We have inserted into an unbiased semiconductor optical amplifier (SOA) a powerful control beam, with photon energy slightly smaller than that of the band-gap of its active region, for exciting two-photon absorption and the quadratic Stark effect. For the available SOA, we estimated these phenomena generated a nonlinear absorption coefficient β= -865 cm/GW and induced an appreciable birefringence inside the amplifier waveguide, which significantly modified the polarization-state of a probe beam. Based on these effects, we have experimentally demonstrated the operation of an all-optical buffer, using an 80 Gb/s optical pulse comb, as well as an unbiased SOA, which was therefore, devoid of amplified spontaneous emission and pattern effects.

NONLINEAR AND FIBER OPTICS: Influence of the Stark effect on the nature of stimulated Raman scattering of ultrashort adiabatic pump radiation

NASA Astrophysics Data System (ADS)

Kryzhanovskiĭ, B. V.

1990-04-01

An investigation is made of the serious limitations on the growth of the amplitude of a Stokes wave associated with the optical Stark effect and with the dispersion of the group velocities of the interacting pulses. It is shown that when the distance traversed exceeds a certain length, the gain due to stimulated Raman scattering reaches saturation whereas the spectrum of the scattered light becomes broader and acquires a line structure. Saturation of the scattering is not manifested at pump intensities sufficient to bleach the scattering medium. The gain can be optimized by altering the offset from a resonance.

Two-point motional Stark effect diagnostic for Madison Symmetric Torus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ko, J.; Den Hartog, D. J.; Caspary, K. J.

2010-10-15

A high-precision spectral motional Stark effect (MSE) diagnostic provides internal magnetic field measurements for Madison Symmetric Torus (MST) plasmas. Currently, MST uses two spatial views - on the magnetic axis and on the midminor (off-axis) radius, the latter added recently. A new analysis scheme has been developed to infer both the pitch angle and the magnitude of the magnetic field from MSE spectra. Systematic errors are reduced by using atomic data from atomic data and analysis structure in the fit. Reconstructed current density and safety factor profiles are more strongly and globally constrained with the addition of the off-axis radiusmore » measurement than with the on-axis one only.« less

Direct measurements of safety factor profiles with motional Stark effect for KSTAR tokamak discharges with internal transport barriers

NASA Astrophysics Data System (ADS)

Ko, J.; Chung, J.

2017-06-01

The safety factor profile evolutions have been measured from the plasma discharges with the external current drive mechanism such as the multi-ion-source neutral beam injection for the Korea Superconducting Tokamak Advanced Research (KSTAR) for the first time. This measurement has been possible by the newly installed motional Stark effect (MSE) diagnostic system that utilizes the polarized Balmer-alpha emission from the energetic neutral deuterium atoms induced by the Stark effect under the Lorentz electric field. The 25-channel KSTAR MSE diagnostic is based on the conventional photoelastic modulator approach with the spatial and temporal resolutions less than 2 cm (for the most of the channels except 2 to 3 channels inside the magnetic axis) and about 10 ms, respectively. The strong Faraday rotation imposed on the optical elements in the diagnostic system is calibrated out from a separate and well-designed polarization measurement procedure using an in-vessel reference polarizer during the toroidal-field ramp-up phase before the plasma experiment starts. The combination of the non-inductive current drive during the ramp-up and shape control enables the formation of the internal transport barrier where the pitch angle profiles indicate flat or slightly hollow profiles in the safety factor.

Regularities And Irregularities Of The Stark Parameters For Single Ionized Noble Gases

NASA Astrophysics Data System (ADS)

Peláez, R. J.; Djurovic, S.; Cirišan, M.; Aparicio, J. A.; Mar S.

2010-07-01

Spectroscopy of ionized noble gases has a great importance for the laboratory and astrophysical plasmas. Generally, spectra of inert gases are important for many physics areas, for example laser physics, fusion diagnostics, photoelectron spectroscopy, collision physics, astrophysics etc. Stark halfwidths as well as shifts of spectral lines are usually employed for plasma diagnostic purposes. For example atomic data of argon krypton and xenon will be useful for the spectral diagnostic of ITER. In addition, the software used for stellar atmosphere simulation like TMAP, and SMART require a large amount of atomic and spectroscopic data. Availability of these parameters will be useful for a further development of stellar atmosphere and evolution models. Stark parameters data of spectral lines can also be useful for verification of theoretical calculations and investigation of regularities and systematic trends of these parameters within a multiplet, supermultiplet or transition array. In the last years, different trends and regularities of Stark parameters (halwidths and shifts of spectral lines) have been analyzed. The conditions related with atomic structure of the element as well as plasma conditions are responsible for regular or irregular behaviors of the Stark parameters. The absence of very close perturbing levels makes Ne II as a good candidate for analysis of the regularities. Other two considered elements Kr II and Xe II with complex spectra present strong perturbations and in some cases an irregularities in Stark parameters appear. In this work we analyze the influence of the perturbations to Stark parameters within the multiplets.

Runge-Lenz wave packet in multichannel Stark photoionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Texier, F.

2005-01-01

In a previous slow photoionization experiment, modulations of ionization rings were manifested for Xe in a constant electric field. The present quantum calculation reveals that the modulation is an effect of the multichannel core scattering and of tunneling waves through the Coulomb-Stark potential barrier: the barrier reduces the number of oscillations that is observed relatively to the number of oscillations of the short range wave functions, and the nonhydrogenic core phase shifts modify the position of the ionization rings. We find a hidden difference, in the ionization process, for two close values of the energy depending on the resonance withmore » the barrier. The ionization intensity is interpreted as a Runge-Lenz wave packet; thus, we can relate the quantum modulation to the classical Coulomb-Stark trajectories. The Runge-Lenz wave packet differs from a usual temporal wave packet because its components are eigenstates of the Runge-Lenz vector z projection and its evolution is not temporal but spatial.« less

Non-resonant dynamic stark control of vibrational motion with optimized laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, Esben F.; Henriksen, Niels E.

2016-06-28

The term dynamic Stark control (DSC) has been used to describe methods of quantum control related to the dynamic Stark effect, i.e., a time-dependent distortion of energy levels. Here, we employ analytical models that present clear and concise interpretations of the principles behind DSC. Within a linearly forced harmonic oscillator model of vibrational excitation, we show how the vibrational amplitude is related to the pulse envelope, and independent of the carrier frequency of the laser pulse, in the DSC regime. Furthermore, we shed light on the DSC regarding the construction of optimal pulse envelopes — from a time-domain as wellmore » as a frequency-domain perspective. Finally, in a numerical study beyond the linearly forced harmonic oscillator model, we show that a pulse envelope can be constructed such that a vibrational excitation into a specific excited vibrational eigenstate is accomplished. The pulse envelope is constructed such that high intensities are avoided in order to eliminate the process of ionization.« less

Femtochemistry in the electronic ground state: Dynamic Stark control of vibrational dynamics

NASA Astrophysics Data System (ADS)

Shu, Chuan-Cun; Thomas, Esben F.; Henriksen, Niels E.

2017-09-01

We study the interplay of vibrational and rotational excitation in a diatomic molecule due to the non-resonant dynamic Stark effect. With a fixed peak intensity, optimal Gaussian pulse durations for maximizing vibrational or rotational transitions are obtained analytically and confirmed numerically for the H2 and Cl2 molecules. In general, pulse trains or more advanced pulse shaping techniques are required in order to obtain significant vibrational excitation. To that end, we demonstrate that a high degree of selectivity between vibrational and rotational excitation is possible with a suitably phase-modulated Gaussian pulse.

The second species of Phanoperla (Plecoptera: Perlidae) from China, P. hainana sp. nov., from Hainan Island.

PubMed

Li, Weihai; Qin, Xuefeng

2016-09-08

The genus Phanoperla Banks was originally established as a subgenus of Neoperla and its genus delimitation was not fully clear until the revisionary work by Zwick (1982). It currently contains 49 known species from the Oriental region (Banks 1938, 1939, Cao & Bae 2009, Cao et al. 2007, DeWalt et al. 2016, Jewett 1975, Kawai 1968, Stark 1983, 1987, Stark & Sheldon 2009, Sivec & Stark 2010, 2011, Stark & Sivec 2007, Sivec et al. 1988, Zwick 1982, Zwick 1986, Zwick & Sivec 1985). Although species of Phanoperla are not rare in many areas of Southeast Asia bordering China, especially Vietnam and India (Cao & Bae 2009, Mason & Stark 2015), P. pallipennis Banks, 1938 is the only known species of the genus known from China. In this paper, we describe a new species of Phanoperla from Hainan Island of the southernmost province of China. The northern portion of the island has a humid subtropical climate, whereas the remainder of the island has tropical monsoon climate.

Solid state optical refrigeration using stark manifold resonances in crystals

DOEpatents

Seletskiy, Denis V.; Epstein, Richard; Hehlen, Markus P.; Sheik-Bahae, Mansoor

2017-02-21

A method and device for cooling electronics is disclosed. The device includes a doped crystal configured to resonate at a Stark manifold resonance capable of cooling the crystal to a temperature of from about 110K to about 170K. The crystal host resonates in response to input from an excitation laser tuned to exploit the Stark manifold resonance corresponding to the cooling of the crystal.

Measurements with magnetic field in the National Spherical Torus Experiment using the motional Stark effect with laser induced fluorescence diagnostic

NASA Astrophysics Data System (ADS)

Foley, E. L.; Levinton, F. M.

2013-04-01

The motional Stark effect with laser-induced fluorescence diagnostic (MSE-LIF) has been installed and tested on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab. The MSE-LIF diagnostic will be capable of measuring radially resolved profiles of magnetic field magnitude or pitch angle in NSTX plasmas. The system includes a diagnostic neutral hydrogen beam and a laser which excites the n = 2 to n = 3 transition. A viewing system has been implemented which will support up to 38 channels from the plasma edge to past the magnetic axis. First measurements of MSE-LIF signals in the presence of small applied magnetic fields in neutral gas are reported.

Implementation of quantum logic gates via Stark-tuned Förster resonance in Rydberg atoms

NASA Astrophysics Data System (ADS)

Huang, Xi-Rong; Hu, Chang-Sheng; Shen, Li-Tuo; Yang, Zhen-Biao; Wu, Huai-Zhi

2018-02-01

We present a scheme for implementation of controlled-Z and controlled-NOT gates via rapid adiabatic passage and Stark-tuned Förster resonance. By sweeping the Förster resonance once without passing through it and adiabatically tuning the angle-dependent Rydberg-Rydberg interaction of the dipolar nature, the system can be effectively described by a two-level system with the adiabatic theorem. The single adiabatic passage leads to a gate fidelity as high as 0.999 and a greatly reduced gate operation time. We investigate the scheme by considering an actual atomic level configuration with rubidium atoms, where the fidelity of the controlled-Z gate is still higher than 0.99 under the influence of the Zeeman effect.

Stark laws and fair market value exceptions: an introduction.

PubMed

Siebrasse, Paul B

2007-01-01

This article will focus on one aspect of complexity in modern healthcare, namely the implications of Stark laws and other fraud and abuse provisions, including anti-kickback statutes and HIPAA. Also, this article explores the prevalence of fair market value as an exception in the Stark laws and discusses the meanings of those exceptions. Finally, the article explores basic approaches to assessing fair market value, including cost, income, and marketing approaches.

Stark problem in terms of the Stokes multipliers for the triconfluent Heun equation

NASA Astrophysics Data System (ADS)

Osherov, V. I.; Ushakov, V. G.

2013-11-01

The solution of the Stark problem is obtained in terms of the Stokes multipliers for the triconfluent Heun equation (the quartic oscillator equation). The Stokes multipliers are found in an analytical form at positive energies. For negative energies, the Stokes parameters are calculated in frames of a consistent asymptotic approach. The scattering phase, positions, and widths of the Stark resonances are determined as solutions of an implicit equation.

Stark broadening of resonant Cr II 3d5-3d44p spectral lines in hot stellar atmospheres

NASA Astrophysics Data System (ADS)

Simić, Z.; Dimitrijević, M. S.; Sahal-Bréchot, S.

2013-07-01

New Stark broadening parameters of interest for the astrophysical, laboratory and technological plasma modelling, investigations and analysis for nine resonant Cr II multiplets have been determined within the semiclassical perturbation approach. In order to demonstrate one possibility for their usage in astrophysical plasma research, obtained results have been applied to the analysis of the Stark broadening influence on stellar spectral line shapes.

The Stark Effect on the Wave Function of Tritium in Relativistic Condition

NASA Astrophysics Data System (ADS)

Supriadi, B.; Prastowo, S. H. B.; Bahri, S.; Ridlo, Z. R.; Prihandono, T.

2018-03-01

Tritium Atom is one of the isotopes of Hydrogen that has two Neutrons in the nucleus and an electron that surrounds the nucleus. The Stark Effect is an effect of a shift or polarization of the atomic spectrum caused by the external electrostatic field. The interaction between the electrons and the external electric field can be reviewed using an approximation method of perturbation theory. The perturbation theory used is a time Independent non-degenerate perturbation and reviewed to second order to obtain correction of Tritium Atomic wave function. The condition that used in the system is a relativistic condition by reviewing the movement of electrons within the Atom. The effects of relativity also affect the correction of the wave function of Atom Tritium in the ground state. Tritium is radioactive material that is still relatively safe, and one of the applications of Tritium Atom is on the battery of betavoltaics (Nano Tritium Battery).

Optical Studies of the Quantum Confined Stark Effect in ALUMINUM(0.3) GALLIUM(0.7) Arsenide/gallium Arsenide Coupled Double Quantum Wells

NASA Astrophysics Data System (ADS)

Kuroda, Roger Tokuichi

1992-01-01

The development of advanced epitaxical growth techniques such as molecular beam epitaxy has led to growth of high quality III-V layers with monolayer control in thickness. This permits design of new and novel heterointerface based electronic, optical and opto-electronic devices which exploit the new and tailorable electronic states in quantum wells. One such property is the Quantum Confined Stark Effect (QCSE) which, in uncoupled multiple quantum wells (MQW), has been used for the self-electro-optic effect device(SEED). Guided by a phenomenological model of the complex dielectric function for the Coupled Double Quantum Well (CDQW), we show results for the QCSE in CDQW show underlying physics differs from the uncoupled MQW in that symmetry forbidden transitions under flat band conditions become allowed under non-flat band conditions. The transfer of oscillator strength from symmetry allowed to the symmetry forbidden transitions offers potential for application as spatial light modulator (SLM). We show the CDQW lowest exciton peak Stark shifts twice as fast as the SQW with equivalent well width, which offers the SLM device a lower operating voltage than SQW. In addition we show the CDQW absorption band edge can blue shift with increasing electric field, which offers other potential for SLM. From transmission measurements, we verify these predictions and compare them with the phenomenological model. The optical device figure of merit Deltaalpha/alpha of the CDQW is comparable with the "best" SQW, but at lower electric field. From photocurrent measurements, we find that the calculated and measured Stark shifts agree. In addition, we extract a Deltaalpha/ alpha from photocurrent which agree with transmission measurements. From electroreflectance measurements, we calculated the aluminum concentration, and the built in electric field from the Franz-Keldysh oscillations due to the Al_{0.3}Ga _{0.7}As barrier regions in the CDQW. (Copies available exclusively from Micrographics Department, Doheny Library, USC, Los Angeles, CA 90089 -0182.).

High-Speed Stark Wavelength Tuning of MidIR Interband Cascade Lasers

DTIC Science & Technology

2007-03-15

STARK WAVELENGTH TUNING OF MidIR ICLs 361 Fig. 2. Lasing spectra of the tunable ICL at different bias currents. injection region at before tunneling ...the energy separation between and (and hence the emission wavelength) undergoes a linear Stark shift that depends on the bias current which controls...response Fig. 3. Lasing spectra of the tunable ICL at different bias modulation frequen- cies. Fig. 4. Dependence of the intensity of the Line 2 on bias

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, M.A.; Schenter, G.K.

We present a hybrid quantum mechanical/molecular mechanical (QM/MM) model for microscopic solvation effects that includes polarizability in the MM region (QM/MMpol). QM/MMpol treatment of both ground and excited states is presented in the formalism. We present QM/MMpol analysis of the ground and electronic excited states of the bacteriochlorophyll b dimer (P) of the photosynthetic reaction center (RC) of Rhodopseudomonas viridis using the INDO/S method. The static-charge potential from the MM model of the RC alone causes Q{sub y1} to have significantly better agreement with the Stark effect results than isolated P. However, consideration of the protein polarization potential is furthermore » required to obtain more complete agreement with Stark effect experiments. Thus, we calculate a Q{sub y1} transition energy at 10826 cm{sup -1} with a ground to excited state change in dipole moment of 4.8 D; an absorption Stark effect angle of 43{degree}; a net shift of 0.15 electrons from the L subunit to the M subunit of P; and a linear dichroism angle (between the transition moment of Q{sub y1} and the pseudo-C{sub 2} axis of the RC) of 81{degree}. These results are in good agreement with experiment. Interestingly, we find that net CT increase is greater for Q{sub y1} than for the second excited state of P (Q{sub y2}), a result that we anticipated in an early model dimer study. 77 refs., 3 figs., 2 tabs.« less

Stark broadening parameter regularities and interpolation and critical evaluation of data for CP star atmospheres research: Stark line shifts

NASA Astrophysics Data System (ADS)

Dimitrijevic, M. S.; Tankosic, D.

1998-04-01

In order to find out if regularities and systematic trends found to be apparent among experimental Stark line shifts allow the accurate interpolation of new data and critical evaluation of experimental results, the exceptions to the established regularities are analysed on the basis of critical reviews of experimental data, and reasons for such exceptions are discussed. We found that such exceptions are mostly due to the situations when: (i) the energy gap between atomic energy levels within a supermultiplet is equal or comparable to the energy gap to the nearest perturbing levels; (ii) the most important perturbing level is embedded between the energy levels of the supermultiplet; (iii) the forbidden transitions have influence on Stark line shifts.

Large, valley-exclusive Bloch-Siegert shift in monolayer WS2

NASA Astrophysics Data System (ADS)

Sie, Edbert J.; Lui, Chun Hung; Lee, Yi-Hsien; Fu, Liang; Kong, Jing; Gedik, Nuh

2017-03-01

Coherent interaction with off-resonance light can be used to shift the energy levels of atoms, molecules, and solids. The dominant effect is the optical Stark shift, but there is an additional contribution from the so-called Bloch-Siegert shift that has eluded direct and exclusive observation in solids. We observed an exceptionally large Bloch-Siegert shift in monolayer tungsten disulfide (WS2) under infrared optical driving. By controlling the light helicity, we could confine the Bloch-Siegert shift to occur only at one valley, and the optical Stark shift at the other valley, because the two effects obey opposite selection rules at different valleys. Such a large and valley-exclusive Bloch-Siegert shift allows for enhanced control over the valleytronic properties of two-dimensional materials.

Accurate calculation of dynamic Stark shifts and depopulation rates of Rydberg energy levels induced by blackbody radiation. Hydrogen, helium, and alkali-metal atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farley, J.W.; Wing, W.H.

1981-05-01

A highly excited (Rydberg) atom bathed in blackbody radiation is perturbed in two ways. A dynamic Stark shift is induced by the off-resonant components of the blackbody radiation. Additionally, electric-dipole transitions to other atomic energy levels are induced by the resonant components of the blackbody radiation. This depopulation effect shortens the Rydberg-state lifetime, thereby broadening the energy level. Calculations of these two effects in many states of hydrogen, helium, and the alkali-metal atoms Li, Na, K, Rb, and Cs are presented for T = 300 K. Contributions from the entire blackbody spectrum and from both discrete and continuous perturbing statesmore » are included. The accuracy is considerably greater than that of previous estimates.« less

Quantum-confined Stark effect at 1.3 μm in Ge/Si(0.35)Ge(0.65) quantum-well structure.

PubMed

Rouifed, Mohamed Said; Chaisakul, Papichaya; Marris-Morini, Delphine; Frigerio, Jacopo; Isella, Giovanni; Chrastina, Daniel; Edmond, Samson; Le Roux, Xavier; Coudevylle, Jean-René; Vivien, Laurent

2012-10-01

Room-temperature quantum-confined Stark effect in a Ge/SiGe quantum-well structure is reported at the wavelength of 1.3 μm. The operating wavelength is tuned by the use of strain engineering. Low-energy plasma-enhanced chemical vapor deposition is used to grow 20 periods of strain-compensated quantum wells (8 nm Ge well and 12 nm Si(0.35)Ge(0.65) barrier) on Si(0.21)Ge(0.79) virtual substrate. The fraction of light absorbed per well allows for a strong modulation around 1.3 μm. The half-width at half-maximum of the excitonic peak of only 12 meV allows for a discussion on physical mechanisms limiting the performances of such devices.

Relative Intensity of a Cross-Over Resonance to Lamb Dips Observed in Stark Spectroscopy of Methane

NASA Astrophysics Data System (ADS)

Okuda, Shoko; Sasada, Hiroyuki

2017-06-01

Last ISMS, we reported on Stark effects of the νb{3} band of methane observed with a sub-Doppler resolution spectrometer. We determined the rotation-induced permanent dipole moment (PEDM) in the vibrational ground state and the vibration-, rotation-, and Coriolis-type-interaction-induced PEDMs in the v_{3}=1 state. Figure illustrates Stark modulation spectrum of the Q(6)E with the external electric field of 31.0 kV/cm and the selection rule of Δ M=±1, where M is the magnetic quantum number. The Δ M=1 and -1 components of the Lamb dips labeled by A and B are resolved, and the central component C is identified with the cross-over resonance. The Lamb dips are assigned to the magnetic quantum numbers of the lower and upper states, (M'',M') according to the Clebsch-Gordan coefficients. We found that the relative intensity of the cross-over resonance to the associated Lamb dips depends on the P, Q, and R branches. We ascribe the dependence to the collisional relaxation processes.

A battered women's movement perspective of Coercive Control.

PubMed

Arnold, Gretchen

2009-12-01

In Coercive Control, Evan Stark calls on battered women's activists to reorient their understanding of abusive relationships. Rather than being primarily about physical violence, he maintains, domestic violence is better conceptualized as men's attempts to destroy women's autonomy and reinstate patriarchy in intimate relationships. His analysis suggests important changes to defending battered women in court, modifications to the kinds of support services the movement provides for battered women, and changes in the laws and law enforcement regarding battering. Stark also maintains that, to end coercive control, the battered women's movement must renew its commitment not only to ensuring the safety of individual women but also to attaining the feminist goal of substantive freedom and equality for women in both public and private life. I contend that Stark's reframing of woman abuse is useful for battered women's advocates and may, in some cases but not in others, lead to more effective practices in battered women's programs. At the same time, it is likely to complicate activists' efforts to mobilize public opinion, resources, and public policy to address the problem of woman abuse.

Laser-driven atomic-probe-beam diagnostics

NASA Astrophysics Data System (ADS)

Knyazev, B. A.; Greenly, J. B.; Hammer, D. A.

2000-12-01

A new laser-driven atomic-probe-beam diagnostic (LAD) is proposed for local, time-resolved measurements of electric field and ion dynamics in the accelerating gap of intense ion beam diodes. LAD adds new features to previous Stark-shift diagnostics which have been progressively developed in several laboratories, from passive observation of Stark effect on ion species or fast (charge-exchanged) neutrals present naturally in diodes, to active Stark atomic spectroscopy (ASAS) in which selected probe atoms were injected into the gap and excited to suitable states by resonant laser radiation. The LAD scheme is a further enhancement of ASAS in which the probe atoms are also used as a local (laser-ionized) ion source at an instant of time. Analysis of the ion energy and angular distribution after leaving the gap enables measurement, at the chosen ionization location in the gap, of both electrostatic potential and the development of ion divergence. Calculations show that all of these quantities can be measured with sub-mm and ns resolution. Using lithium or sodium probe atoms, fields from 0.1 to 10 MV/cm can be measured.

Photoelectron imaging of autoionizing states of xenon: Effect of external electric fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shubert, V. Alvin; Pratt, Stephen T.

Velocity map photoelectron imaging was used to study the photoelectron angular distributions of autoionizing Stark states of atomic xenon excited just below the Xe{sup +} {sup 2} P{sub 1/2}{sup o} threshold at fields ranging from 50 to 700 V/cm. Two-color, two-photon resonant, three-photon excitation via the 6p{sup '}[1/2]{sub 0} level was used to probe the region of interest. The wavelength scans show a similar evolution of structure to that observed in single-photon excitation [Ernst et al., Phys. Rev. A 37, 4172 (1988)]. The photoelectron angular distributions following autoionization of the Stark states provide information on the decay of excited statesmore » in electron fields. In the present experiments, the large autoionization width of the ({sup 2} P{sub 1/2}{sup o})nd[3/2]{sub 1}{sup o} series dominates the decay processes, and thus controls the angular distributions. However, the angular distributions of the Stark states also indicate the presence of other decay channels contributing to the decay of these states.« less

Semiclassical perturbation Stark widths of singly charged argon spectral lines

NASA Astrophysics Data System (ADS)

Hamdi, Rafik; Ben Nessib, Nabil; Sahal-Bréchot, Sylvie; Dimitrijević, Milan S.

2018-03-01

Using a semiclassical perturbation approach with the impact approximation, Stark widths for singly charged argon (Ar II) spectral lines have been calculated. Energy levels and oscillator strengths needed for this calculation have been determined using the Hartree-Fock method with relativistic corrections. Our Stark widths are compared with experimental results for 178 spectral lines. Our results may be of interest not only for laboratory plasma, lasers and technological plasmas but also for white dwarfs and A- and B-type stars.

Adhesion formation after previous caesarean section-a meta-analysis and systematic review.

PubMed

Shi, Z; Ma, L; Yang, Y; Wang, H; Schreiber, A; Li, X; Tai, S; Zhao, X; Teng, J; Zhang, L; Lu, W; An, Y; Alla, N R; Cui, T

2011-03-01

The optimal technique for performing caesarean section with respect to minimising postoperative adhesions has not been determined. To evaluate adhesion formation for three common caesarean section techniques in women undergoing repeat caesarean section surgeries. A database was constructed from Medline, EMBASE, Cochrane Library, National Science Digital Library, China Biological Medicine Database and through contact with experts in this field from January 1990 to May 2010. Studies were included if they examined adhesion formation in repeat caesarean sections as a primary objective, delineated a clear study design, specified an adhesion scoring system, and had sufficient patient exclusion criteria. We abstracted data regarding adhesion formation. The Mantel-Haenszel random-effects model was employed for all analyses using odds ratio or inverse variance, along with 95% CI. Thirty-three qualified studies including 4423 women were analysed. There were 406 adhesions among 571 women and 238 adhesions among 596 women in the Stark's caesarean section (also known as Misgav-Ladach method) group and modified Stark's caesarean section group, respectively, with pooled OR 4.69 (95% CI 3.32-6.62; P < 0.01, 12 studies); 1173 adhesions among 1555 women and 1179 adhesions among 1625 women in Stark's caesarean section group and classic lower-segment caesarean section group, respectively, with pooled odds ratio 1.28 (95% CI 0.97-1.68; P = 0.08, 21 studies); and 29 adhesions from 102 women and 115 adhesions from 193 women in modified Stark's caesarean section group and classic lower-segment caesarean section group, respectively, with pooled odds ratio 0.28 (95% CI 0.10-0.82; P = 0.02, two studies). Closure of the peritoneum in modified Stark's caesarean section resulted in less adhesion formation and should be recommended. © 2010 The Authors Journal compilation © RCOG 2010 BJOG An International Journal of Obstetrics and Gynaecology.

Rapid-Adiabatic Control of Ro-Vibrational Populations in Polyatomic Molecules

NASA Astrophysics Data System (ADS)

Zak, Emil J.; Yachmenev, Andrey

2017-06-01

We present a simple method for control of ro-vibrational populations in polyatomic molecules in the presence of inhomogeneous electric fields [1]. Cooling and trapping of heavy polar polyatomic molecules has become one of the frontier goals in high-resolution molecular spectroscopy, especially in the context of parity violation measurement in chiral compounds [2]. A key step toward reaching this goal would be development of a robust and efficient protocol for control of populations of ro-vibrational states in polyatomic, often floppy molecules. Here we demonstrate a modification of the stark-chirped rapid-adiabatic-passage technique (SCRAP) [3], designed for achieving high levels of control of ro-vibrational populations over a selected region in space. The new method employs inhomogeneous electric fields to generate space- and time- controlled Stark-shifts of energy levels in molecules. Adiabatic passage between ro-vibrational states is enabled by the pump pulse, which raises the value of the Rabi frequency. This Stark-chirped population transfer can be used in manipulation of population differences between high-field-seeking and low-field-seeking states of molecules in the Stark decelerator [4]. Appropriate timing of voltages on electric rods located along the decelerator combined with a single pump laser renders our method as potentially more efficient than traditional Stark decelerator techniques. Simulations for NH_3 show significant improvement in effectiveness of cooling, with respect to the standard 'moving-potential' method [5]. At the same time a high phase-space acceptance of the molecular packet is maintained. E. J. Zak, A. Yachmenev (submitted). C. Medcraft, R. Wolf, M. Schnell, Angew. Chem. Int. Ed., 53, 43, 11656-11659 (2014) M. Oberst, H. Munch, T. Halfman, PRL 99, 173001 (2007). K. Wohlfart, F. Grätz, F. Filsinger, H. Haak, G. Meijer, J. Küpper, Phys. Rev. A 77, 031404(R) (2008). H. L. Bethlem, F. M. H. Crompvoets, R. T. Jongma, S. Y. T. van de Meerakker, G. Meijer, Phys. Rev. A, 65, 053416 (2002).

Nonperturbative quantum control via the nonresonant dynamic Stark effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sussman, Benjamin J.; Stolow, Albert; Department of Physics, Queen's University, Kingston, Ontario, K7L 3N6

2005-05-15

The nonresonant dynamic Stark effect (NRDSE) is investigated as a general tool for quantum control in the intermediate field strength regime (nonperturbative but nonionizing). We illustrate this scheme for the case of nonadiabatic molecular photodissociation at an avoided crossing. Using the NRDSE exclusively, both the electronic branching ratio and predissociation lifetime may be controlled. Infrared control pulses are used to modify the field-free dynamical evolution during traversal of the avoided crossing, thus controlling the nonadiabatic branching ratio. Predissociation lifetimes may be either increased or decreased using properly timed short infrared pulses to modify phase differences between the diabatic wave packets.more » In contrast with the limiting cases of perturbative control (interference between transitions) and strong field control with ionizing laser fields, control via the NRDSE may be thought of as reversibly modifying the effective Hamiltonian during system propagation.« less

Valley-selective optical Stark effect in monolayer WS2

NASA Astrophysics Data System (ADS)

Gedik, Nuh

Monolayer semiconducting transition-metal dichalcogenides (TMDs) have a pair of valleys that, by time-reversal symmetry, are energetically degenerate. Lifting the valley degeneracy in these materials is of great interest because it would allow for valley specific band engineering and offer additional control in valleytronic applications. In this talk, I will show that circularly polarized light, which breaks time-reversal symmetry, can be used to lift the valley degeneracy by means of the optical Stark effect. We demonstrate that this effect is capable of raising the exciton level in monolayer TMD WS2 by as much as 18 meV in a controllable valley-selective manner. The resulting energy shift is extremely large, comparable to the shift that would be obtained using a very high magnetic field (approximately 100 Tesla). These results offer a novel way to control valley degree of freedom, and may provide a means to realize new valley-selective Floquet topological state of matter.

Entanglement of polar symmetric top molecules as candidate qubits.

PubMed

Wei, Qi; Kais, Sabre; Friedrich, Bretislav; Herschbach, Dudley

2011-10-21

Proposals for quantum computing using rotational states of polar molecules as qubits have previously considered only diatomic molecules. For these the Stark effect is second-order, so a sizable external electric field is required to produce the requisite dipole moments in the laboratory frame. Here we consider use of polar symmetric top molecules. These offer advantages resulting from a first-order Stark effect, which renders the effective dipole moments nearly independent of the field strength. That permits use of much lower external field strengths for addressing sites. Moreover, for a particular choice of qubits, the electric dipole interactions become isomorphous with NMR systems for which many techniques enhancing logic gate operations have been developed. Also inviting is the wider chemical scope, since many symmetric top organic molecules provide options for auxiliary storage qubits in spin and hyperfine structure or in internal rotation states. © 2011 American Institute of Physics

A controlled ac Stark echo for quantum memories.

PubMed

Ham, Byoung S

2017-08-09

A quantum memory protocol of controlled ac Stark echoes (CASE) based on a double rephasing photon echo scheme via controlled Rabi flopping is proposed. The double rephasing scheme of photon echoes inherently satisfies the no-population inversion requirement for quantum memories, but the resultant absorptive echo remains a fundamental problem. Herein, it is reported that the first echo in the double rephasing scheme can be dynamically controlled so that it does not affect the second echo, which is accomplished by using unbalanced ac Stark shifts. Then, the second echo is coherently controlled to be emissive via controlled coherence conversion. Finally a near perfect ultralong CASE is presented using a backward echo scheme. Compared with other methods such as dc Stark echoes, the present protocol is all-optical with advantages of wavelength-selective dynamic control of quantum processing for erasing, buffering, and channel multiplexing.

Improved Frequency Fluctuation Model for Spectral Line Shape Calculations in Fusion Plasmas

NASA Astrophysics Data System (ADS)

Ferri, S.; Calisti, A.; Mossé, C.; Talin, B.; Lisitsa, V.

2010-10-01

A very fast method to calculate spectral line shapes emitted by plasmas accounting for charge particle dynamics and effects of an external magnetic field is proposed. This method relies on a new formulation of the Frequency Fluctuation Model (FFM), which yields to an expression of the dynamic line profile as a functional of the static distribution function of frequencies. This highly efficient formalism, not limited to hydrogen-like systems, allows to calculate pure Stark and Stark-Zeeman line shapes for a wide range of density, temperature and magnetic field values, which is of importance in plasma physics and astrophysics. Various applications of this method are presented for conditions related to fusion plasmas.

Fast optical cooling of a nanomechanical cantilever by a dynamical Stark-shift gate.

PubMed

Yan, Leilei; Zhang, Jian-Qi; Zhang, Shuo; Feng, Mang

2015-10-12

The efficient cooling of nanomechanical resonators is essential to exploration of quantum properties of the macroscopic or mesoscopic systems. We propose such a laser-cooling scheme for a nanomechanical cantilever, which works even for the low-frequency mechanical mode and under weak cooling lasers. The cantilever is coupled by a diamond nitrogen-vacancy center under a strong magnetic field gradient and the cooling is assisted by a dynamical Stark-shift gate. Our scheme can effectively enhance the desired cooling efficiency by avoiding the off-resonant and undesired carrier transitions, and thereby cool the cantilever down to the vicinity of the vibrational ground state in a fast fashion.

Fast optical cooling of a nanomechanical cantilever by a dynamical Stark-shift gate

PubMed Central

Yan, Leilei; Zhang, Jian-Qi; Zhang, Shuo; Feng, Mang

2015-01-01

The efficient cooling of nanomechanical resonators is essential to exploration of quantum properties of the macroscopic or mesoscopic systems. We propose such a laser-cooling scheme for a nanomechanical cantilever, which works even for the low-frequency mechanical mode and under weak cooling lasers. The cantilever is coupled by a diamond nitrogen-vacancy center under a strong magnetic field gradient and the cooling is assisted by a dynamical Stark-shift gate. Our scheme can effectively enhance the desired cooling efficiency by avoiding the off-resonant and undesired carrier transitions, and thereby cool the cantilever down to the vicinity of the vibrational ground state in a fast fashion. PMID:26455901

Possible stabilization of the frequency of a CO/sub 2/ laser using an external Stark cell containing 1-1 difluoroethane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avtonomov, V.P.; Alexandrescu, R.; Dumitras, D.

1979-02-01

Results are presented of measurements of the Stark modulation index and absorption coefficient of CO/sub 2/ laser radiation due to the P (24) line by 1-1 difluorethane (C/sub 2/H/sub 4/F/sub 2/). The possibility of stabilizing the CO/sub 2/ laser frequency using a Stark cell is demonstrated and the laser frequency tuning efficiency within the P (24) line of the 00/sup 0/1--10/sup 0/0 transition is determined.

Vibrational stark effects to identify ion pairing and determine reduction potentials in electrolyte-free environments

DOE PAGES

Mani, Tomoyasu; Grills, David C.; Miller, John R.

2015-01-02

A recently-developed instrument for time-resolved infrared detection following pulse radiolysis has been used to measure the ν(C≡N) IR band of the radical anion of a CN-substituted fluorene in tetrahydrofuran. Specific vibrational frequencies can exhibit distinct frequency shifts due to ion-pairing, which can be explained in the framework of the vibrational Stark effect. Measurements of the ratio of free ions and ion-pairs in different electrolyte concentrations allowed us to obtain an association constant and free energy change for ion-pairing. As a result, this new method has the potential to probe the geometry of ion-pairing and allows the reduction potentials of moleculesmore » to be determined in the absence of electrolyte in an environment of low dielectric constant.« less

Density effects on the electronic contribution to hydrogen Lyman alpha Stark profiles

NASA Astrophysics Data System (ADS)

Motapon, O.

1998-01-01

The quantum unified theory of Stark broadening (Tran Minh et al. 1975, Feautrier et al. 1976) is used to study the density effects on the electronic contribution to the hydrogen Lyman alpha lineshape. The contribution of the first angular momenta to the total profile is obtained by an extrapolation method, and the results agree with other approaches. The comparison made with Vidal et al. (1973) shows a good agreement; and the electronic profile is found to be linear in density for | Delta lambda right | greater than 8 Angstroms for densities below 10(17) cm(-3) , while the density dependence becomes more complex for | Delta lambda right | less than 8 Angstroms. The wing profiles are calculated at various temperatures scaling from 2500 to 40000K and a polynomial fit of these profiles is given.

Sensitivity of MSE measurements on the beam atomic level population

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruiz, C., E-mail: carlos.ruiz@wisc.edu; Kumar, S. T. A.; Anderson, F. S. B.

The effect of variation in atomic level population of a neutral beam on the Motional Stark Effect (MSE) measurements is investigated in the low density plasmas of HSX stellarator. A 30 KeV, 4 A, 3 ms hydrogen diagnostic neutral beam is injected into HSX plasmas of line averaged electron density ranging from 2 to 4 ⋅ 10{sup 18} m{sup −3} at a magnetic field of 1 T. For this density range, the excited level population of the hydrogen neutral beam is expected to undergo variations. Doppler shifted and Stark split H{sub α} and H{sub β} emissions from the beam aremore » simultaneously measured using two cross-calibrated spectrometers. The emission spectrum is simulated and fit to the experimental measurements and the deviation from a statistically populated beam is investigated.« less

Stark sublevels investigation in Y2WO6:Tm3+-Yb3+ phosphor for thermometry and internal temperature measurement

NASA Astrophysics Data System (ADS)

Soni, Abhishek Kumar

2018-05-01

Intensity ratio investigation in the Y2WO6:Tm3+-Yb3+ phosphors synthesized by solid state reaction method has been discussed first time under 980 nm laser diode excitation with the help of multiple peak fitting. The temperature dependent upconversion emission study has been performed for optical temperature sensing by using stark sublevels of 1G4 level of Tm3+ ion. The intensity of the two stark sublevels is varied due to the thermalization under the application of external temperature. The energy gap has been calculated about ∼427 cm‑1 of the two stark sublevels via Boltzmann’s population distribution law. The calculated sensitivity (maximum about ∼34 × 10‑4 K‑1 at 303 K) and optical heating properties prove the utility of the prepared phosphor in making optical temperature sensing probe and optical heater.

A new questionnaire for measuring quality of life - the Stark QoL.

PubMed

Hardt, Jochen

2015-10-26

The Stark questionnaire measures health-related quality of life (QoL) using pictures almost exclusively. It is supplemented by a minimum of words. It comprises a mental and a physical health component. A German sample of n = 500 subjects, age and gender stratified, filled out the Stark Qol questionnaire along with various other questionnaires via internet. The physical component shows good reliability (Cronbach's alpha = McDonalds Omega = greatest lower bound = .93), the mental component can be improved (Cronbach's alpha = .63, McDonalds Omega = .72, greatest lower bound = .77). Confirmatory factor analysis shows a good fit (Bentlers CFI = .97). Construct validity was proven. The Stark QoL is a promising new development in measuring QoL, it is a short and easy to apply questionnaire. Additionally, it is particularly promising for international research.

Virtual Atomic and Molecular Data Center (VAMDC) and Stark-B Database

NASA Astrophysics Data System (ADS)

Dimitrijevic, M. S.; Sahal-Brechot, S.; Kovacevic, A.; Jevremovic, D.; Popovic, L. C.; VAMDC Consortium; Dubernet, Marie-Lise

2012-01-01

Virtual Atomic and Molecular Data Center (VAMDC) is an European FP7 project with aims to build a flexible and interoperable e-science environment based interface to the existing Atomic and Molecular data. The VAMDC will be built upon the expertise of existing Atomic and Molecular databases, data producers and service providers with the specific aim of creating an infrastructure that is easily tuned to the requirements of a wide variety of users in academic, governmental, industrial or public communities. In VAMDC will enter also STARK-B database, containing Stark broadening parameters for a large number of lines, obtained by the semiclassical perturbation method during more than 30 years of collaboration of authors of this work (MSD and SSB) and their co-workers. In this contribution we will review the VAMDC project, STARK-B database and discuss the benefits of both for the corresponding data users.

Spectroscopic analysis of femtosecond laser plasma filament in air

NASA Astrophysics Data System (ADS)

Bernhardt, J.; Liu, W.; Théberge, F.; Xu, H. L.; Daigle, J. F.; Châteauneuf, M.; Dubois, J.; Chin, S. L.

2008-03-01

We report a spectroscopic analysis of a filament generated by a femtosecond laser pulse in air. In the filament spectra, the characteristic Stark broadened atomic oxygen triplet centered at 777.4 nm has been observed. The measured electron impact Stark broadening parameter of the triplet is larger than the theoretical value by Griem [H.R. Griem, Plasma Spectroscopy, McGraw Hill, New York, 1964] by a factor 6.7 . Using the experimental value 0.0166nm , the plasma densities derived from Stark broadening agree well with those most recently obtained from Théberge et al.'s measurement of the nitrogen fluorescence calibrated by longitudinal diffraction [F. Théberge, W. Liu, P.T. Simard, A. Becker, S. L. Chin, Phys. Rev. E 74 (2006) 036406]. However, the Stark broadening approach is much simpler and can be used to non-invasively measure the filament plasma density distribution in air under different propagation conditions.

Stark broadening of several Bi IV spectral lines of astrophysical interest

NASA Astrophysics Data System (ADS)

Colón, C.; Moreno-Díaz, C.; de Andrés-García, I.; Alonso-Medina, A.

2017-09-01

The presence of spectral lines of bismuth in stellar atmospheres has been reported in different stars. The anomalous values of the spectral intensities of Bi II and Bi III, compared to the theoretical Local Termodinamic Equilibrium (LTE) standards of Bi I/Bi II/Bi III, have been reported in the spectra obtained with the High Resolution Spectrograph of the Hubble/Goddard Space Telescope in the chemically peculiar stars HgMn stars χ Lupi and HR 7775. Spectral lines of 1436.8, 1902.3, 2630.9 and 2936.7 Å of Bi II and 1423.4 Å of Bi III were reported and their relative intensities were measured in these studies Litzén & Wahlgren 2002. These lines are overlapped with spectral lines of 1437.65, 2630.1 and 2937.1 Å of Bi IV. A study of the Stark broadening parameters of Bi IV spectral lines can help to study these overlaps. In this paper, using the Griem semi-empirical approach, we report calculated values of the Stark parameters for 64 spectral lines of Bi IV. The matrix elements used in these calculations have been determined from 17 configurations of Bi IV. They were calculated using the cowan code including core polarization effects. Data are displayed for an electron density of 1017 cm-3 and temperatures T = 10 000-160 000 K. Also calculated radiative lifetimes for 12 levels with experimental lifetime are presented, in order to test the goodness of our calculations. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed.

Influence of non-local thermodynamic equilibrium and Zeeman effects on magnetic equilibrium reconstruction using spectral motional Stark effect diagnostic

NASA Astrophysics Data System (ADS)

Reimer, R.; Marchuk, O.; Geiger, B.; Mc Carthy, P. J.; Dunne, M.; Hobirk, J.; Wolf, R.; ASDEX Upgrade Team

2017-08-01

The Motional Stark Effect (MSE) diagnostic is a well established technique to infer the local internal magnetic field in fusion plasmas. In this paper, the existing forward model which describes the MSE data is extended by the Zeeman effect, fine-structure, and relativistic corrections in the interpretation of the MSE spectra for different experimental conditions at the tokamak ASDEX Upgrade. The contribution of the non-Local Thermodynamic Equilibrium (non-LTE) populations among the magnetic sub-levels and the Zeeman effect on the derived plasma parameters is different. The obtained pitch angle is changed by 3 ° … 4 ° and by 0 . 5 ° … 1 ° including the non-LTE and the Zeeman effects into the standard statistical MSE model. The total correction is about 4°. Moreover, the variation of the magnetic field strength is significantly changed by 2.2% due to the Zeeman effect only. While the data on the derived pitch angle still could not be tested against the other diagnostics, the results from an equilibrium reconstruction solver confirm the obtained values for magnetic field strength.

Stark effect spectrophone for continuous absorption spectra monitoring. [a technique for gas analysis

NASA Technical Reports Server (NTRS)

Kavaya, M. J. (Inventor)

1981-01-01

A Stark effect spectrophone using a pulsed or continuous wave laser having a beam with one or more absorption lines of a constituent of an unknown gas is described. The laser beam is directed through windows of a closed cell while the unknown gas to be modified flows continuously through the cell between electric field plates disposed in the cell on opposite sides of the beam path through the cell. When the beam is pulsed, energy absorbed by the gas increases at each point along the beam path according to the spectral lines of the constituents of the gas for the particular field strengths at those points. The pressure measurement at each point during each pulse of energy yields a plot of absorption as a function of electric field for simultaneous detection of the gas constituents. Provision for signal averaging and modulation is included.

Combining ligand-induced quantum-confined stark effect with type II heterojunction bilayer structure in CdTe and CdSe nanocrystal-based solar cells.

PubMed

Yaacobi-Gross, Nir; Garphunkin, Natalia; Solomeshch, Olga; Vaneski, Aleksandar; Susha, Andrei S; Rogach, Andrey L; Tessler, Nir

2012-04-24

We show that it is possible to combine several charge generation strategies in a single device structure, the performance of which benefits from all methods used. Exploiting the inherent type II heterojunction between layered structures of CdSe and CdTe colloidal quantum dots, we systematically study different ways of combining such nanocrystals of different size and surface chemistry and with different linking agents in a bilayer solar cell configuration. We demonstrate the beneficial use of two distinctly different sizes of NCs not only to improve the solar spectrum matching but also to reduce exciton binding energy, allowing their efficient dissociation at the interface. We further make use of the ligand-induced quantum-confined Stark effect in order to enhance charge generation and, hence, overall efficiency of nanocrystal-based solar cells.

Feasibility of a motional Stark effect system on the TCV tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siegrist, M.R.; Hawkes, N.; Weisen, H.

This paper presents a feasibility study for a motional Stark effect (MSE) [F. M. Levinton et al., Phys. Rev. Lett. 63, 2060 (1989)] diagnostic on the TCV tokamak. A numerical simulation code has been used to identify the optimal port arrangement and geometrical layout. It predicts the expected measurement accuracy for a range of typical plasma scenarios. With the existing neutral beam injector (NBI) and a detection system based on current day technology, it should be possible to determine the safety factor with an accuracy of the order of 5%. A vertically injected beam through the plasma center would allowmore » one to measure plasmas which are centered above the midplane, a common occurrence in connection with electron cyclotron resonance heating and electron cyclotron current drive experiments. In this case a new and ideally more powerful NBI would be required.« less

[Study on physical deviation factors on laser induced breakdown spectroscopy measurement].

PubMed

Wan, Xiong; Wang, Peng; Wang, Qi; Zhang, Qing; Zhang, Zhi-Min; Zhang, Hua-Ming

2013-10-01

In order to eliminate the deviation between the measured LIBS spectral line and the standard LIBS spectral line, and improve the accuracy of elements measurement, a research of physical deviation factors in laser induced breakdown spectroscopy technology was proposed. Under the same experimental conditions, the relationship of ablated hole effect and spectral wavelength was tested, the Stark broadening data of Mg plasma laser induced breakdown spectroscopy with sampling time-delay from 1.00 to 3.00 micros was also studied, thus the physical deviation influences such as ablated hole effect and Stark broadening could be obtained while collecting the spectrum. The results and the method of the research and analysis can also be applied to other laser induced breakdown spectroscopy experiment system, which is of great significance to improve the accuracy of LIBS elements measuring and is also important to the research on the optimum sampling time-delay of LIBS.

Probing the plasma near high power wave launchers in fusion devices for static and dynamic electric fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klepper, C Christopher; Martin, Elijah H; Isler, Ralph C

2014-01-01

An exploratory study was carried out in the long-pulse tokamak Tore Supra, to determine if electric fields in the plasma around high-power, RF wave launchers could be measured with non-intrusive, passive, optical emission spectroscopy. The focus was in particular on the use of the external electric field Stark effect. The feasibility was found to be strongly dependent on the spatial extent of the electric fields and overlap between regions of strong (> 1 kV/cm) electric fields and regions of plasma particle recycling and plasma-induced, spectral line emission. Most amenable to the measurement was the RF electric field in edge plasma,more » in front of a lower hybrid heating and current drive launcher. Electric field strengths and direction, derived from fitting the acquired spectra to a model including time-dependent Stark effect and the tokamak-range magnetic field Zeeman-effect, were found to be in good agreement with full-wave modeling of the observed launcher.« less

Quantum carpets in a one-dimensional tilted optical lattices

NASA Astrophysics Data System (ADS)

Parra Murillo, Carlos Alberto; Muã+/-Oz Arias, Manuel Humberto; Madroã+/-Ero, Javier

A unit filling Bose-Hubbard Hamiltonian embedded in a strong Stark field is studied in the off-resonant regime inhibiting single- and many-particle first-order tunneling resonances. We investigate the occurrence of coherent dipole wavelike propagation along an optical lattice by means of an effective Hamiltonian accounting for second-order tunneling processes. It is shown that dipole wave function evolution in the short-time limit is ballistic and that finite-size effects induce dynamical self-interference patterns known as quantum carpets. We also present the effects of the border right after the first reflection, showing that the wave function diffuses normally with the variance changing linearly in time. This work extends the rich physical phenomenology of tilted one-dimensional lattice systems in a scenario of many interacting quantum particles, the so-called many-body Wannier-Stark system. The authors acknownledge the finantial support of the Universidad del Valle (project CI 7996). C. A. Parra-Murillo greatfully acknowledges the financial support of COLCIENCIAS (Grant 656).

Probing the plasma near high power wave launchers in fusion devices for static and dynamic electric fields (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klepper, C. C., E-mail: kleppercc@ornl.gov; Isler, R. C.; Biewer, T. M.

2014-11-15

An exploratory study was carried out in the long-pulse tokamak Tore Supra, to determine if electric fields in the plasma around high-power, RF wave launchers could be measured with non-intrusive, passive, optical emission spectroscopy. The focus was in particular on the use of the external electric field Stark effect. The feasibility was found to be strongly dependent on the spatial extent of the electric fields and overlap between regions of strong (>∼1 kV/cm) electric fields and regions of plasma particle recycling and plasma-induced, spectral line emission. Most amenable to the measurement was the RF electric field in edge plasma, inmore » front of a lower hybrid heating and current drive launcher. Electric field strengths and direction, derived from fitting the acquired spectra to a model including time-dependent Stark effect and the tokamak-range magnetic field Zeeman-effect, were found to be in good agreement with full-wave modeling of the observed launcher.« less

Probing the plasma near high power wave launchers in fusion devices for static and dynamic electric fields (invited).

PubMed

Klepper, C C; Martin, E H; Isler, R C; Colas, L; Goniche, M; Hillairet, J; Panayotis, S; Pegourié, B; Jacquot, J; Lotte, Ph; Colledani, G; Biewer, T M; Caughman, J B; Ekedahl, A; Green, D L; Harris, J H; Hillis, D L; Shannon, S C; Litaudon, X

2014-11-01

An exploratory study was carried out in the long-pulse tokamak Tore Supra, to determine if electric fields in the plasma around high-power, RF wave launchers could be measured with non-intrusive, passive, optical emission spectroscopy. The focus was in particular on the use of the external electric field Stark effect. The feasibility was found to be strongly dependent on the spatial extent of the electric fields and overlap between regions of strong (>∼1 kV/cm) electric fields and regions of plasma particle recycling and plasma-induced, spectral line emission. Most amenable to the measurement was the RF electric field in edge plasma, in front of a lower hybrid heating and current drive launcher. Electric field strengths and direction, derived from fitting the acquired spectra to a model including time-dependent Stark effect and the tokamak-range magnetic field Zeeman-effect, were found to be in good agreement with full-wave modeling of the observed launcher.

Assessing Visual Delays using Pupil Oscillations

NASA Technical Reports Server (NTRS)

Mulligan, Jeffrey B.

2012-01-01

Stark (1962) demonstrated vigorous pupil oscillations by illuminating the retina with a beam of light focussed to a small spot near the edge of the pupil. Small constrictions of the pupil then are sufficient to completely block the beam, amplifying the normal relationship between pupil area and retinal illuminance. In addition to this simple and elegant method, Stark also investigated more complex feedback systems using an electronic "clamping box" which provided arbitrary gain and phase delay between a measurement of pupil area and an electronically controlled light source. We have replicated Stark's results using a video-based pupillometer to control the luminance of a display monitor. Pupil oscillations were induced by imposing a linear relationship between pupil area and display luminance, with a variable delay. Slopes of the period-vs-delay function for 3 subjects are close to the predicted value of 2 (1.96-2.39), and the implied delays range from 254 to 376 508 to 652 milliseconds. Our setup allows us to extend Stark's work by investigating a broader class of stimuli.

Electron-Impact Excitation of Ions Effects of Presence of Another Ion

NASA Astrophysics Data System (ADS)

Ohsaki, Akihiko; Nagasaki, Satoshi; Uramoto, Sei-iti; Takayanagi, Kazuo

2000-02-01

Present work gives for the first time the formulation of the two-center Coulomb-Born approximation (TCCBA) and presents some calculations for the electron-impact excitations in electron-ion-ion systems.The effect of the third body was relatively small in the cases studied so far. However, if the third body is a bare ion with a charge larger than the target ion, there will be a marked influence of the three-body collisions.Utilizing TCCBA we present the total and partial cross sections of hydrogen-like ions He+(Z=2), and C5+(Z=6) in the hydrogen plasma from the ground states 1s to the excited states 2s and 2p0, 2p± for the collision energies from 0.4Z2 to 2Z2 a.u.; for the excited states of the target ions, Stark effect is also studied.It is found that the presence of another ion have little effect on the 1s-2s transition and the 2s-2p Stark mixing has a prominent effect.

Mixing of Exciton and Charge-Transfer States in Photosystem II Reaction Centers: Modeling of Stark Spectra with Modified Redfield Theory

PubMed Central

Novoderezhkin, Vladimir I.; Dekker, Jan P.; van Grondelle, Rienk

2007-01-01

We propose an exciton model for the Photosystem II reaction center (RC) based on a quantitative simultaneous fit of the absorption, linear dichroism, circular dichroism, steady-state fluorescence, triplet-minus-singlet, and Stark spectra together with the spectra of pheophytin-modified RCs, and so-called RC5 complexes that lack one of the peripheral chlorophylls. In this model, the excited state manifold includes a primary charge-transfer (CT) state that is supposed to be strongly mixed with the pure exciton states. We generalize the exciton theory of Stark spectra by 1), taking into account the coupling to a CT state (whose static dipole cannot be treated as a small parameter in contrast to usual excited states); and 2), expressing the line shape functions in terms of the modified Redfield approach (the same as used for modeling of the linear responses). This allows a consistent modeling of the whole set of experimental data using a unified physical picture. We show that the fluorescence and Stark spectra are extremely sensitive to the assignment of the primary CT state, its energy, and coupling to the excited states. The best fit of the data is obtained supposing that the initial charge separation occurs within the special-pair PD1PD2. Additionally, the scheme with primary electron transfer from the accessory chlorophyll to pheophytin gave a reasonable quantitative fit. We show that the effectiveness of these two pathways is strongly dependent on the realization of the energetic disorder. Supposing a mixed scheme of primary charge separation with a disorder-controlled competition of the two channels, we can explain the coexistence of fast sub-ps and slow ps components of the Phe-anion formation as revealed by different ultrafast spectroscopic techniques. PMID:17526589

A Riemann-Hilbert approach to the inverse problem for the Stark operator on the line

NASA Astrophysics Data System (ADS)

Its, A.; Sukhanov, V.

2016-05-01

The paper is concerned with the inverse scattering problem for the Stark operator on the line with a potential from the Schwartz class. In our study of the inverse problem, we use the Riemann-Hilbert formalism. This allows us to overcome the principal technical difficulties which arise in the more traditional approaches based on the Gel’fand-Levitan-Marchenko equations, and indeed solve the problem. We also produce a complete description of the relevant scattering data (which have not been obtained in the previous works on the Stark operator) and establish the bijection between the Schwartz class potentials and the scattering data.

Stark broadening of the B III 2s-2p lines

NASA Astrophysics Data System (ADS)

Griem, Hans R.; Ralchenko, Yuri V.; Bray, Igor

1997-12-01

We present a quantum-mechanical calculation of Stark linewidths from electron-ion collisions for the 2s1/2-2p1/2,3/2, λ=2066 and 2067 Å, resonance transitions in B III. The results confirm previous quantum-mechanical R-matrix calculations, but contradict recent measurements and semiclassical and some semiempirical calculations. The differences between the calculations can be attributed to the dominance of small L partial waves in the electron-atom scattering, while the large Stark widths inferred from the measurements would be substantially reduced if allowance is made for hydrodynamic turbulence from high-Reynolds-number flows and the associated Doppler broadening.

Relative Age Effect in Masters Sports: Replication and Extension

ERIC Educational Resources Information Center

Medic, Nikola; Starkes, Janet L.; Weir, Patricia L.; Young, Bradley W.; Grove, J. Robert

2009-01-01

The relative age effect refers to the performance-related advantage of being born early in a cohort or selection year. Until recently it was unknown whether the relative age effect generalizes across the lifespan. Medic, Starkes, and Young (2007) reasoned that the 5-year age categories that are widely used in masters-level sports to organize…

Existence of the Stark-Wannier quantum resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sacchetti, Andrea, E-mail: andrea.sacchetti@unimore.it

2014-12-15

In this paper, we prove the existence of the Stark-Wannier quantum resonances for one-dimensional Schrödinger operators with smooth periodic potential and small external homogeneous electric field. Such a result extends the existence result previously obtained in the case of periodic potentials with a finite number of open gaps.

FOCUSED FEASIBILITY STUDY OF PHYTOREMEDIATION ALTERNATIVE FOR THE INDUSTRIAL EXCESS LANDFILL SITE IN STARK COUNTY, OHIO.

EPA Science Inventory

Focused feasibility study of phytoremediation alternative for the Industrial Excess Landfill site in Stark County, Ohio. More information can be found on the NPL Fact Sheet for this site at www.epa.gov/region5/superfund/npl/ohio/OHD000377971.htm

Additions to the stoneflies (Plecoptera) of Mount Rainier National Park, Washington, U.S.A.

USGS Publications Warehouse

Kondratieff, B.C.; Lechleitner, R.A.; Zuellig, R.E.

2006-01-01

In summary, 88 species of stoneflies are now known from MRNP, representing 65% of the recorded Washington State fauna (Stark and Baumann 2005). At least two of these species are apparently restricted to the MRNP, Soliperla fenderi (Jewett) (Stark and Gustafson 2004) and P. lechleitneri.

Performance of spectral MSE diagnostic on C-Mod and ITER

NASA Astrophysics Data System (ADS)

Liao, Ken; Rowan, William; Mumgaard, Robert; Granetz, Robert; Scott, Steve; Marchuk, Oleksandr; Ralchenko, Yuri; Alcator C-Mod Team

2015-11-01

Magnetic field was measured on Alcator C-mod by applying spectral Motional Stark Effect techniques based on line shift (MSE-LS) and line ratio (MSE-LR) to the H-alpha emission spectrum of the diagnostic neutral beam atoms. The high field of Alcator C-mod allows measurements to be made at close to ITER values of Stark splitting (~ Bv⊥) with similar background levels to those expected for ITER. Accurate modeling of the spectrum requires a non-statistical, collisional-radiative analysis of the excited beam population and quadratic and Zeeman corrections to the Stark shift. A detailed synthetic diagnostic was developed and used to estimate the performance of the diagnostic at C-Mod and ITER parameters. Our analysis includes the sensitivity to view and beam geometry, aperture and divergence broadening, magnetic field, pixel size, background noise, and signal levels. Analysis of preliminary experiments agree with Kinetic+(polarization)MSE EFIT within ~2° in pitch angle and simulations predict uncertainties of 20 mT in | B | and <2° in pitch angle. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG03-96ER-54373 and DE-FC02-99ER54512.

Gravitational red shift tests and a spectroscopy in Japan

NASA Astrophysics Data System (ADS)

Yokoo, Hiromitsu

Japanese astronomers and physicians tried to test the Einstein theory by gravitational red shift tests at 1920's. Spectroscopists in Japan contributed to Stark broadening of spectrum lines. Rikiti Kinoshita (1877 - 1935) probably started experiments according to Voigt's prediction earlier than Stark. Tokyo Astronomical Observatory constructed and used another Einstein Tower in Mitaka.

Laser for high frequency modulated interferometry

DOEpatents

Mansfield, D.K.; Vocaturo, M.; Guttadora, L.J.

1991-07-23

A Stark-tuned laser operating in the 119 micron line of CH[sub 3]OH has an output power of several tens of milliwatts at 30 Watts of pump power while exhibiting a doublet splitting of about ten MHz with the application of a Stark field on the order of 500 volts/cm. This output power allows for use of the laser in a multi-channel interferometer, while its high operating frequency permits the interferometer to measure rapid electron density changes in a pellet injected or otherwise fueled plasma such as encountered in magnetic fusion devices. The laser includes a long far-infrared (FIR) pyrex resonator tube disposed within a cylindrical water jacket and incorporating charged electrodes for applying the Stark field to a gas confined therein. With the electrodes located within the resonator tube, the resonator tube walls are cooled by a flowing coolant without electrical breakdown in the coolant liquid during application of the Stark field. Wall cooling allows for substantially increased FIR output powers. Provision is made for introducing a buffer gas into the resonator tube for increasing laser output power and its operating bandwidth. 10 figures.

Laser for high frequency modulated interferometry

DOEpatents

Mansfield, Dennis K.; Vocaturo, Michael; Guttadora, Lawrence J.

1991-01-01

A Stark-tuned laser operating in the 119 micron line of CH.sub.3 OH has an output power of several tens of milliwatts at 30 Watts of pump power while exhibiting a doublet splitting of about ten MHz with the application of a Stark field on the order of 500 volts/cm. This output power allows for use of the laser in a multi-channel interferometer, while its high operating frequency permits the interferometer to measure rapid electron density changes in a pellet injected or otherwise fueled plasma such as encountered in magnetic fusion devices. The laser includes a long far-infrared (FIR) pyrex resonator tube disposed within a cylindrical water jacket and incorporating charged electrodes for applying the Stark field to a gas confined therein. With the electrodes located within the resonator tube, the resonator tube walls are cooled by a flowing coolant without electrical breakdown in the coolant liquid during application of the Stark field. Wall cooling allows for substantially increased FIR output powers. Provision is made for introducing a buffer gas into the resonator tube for increasing laser output power and its operating bandwidth.

Exceptions to the Stark law: practical considerations for surgeons.

PubMed

Satiani, Bhagwan

2006-03-01

The purpose of this study was to provide an understanding of the applicable legislative exceptions to prohibitions under the Stark law, which governs common legitimate business relationships in surgical practice. Stark I and II prohibits all referrals (and claims) for the provision of designated health services for federal reimbursement if a physician or immediate family member has any financial relationship with the entity. Regardless of intent (unlike the antikickback statute), any financial relationship is illegal unless specifically excepted by statute. These exceptions are relevant to ownership, compensation arrangements, or both. The most important ones relevant to surgeons are as follows: physician service exception (services rendered in an intragroup referral); in-office ancillary services exception (office-based vascular laboratory); the whole hospital exception (ownership interest in a hospital or department); lease exception (conditions that must be met for a lease not to be considered illegal); bona fide employment exception (important to academic medical centers); personal services arrangement exception (vascular laboratory medical directorship); physician incentive plans exception (if volume or value of referrals are an issue); hospital-affiliated group practice exception (physician services billed by a hospital); recruitment arrangement exception (inducements by hospitals to relocate); items/services exception (transcription services purchased from a hospital); fair market value exception (covers services provided to health care entities); indirect compensation arrangements (dealings between a hospital and entity owned by physicians); and academic medical centers exception (new phase II rules broaden the definition of academic medical centers and ease the requirement that practice plans be tax-exempt organizations, among other changes. Although expert legal advice is required for navigation through the maze of Stark laws, it is incumbent on surgeons in private practice and at academic centers to have basic knowledge of exceptions under this burdensome statute. Antikickback "safe harbors" provide some protection against possible Stark violations. Penalties for violating Stark laws are severe, including fines of up to $15,000 per service and the economic threat of exclusion from participation in federal health care programs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramírez-Morales, A.; Martínez-Orozco, J. C.; Rodríguez-Vargas, I.

The main characteristics of the quantum confined Stark effect (QCSE) are studied theoretically in quantum wells of Gaussian profile. The semi-empirical tight-binding model and the Green function formalism are applied in the numerical calculations. A comparison of the QCSE in quantum wells with different kinds of confining potential is presented.

The motional stark effect with laser-induced fluorescence diagnostic

NASA Astrophysics Data System (ADS)

Foley, E. L.; Levinton, F. M.

2010-05-01

The motional Stark effect (MSE) diagnostic is the worldwide standard technique for internal magnetic field pitch angle measurements in magnetized plasmas. Traditionally, it is based on using polarimetry to measure the polarization direction of light emitted from a hydrogenic species in a neutral beam. As the beam passes through the magnetized plasma at a high velocity, in its rest frame it perceives a Lorentz electric field. This field causes the H-alpha emission to be split and polarized. A new technique under development adds laser-induced fluorescence (LIF) to a diagnostic neutral beam (DNB) for an MSE measurement that will enable radially resolved magnetic field magnitude as well as pitch angle measurements in even low-field (<1 T) experiments. An MSE-LIF system will be installed on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory. It will enable reconstructions of the plasma pressure, q-profile and current as well as, in conjunction with the existing MSE system, measurements of radial electric fields.

Temperature Effects on the Optical Parameters of a Passively Q-Switched Diode-Side Pumped Yb,Er-Laser

NASA Astrophysics Data System (ADS)

Bogdanovich, M. V.; Izyneev, A. A.; Lantsov, K. I.; Lepchenkov, K. V.; Ryabtsev, A. G.; Pavlovskii, V. N.; Sadovskii, P. I.; Svitenkov, I. E.; Shchemelev, M. A.

2018-03-01

Temperature effects on photoluminescence and absorption spectra of the active medium (LGS-DE erbium phosphate glass) and passive Q-switch (MgAl2O4:Co2+ crystal) of a diode-side pumped Yb,Er-laser are studied. The obtained data are applied to an analysis of the spectral and energetic characteristics of compact erbium emitters. It is established that the dominant generation channel in the temperature range 233-328 K is the optical transition between lower Stark sublevels of Er3+ states 4I13/2 and 4I15/2 (λ = 1532.0-1533.9 nm). A rate-equation system taking into account thermal population of Stark sublevels of states 4I13/2 and 4I15/2 is proposed to describe the experimental temperature dependence of the threshold absorbed power of the pumping radiation. This system and the lasing threshold enable modeling of Yb,Er-emitter output energetic and temporal characteristics.

Giant Stark effect in double-stranded porphyrin ladder polymers

NASA Astrophysics Data System (ADS)

Pramanik, Anup; Kang, Hong Seok

2011-03-01

Using the first-principles calculations, we have investigated the stability and the electronic structure of two types of recently synthesized one-dimensional nanoribbons, i.e., double-stranded zinc(II) porphyrin ladder polymer (LADDER) arrays. First, electronic structure calculations were used to show that the LADDER is a semiconductor. Most importantly, the application of a transverse electric field significantly reduces the band gap of the LADDER, ultimately converting the LADDER to a metal at a field strength of 0.1 V/Å. The giant Stark effect in this case is almost as strong as that in boron nitride nanotubes and nanoribbons. In the presence of an electric field, hole conduction and electronic conduction will occur entirely through spatially separated strands, rendering these materials useful for nanoelectronic devices. Second, the substitution of hydrogen atoms in the porphyrin units or that of zinc ions with other kinds of chemical species is found to increase the binding strength of the LADDER and reduce the band gap.

Measuring Electric Fields in Biological Matter Using the Vibrational Stark Effect of Nitrile Probes

NASA Astrophysics Data System (ADS)

Slocum, Joshua D.; Webb, Lauren J.

2018-04-01

Measurement of the electrostatic interactions that give rise to biological functions has been a longstanding challenge in biophysics. Advances in spectroscopic techniques over the past two decades have allowed for the direct measurement of electric fields in a wide variety of biological molecules and systems via the vibrational Stark effect (VSE). The frequency of the nitrile stretching oscillation has received much attention as an electric field reporter because of its sensitivity to electric fields and its occurrence in a relatively transparent region of the infrared spectrum. Despite these advantages and its wide use as a VSE probe, the nitrile stretching frequency is sensitive to hydrogen bonding in a way that complicates the straightforward relationship between measured frequency and environmental electric field. Here we highlight recent applications of nitrile VSE probes with an emphasis on experiments that have helped shape our understanding of the determinants of nitrile frequencies in both hydrogen bonding and nonhydrogen bonding environments.

Polarisation of the Balmer-α emission in crossed electric and magnetic fields

NASA Astrophysics Data System (ADS)

Thorman, Alex

2018-03-01

An analysis of the polarisation structure of the Balmer-α emission in the presence of electric and magnetic fields is presented, with an emphasis on motional Stark effect polarimetry for fusion plasma diagnostics. When the fields are orthogonal, as is the case for neutral heating beams injected into a magnetised plasma, some degeneracy remains in the Stark-Zeeman energy levels and the magnetic quantum number is not well defined. The polarisation structure from the degenerate states is underdetermined and therefore volatile to weaker interactions that resolve this degeneracy, a critical subtlety that has previously been overlooked. A perturbation theory analysis finds distinct polarisation structures for the σ emission that apply when the fine-structure and microscopic electric fields are considered. It is found that only the σ ± 1 polarisation orientation is sensitive to upper-state populations (which are non-statistically weighted for neutral beam injection into a target gas), but with appropriate viewing geometries and beam injection directions the effect can be made negligible.

To Bind Ties between the School and Tribal Life: Educational Policy for Africans under George Stark in Zimbabwe.

ERIC Educational Resources Information Center

Mungazi, Dickson A.

1989-01-01

Contends that educational policy in Zimbabwe from 1934 to 1954 served the political purposes of the colonial government and neglected genuine educational development of the colonized Africans. During George Stark's tenure as Director of Native Education, Zimbabweans were consigned to "practical training" programs and were denied access…

Gendering Coercive Control.

PubMed

Anderson, Kristin L

2009-12-01

This article examines the theory of gender presented in Stark's Coercive Control: How Men Entrap Women in Personal Life. Stark suggests that gender is a form of structural inequality that makes women more vulnerable than men to the strategies of coercive control. However, Stark assumes rather than demonstrates that gendered structural inequality increases women's vulnerability. In this article, the author applies the multilevel theory of gender as identity, interaction, and social structure to document the multiple ways coercive control is gendered. The author argues that, to understand the gender dynamics of coercive control, researchers must examine the interactions across levels of gender. The author concludes with an assessment of the prospects and pitfalls of applying the concept of coercive control to renew the feminist social movement to end domestic violence.

A new species of Perlesta (Plecoptera: Perlidae) from North Carolina with additional records for North Carolina and Virginia

USGS Publications Warehouse

Kondratieff, B.C.; Zuellig, R.E.; Lenat, D.R.

2011-01-01

Twenty-eight species of Nearctic Perlesta are currently recognized (Stark 1989, 2004; Kondratieff et al. 2006, 2008; Grubbs and DeWalt 2008, Grubbs and DeWalt 2011, Kondratieff and Myers 2011). Interestingly, but needing confirmation, Perlesta has been recently recorded from Central America (Gutiérrez-Fonseca and Springer 2011). Continued collecting and study of Perlesta from North Carolina by the authors revealed one additional undescribed species. Ten species of Perlesta currently have been recorded from North Carolina (Stark 1989, 2004, Kondratieff et al. 2006, 2008, Grubbs and DeWalt 2008). Additionally, new Perlesta species records are given for Virginia. The terminology used in the description of the male adult follows Stark (1989, 2004).

Shift measurements of the stark-broadened ionized helium lines at 1640 and 1215 angstrom. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Vanzandt, J. R.

1976-01-01

Time-resolved measurements were made of the shifts of the ionized helium lines at 1,640 A (n = 3 approaches 2) and 1,215 A (n = 4 approaches 2), and of the Stark profile of the 1,215 A wavelength line. An electromagnetic shock tube was used as a light source. The plasma conditions corresponded to electron temperatures of approximately 3.5 eV and electron densities of 0.8 to 1.8 x 10 to the 17th power/cubic cm. The measured shifts fell between two previous estimates of plasma polarization shifts. The measured Stark width of the 1,215 A wavelength line was up to 30% greater than the theoretical width.

Ultrafast control of strong light-matter coupling

NASA Astrophysics Data System (ADS)

Lange, Christoph; Cancellieri, Emiliano; Panna, Dmitry; Whittaker, David M.; Steger, Mark; Snoke, David W.; Pfeiffer, Loren N.; West, Kenneth W.; Hayat, Alex

2018-01-01

We dynamically modulate strong light-matter coupling in a GaAs/AlGaAs microcavity using intense ultrashort laser pulses tuned below the interband exciton energy, which induce a transient Stark shift of the cavity polaritons. For 225-fs pulses, shorter than the cavity Rabi cycle period of 1000 fs, this shift decouples excitons and cavity photons for the duration of the pulse, interrupting the periodic energy exchange between photonic and electronic states. For 1500-fs pulses, longer than the Rabi cycle period, however, the Stark shift does not affect the strong coupling. The two regimes are marked by distinctly different line shapes in ultrafast reflectivity measurements—regardless of the Stark field intensity. The crossover marks the transition from adiabatic to diabatic switching of strong light-matter coupling.

The Investigation of Laser Ignited Plasma with the Application of Current Probes

NASA Astrophysics Data System (ADS)

Olsson, Trevor; Amos, James; Ujj, Laszlo

Among a variety of atomic emission spectroscopy methods Laser-induced breakdown spectroscopy (LIBS) is the one which can analyze any solid, liquid or gas sample. The elemental composition and the relative abundance of the constituent elements in the samples can be determined when the emission spectra of short laser pulses igniting plasma is then recorded and analyzed(e.g.). In our studies we have made a LIBS system which includes, but is not limited to investigating the physical phenomena and properties of the emitting plasma. Active research is going on concerning Lithium-ion batteries to increase the stored charge and energy per volume properties of the device. LIBS is proposed to test the manufacturing process and analyze the chemical constituents of the newly developed batteries. The composition of the battery itself consists of two pieces of foil, typically aluminum and copper acting as a cathode and anode respectively. Separating these two pieces of foil is a lithium based compound. The general chemical composition is Lix [Metal]y Oz where [Metal] is the specific element that is used to achieve the purpose of the battery (one metal may increase the out-put while another helps with capacity etc.). We have chosen the Li-Ion battery composed of LiCoO2 from a mobile phone in order to investigate the Stark-effect (Stark shift and Stark broadening) of the lithium present in the sample. Effects of line broadening and reabsorption of the signals are addressed by recording LIBS spectra from the powder electrolyte extracted from a Lithium-ion battery.

Elemental misinterpretation in automated analysis of LIBS spectra.

PubMed

Hübert, Waldemar; Ankerhold, Georg

2011-07-01

In this work, the Stark effect is shown to be mainly responsible for wrong elemental allocation by automated laser-induced breakdown spectroscopy (LIBS) software solutions. Due to broadening and shift of an elemental emission line affected by the Stark effect, its measured spectral position might interfere with the line position of several other elements. The micro-plasma is generated by focusing a frequency-doubled 200 mJ pulsed Nd/YAG laser on an aluminum target and furthermore on a brass sample in air at atmospheric pressure. After laser pulse excitation, we have measured the temporal evolution of the Al(II) ion line at 281.6 nm (4s(1)S-3p(1)P) during the decay of the laser-induced plasma. Depending on laser pulse power, the center of the measured line is red-shifted by 130 pm (490 GHz) with respect to the exact line position. In this case, the well-known spectral line positions of two moderate and strong lines of other elements coincide with the actual shifted position of the Al(II) line. Consequently, a time-resolving software analysis can lead to an elemental misinterpretation. To avoid a wrong interpretation of LIBS spectra in automated analysis software for a given LIBS system, we recommend using larger gate delays incorporating Stark broadening parameters and using a range of tolerance, which is non-symmetric around the measured line center. These suggestions may help to improve time-resolving LIBS software promising a smaller probability of wrong elemental identification and making LIBS more attractive for industrial applications.

A Comparative Study of Gold Bonding via Electronic Spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Ruohan

The bonding and electrostatic properties of gold containing molecules are highly influenced by relativistic effects. To understand this facet on bonding, a series of simple diatomic AuX (X=F, Cl, O and S) molecules, where upon bond formation the Au atom donates or accepts electrons, was investigated and discussed in this thesis. First, the optical field-free, Stark, and Zeeman spectroscopic studies have been performed on AuF and AuCl. The simple polar bonds between Au and typical halogens (i.e. F and Cl) can be well characterized by the electronic structure studies and the permanent electric dipole moments, mu el. The spectroscopic parameters have been precisely determined for the [17.7]1, [17.8]0+ and X1Sigma + states of AuF, and the [17.07]1, [17.20]0+ and X1Sigma+ states of AuCl. The mu el have been determined for ground and excited states of AuF and AuCl. The results from the hyperfine analysis and Stark measurement support the assignments that the [17.7]1 and [17.8]0+ states of AuF are the components of a 3pi state. Similarly, the analysis demonstrated the [19.07]1 and [19.20]0+ states are the components of the 3pi state of AuCl. Second, my study focused on AuO and AuS because the bonding between gold and sulfur/oxygen is a key component to numerous established and emerging technologies that have applications as far ranging as medical imaging, catalysis, electronics, and material science. The high-resolution spectra were record and analyzed to obtain the geometric and electronic structural data for the ground and excited states. The electric dipole moment, muel , and the magnetic dipole moment, mum, has been the precisely measured by applying external static electric and magnetic fields. muel and mum are used to give insight into the unusual complex bonding in these molecules. In addition to direct studies on the gold-containing molecules, other studies of related molecules are included here as well. These works contain the pure rotation measurement of PtC, the hyperfine and Stark spectroscopic studies of PtF, and the Stark and Zeeman spectroscopic studies of MgH and MgD. Finally, a perspective discussion and conclusion will summarize the results of AuF, AuCl, AuO, and AuS from this work (bond lengths, dipole moment, etc.). The highly quantitative information derived from this work is the foundation of a chemical description of matter and essential for kinetic energy manipulation via Stark and Zeeman interactions. This data set also establishes a synergism with computation chemists who are developing new methodologies for treating relativistic effects and electron correlation.

Advancing College Opportunity: An Impact Evaluation of the Growth of Dual Credit in Stark and Wayne Counties, Ohio

ERIC Educational Resources Information Center

Rochford, Joseph A.; O'Neill, Adrienne; Gelb, Adele

2009-01-01

This impact evaluation looks at three years of growth for "high school-based dual credit" courses exclusive of Canton's Early College High School in Stark and Wayne Counties. As "high school based dual credit" is increasingly implemented in low wealth and urban districts, accompanied by an increase in high school teachers…

Ready to Go: Using the EXPLORE Test to Increase 8th Grade Readiness for Success

ERIC Educational Resources Information Center

Rochford, Joseph A.; O'Neill, Adrienne; Gelb, Adele

2010-01-01

During the 2009-10 academic year, 1,444 8th grade students in the Canton City, Plain and Marlington Local School Districts (hereafter called Stark students) took the EXPLORE Test as part of a pilot project, "Ready to Go: Increasing Eighth Grade Readiness," sponsored by the Stark Education Partnership with funding from the Ohio College…

Strong optical field ionisation of solids

NASA Astrophysics Data System (ADS)

McDonald, C. R.; Ben Taher, A.; Brabec, T.

2017-11-01

Population transfer from the valence to conduction band in the presence of an intense laser field is explored theoretically in semiconductors and dielectrics. Experiments performed on dielectrics exposed to an intense laser field have divulged a population dynamics between valence and conduction band that differs from that observed in semiconductors. Our paper explores two aspects of ionisation in solids. (i) Contemporary ionisation theories do not take account of the coupling between the valence and conduction bands resulting in the absence the dynamic Stark shift. Our single-particle analysis identifies the absence of the dynamic Stark shift as a possible cause for the contrasting ionisation behaviours observed in dielectric and semiconductor materials. The dynamic Stark shift results in an increased bandgap as the laser intensity is increased. This suppresses ionisation to an extent where the main population dynamics results from virtual oscillations in the conduction band population. The dynamic Stark shift mainly affects larger bandgap materials which can be exposed to decidedly higher laser intensities. (ii) In the presence of laser dressed virtual population of the conduction band, elastic collisions potentially transmute virtual into real population resulting in ionisation. This process is explored in the context of the relaxation time approximation.

Reframing violence against women as a human rights violation: Evan Stark's Coercive Control.

PubMed

Libal, Kathryn; Parekh, Serena

2009-12-01

Evan Stark claims that partner-perpetrated physical abuse and other forms of violence against women ought to be understood as a human rights violation. The authors engage Stark's rhetorically powerful political and analytical innovation by outlining one theoretical and one practical challenge to shifting the paradigm that researchers, advocates, and policy makers use to describe, explain, and remedy the harms of coercive control from misdemeanor assault to human rights violation. The theoretical challenge involves overcoming the public/ private dichotomy that underpins liberal conceptions of human rights.The practical challenge involves using the human rights framework in the United States, given public indifference to human rights rhetoric or law, reluctance of U.S. policy makers to submit to scrutiny or justice-oriented processes under international law on issues of human rights and especially war crimes, and the consequent U.S. legacy of refusal to participate meaningfully in the international human rights process. The authors conclude that employing a human rights framework holds potential in the United States, but the paradigm shift Stark advocates will not materialize without widespread mobilization of interest in and understanding of human rights among domestic violence advocates and the society in general.

Study of Stark broadening of Li I 460 and 497 nm spectral lines with independent plasma diagnostics by Thomson scattering

NASA Astrophysics Data System (ADS)

Dzierżȩga, Krzysztof; Piȩta, Tomasz; Zawadzki, Witold; Stambulchik, Evgeny; Gavrilović-Božović, Marijana; Jovićević, Sonja; Pokrzywka, Bartłomiej

2018-02-01

We present results of experimental and theoretical studies of the Stark broadening of the Li I 460 nm spectral line with forbidden components and of the isolated 497 nm line. Plasma was induced by Nd:YAG laser radiation at 1064 nm with pulse duration ˜4.5 ns. Laser-induced plasma was generated in front of the alumina pellet, with some content of Li2CO3, placed in a vacuum chamber filled with argon under reduced pressure. Plasma diagnostics was performed using the laser Thomson scattering technique, free from assumptions about the plasma equilibrium state and its composition and so independently of plasma emission spectra. Spatially resolved spectra with Li lines were obtained from the measured, laterally integrated ones applying the inverse Abel transform. The Stark profiles were calculated by computer simulation method assuming a plasma in the local thermodynamic equilibrium. Calculations were performed for experimentally-inferred electron densities and temperatures, from 1.422 × 1023 to 3.55 × 1022 m-3 and from 1.96 eV to 1.04 eV, respectively. Our studies show very good agreement between experimental Stark profiles and those computer simulated.

Stark broadening of Ca IV spectral lines of astrophysical interest

NASA Astrophysics Data System (ADS)

Alonso-Medina, A.; Colón, C.

2014-12-01

Ca IV emission lines are under the preview of Solar Ultraviolet Measurements of Emitted Radiation device aboard the Solar and Heliospheric Observatory. Also, lines of the Ca IV in planetary nebulae NGC 7027 were detected with the Short Wavelength Spectrometer on board the Infrared Space Observatory. These facts justify an attempt to provide new spectroscopic parameters of Ca IV. There are no theoretical or experimental Stark broadening data for Ca IV. Using the Griem semi-empirical approach and the COWAN code, we report in this paper calculated values of the Stark broadening parameters for 467 lines of Ca IV. They were calculated using a set of wavefunctions obtained by using Hartree-Fock relativistic calculations. These lines arising from 3s23p4ns (n = 4, 5), 3s23p44p, 3s23p4nd (n = 3, 4) configurations. Stark widths and shifts are presented for an electron density of 1017 cm-3 and temperatures T = 10 000, 20 000 and 50 200 K. As these data cannot be compared to others in the literature, we present an analysis of the different regularities of the values presented in this work.

Determination of Stark parameters by cross-calibration in a multi-element laser-induced plasma

NASA Astrophysics Data System (ADS)

Liu, Hao; Truscott, Benjamin S.; Ashfold, Michael N. R.

2016-05-01

We illustrate a Stark broadening analysis of the electron density Ne and temperature Te in a laser-induced plasma (LIP), using a model free of assumptions regarding local thermodynamic equilibrium (LTE). The method relies on Stark parameters determined also without assuming LTE, which are often unknown and unavailable in the literature. Here, we demonstrate that the necessary values can be obtained in situ by cross-calibration between the spectral lines of different charge states, and even different elements, given determinations of Ne and Te based on appropriate parameters for at least one observed transition. This approach enables essentially free choice between species on which to base the analysis, extending the range over which these properties can be measured and giving improved access to low-density plasmas out of LTE. Because of the availability of suitable tabulated values for several charge states of both Si and C, the example of a SiC LIP is taken to illustrate the consistency and accuracy of the procedure. The cross-calibrated Stark parameters are at least as reliable as values obtained by other means, offering a straightforward route to extending the literature in this area.

Multiple Temperature-Sensing Behavior of Green and Red Upconversion Emissions from Stark Sublevels of Er³⁺.

PubMed

Cao, Baosheng; Wu, Jinlei; Wang, Xuehan; He, Yangyang; Feng, Zhiqing; Dong, Bin

2015-12-10

Upconversion luminescence properties from the emissions of Stark sublevels of Er(3+) were investigated in Er(3+)-Yb(3+)-Mo(6+)-codoped TiO₂ phosphors in this study. According to the energy levels split from Er(3+), green and red emissions from the transitions of four coupled energy levels, ²H11/2(I)/²H11/2(II), ⁴S3/2(I)/⁴S3/2(II), ⁴F9/2(I)/⁴F9/2(II), and ²H11/2(I) + ²H11/2(II)/⁴S3/2(I) + ⁴S3/2(II), were observed under 976 nm laser diode excitation. By utilizing the fluorescence intensity ratio (FIR) technique, temperature-dependent upconversion emissions from these four coupled energy levels were analyzed at length. The optical temperature-sensing behaviors of sensing sensitivity, measurement error, and operating temperature for the four coupled energy levels are discussed, all of which are closely related to the energy gap of the coupled energy levels, FIR value, and luminescence intensity. Experimental results suggest that Er(3+)-Yb(3+)-Mo(6+)-codoped TiO₂ phosphor with four pairs of energy levels coupled by Stark sublevels provides a new and effective route to realize multiple optical temperature-sensing through a wide range of temperatures in an independent system.

Entanglement analysis of a two-atom nonlinear Jaynes-Cummings model with nondegenerate two-photon transition, Kerr nonlinearity, and two-mode Stark shift

NASA Astrophysics Data System (ADS)

Baghshahi, H. R.; Tavassoly, M. K.; Faghihi, M. J.

2014-12-01

An entangled state, as an essential tool in quantum information processing, may be generated through the interaction between light and matter in cavity quantum electrodynamics. In this paper, we study the interaction between two two-level atoms and a two-mode field in an optical cavity enclosed by a medium with Kerr nonlinearity in the presence of a detuning parameter and Stark effect. It is assumed that the atom-field coupling and third-order susceptibility of the Kerr medium depend on the intensity of the light. In order to investigate the dynamics of the introduced system, we obtain the exact analytical form of the state vector of the considered atom-field system under initial conditions which may be prepared for the atoms (in a coherent superposition of their ground and upper states) and the fields (in a standard coherent state). Then, in order to evaluate the degree of entanglement between the subsystems, we investigate the dynamics of the entanglement by employing the entanglement of formation. Finally, we analyze in detail the influences of the Stark shift, the deformed Kerr medium, the intensity-dependent coupling, and also the detuning parameter on the behavior of this measure for different subsystems. The numerical results show that the amount of entanglement between the different subsystems can be controlled by choosing the evolved parameters appropriately.

Quantum confined Stark effects of single dopant in polarized hemispherical quantum dot: Two-dimensional finite difference approach and Ritz-Hassé variation method

NASA Astrophysics Data System (ADS)

El Harouny, El Hassan; Nakra Mohajer, Soukaina; Ibral, Asmaa; El Khamkhami, Jamal; Assaid, El Mahdi

2018-05-01

Eigenvalues equation of hydrogen-like off-center single donor impurity confined in polarized homogeneous hemispherical quantum dot deposited on a wetting layer, capped by insulated matrix and submitted to external uniform electric field is solved in the framework of the effective mass approximation. An infinitely deep potential is used to describe effects of quantum confinement due to conduction band offsets at surfaces where quantum dot and surrounding materials meet. Single donor ground state total and binding energies in presence of electric field are determined via two-dimensional finite difference approach and Ritz-Hassé variation principle. For the latter method, attractive coulomb correlation between electron and ionized single donor is taken into account in the expression of trial wave function. It appears that off-center single dopant binding energy, spatial extension and radial probability density are strongly dependent on hemisphere radius and single dopant position inside quantum dot. Influence of a uniform electric field is also investigated. It shows that Stark effect appears even for very small size dots and that single dopant energy shift is more significant when the single donor is near hemispherical surface.

A motional Stark effect diagnostic analysis routine for improved resolution of iota in the core of the large helical device.

PubMed

Dobbins, T J; Ida, K; Suzuki, C; Yoshinuma, M; Kobayashi, T; Suzuki, Y; Yoshida, M

2017-09-01

A new Motional Stark Effect (MSE) analysis routine has been developed for improved spatial resolution in the core of the Large Helical Device (LHD). The routine was developed to reduce the dependency of the analysis on the Pfirsch-Schlüter (PS) current in the core. The technique used the change in the polarization angle as a function of flux in order to find the value of diota/dflux at each measurement location. By integrating inwards from the edge, the iota profile can be recovered from this method. This reduces the results' dependency on the PS current because the effect of the PS current on the MSE measurement is almost constant as a function of flux in the core; therefore, the uncertainty in the PS current has a minimal effect on the calculation of the iota profile. In addition, the VMEC database was remapped from flux into r/a space by interpolating in mode space in order to improve the database core resolution. These changes resulted in a much smoother iota profile, conforming more to the physics expectations of standard discharge scenarios in the core of the LHD.

Can the Stark-Einstein law resolve the measurement problem from an animate perspective?

PubMed

Thaheld, Fred H

2015-09-01

Analysis of the Stark-Einstein law as it applies to the retinal molecule, which is part of the rhodopsin molecule within the rod cells of the retina, reveals that it may provide the solution to the measurement problem from an animate perspective. That it represents a natural boundary where the Schrödinger equation or wave function automatically goes from linear to nonlinear while remaining in a deterministic state. It will be possible in the near future to subject this theory to empirical tests as has been previously proposed. This analysis provides a contrast to the many decades well studied and debated inanimate measurement problem and would represent an addition to the Stark-Einstein law involving information carried by the photon. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Stark effect on an excited hydrogen atom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barratt, C.

1983-07-01

The method of degenerate perturbation theory is used to study the dipolar nature of an excited hydrogen atom in an external electric field. The dependence of the atoms perturbed energy levels on the principal and magnetic quantum numbers, n and m, is investigated, along with the perturbed wave functions.

Ability Versus Will: The Reason Insurgents Surrender

DTIC Science & Technology

2010-06-01

quit as well. The adage that it takes two to tango does not necessarily hold for decisions involving war, however. More than one party is required to...intended effects . Furthermore, the indirect casualties have a timeline that can extend several months, if not years. The effects can take some...not as prominent as if there were numerous, stark differences between the two . To be an effective impetus for insurgency ideology usually requires

Person/Job Fit Model of Communication Apprehension in Organizations

DTIC Science & Technology

1994-05-01

low apprehensives the pattern was the reverse. Stark, Morley, and Shockley - Zalabak (1987) re- ported that low apprehensives deliberately sought out and...Sheahan, M. E. (1978). Measuring communication apprehension. Journal of Communication, 28, 104-111. Stark, P. S., Morley, D. D., & Shockley - Zalabak ...Armstrong Laboratory Human Resources Directorate Communication skills are highly valued in American culture , partly because the majority of high-status jobs

Expanding College Opportunity: An Annual Report on Dual Credit and Other Post Secondary Opportunities for Stark County High School Students

ERIC Educational Resources Information Center

Rochford, Joseph A.; O'Neill, Adrienne; Gelb, Adele; Ross, Kimberly J.; Ughrin, Tina

2014-01-01

This is the eighth annual report by the Stark Education Partnership on dual enrollment and other post secondary opportunities (PSOs) for the county's high school students. In addition to dual enrollment, this report looks at a portfolio of the county's PSOs that includes Canton Early College High School, and the opportunity to bank future college…

Microscopic Description of Spontaneous Emission in Stark Chirped Rapid Adiabatic Passages

NASA Astrophysics Data System (ADS)

Shi, Xuan; Yuan, Hao; Zhao, Hong-Quan

2018-01-01

A microscopic approach describing the effect of spontaneous emission in the stark-chirped rapid adiabatic passages (SCRAPs) for quantum computation is presented. Apart from the phenomenological model, this microscopic one can investigate the dependence of the population dynamics both on the temperature of the environment and the decay rate γ. With flux-biased Josephson qubits as a specifical example, we study the efficiency of the SCRAP for realizing the basic Pauli-X and iSWAP gates. Our results show clearly that the behavior of the population transfer described by the microscopic model is similar with the phenomenological one at zero temperature. In the limit of very high temperature, the population probabilities of the qubit states exhibit strong stability properties. High efficiency for the quantum gate manipulations in SCRAPs is available against the weak decay rate γ ≪ 1 at low temperature.

Infrared Stark and Zeeman spectroscopy of OH–CO: The entrance channel complex along the OH + CO → trans-HOCO reaction pathway

DOE PAGES

Brice, Joseph T.; Liang, Tao; Raston, Paul L.; ...

2016-09-27

Here, sequential capture of OH and CO by superfluid helium droplets leads exclusively to the formation of the linear, entrance-channel complex, OH-CO. This species is characterized by infrared laser Stark and Zeeman spectroscopy via measurements of the fundamental OH stretching vibration. Experimental dipole moments are in disagreement with ab initio calculations at the equilibrium geometry, indicating large-amplitude motion on the ground state potential energy surface. Vibrational averaging along the hydroxyl bending coordinate recovers 80% of the observed deviation from the equilibrium dipole moment. Inhomogeneous line broadening in the zero-field spectrum is modeled with an effective Hamiltonian approach that aims tomore » account for the anisotropic molecule-helium interaction potential that arises as the OH-CO complex is displaced from the center of the droplet.« less

Improving sensitivity to magnetic fields and electric dipole moments by using measurements of individual magnetic sublevels

NASA Astrophysics Data System (ADS)

Tang, Cheng; Zhang, Teng; Weiss, David S.

2018-03-01

We explore ways to use the ability to measure the populations of individual magnetic sublevels to improve the sensitivity of magnetic field measurements and measurements of atomic electric dipole moments (EDMs). When atoms are initialized in the m =0 magnetic sublevel, the shot-noise-limited uncertainty of these measurements is 1 /√{2 F (F +1 ) } smaller than that of a Larmor precession measurement. When the populations in the even (or odd) magnetic sublevels are combined, we show that these measurements are independent of the tensor Stark shift and the second order Zeeman shift. We discuss the complicating effect of a transverse magnetic field and show that when the ratio of the tensor Stark shift to the transverse magnetic field is sufficiently large, an EDM measurement with atoms initialized in the superposition of the stretched states can reach the optimal sensitivity.

An expanded genetic code for probing the role of electrostatics in enzyme catalysis by vibrational Stark spectroscopy.

PubMed

Völler, Jan-Stefan; Biava, Hernan; Hildebrandt, Peter; Budisa, Nediljko

2017-11-01

To find experimental validation for electrostatic interactions essential for catalytic reactions represents a challenge due to practical limitations in assessing electric fields within protein structures. This review examines the applications of non-canonical amino acids (ncAAs) as genetically encoded probes for studying the role of electrostatic interactions in enzyme catalysis. ncAAs constitute sensitive spectroscopic probes to detect local electric fields by exploiting the vibrational Stark effect (VSE) and thus have the potential to map the protein electrostatics. Mapping the electrostatics in proteins will improve our understanding of natural catalytic processes and, in beyond, will be helpful for biocatalyst engineering. This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple formula for estimating Stark widths of neutral lines. [of stellar atmospheres

NASA Technical Reports Server (NTRS)

Freudenstein, S. A.; Cooper, J.

1978-01-01

A simple formula for the prediction of Stark widths of neutral lines similar to the semiempirical method of Griem (1968) for ion lines is presented. This formula is a simplification of the quantum-mechanical classical path impact theory and can be used for complicated atoms for which detailed calculations are not readily available, provided that the effective position of the closest interacting level is known. The expression does not require the use of a computer. The formula has been applied to a limited number of neutral lines of interest, and the width obtained is compared with the much more complete calculations of Bennett and Griem (1971). The agreement generally is well within 50% of the published value for the lines investigated. Comparisons with other formulas are also made. In addition, a simple estimate for the ion-broadening parameter is given.

Electron density measurement in gas discharge plasmas by optical and acoustic methods

NASA Astrophysics Data System (ADS)

Biagioni, A.; Anania, M. P.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Mostacci, A.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2016-08-01

Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

Stark shift of impurity doped quantum dots: Role of noise

NASA Astrophysics Data System (ADS)

Arif, Sk. Md.; Bera, Aindrila; Ghosh, Anuja; Ghosh, Manas

2018-02-01

Present study makes a punctilious investigation of the profiles of Stark shift (SS) of doped GaAs quantum dot (QD) under the supervision of Gaussian white noise. A few physical parameters have been varied and the consequent variations in the SS profiles have been monitored. The said physical parameters comprise of magnetic field, confinement potential, dopant location, dopant potential, noise strength, aluminium concentration (only for AlxGa1-x As alloy QD), position-dependent effective mass (PDEM), position-dependent dielectric screening function (PDDSF), anisotropy, hydrostatic pressure (HP) and temperature. The SS profiles unfurl interesting features that heavily depend upon the particular physical quantity concerned, presence/absence of noise and the manner (additive/multiplicative) noise enters the system. The study highlights feasible means of maximizing SS of doped QD in presence of noise by suitable adjustment of several control parameters. The study deems importance in view of technological applications of QD devices where noise plays some prominent role.

Anomalous broadening and shift of emission lines in a femtosecond laser plasma filament in air

NASA Astrophysics Data System (ADS)

Ilyin, A. A.; Golik, S. S.; Shmirko, K. A.; Mayor, A. Yu.; Proschenko, D. Yu.

2017-12-01

The temporal evolution of the width and shift of N I 746.8 and O I 777.4 nm lines is investigated in a filament plasma produced by a tightly focused femtosecond laser pulse (0.9 mJ, 48 fs). The nitrogen line shift and width are determined by the joint action of electron impact shift and the far-off resonance AC Stark effect. The intensive (I = 1.2·1010 W/cm2) electric field of ASE (amplified spontaneous emission) and post-pulses result in a possible LS coupling break for the O I 3p 5P level and the generation of Rabi sidebands. The blueshifted main femtosecond pulse and Rabi sideband cause the stimulated emission of the N2 1+ system. The maximal widths of emission lines are approximately 6.7 times larger than the calculated Stark widths.

How to tell a new story about battering.

PubMed

Polletta, Francesca

2009-12-01

As Evan Stark observes, getting domestic violence against women recognized as coercive control will require a major effort of storytelling. Women's accounts of subjugation have to be narrated in a way that is both true to their experiences and capable of eliciting public understanding, sympathy, and action. This essay draws on an interdisciplinary literature on narrative to show why doing that poses such a formidable challenge. In lieu of the tragic form that has dominated battered women's storytelling, and in lieu of the quest and mystery forms that appear in Stark's own accounts, this article argues for using a rebirth story line.This genre, which has affinities with the fairytales Snow White and Sleeping Beauty, seems an unlikely vehicle for asserting battered women's combination of victimization and agency. Drawing on the stories told by battered women as part of a successful reform effort, however, this article shows how women have used the form effectively.

Far infrared maser communications technology

NASA Technical Reports Server (NTRS)

Claspy, P. C.; Pao, Y. H.

1975-01-01

An optically pumped FIR laser was constructed and tested. Optimum operating conditions were determined with CH3OH as the lasing medium. The laser was found to operate equally well with flowing gas or in a sealed off configuration. The FIR cavity stability and pump laser stability were found to have significant problems. The absorption coefficient per unit pressure of 1-1 difluoroethylene at the P(22) and P(24) lines of the 10.4 micron CO2 band was measured. The FIR line pumped by P(22) occurs at approximately 890 microns, which may be in an atmospheric transmission window. It was found that significant Stark tuning of absorption lines of methanol and 1-1 difluoroethylene can be accomplished, even at the usual 100 to 300 mTorr operating pressures of FIR lasers. This means that the use of Stark tuning may enable more effective use of pump laser output.

Ferroelectric nanotraps for polar molecules

NASA Astrophysics Data System (ADS)

Dutta, Omjyoti; Giedke, G.

2018-02-01

We propose and analyze an electrostatic-optical nanoscale trap for cold diatomic polar molecules. The main ingredient of our proposal is a square array of ferroelectric nanorods with alternating polarization. We show that, in contrast to electrostatic traps using the linear Stark effect, a quadratic Stark potential supports long-lived trapped states. The molecules are kept at a fixed height from the nanorods by a standing-wave optical dipole trap. For the molecules and materials considered, we find nanotraps with trap frequency up to 1 MHz, ground-state width ˜20 nm with lattice periodicity of ˜200 nm . Analyzing the loss mechanisms due to nonadiabaticity, surface-induced radiative transitions, and laser-induced transitions, we show the existence of trapped states with lifetime ˜1 s , competitive with current traps created via optical mechanisms. As an application we extend our discussion to a one-dimensional (1D) array of nanotraps to simulate a long-range spin Hamiltonian in our structure.

Some properties of Stark states of hydrogenic atoms and ions

NASA Astrophysics Data System (ADS)

Hey, J. D.

2007-10-01

The motivation for this work is the problem of providing accurate values of the atomic transition matrix elements for the Stark components of Rydberg Rydberg transitions in atomic hydrogen and hydrogenic ions, for use in spectral line broadening calculations applicable to cool, low-density plasmas, such as those found in H II regions. Since conventional methods of calculating these transition matrix elements cannot be used for the high principal quantum numbers now easily attained in radio astronomical spectra, we attempt to show that the recurrence relation (ladder operator) method recently employed by Watson (2006 J. Phys. B: At. Mol. Opt. Phys. 39 1889 97) and Hey (2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641 64) can be taken over into the parabolic coordinate system used to describe the Stark states of the atomic (ionic) radiators. The present method is therefore suggested as potentially useful for extending the work of Griem (1967 Astrophys. J. 148 547 58, 2005 Astrophys. J. 620 L133 4), Watson (2006), Stambulchik et al (2007 Phys. Rev. E 75 016401(9 pp) on Stark broadening in transitions between states of high principal quantum number, to physical conditions where the binary, impact approximation is no longer strictly applicable to both electron and ion perturbers. Another possible field of application is the study of Stark mixing transitions in 'ultracold' Rydberg atoms perturbed by long-range interactions with slow atoms and ions. Preparatory to the derivation of recurrence relations for states of different principal quantum number, a number of properties and recurrence relations are also found for states of identical principal quantum number, including the analogue in parabolic coordinates to the relations of Pasternack (1937 Proc. Natl Acad. Sci. USA 23 91 4, 250) in spherical polar coordinates.

Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

NASA Astrophysics Data System (ADS)

Broderick, Bernadette M.; McCaslin, Laura; Moradi, Christopher P.; Stanton, John F.; Douberly, Gary E.

2015-04-01

Singlet dihydroxycarbene ( HO C ̈ OH ) is produced via pyrolytic decomposition of oxalic acid, captured by helium nanodroplets, and probed with infrared laser Stark spectroscopy. Rovibrational bands in the OH stretch region are assigned to either trans,trans- or trans,cis-rotamers on the basis of symmetry type, nuclear spin statistical weights, and comparisons to electronic structure theory calculations. Stark spectroscopy provides the inertial components of the permanent electric dipole moments for these rotamers. The dipole components for trans, trans- and trans, cis-rotamers are (μa, μb) = (0.00, 0.68(6)) and (1.63(3), 1.50(5)), respectively. The infrared spectra lack evidence for the higher energy cis,cis-rotamer, which is consistent with a previously proposed pyrolytic decomposition mechanism of oxalic acid and computations of HO C ̈ OH torsional interconversion and tautomerization barriers.

Topology of surfaces for molecular Stark energy, alignment, and orientation generated by combined permanent and induced electric dipole interactions.

PubMed

Schmidt, Burkhard; Friedrich, Bretislav

2014-02-14

We show that combined permanent and induced electric dipole interactions of linear polar and polarizable molecules with collinear electric fields lead to a sui generis topology of the corresponding Stark energy surfaces and of other observables - such as alignment and orientation cosines - in the plane spanned by the permanent and induced dipole interaction parameters. We find that the loci of the intersections of the surfaces can be traced analytically and that the eigenstates as well as the number of their intersections can be characterized by a single integer index. The value of the index, distinctive for a particular ratio of the interaction parameters, brings out a close kinship with the eigenproperties obtained previously for a class of Stark states via the apparatus of supersymmetric quantum mechanics.

Development of a wavy Stark velocity filter for studying interstellar chemistry

NASA Astrophysics Data System (ADS)

Okada, Kunihiro; Takada, Yusuke; Kimura, Naoki; Wada, Michiharu; Schuessler, Hans A.

2017-08-01

Cold polar molecules are key to both the understanding of fundamental physics and the characterization of the chemical evolution of interstellar clouds. To facilitate such studies over a wide range of temperatures, we developed a new type of Stark velocity filter for changing the translational and rotational temperatures of velocity-selected polar molecules without changing the output beam position. The translational temperature of guided polar molecules can be significantly varied by exchanging the wavy deflection section with one having a different radius of the curvature and a different deflection angle. Combining in addition a temperature variable gas cell with the wavy Stark velocity filter enables to observe the translational and rotational temperature dependence of the reaction-rate constants of cold ion-polar molecule reactions over the interesting temperature range of 10-100 K.

Magnetron Sputtered Pulsed Laser Deposition Scale Up

DTIC Science & Technology

2003-08-14

2:721-726 34 S. J. P. Laube and E. F. Stark, “ Artificial Intellegence in Process Control of Pulsed Laser Deposition”, Proceedings of...The model would be based on mathematical simulation of real process data, neural-networks, or other artificial intelligence methods based on in situ...Laube and E. F. Stark, Proc. Symp. Artificial Intel. Real Time Control, Valencia, Spain, 3-5 Oct. ,1994, p.159-163. International Federation of

Toward Finding Driving Communications Factors in the System of Systems Survivability Simulation Model

DTIC Science & Technology

2014-03-01

BLANK 53 LIST OF REFERENCES Bernstein Jr ., R., Flores , R., & Starks, M. (2006). Objectives and capabilities of the system of...Reader Robert Dell Chair, Department of Operations Research iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT The System of Systems...larger system (Starks & Flores , 2004). One of the primary concerns for a new platform is its survivability, lethality, and vulnerability (SLV) as part

The Effect of Intense Laser Radiation on Atomic Collisions

NASA Astrophysics Data System (ADS)

Young, Stephen Michael Radley

1991-02-01

Available from UMI in association with The British Library. Requires signed TDF. We have carried out theoretical and experimental studies into the effect of intense laser radiation on atomic collisions. The first experiment used neon. Excitation by electron impact in a gas discharge demanded a pressure of at least 0.075 Torr. Measurement of the intensity of 3^1S_0to 3^1P_1 fluorescence has been made for the case where high intensity ASE wings in the laser profile and background laser scatter are unimportant, with the laser tuned to resonance. The field intensity required to produce strong field fluorescence (exemplified by the Mollow triplet) was found to give rise to complications capable of screening the effects sought. Our theoretical model has suggested that at finite detunings, line-centre fluorescence will dominate Rayleigh scatter and omega_3 fluorescence. Our measurements provide information on the saturation of neon fluorescence but not of the variation of the intense field collision rate. Absorption of weak field 253.7 nm laser photons by ground state mercury atoms yielded a high 6 ^3P_1 population at a lower pressure of 0.02 Torr. The Mollow triplet has been observed in the self-broadened mercury system. Dressing of the upper transition (6^3P_1rightarrow 7^3S_1) by an intense laser close to 435.8 nm yielded the strong field signal. Polarisation studies were made possible by the 3-level mercury system (radiation trapping in a 2-level system would depolarise fluorescence) perturbed by argon. The studies yielded results that were explainable in terms of the selective population of Stark shifted dressed states by a detuned, weak probe field. Use has been made of the electric-dipole radiation selection rule m_{J}=0 rightarrow m_{J^' } = 0 unless J=J^' to devise a 'Stark shift collision switch'. The competition between collision and radiation induced transitions within the mercury atom has then been studied. The resonant, strong lambda 435.8 nm field was used in conjunction with the weak lambda 253.7 nm field detuned by 0 to 6 cm^ {-1}. Measurement of fluorescence intensity in two perpendicular planes of polarisation has revealed the dominant | e_1> to | e_2> excitation channel as a function of the Stark shift by way of the U.V. detuning. Competition between the channels was dependent on the generalised Rabi frequency. However, we could only monitor the relative strength of the channels and were thus unable to say that the Stark shift switched collisions off. (Abstract shortened by UMI.).

The Effect of Microstructure on the Properties of High Strength Aluminum Alloys

DTIC Science & Technology

1980-02-01

precracked samples were loaded with opposing bolts to constant crack opening displacement (COD) values. The notch with the precrack was sealed with Scotch tape ...Respectfully submitted: Edgar K. Starke, Jr. Principal Investigator Si Il I REFERENCES 1. P. C. Paris and F. Erdogan , J. Basic Eng., Vol. 85, 1963, p. 528

Moving across Borders: Immigrant Women's Encounters with Globalization, the Knowledge Economy and Lifelong Learning

ERIC Educational Resources Information Center

Gibb, Tara; Hamdon, Evelyn

2010-01-01

The (un)reality of open/porous borders is starkly represented/manifested in the experiences of immigrant women in lifelong learning contexts. While globalization effectively destroys some borders, it simultaneously creates new ones. State institutions respond to global reconfigurations of borders at local levels by establishing policies that…

Single molecule quantum-confined Stark effect measurements of semiconductor nanoparticles at room temperature

NASA Astrophysics Data System (ADS)

Park, Kyoung Won; Deutsch, Zvicka; Li, J. Jack; Oron, Dan; Weiss, Shimon

2013-02-01

We investigate the quantum confined Stark effect (QCSE) of various nanoparticles (NPs) on the single molecule level at room temperature. We tested 8 different NPs with different geometry, material composition and electronic structure, and measured their QCSE by single molecule spectroscopy. This study reveals that suppressing the Coulomb interaction force between electron and hole by asymmetric type-II interface is critical for an enhanced QCSE. For example, ZnSe-CdS and CdSe(Te)-CdS-CdZnSe asymmetric nanorods (type-II) display respectively twice and more than three times larger QCSE than that of simple type-I nanorods (CdSe). In addition, wavelength blue-shift of QCSE and roughly linear Δλ-F (emission wavelength shift vs. the applied electric field) relation are observed for the type-II nanorods. Experimental results (Δλ-F or ΔE-F) are successfully reproduced by self-consistent quantum mechanical calculation. Intensity reduction in blue-shifted spectrum is also accounted for. Both calculations and experiments suggest that the magnitude of the QCSE is predominantly determined by the degree of initial charge separation in these structures.

Electric Fields near RF Heating and Current Drive Antennas in Tore Supra Measured with Dynamic Stark Effect Spectroscopy*

NASA Astrophysics Data System (ADS)

Klepper, C. C.; Martin, E. H.; Isler, R. C.; Colas, L.; Hillairet, J.; Marandet, Y.; Lotte, Ph.; Colledani, G.; Martin, V.; Hillis, D. L.; Harris, J. H.; Saoutic, B.

2011-10-01

Computational models of the interaction between RF waves and the scrape-off layer plasma near ion cyclotron resonant heating (ICRH) and lower hybrid current drive launch antennas are continuously improving. These models mainly predict the RF electric fields produced in the SOL and, therefore, the best measurement for verification of these models would be a direct measurement of these electric fields. Both types of launch antennas are used on Tore Supra and are designed for high power (up to 4MW/antenna) and long pulse (> > 25s) operation. Direct, non-intrusive measurement of the RF electric fields in the vicinity of these structures is achieved by fitting spectral profiles of deuterium Balmer-alpha and Balmer-beta to a model that includes the dynamic, external-field Stark effect, as well as Zeeman splitting and Doppler broadening mechanisms. The measurements are compared to the mentioned, near-field region, RF antenna models. *Work supported in part by the US DOE under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.

Tunable room-temperature spin-selective optical Stark effect in solution-processed layered halide perovskites.

PubMed

Giovanni, David; Chong, Wee Kiang; Dewi, Herlina Arianita; Thirumal, Krishnamoorthy; Neogi, Ishita; Ramesh, Ramamoorthy; Mhaisalkar, Subodh; Mathews, Nripan; Sum, Tze Chien

2016-06-01

Ultrafast spin manipulation for opto-spin logic applications requires material systems that have strong spin-selective light-matter interaction. Conventional inorganic semiconductor nanostructures [for example, epitaxial II to VI quantum dots and III to V multiple quantum wells (MQWs)] are considered forerunners but encounter challenges such as lattice matching and cryogenic cooling requirements. Two-dimensional halide perovskite semiconductors, combining intrinsic tunable MQW structures and large oscillator strengths with facile solution processability, can offer breakthroughs in this area. We demonstrate novel room-temperature, strong ultrafast spin-selective optical Stark effect in solution-processed (C6H4FC2H4NH3)2PbI4 perovskite thin films. Exciton spin states are selectively tuned by ~6.3 meV using circularly polarized optical pulses without any external photonic cavity (that is, corresponding to a Rabi energy of ~55 meV and equivalent to applying a 70 T magnetic field), which is much larger than any conventional system. The facile halide and organic replacement in these perovskites affords control of the dielectric confinement and thus presents a straightforward strategy for tuning light-matter coupling strength.

Simultaneous influence of Stark effect and excessive line broadening on the Hα line

NASA Astrophysics Data System (ADS)

Cvetanović, Nikola; Ivković, Saša S.; Obradović, Bratislav M.; Kuraica, Milorad M.

2017-12-01

The aim of this paper is to study the combined influence of the Stark effect and the excessive Doppler broadening on the Balmer alpha line in hydrogen discharges. Since this line is a good candidate for measuring electric field in various types of discharges with different gas compositions, a simple method for field measurement based on polarization spectroscopy is developed, that includes all the excitation mechanisms. To simultaneously test the flexibility of the fitting procedure and investigate the excessive broadening, we applied the fitting procedure on line profiles obtained at a range of conditions from two different discharges. The range of pressures and voltages was examined in an abnormal glow and in dielectric barrier discharge operating with hydrogen gas. The model fitting function was able to respond and follow the change in the line profile caused by the change of conditions. This procedure can therefore be recommended for electric field measurement. Contribution to the "Topical Issue: Physics of Ionized Gases (SPIG 2016)", edited by Goran Poparic, Bratislav Obradovic, Dragana Maric and Aleksandar Milosavljevic.

On the Absolutely Continuous Spectrum of Stark Operators

NASA Astrophysics Data System (ADS)

Perelman, Galina

The stability of the absolutely continuous spectrum of the one-dimensional Stark operator under perturbations of the potential is discussed. The focus is on proving this stability under minimal assumptions on smoothness of the perturbation. A general criterion is presented together with some applications. These include the case of periodic perturbations where we show that any perturbation vL1()∩H-1/2() preserves the a.c. spectrum.

Reaching for 80%: How Post Secondary Opportunities in High Schools Are Changing the College Going Culture in Stark County, Ohio

ERIC Educational Resources Information Center

Rochford, Joseph A.; O'Neill, Adrienne; Gelb, Adele; Ross, Kimberly J.

2011-01-01

In 2002, the Stark County Preschool through College (P-16) Compact set the goal of achieving an 80% college going rate. Such a goal seemed both audacious and daunting for a community where in 2001 only 17.9% of the adults held a Bachelor's Degree, or higher, and where only 49% of all high school graduates went directly to college. Nine years have…

Functional Specialization in the Lower and Upper Visual Fields in Humans: Its Ecological Origins and Neurophysiological Implications

DTIC Science & Technology

1990-01-01

in that the with this hypothesis are the many reports (e.g., Adler - crossed-disparity system does appear to develop first Grinberg & Stark 1978... Rodman et al. 1986) that survives as independent of hemispheric asymmetries and additive to striate lesions critically depends on the superior...Perfomance. IRAAI human brain. No longer can visual cortical physiology Adler -Grinberg, D. & Stark, L. (1978) Eye movements, scanpaths, and dyslexia

Catching flies with vinegar: a critique of the Centers for Medicare and Medicaid self-disclosure program.

PubMed

Veilleux, Jean Wright

2012-01-01

This Article argues that the current approach of the Department of Health and Human Services and the Centers for Medicare and Medicaid Services (CMS) to enforcement of the Ethics in Patient Referrals Act (the "Stark Law") is unnecessarily punitive and discourages health-care providers from self-disclosing even very minor violations of the Stark Law. This Article suggests a number of specific changes to encourage provider self-disclosure and proposes that CMS create a demonstration project under the authority of the Patient Protection and Affordable Care Act to test the reforms. A demonstration project provides the perfect vehicle to prove that increased self-disclosure protocols for the Stark Law can decrease the government's costs of enforcement, improve program integrity, and encourage providers to deal responsibly with the inevitable minor lapses in compliance that arise in such an enormous government program as Medicare.

Wannier-Stark localization of a strongly coupled asymmetric double-well GaAs/AlAs superlattice

NASA Astrophysics Data System (ADS)

Kawashima, Kenji; Matsumoto, Takeshi; Arima, Kiyotoku; Ohsumi, Takahiro; Nogami, Takamitsu; Satoh, Kazuo; Fujiwara, Kenzo

2000-06-01

A novel new type of superlattice (SL) structure which consists of strongly coupled asymmetric double-well (ADW) in one period have been investigated to introduce a new degree of freedom for the device funtionality. The GaAs/A1As ADS-SL contained in a p-i-n diode structure was grown by molecular beam epitaxy, and the electroabsorption properties were measured by low temperature photocurrent spectroscopy. It is found that the introduction of the confinement potential asymmetry with respect to electric field will lead to the selectivity of spatially indirect Stark-ladder transitions associated with two different types of the localized hole states, thus providing a new way of modulating the oscillator strengths. Assignment of the possible optical transitions from the miniband to the Stark-ladder regimes as a function of field strength is elucidated in detail by transfer matrix calculations.

Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

DOE PAGES

Broderick, Bernadette M.; McCaslin, Laura; Moradi, Christopher P.; ...

2015-04-14

Singlet dihydroxycarbene (HOmore » $$\\ddot C$$OH) is produced via pyrolytic decomposition of oxalic acid, captured by helium nanodroplets, and probed with infrared laser Stark spectroscopy. Rovibrational bands in the OH stretch region are assigned to either trans, trans-or trans, cis-rotamers on the basis of symmetry type, nuclear spin statistical weights, and comparisons to electronic structure theory calculations. Stark spectroscopy provides the inertial components of the permanent electric dipole moments for these rotamers. The dipole components for trans, trans-and trans, cis-rotamers are (μ a, μ b) = (0.00,0.68(6)) and (1.63(3), 1.50(5)), respectively. The infrared spectra lack evidence for the higher energy cis,cis-rotamer, which is consistent with a previously proposed pyrolytic decomposition mechanism of oxalic acid and computations of HO$$\\ddot C$$OH torsional interconversion and tautomerization barriers.« less

Magnetic quantum phase transition in Cr-doped Bi 2(Se xTe 1-x) 3 driven by the Stark effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Zuocheng; Feng, Xiao; Wang, Jing

The interplay between magnetism and topology, as exemplified in the magnetic skyrmion systems, has emerged as a rich playground for finding novel quantum phenomena and applications in future information technology. Magnetic topological insulators (TI) have attracted much recent attention, especially after the experimental realization of quantum anomalous Hall effect. Future applications of magnetic TI hinge on the accurate manipulation of magnetism and topology by external perturbations, preferably with a gate electric field. In this work, we investigate the magneto transport properties of Cr doped Bi 2(Se xTe 1-x) 3 TI across the topological quantum critical point (QCP). We find thatmore » the external gate voltage has negligible effect on the magnetic order for samples far away from the topological QCP. However, for the sample near the QCP, we observe a ferromagnetic (FM) to paramagnetic (PM) phase transition driven by the gate electric field. Theoretical calculations show that a perpendicular electric field causes a shift of electronic energy levels due to the Stark effect, which induces a topological quantum phase transition and consequently a magnetic phase transition. Finally, the in situ electrical control of the topological and magnetic properties of TI shed important new lights on future topological electronic or spintronic device applications.« less

Magnetic quantum phase transition in Cr-doped Bi 2(Se xTe 1-x) 3 driven by the Stark effect

DOE PAGES

Zhang, Zuocheng; Feng, Xiao; Wang, Jing; ...

2017-08-07

The interplay between magnetism and topology, as exemplified in the magnetic skyrmion systems, has emerged as a rich playground for finding novel quantum phenomena and applications in future information technology. Magnetic topological insulators (TI) have attracted much recent attention, especially after the experimental realization of quantum anomalous Hall effect. Future applications of magnetic TI hinge on the accurate manipulation of magnetism and topology by external perturbations, preferably with a gate electric field. In this work, we investigate the magneto transport properties of Cr doped Bi 2(Se xTe 1-x) 3 TI across the topological quantum critical point (QCP). We find thatmore » the external gate voltage has negligible effect on the magnetic order for samples far away from the topological QCP. However, for the sample near the QCP, we observe a ferromagnetic (FM) to paramagnetic (PM) phase transition driven by the gate electric field. Theoretical calculations show that a perpendicular electric field causes a shift of electronic energy levels due to the Stark effect, which induces a topological quantum phase transition and consequently a magnetic phase transition. Finally, the in situ electrical control of the topological and magnetic properties of TI shed important new lights on future topological electronic or spintronic device applications.« less

Electric field determination in the plasma-antenna boundary of a lower-hybrid wave launcher in Tore Supra through dynamic Stark-effect spectroscopy

NASA Astrophysics Data System (ADS)

Martin, E. H.; Goniche, M.; Klepper, C. C.; Hillairet, J.; Isler, R. C.; Bottereau, C.; Colas, L.; Ekedahl, A.; Panayotis, S.; Pegourie, B.; Lotte, Ph; Colledani, G.; Caughman, J. B.; Harris, J. H.; Hillis, D. L.; Shannon, S. C.; Clairet, F.; Litaudon, X.

2015-06-01

Interaction of radio-frequency (RF) waves with the plasma in the near-field of a high-power wave launcher is now seen to be an important topic, both in understanding the channeling of these waves through the plasma boundary and in avoiding power losses in the edge. In a recent Letter, a direct non-intrusive measurement of a near antenna RF electric field in the range of lower hybrid (LH) frequencies (ELH) was announced (2013 Phys. Rev. Lett. 110 215005). This measurement was achieved through the fitting of Balmer series deuterium spectral lines utilizing a time dependent (dynamic) Stark effect model. In this article, the analysis of the spectral data is discussed in detail and applied to a larger range of measurements and the accuracy and limitations of the experimental technique are investigated. It was found through an analysis of numerous Tore Supra discharges that good quantitative agreement exists between the measured and full-wave modeled ELH when the launched power exceeds 0.5 MW. For low power the measurement becomes inaccurate utilizing the implemented passive spectroscopic technique because the spectral noise overwhelms the effect of the RF electric field on the line profile. Additionally, effects of the ponderomotive force are suspected at sufficiently high power.

The Effect of Studying Tech Prep in High School and College Academic Performance

ERIC Educational Resources Information Center

Ray, Larry A.

2011-01-01

This study examined the academic performance of Tech Prep students (referred to as participants) in comparison to non-Tech Prep students (referred to as non-participants) entering a two-year community college from sixteen different high schools in Stark County, Ohio. This study provided a quantitative analysis of students' academic experiences to…

Phonon assisted carrier motion on the Wannier-Stark ladder

NASA Astrophysics Data System (ADS)

Cheung, Alfred; Berciu, Mona

2014-03-01

It is well known that at zero temperature and in the absence of electron-phonon coupling, the presence of an electric field leads to localization of carriers residing in a single band of finite bandwidth. In this talk, we will present an implementation of the self-consistent Born approximation (SCBA) to study the effect of weak electron-phonon coupling on the motion of a carrier in a biased system. At moderate and strong electron-phonon coupling, we supplement the SCBA, describing the string of phonons left behind by the carrier, with the momentum average approximation to describe the phonon cloud that accompanies the resulting polaron. We find that coupling to the lattice delocalizes the carrier, as expected, although long-lived resonances resulting from the Wannier-Stark states of the polaron may appear in certain regions of the parameter space. We end with a discussion of how our method can be improved to model disorder, other types of electron-phonon coupling, and electron-hole pair dissociation in a biased system.

Stark tuning and electrical charge state control of single divacancies in silicon carbide

NASA Astrophysics Data System (ADS)

de las Casas, Charles F.; Christle, David J.; Ul Hassan, Jawad; Ohshima, Takeshi; Son, Nguyen T.; Awschalom, David D.

2017-12-01

Neutrally charged divacancies in silicon carbide (SiC) are paramagnetic color centers whose long coherence times and near-telecom operating wavelengths make them promising for scalable quantum communication technologies compatible with existing fiber optic networks. However, local strain inhomogeneity can randomly perturb their optical transition frequencies, which degrades the indistinguishability of photons emitted from separate defects and hinders their coupling to optical cavities. Here, we show that electric fields can be used to tune the optical transition frequencies of single neutral divacancy defects in 4H-SiC over a range of several GHz via the DC Stark effect. The same technique can also control the charge state of the defect on microsecond timescales, which we use to stabilize unstable or non-neutral divacancies into their neutral charge state. Using fluorescence-based charge state detection, we show that both 975 nm and 1130 nm excitation can prepare their neutral charge state with near unity efficiency.

Dynamic Stark spectroscopic measurements of microwave electric fields inside the plasma near a high-power antenna.

PubMed

Klepper, C C; Isler, R C; Hillairet, J; Martin, E H; Colas, L; Ekedahl, A; Goniche, M; Harris, J H; Hillis, D L; Panayotis, S; Pegourié, B; Lotte, Ph; Colledani, G; Martin, V

2013-05-24

Fully dynamic Stark effect visible spectroscopy was used for the first time to directly measure the local rf electric field in the boundary plasma near a high-power antenna in high-performance, magnetically confined, fusion energy experiment. The measurement was performed in the superconducting tokamak Tore Supra, in the near field of a 1–3 MW, lower-hybrid, 3.7 GHz wave-launch antenna, and combined with modeling of neutral atom transport to estimate the local rf electric field amplitude (as low as 1–2 kV/cm) and direction in this region. The measurement was then shown to be consistent with the predicted values from a 2D full-wave propagation model. Notably the measurement confirmed that the electric field direction deviates substantially from the direction in which it is launched by the waveguides as it penetrates only a few cm radially inward into the plasma from the waveguides, consistent with the model.

Application of Ada (Trade Name) Higher Order Language to Guidance and Control

DTIC Science & Technology

1986-05-01

name "DoD-0"). The name Ada honors the mathematician of the 19th century who, as colleague to Charles Babbage , developed an instruction set for the as...Avenue St Charles , MO 63301 USA SPEAKERS Mr R.E.Bolz 6751 South Dahlia Court Modem Prograimning Languages Littleton, CO 80122 USA Dr O.Roubine...WHITTREDGE, R. S. PAA : C/( Charles Stark Draper Laboratory, Inc., Cambridge, MA) CORP: Draper ( Charles Stark) Lab., Inc., Cambridge, Mass. IN

Independent variations of applied voltage and injection current for controlling the quantum-confined Stark effect in an InGaN/GaN quantum-well light-emitting diode.

PubMed

Chen, Horng-Shyang; Liu, Zhan Hui; Shih, Pei-Ying; Su, Chia-Ying; Chen, Chih-Yen; Lin, Chun-Han; Yao, Yu-Feng; Kiang, Yean-Woei; Yang, C C

2014-04-07

A reverse-biased voltage is applied to either device in the vertical configuration of two light-emitting diodes (LEDs) grown on patterned and flat Si (110) substrates with weak and strong quantum-confined Stark effects (QCSEs), respectively, in the InGaN/GaN quantum wells for independently controlling the applied voltage across and the injection current into the p-i-n junction in the lateral configuration of LED operation. The results show that more carrier supply is needed in the LED of weaker QCSE to produce a carrier screening effect for balancing the potential tilt in increasing the forward-biased voltage, when compared with the LED of stronger QCSE. The small spectral shift range in increasing injection current in the LED of weaker QCSE is attributed not only to the weaker QCSE, but also to its smaller device resistance such that a given increment of applied voltage leads to a larger increment of injection current. From a viewpoint of practical application in LED operation, by applying a reverse-biased voltage in the vertical configuration, the applied voltage and injection current in the lateral configuration can be independently controlled by adjusting the vertical voltage for keeping the emission spectral peak fixed.

Study of Stark Effect in n-doped 1.55 μm InN0.92yP1-1.92yBiy/InP MQWs

NASA Astrophysics Data System (ADS)

Bilel, C.; Chakir, K.; Rebey, A.; Alrowaili, Z. A.

2018-05-01

The effect of an applied electric field on electronic band structure and optical absorption properties of n-doped InN0.92y P1-1.92y Bi y /InP multiple quantum wells (MQWs) was theoretically studied using a self-consistent calculation combined with the 16-band anti-crossing model. The incorporation of N and Bi atoms into an InP host matrix leads to rapid reduction of the band gap energy covering a large infrared range. The optimization of the well parameters, such as the well/barrier widths, N/Bi compositions and doping density, allowed us to obtain InN0.92y P1-1.92y Bi y /InP MQWs operating at the wavelength 1.55 μm. Application of the electric field causes a red-shift of the fundamental transition energy T 1 accompanied by a significant change in the spatial distribution of confined electron density. The Stark effect on the absorption coefficient of n-doped InN0.92y P1-1.92y Bi y /InP MQWs was investigated. The Bi composition of these MQWs was adjusted for each electric field value in order to maintain the wavelength emission at 1.55 μm.

Calculations of the Electric Fields in Liquid Solutions

PubMed Central

Fried, Stephen D.; Wang, Lee-Ping; Boxer, Steven G.; Ren, Pengyu; Pande, Vijay S.

2014-01-01

The electric field created by a condensed phase environment is a powerful and convenient descriptor for intermolecular interactions. Not only does it provide a unifying language to compare many different types of interactions, but it also possesses clear connections to experimental observables, such as vibrational Stark effects. We calculate here the electric fields experienced by a vibrational chromophore (the carbonyl group of acetophenone) in an array of solvents of diverse polarities using molecular dynamics simulations with the AMOEBA polarizable force field. The mean and variance of the calculated electric fields correlate well with solvent-induced frequency shifts and band broadening, suggesting Stark effects as the underlying mechanism of these key solution phase spectral effects. Compared to fixed-charge and continuum models, AMOEBA was the only model examined that could describe non-polar, polar, and hydrogen bonding environments in a consistent fashion. Nevertheless, we found that fixed-charge force fields and continuum models were able to replicate some results of the polarizable simulations accurately, allowing us to clearly identify which properties and situations require explicit polarization and/or atomistic representations to be modeled properly, and for which properties and situations simpler models are sufficient. We also discuss the ramifications of these results for modeling electrostatics in complex environments, such as proteins. PMID:24304155

Effect of the corrected ionization potential and spatial distribution on the angular and energy distribution in tunnel ionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrović, V. M.; Miladinović, T. B., E-mail: tanja.miladinovic@gmail.com

2016-05-15

Within the framework of the Ammosov–Delone–Krainov theory, we consider the angular and energy distribution of outgoing electrons due to ionization by a circularly polarized electromagnetic field. A correction of the ground ionization potential by the ponderomotive and Stark shift is incorporated in both distributions. Spatial dependence is analyzed.

Probing different regimes of strong field light-matter interaction with semiconductor quantum dots and few cavity photons

NASA Astrophysics Data System (ADS)

Hargart, F.; Roy-Choudhury, K.; John, T.; Portalupi, S. L.; Schneider, C.; Höfling, S.; Kamp, M.; Hughes, S.; Michler, P.

2016-12-01

In this work we present an extensive experimental and theoretical investigation of different regimes of strong field light-matter interaction for cavity-driven quantum dot (QD) cavity systems. The electric field enhancement inside a high-Q micropillar cavity facilitates exceptionally strong interaction with few cavity photons, enabling the simultaneous investigation for a wide range of QD-laser detuning. In case of a resonant drive, the formation of dressed states and a Mollow triplet sideband splitting of up to 45 μeV is measured for a mean cavity photon number < {n}c> ≤slant 1. In the asymptotic limit of the linear AC Stark effect we systematically investigate the power and detuning dependence of more than 400 QDs. Some QD-cavity systems exhibit an unexpected anomalous Stark shift, which can be explained by an extended dressed 4-level QD model. We provide a detailed analysis of the QD-cavity systems properties enabling this novel effect. The experimental results are successfully reproduced using a polaron master equation approach for the QD-cavity system, which includes the driving laser field, exciton-cavity and exciton-phonon interactions.

Tunable room-temperature spin-selective optical Stark effect in solution-processed layered halide perovskites

PubMed Central

Giovanni, David; Chong, Wee Kiang; Dewi, Herlina Arianita; Thirumal, Krishnamoorthy; Neogi, Ishita; Ramesh, Ramamoorthy; Mhaisalkar, Subodh; Mathews, Nripan; Sum, Tze Chien

2016-01-01

Ultrafast spin manipulation for opto–spin logic applications requires material systems that have strong spin-selective light-matter interaction. Conventional inorganic semiconductor nanostructures [for example, epitaxial II to VI quantum dots and III to V multiple quantum wells (MQWs)] are considered forerunners but encounter challenges such as lattice matching and cryogenic cooling requirements. Two-dimensional halide perovskite semiconductors, combining intrinsic tunable MQW structures and large oscillator strengths with facile solution processability, can offer breakthroughs in this area. We demonstrate novel room-temperature, strong ultrafast spin-selective optical Stark effect in solution-processed (C6H4FC2H4NH3)2PbI4 perovskite thin films. Exciton spin states are selectively tuned by ~6.3 meV using circularly polarized optical pulses without any external photonic cavity (that is, corresponding to a Rabi energy of ~55 meV and equivalent to applying a 70 T magnetic field), which is much larger than any conventional system. The facile halide and organic replacement in these perovskites affords control of the dielectric confinement and thus presents a straightforward strategy for tuning light-matter coupling strength. PMID:27386583

Dynamische Motorvermessung mit verschiedenen Methoden und Modellen

NASA Astrophysics Data System (ADS)

Schreiber, Alexander

Die stark zunehmenden gesetzlichen und wirtschaftlichen Vorgaben zur Senkung von Kraftstoffverbrauch und Abgasemissionen stellen große Anforderungen an die weitere Entwicklung von Benzin- und Dieselmotoren. Hierbei sind grundlegende Fortschritte durch Konstruktion und auslegungsbedingte Maßnahmen im Bereich der Einspritzung, Gemischaufbereitung, Aufladung, Brennverfahren und Abgasnachbehandlung zu erreichen. Ein wesentlicher Teil dieser Verbesserungen wird jedoch durch eine Zunahme von Variabilitäten erreicht wie z.B. verstellbaren Vor-, Haupt- und Nacheinspritzungen, variablem Raildruck, variablen Nockenwellensteuerwinkeln, Ventilhüben, Drall-/Tumbleklappen sowie verstellbaren Abgasturbinen, Abgasrückführströmen und Abgasnachbehandlungssystemen. Dadurch steigt die Zahl der Stellglieder (Aktoren) stark an. Hinzu kommen zusätzliche Sensoren wie z.B. für Luftzahl, NOx, Brennraumdruck, Abgastemperatur und Abgasdruck. Deshalb nimmt der Umfang der Steuerungs-, Regelungs- und Diagnosefunktionen in der Motorelektronik (ECU) stark zu. Bild 7-1 zeigt als Beispiel den Signalfluss für die gesteuerten und geregelten Größen eines Dieselmotors in einer beispielhaften Prüfstandsumgebung.

Accelerated and Airy-Bloch oscillations

NASA Astrophysics Data System (ADS)

Longhi, Stefano

2016-09-01

A quantum particle subjected to a constant force undergoes an accelerated motion following a parabolic path, which differs from the classical motion just because of wave packet spreading (quantum diffusion). However, when a periodic potential is added (such as in a crystal) the particle undergoes Bragg scattering and an oscillatory (rather than accelerated) motion is found, corresponding to the famous Bloch oscillations (BOs). Here, we introduce an exactly-solvable quantum Hamiltonian model, corresponding to a generalized Wannier-Stark Hamiltonian Ĥ, in which a quantum particle shows an intermediate dynamical behavior, namely an oscillatory motion superimposed to an accelerated one. Such a novel dynamical behavior is referred to as accelerated BOs. Analytical expressions of the spectrum, improper eigenfunctions and propagator of the generalized Wannier-Stark Hamiltonian Ĥ are derived. Finally, it is shown that acceleration and quantum diffusion in the generalized Wannier-Stark Hamiltonian are prevented for Airy wave packets, which undergo a periodic breathing dynamics that can be referred to as Airy-Bloch oscillations.

Optical absorption and emission bands of Tm 3+ ions in calcium niobium gallium garnet crystal

NASA Astrophysics Data System (ADS)

Tsuboi, Taiju; Tanigawa, Masayuki; Shimamura, Kiyoshi

2000-12-01

Absorption spectra of Tm 3+ ions in Ca 3Nb 1.6875Ga 3.1875O 12 (CNGG) crystal have been investigated at various temperatures between 15 and 296 K. Luminescence spectra in a spectral region of 400-1750 nm are investigated under excitation into various excited states of Tm 3+ and the conduction band of CNGG at room temperature. The absorption and emission bands of Tm 3+ in CNGG are observed to be broader than those observed in other Tm 3+-doped crystals such as LiNbO 3. This is due to the disordered structure of CNGG. From the temperature dependence of absorption spectra, five Stark levels are derived for the 3H 6 ground state. The highest Stark level is found to be 351 cm -1 above the ground level. It is suggested that the low efficiency of the 2.02 μm lasing at room temperature is due to the narrow splitting of the Stark levels.

Direct Measurement of the Effect of Cholesterol and 6-Ketocholestanol on the Membrane Dipole Electric Field Using Vibrational Stark Effect Spectroscopy Coupled with Molecular Dynamics Simulations.

PubMed

Shrestha, Rebika; Anderson, Cari M; Cardenas, Alfredo E; Elber, Ron; Webb, Lauren J

2017-04-20

Biological membranes are heterogeneous structures with complex electrostatic profiles arising from lipids, sterols, membrane proteins, and water molecules. We investigated the effect of cholesterol and its derivative 6-ketocholestanol (6-kc) on membrane electrostatics by directly measuring the dipole electric field (F⃗ d ) within lipid bilayers containing cholesterol or 6-kc at concentrations of 0-40 mol% through the vibrational Stark effect (VSE). We found that adding low concentrations of cholesterol, up to ∼10 mol %, increases F⃗ d , while adding more cholesterol up to 40 mol% lowers F⃗ d . In contrast, we measured a monotonic increase in F⃗ d as 6-kc concentration increased. We propose that this membrane electric field is affected by multiple factors: the polarity of the sterol molecules, the reorientation of the phospholipid dipole due to sterol, and the impact of the sterol on hydrogen bonding with surface water. We used molecular dynamics simulations to examine the distribution of phospholipids, sterol, and helix in bilayers containing these sterols. At low concentrations, we observed clustering of sterols near the vibrational probe whereas at high concentrations, we observed spatial correlation between the positions of the sterol molecules. This work demonstrates how a one-atom difference in a sterol changes the physicochemical and electric field properties of the bilayer.

Electric field determination in the plasma-antenna boundary of a lower-hybrid wave launcher in Tore Supra through dynamic Stark-effect spectroscopy

DOE PAGES

Martin, Elijah H.; Goniche, M.; Klepper, C. Christopher; ...

2015-04-22

Interaction of radio-frequency (RF) waves with the plasma in the near-field of a high-power wave launcher is now seen to be important, both in understanding the channeling of these waves through the plasma boundary and in avoiding power losses in the edge. In a recent Letter a direct non-intrusive measurement of a near antenna RF electric field in the range of lower hybrid (LH) frequencies (more » $$E_{LH}$$) was announced (Phys. Rev. Lett., 110:215005, 2013). The measurement was achieved through the fitting of Balmer series deuterium spectral lines utilizing a time dependent (dynamic) Stark effect model. In this article, the processing of the spectral data is discussed in detail and applied to a larger range of measurements and the accuracy and limitations of the experimental technique is investigated. We find through an analysis of numerous Tore Supra pulses that good quantitative agreement exists between the measured and full-wave modeled $$E_{LH}$$ when the launched power exceeds 0.5MW. For low power the measurement becomes formidable utilizing the implemented passive spectroscopic technique because the spectral noise overwhelms the effect of the RF electric field on the line profile. Additionally, effects of the ponderomotive force are suspected at sufficiently high power.« less

Correlated electron-nuclear dynamics in above-threshold multiphoton ionization of asymmetric molecule.

PubMed

Wang, Zhuo; Li, Min; Zhou, Yueming; Lan, Pengfei; Lu, Peixiang

2017-02-20

The partition of the photon energy into the subsystems of molecules determines many photon-induced chemical and physical dynamics in laser-molecule interactions. The electron-nuclear energy sharing from multiphoton ionization of molecules has been used to uncover the correlated dynamics of the electron and fragments. However, most previous studies focus on symmetric molecules. Here we study the electron-nuclear energy sharing in strong-field photoionization of HeH 2+ by solving the one-dimensional time-dependent Schrödinger equation (TDSE). Compared with symmetric molecules, the joint electron-nuclear energy spectrum (JES) of HeH 2+ reveals an anomalous energy shift at certain nuclear energies, while it disappears at higher and lower nuclear energies. Through tracing the time evolution of the wavepacket of bound states, we identify that this energy shift originates from the joint effect of the Stark shift, associated with the permanent dipole, and the Autler-Townes effect due to the coupling of the 2pσ and 2sσ states in strong fields. The energy shift in the JES appears at certain nuclear distances only when both Stark effect and Autler-Townes effect play important roles. We further demonstrate that the electron-nuclei energy sharing can be controlled by varying laser intensity for asymmetric molecules, providing alternative approaches to manipulate photochemical reactions for more complex molecules.

[Two observations of evisceration after caesarean section performed according the so-called Stark procedure].

PubMed

Fournié, A; Madzou, S; Sentilhes, L; Descamps, P

2008-12-01

Two cases of evisceration after caesarean sections performed according the Misgav Ladach General Hospital procedure (Stark's procedure) are reported. In these cases, omentum was sutured between the edges of fascia recti, creating a weakness of the abdominal sheath. These cases claim about a strict procedure for fascia suture. Also, these cases question about the parietal peritoneal closure and the drawing of rectus muscles, which are vertical breaks; so, these sutures close transversal incision of the abdominal wall with cross sutures, which are very secure.

Emergency Operations Center ribbon cutting

NASA Technical Reports Server (NTRS)

2009-01-01

Center Director Gene Goldman and special guests celebrate the opening of the site's new Emergency Operations Center on June 2. Participants included (l t r): Steven Cooper, deputy director of the National Weather Service Southern Region; Tom Luedtke, NASA associate administrator for institutions and management; Charles Scales, NASA associate deputy administrator; Mississippi Gov. Haley Barbour; Gene Goldman, director of Stennis Space Center; Jack Forsythe, NASA assistant administrator for the Office of Security and Program Protection; Dr. Richard Williams, NASA chief health and medical officer; and Weldon Starks, president of Starks Contracting Company Inc. of Biloxi.

Emergency Operations Center ribbon cutting

NASA Image and Video Library

2009-06-02

Center Director Gene Goldman and special guests celebrate the opening of the site's new Emergency Operations Center on June 2. Participants included (l t r): Steven Cooper, deputy director of the National Weather Service Southern Region; Tom Luedtke, NASA associate administrator for institutions and management; Charles Scales, NASA associate deputy administrator; Mississippi Gov. Haley Barbour; Gene Goldman, director of Stennis Space Center; Jack Forsythe, NASA assistant administrator for the Office of Security and Program Protection; Dr. Richard Williams, NASA chief health and medical officer; and Weldon Starks, president of Starks Contracting Company Inc. of Biloxi.

Validation of the Noncommissioned Officer Special Assignment Battery

DTIC Science & Technology

2013-03-01

scoring designed to reduce the effects of faking in personality assessment [ Doctoral Dissertation]. University of Illinois at Urbana-Champaign. Stark, S...conducted factor analyses to determine whether these scales could be reasonably combined to create a reduced number of criteria for examining WAI and NSAB...has been that previously validated instruments for this purpose required proctored testing. To make it easier for Soldiers to be tested, reduce

Magnetic quantum phase transition in Cr-doped Bi2(SexTe1-x)3 driven by the Stark effect

NASA Astrophysics Data System (ADS)

Zhang, Zuocheng; Feng, Xiao; Wang, Jing; Lian, Biao; Zhang, Jinsong; Chang, Cuizu; Guo, Minghua; Ou, Yunbo; Feng, Yang; Zhang, Shou-Cheng; He, Ke; Ma, Xucun; Xue, Qi-Kun; Wang, Yayu

2017-10-01

The recent experimental observation of the quantum anomalous Hall effect has cast significant attention on magnetic topological insulators. In these magnetic counterparts of conventional topological insulators such as Bi2Te3, a long-range ferromagnetic state can be established by chemical doping with transition-metal elements. However, a much richer electronic phase diagram can emerge and, in the specific case of Cr-doped Bi2(SexTe1-x)3, a magnetic quantum phase transition tuned by the actual chemical composition has been reported. From an application-oriented perspective, the relevance of these results hinges on the possibility to manipulate magnetism and electronic band topology by external perturbations such as an electric field generated by gate electrodes—similar to what has been achieved in conventional diluted magnetic semiconductors. Here, we investigate the magneto-transport properties of Cr-doped Bi2(SexTe1-x)3 with different compositions under the effect of a gate voltage. The electric field has a negligible effect on magnetic order for all investigated compositions, with the remarkable exception of the sample close to the topological quantum critical point, where the gate voltage reversibly drives a ferromagnetic-to-paramagnetic phase transition. Theoretical calculations show that a perpendicular electric field causes a shift in the electronic energy levels due to the Stark effect, which induces a topological quantum phase transition and, in turn, a magnetic phase transition.

Fatigue Crack Initiation Mechanics of Metal Aircraft Structures

DTIC Science & Technology

1988-08-01

Thresholds) (Ref. 6) and are included as Appendix A. In summary, two flow stresses were identified. Microplastic flow takes place in all grains at fully...R.O. Ritchie and E.A. Starke, EMAS, 93-101 (1987). 7. M.R. James and W.L. Morris, "Load Sequence Effects on the Deformation of Isolated Microplastic ...417 (1980). 17. M.R. James and W.L. Morris, "The Effect of Microplastic Surface Deformation on the Growth of Small Cracks," Small Fatigue Cracks, R.O

Electroabsorption Spectroscopy Measurements of the Exciton Binding Energy, ElectronHole Reduced Effective Mass, and Band Gap in the Perovskite CHsub3NHsub3PbIsub3

DTIC Science & Technology

2016-07-28

can essentially be described in terms of free carrier generation . KEYWORDS: solar cell, photovoltaic, Franz−Keldysh effect, Wannier exciton, Stark...optoelectronic devices such as lasers,1,2 LEDs,3 and solar cells,4−6 despite requiring only inexpensive and relatively crude processing conditions...compared to current high-performance crystalline semiconductors. The archetypal material, CH3NH3PbI3, has exhibited excellent power con- version

Stark width and shift for electron number density diagnostics of low temperature plasma: Application to silicon Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Ivković, M.; Konjević, N.

2017-05-01

In this work we summarize, analyze and critically evaluate experimental procedures and results of LIBS electron number density plasma characterization using as examples Stark broadened Si I and Si II line profiles. Selected publications are covering the time period from very beginning of silicon LIBS studies until the end of the year 2015. To perform the analysis of experimental LIBS data, the testing of available semiclassical theoretical Stark broadening parameters for Si I and Si II lines was accomplished first. This is followed by the description of experimental setups, results and details of experimental procedure relevant for the line shape analysis of spectral lines used for plasma characterization. Although most of results and conclusions of this analysis are related to the application of silicon lines for LIBS characterization they are of general importance and may be applied to other elements and different low-temperature plasma sources. The analysis of experimental procedures used for LIBS diagnostics from emission profiles of non-hydrogenic spectral lines is carried out in the following order: the influence of laser ablation and crater formation, spatial and temporal plasma observation, line self-absorption and experimental profile deconvolution, the contribution of ion broadening in comparison with electron impacts contributions to the line width in case of neutral atom line and some other aspects of line shape analysis are considered. The application of Stark shift for LIBS diagnostics is demonstrated and discussed. Finally, the recommendations for an improvement of experimental procedures for LIBS electron number density plasma characterization are offered.

The motional Stark effect diagnostic for ITER using a line-shift approach.

PubMed

Foley, E L; Levinton, F M; Yuh, H Y; Zakharov, L E

2008-10-01

The United States has been tasked with the development and implementation of a motional Stark effect (MSE) system on ITER. In the harsh ITER environment, MSE is particularly susceptible to degradation, as it depends on polarimetry, and the polarization reflection properties of surfaces are highly sensitive to thin film effects due to plasma deposition and erosion of a first mirror. Here we present the results of a comprehensive study considering a new MSE-based approach to internal plasma magnetic field measurements for ITER. The proposed method uses the line shifts in the MSE spectrum (MSE-LS) to provide a radial profile of the magnetic field magnitude. To determine the utility of MSE-LS for equilibrium reconstruction, studies were performed using the ESC-ERV code system. A near-term opportunity to test the use of MSE-LS for equilibrium reconstruction is being pursued in the implementation of MSE with laser-induced fluorescence on NSTX. Though the field values and beam energies are very different from ITER, the use of a laser allows precision spectroscopy with a similar ratio of linewidth to line spacing on NSTX as would be achievable with a passive system on ITER. Simulation results for ITER and NSTX are presented, and the relative merits of the traditional line polarization approach and the new line-shift approach are discussed.

[Photoeffects, Einstein's light quanta and the history of their acceptance].

PubMed

Wiederkehr, Karl Heinrich

2006-01-01

It is generally supposed, that the discovery of the efficacy-quantum by Planck was the impetus to Einstein's hypothesis of lightquanta. With its help Einstein could explain the external light-electrical effect. But even years before Einstein had worked at the photoeffect and already made experiments on it. For that reason the article gives a short survey about the history of the lightelectric effects. Lenard's basical work about the release of the photoelectrons is dealt with in detail, without which Einstein would scarcely have found his lightquanta. Furthermore it is shown how difficult it was for the physicists to give up--at least partially--the traditional view of the undulation-nature of light, and how they searched to explain the great energies of the photoelectrons. On the other side it is set forth how Einstein's formula of lightquanta was gradually confirmed. The tragical development of Einstein's personal relations with Johannes Stark and Philipp Lenard are briefly described. Stark was one of the few who supported Einstein's ideas at the beginning. Only with the Compton-effect, which could only be quantitatively interpreted by means of lightquanta and the special theory of relativity 1923, the way was free for the general acceptance of the lightquanta. Einstein did not agree to the obtained dualism of undulation and corpuscle; he had a different solution in mind about the fusion of the two forms of appearance of light.

SERS and DFT study of water on metal cathodes of silver, gold and platinum nanoparticles.

PubMed

Li, Jian-Feng; Huang, Yi-Fan; Duan, Sai; Pang, Ran; Wu, De-Yin; Ren, Bin; Xu, Xin; Tian, Zhong-Qun

2010-03-14

The observed surface-enhanced Raman scattering (SERS) spectra of water adsorbed on metal film electrodes of silver, gold, and platinum nanoparticles were used to infer interfacial water structures on the basis of the change of the electrochemical vibrational Stark tuning rates and the relative Raman intensity of the stretching and bending modes. To explain the increase of the relative Raman intensity ratio of the bending and stretching vibrations at the very negative potential region, density functional theory calculations provide the conceptual model. The specific enhancement effect for the bending mode was closely associated with the water adsorption structure in a hydrogen bonded configuration through its H-end binding to surface sites with large polarizability due to strong cathodic polarization. The present results allow us to propose that interfacial water molecules exist on these metal cathodes with different hydrogen bonding interactions, i.e., the HO-HH-Pt dihydrogen bond for platinum and the HO-HAg(Au) for silver and gold. This dihydrogen bonding configuration on platinum is further supported from observation of the Pt-H stretching band. Furthermore, the influences of the pH effect on SERS intensity and vibrational Stark effect on the gold electrode indicate that the O-H stretching SERS signals are enhanced in the alkaline solutions because of the hydrated hydroxide surface species adsorbed on the gold cathode.

Distinct exciton dissociation behavior of organolead trihalide perovskite and excitonic semiconductors studied in a same device

DOE PAGES

Hu, Miao; Bi, Cheng; Yuan, Yongbo; ...

2015-01-15

The nonexcitonic character for organometal trihalide perovskites is demonstrated by examining the field-dependent exciton dissociation behavior. Moreover, it is found that photogenerated excitons can be effectively dissociated into free charges inside perovskite without the assistance of charge extraction layer or external field, which is a stark contrast to the charge-separation behavior in excitonic materials in the same photovoltaic operation system.

Ultrasensitive Laser Spectroscopy in Solids: Statistical Fine Structure and Single-Molecule Detection

DTIC Science & Technology

1990-03-28

observation, detection of the optical absorption of a single pentacene molecule in a p-terphenyl crystal, opens the door to new studies of single local ...produce appreciable quadratic Stark shifting. Such effects would greatly perturb the local field around the pentacene molecule, making detection of the...of the local surroundings of pentacene molecules with single injected charge carriers nearby may become an interesting field; however, for the

Comparative absorption, electroabsorption and electrochemical studies of intervalence electron transfer and electronic coupling in cyanide-bridged bimetallic systems: ancillary ligand effects

NASA Astrophysics Data System (ADS)

Vance, Fredrick W.; Slone, Robert V.; Stern, Charlotte L.; Hupp, Joseph T.

2000-03-01

Electroabsorption or Stark spectroscopy has been used to evaluate the systems (NC) 5M II-CN-Ru III(NH 3) 51- and (NC) 5M II-CN-Ru III(NH 3) 4py 1-, where M II=Fe II or Ru II. When a pyridine ligand is present in the axial position on the Ru III acceptor, the effective optical electron transfer distance - as measured by the change in dipole moment, |Δ μ| - is increased by more than 35% relative to the ammine substituted counterpart. Comparison of the charge transfer distances to the crystal structure of Na[(CN) 5Fe-CN-Ru(NH 3) 4py] · 6H 2O reveals that the Stark derived distances are ˜50% to ˜90% of the geometric separation of the metal centers. The differences result in an upward revision in the Hush delocalization parameter, c b2, and of the electronic coupling matrix element, H ab, relative to those parameters obtained exclusively from electronic absorption measurements. The revised parameters are compared to those, which are obtained via electrochemical techniques and found to be in only fair agreement. We conclude that the absorption/electroabsorption analysis likely yields a more reliable set of mixing and coupling parameters.

Tuning the Electronic, Optical, and Magnetic Properties of Monolayer GaSe with a Vertical Electric Field

NASA Astrophysics Data System (ADS)

Ke, Congming; Wu, Yaping; Guo, Guang-Yu; Lin, Wei; Wu, Zhiming; Zhou, Changjie; Kang, Junyong

2018-04-01

Inspired by two-dimensional material with their unique physical properties and innovative device applications, here we report a design framework on monolayer GaSe, an important member of the two-dimensional material family, in an effort to tune the electronic, optical, and magnetic properties through a vertical electric field. A transition from indirect to direct band gap in monolayer GaSe is found with an electric field of 0.09 V /Å . The giant Stark effect results in a reduction of the band gap with a Stark coefficient of 3.54 Å. Optical and dielectric properties of monolayer GaSe are dependent on the vertical electric field. A large regulation range for polarization E ∥c ^ is found for the static dielectric constant. The optical anisotropy with the dipole transition from E ∥c ^ to E ⊥c ^ is achieved. Induced by the spin-orbit coupling, spin-splitting energy at the valence band maximum increases linearly with the electric field. The effective mass of holes is highly susceptible to the vertical electric field. Switchable spin-polarization features in spin texture of monolayer GaSe are predicted. The tunable electronic, optical, and magnetic properties of monolayer GaSe hold great promise for applications in both the optoelectronic and spintronic devices.

A new species of Neoperla from China, with a redescription of the female of N. mnong Stark, 1987 (Plecoptera, Perlidae).

PubMed

Chen, Zhi-Teng; Du, Yu-Zhou

2016-01-01

A new species of the Neoperla clymene group (Plecoptera, Perlidae), Neoperla chebalinga sp. n. from Guangdong Province of southern China is described, illustrated, and compared with related taxa. The new species is characterized by the slender aedeagal tube, strongly sclerotized dorsally, and weakly sclerotized ventrally with an upcurved, medial, finger-like membranous lobe. Additionally the aedeagal sac gradually tapers to a blunt apex with a dorsoapical patch of spines. A supplementary description of the female of Neoperla mnong Stark, 1987 from Guangdong Province, China is also given.

A new species of Neoperla from China, with a redescription of the female of N. mnong Stark, 1987 (Plecoptera, Perlidae)

PubMed Central

Chen, Zhi-Teng; Du, Yu-Zhou

2016-01-01

Abstract A new species of the Neoperla clymene group (Plecoptera, Perlidae), Neoperla chebalinga sp. n. from Guangdong Province of southern China is described, illustrated, and compared with related taxa. The new species is characterized by the slender aedeagal tube, strongly sclerotized dorsally, and weakly sclerotized ventrally with an upcurved, medial, finger-like membranous lobe. Additionally the aedeagal sac gradually tapers to a blunt apex with a dorsoapical patch of spines. A supplementary description of the female of Neoperla mnong Stark, 1987 from Guangdong Province, China is also given. PMID:27667948

Coupled-cluster treatment of molecular strong-field ionization

NASA Astrophysics Data System (ADS)

Jagau, Thomas-C.

2018-05-01

Ionization rates and Stark shifts of H2, CO, O2, H2O, and CH4 in static electric fields have been computed with coupled-cluster methods in a basis set of atom-centered Gaussian functions with a complex-scaled exponent. Consideration of electron correlation is found to be of great importance even for a qualitatively correct description of the dependence of ionization rates and Stark shifts on the strength and orientation of the external field. The analysis of the second moments of the molecular charge distribution suggests a simple criterion for distinguishing tunnel and barrier suppression ionization in polyatomic molecules.

Dynamical Chaos in the Wisdom-Holman Integrator: Origins and Solutions

NASA Technical Reports Server (NTRS)

Rauch, Kevin P.; Holman, Matthew

1999-01-01

We examine the nonlinear stability of the Wisdom-Holman (WH) symplectic mapping applied to the integration of perturbed, highly eccentric (e-0.9) two-body orbits. We find that the method is unstable and introduces artificial chaos into the computed trajectories for this class of problems, unless the step size chosen 1s small enough that PeriaPse is always resolved, in which case the method is generically stable. This 'radial orbit instability' persists even for weakly perturbed systems. Using the Stark problem as a fiducial test case, we investigate the dynamical origin of this instability and argue that the numerical chaos results from the overlap of step-size resonances; interestingly, for the Stark-problem many of these resonances appear to be absolutely stable. We similarly examine the robustness of several alternative integration methods: a time-regularized version of the WH mapping suggested by Mikkola; the potential-splitting (PS) method of Duncan, Levison, Lee; and two original methods incorporating approximations based on Stark motion instead of Keplerian motion. The two fixed point problem and a related, more general problem are used to conduct a comparative test of the various methods for several types of motion. Among the algorithms tested, the time-transformed WH mapping is clearly the most efficient and stable method of integrating eccentric, nearly Keplerian orbits in the absence of close encounters. For test particles subject to both high eccentricities and very close encounters, we find an enhanced version of the PS method-incorporating time regularization, force-center switching, and an improved kernel function-to be both economical and highly versatile. We conclude that Stark-based methods are of marginal utility in N-body type integrations. Additional implications for the symplectic integration of N-body systems are discussed.

Stark widths and shifts for spectral lines of Sn IV

NASA Astrophysics Data System (ADS)

de Andrés-García, I.; Alonso-Medina, A.; Colón, C.

2016-01-01

In this paper, we present theoretical Stark widths and shifts calculated corresponding to 66 spectral lines of Sn IV. We use the Griem semi-empirical approach and the COWAN computer code. For the intermediate coupling calculations, the standard method of least-squares fitting from experimental energy levels was used. Data are presented for an electron density of 1017 cm-3 and temperatures T = 1.1-5.0 (104 K). The matrix elements used in these calculations have been determined from 34 configurations of Sn IV: 4d10ns(n = 5-10), 4d10nd(n = 5-8), 4d95s2, 4d95p2, 4d95s5d, 4d85s5p2 and 4d105g for even parity and 4d10np(n = 5-8), 4d10nf (n = 4-6), 4d95snp(n = 5-8), 4d85s25p and 4d95snf (n = 4-10) for odd parity. Also, in order to test the matrix elements used in our calculations, we present calculated values of radiative lifetimes of 14 levels of Sn IV. There is good agreement between our calculations and the experimental radiative lifetimes obtained from the bibliography. The spectral lines of Sn IV are observed in UV spectra of HD 149499 B obtained with the Far Ultraviolet Spectroscopic Explorer, the Goddard High Resolution Spectrograph and the International Ultraviolet Explorer. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. Also our values of Stark broadening parameters have been compared with the data available in the bibliography.

Theoretical Stark broadening parameters for spectral lines arising from the 2p5ns, 2p5np and 2p5nd electronic configurations of Mg III

NASA Astrophysics Data System (ADS)

Colón, C.; Moreno-Díaz, C.; Alonso-Medina, A.

2013-10-01

In the present work we report theoretical Stark widths and shifts calculated using the Griem semi-empirical approach, corresponding to 237 spectral lines of Mg III. Data are presented for an electron density of 1017 cm-3 and temperatures T = 0.5-10.0 (104K). The matrix elements used in these calculations have been determined from 23 configurations of Mg III: 2s22p6, 2s22p53p, 2s22p54p, 2s22p54f and 2s22p55f for even parity and 2s22p5ns (n = 3-6), 2s22p5nd (n = 3-9), 2s22p55g and 2s2p6np (n = 3-8) for odd parity. For the intermediate coupling (IC) calculations, we use the standard method of least-squares fitting from experimental energy levels by means of the Cowan computer code. Also, in order to test the matrix elements used in our calculations, we present calculated values of 70 transition probabilities of Mg III spectral lines and 14 calculated values of radiative lifetimes of Mg III levels. There is good agreement between our calculations and experimental radiative lifetimes. Spectral lines of Mg III are relevant in astrophysics and also play an important role in the spectral analysis of laboratory plasma. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. No values of Stark parameters can be found in the bibliography.

[The reconstruction of welding arc 3D electron density distribution based on Stark broadening].

PubMed

Zhang, Wang; Hua, Xue-Ming; Pan, Cheng-Gang; Li, Fang; Wang, Min

2012-10-01

The three-dimensional electron density is very important for welding arc quality control. In the present paper, Side-on characteristic line profile was collected by a spectrometer, and the lateral experimental data were approximated by a polynomial fitting. By applying an Abel inversion technique, the authors obtained the radial intensity distribution at each wavelength and thus constructed a profile for the radial positions. The Fourier transform was used to separate the Lorentz linear from the spectrum reconstructed, thus got the accurate Stark width. And we calculated the electronic density three-dimensional distribution of the TIG welding are plasma.

On The Stark Shift of Ar II 472.68 nm Spectral Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mijatovic, Z.; Gajo, T.; Vujicic, B.

The Stark shift of Ar II 472.68 nm (transition 4s2P - 4p2D deg. ) spectral lines emitted from T-tube plasmas was considered. The electron density ranged from (1.63-2.2){center_dot}1023 m-3 and was determined using laser interferometry. The plasma temperature, derived from the Gaussian part of recorded line profiles was found to be in the range (15000-43300) K. Experimental shifts were compared to theoretical values obtained from the semiempirical formula [M. S. Dimitrijevic and N. Konjevic, J. Quant. Spectrosc. Radiat. Transfer 24, 451 (1980)]. This comparison showed good agreement between experimental results and theory.

Green procedure using limonene in the Dean-Stark apparatus for moisture determination in food products.

PubMed

Veillet, Sébastien; Tomao, Valérie; Ruiz, Karine; Chemat, Farid

2010-07-26

In the past 10 years, trends in analytical chemistry have turned toward the green chemistry which endeavours to develop new techniques that reduce the influence of chemicals on the environment. The challenge of the green analytical chemistry is to develop techniques that meet the request for information output while reducing the environmental impact of the analyses. For this purpose petroleum-based solvents have to be avoided. Therefore, increasing interest was given to new green solvents such as limonene and their potential as alternative solvents in analytical chemistry. In this work limonene was used instead of toluene in the Dean-Stark procedure. Moisture determination on wide range of food matrices was performed either using toluene or limonene. Both solvents gave similar water percentages in food materials, i.e. 89.3+/-0.5 and 89.5+/-0.7 for carrot, 68.0+/-0.7 and 68.6+/-1.9 for garlic, 64.1+/-0.5 and 64.0+/-0.3 for minced meat with toluene and limonene, respectively. Consequently limonene could be used as a good alternative solvent in the Dean-Stark procedure. Copyright 2010 Elsevier B.V. All rights reserved.

Armed conflict and child health.

PubMed

Rieder, Michael; Choonara, Imti

2012-01-01

Armed conflict has a major impact on child health throughout the world. One in six children worldwide lives in an area of armed conflict and civilians are more likely to die than soldiers as a result of the conflict. In stark contrast to the effect on children, the international arms trade results in huge profits for the large corporations involved in producing arms, weapons and munitions. Armed conflict is not inevitable but is an important health issue that should be prevented.

Experimental and Theoretical Study of the Temperature Performance of Type-II Quantum Well Lasers

DTIC Science & Technology

2007-05-31

performance of type-II Interband Cascade (IC) GaSb-based semiconductor lasers has been developed. The method includes comparing the temperature-concentration... dependence at the laser threshold with steady-state carrier heating characteristics. The number of cascades in prototype type-II IC lasers has been...Monroy, and R.L.Tober, "Wavelength Tuning of Interband Cascade Laser Based on the Stark Effect", in “Future Trends in Microelectronics” ed. by

Magnetic field amplitude and pitch angle measurements using Spectral MSE on EAST

NASA Astrophysics Data System (ADS)

Liao, Ken; Rowan, William; Fu, Jia; Li, Ying-Ying; Lyu, Bo; Marchuk, Oleksandr; Ralchenko, Yuri

2017-10-01

We have developed the Spectral Motional Stark Effect technique for measuring magnetic field amplitude and pitch angle on EAST. The experiments were conducted using the tangential co-injection heating beam at A port and Beam Emission Spectroscopy array at D port. A spatial calibration of the observation channels was conducted before the campaign. As a first check, the measured magnetic field amplitude was compared to prediction. Since the toroidal field is dominant, we recovered the expected 1/R shape over the spatial range 1.75

Strong quantum-confined Stark effect in a lattice-matched GeSiSn/GeSn multi-quantum-well structure

NASA Astrophysics Data System (ADS)

Peng, Ruizhi; Chunfuzhang; Han, Genquan; Hao, Yue

2017-06-01

This paper presents modeling and simulation of a multiple quantum well structure formed with Ge0.95Sn0.05 quantum wells separated by Ge0.51Si0.35Sn0.14 barriers for the applications. These alloy compositions are chosen to satisfy two conditions simultaneously: type-I band alignment between Ge0.95Sn0.05/Ge0.51Si0.35Sn0.14 and a lattice match between wells and barriers. This lattice match ensures that the strain-free structure can be grown upon a relaxed Ge0.51Si0.35Sn0.14 buffer on a silicon substrate - a CMOS compatible process. A electro-absorption modulator with the Ge0.95Sn0.05/Ge0.51Si0.35Sn0.14 multiple quantum well structure based on quantum-confined Stark effect(QCSE) is demonstrated in theory. The energy band diagrams of the GeSiSn/GeSn multi-quantum-well structure at 0 and 0.5V bias are calculated, respectively. And the corresponding absorption coefficients as a function of cut-off energy for this multiple quantum well structure at 0 and 0.5Vbias are also obtained, respectively. The reduction of cut-off energy is observed with the applying of the external electric field, indicating a strong QCSE in the structure.

New Stark regulations: Key issues for health care decision-makers.

PubMed

Johnson, B A; Niederman, G A; Bowman, L E; McCullough, A C

1998-01-01

On Jan. 9, 1998, The Health Care Financing Administration (HCFA) issued long-awaited Proposed Regulations for what has become known as Stark II. The regulations are subject to a comment period and later refinement. However, they lay out HCFA's basic understanding of what kinds of practices constitute an illegal kickback. In general terms, the law prohibits physicians from referring Medicare or Medicaid patients to entities with which they (or an immediate family member) have a "financial relationship" for the delivery of a specific list of designated health services. There are, however, exceptions also included in the new proposal. Group practices will want to pay special attention to HCFA's new definition of group practice.

Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

NASA Astrophysics Data System (ADS)

Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2016-09-01

Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

Inelastic light scattering from plasmons tunneling between Wannier-Stark states

NASA Astrophysics Data System (ADS)

Fluegel, B.; Pfeiffer, L. N.; West, K.; Mascarenhas, A.

2018-06-01

Using inelastic light scattering, we measure the zone-center electronic excitation modes in a set of multiple quantum wells. The width of the wavefunction barriers was chosen such that it prevents significant coupling of the electron ground states between wells yet is transparent to electron tunneling under an electric field. Under these conditions, we find charge-density-like and spin-density-like plasmons whose energies do not correspond to the excitations calculated for either a single well or a set of Coulomb-coupled wells. The observed energies are proportional to the electric field strength and the lower energy modes agree with predictions for plasmons tunneling between the Wannier-Stark ladder states.

Science Translator: An Interview with Louisa Stark.

PubMed

Stark, Louisa A

2015-07-01

The Genetics Society of America's Elizabeth W. Jones Award for Excellence in Education recognizes significant and sustained impact on genetics education. The 2015 awardee, Louisa Stark, has made a major impact on global access to genetics education through her work as director of the University of Utah Genetic Science Learning Center. The Center's Learn.Genetics and Teach.Genetics websites are the most widely used online genetic education resources in the world. In 2014, they were visited by 18 million students, educators, scientists, and members of the public. With over 60 million page views annually, Learn.Genetics is among the most used sites on the Web. Copyright © 2015 by the Genetics Society of America.

Method for correction of measured polarization angles from motional Stark effect spectroscopy for the effects of electric fields

DOE PAGES

Luce, T. C.; Petty, C. C.; Meyer, W. H.; ...

2016-11-02

An approximate method to correct the motional Stark effect (MSE) spectroscopy for the effects of intrinsic plasma electric fields has been developed. The motivation for using an approximate method is to incorporate electric field effects for between-pulse or real-time analysis of the current density or safety factor profile. The toroidal velocity term in the momentum balance equation is normally the dominant contribution to the electric field orthogonal to the flux surface over most of the plasma. When this approximation is valid, the correction to the MSE data can be included in a form like that used when electric field effectsmore » are neglected. This allows measurements of the toroidal velocity to be integrated into the interpretation of the MSE polarization angles without changing how the data is treated in existing codes. In some cases, such as the DIII-D system, the correction is especially simple, due to the details of the neutral beam and MSE viewing geometry. The correction method is compared using DIII-D data in a variety of plasma conditions to analysis that assumes no radial electric field is present and to analysis that uses the standard correction method, which involves significant human intervention for profile fitting. The comparison shows that the new correction method is close to the standard one, and in all cases appears to offer a better result than use of the uncorrected data. Lastly, the method has been integrated into the standard DIII-D equilibrium reconstruction code in use for analysis between plasma pulses and is sufficiently fast that it will be implemented in real-time equilibrium analysis for control applications.« less

Quantum confined stark effect on the binding energy of exciton in type II quantum heterostructure

NASA Astrophysics Data System (ADS)

Suseel, Rahul K.; Mathew, Vincent

2018-05-01

In this work, we have investigated the effect of external electric field on the strongly confined excitonic properties of CdTe/CdSe/CdTe/CdSe type-II quantum dot heterostructures. Within the effective mass approximation, we solved the Poisson-Schrodinger equations of the exciton in nanostructure using relaxation method in a self-consistent iterative manner. We changed both the external electric field and core radius of the quantum dot, to study the behavior of binding energy of exciton. Our studies show that the external electric field destroys the positional flipped state of exciton by modifying the confining potentials of electron and hole.

In-depth study of intra-Stark spectroscopy in the x-ray range in relativistic laser-plasma interactions

NASA Astrophysics Data System (ADS)

Oks, E.; Dalimier, E.; Faenov, A. Ya; Angelo, P.; Pikuz, S. A.; Pikuz, T. A.; Skobelev, I. Yu; Ryazanzev, S. N.; Durey, P.; Doehl, L.; Farley, D.; Baird, C.; Lancaster, K. L.; Murphy, C. D.; Booth, N.; Spindloe, C.; McKenna, P.; Neumann, N.; Roth, M.; Kodama, R.; Woolsey, N.

2017-12-01

Intra-Stark spectroscopy (ISS) is the spectroscopy within the quasistatic Stark profile of a spectral line. The present paper advances the ISS-based study of the relativistic laser-plasma interaction from our previous paper (Oks et al 2017 Opt. Express 25 1958). By improving the experimental conditions and the diagnostics, it provides an in-depth spectroscopic study of the simultaneous production of the Langmuir waves and of the ion acoustic turbulence at the surface of the relativistic critical density. It demonstrates a reliable reproducibility of the Langmuir-wave-induced dips at the same locations in the experimental profiles of Si XIV Ly-beta line, as well as of the deduced parameters (fields) of the Langmuir waves and ion acoustic turbulence in several individual 1 ps laser pulses and of the peak irradiances of 1-3 × 1020 W cm-2. Besides, this study employs for the first time the most rigorous condition of the dynamic resonance, on which the ISS phenomenon is based, compared to all previous studies in all kinds of plasmas in a wide range of electron densities. It shows how different interplays between the Langmuir wave field and the field of the ion acoustic turbulence lead to distinct spectral line profiles, including the disappearance of the Langmuir-wave-induced dips.

Armed conflict and child health

PubMed Central

Rieder, Michael; Choonara, Imti

2012-01-01

Summary Armed conflict has a major impact on child health throughout the world. One in six children worldwide lives in an area of armed conflict and civilians are more likely to die than soldiers as a result of the conflict. In stark contrast to the effect on children, the international arms trade results in huge profits for the large corporations involved in producing arms, weapons and munitions. Armed conflict is not inevitable but is an important health issue that should be prevented. PMID:21393303

The EIT- and N- joint resonance lineshape asymmetry

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Hancox, Cindy; Hohensee, Michael; Phillips, David; Walsworth, Ron

2008-03-01

The solution of a quantum optics model for the joint EIT- and N- resonance explains the experimentally observed two-photon lineshape asymmetry as arising from interference and AC stark effects. This solution is evaluated for various light field intensities, detunings and couplings associated with experiments performed on the D1 and D2 transition of 87Rb. Because of its contribution to clock instability, lineshape asymmetry remains perhaps the main impediment to improving all-optical time standards based on the joint resonance.

The Effect of Alloy Composition and Processing on the Structure and Properties of I/M Al-Li-X Alloys

DTIC Science & Technology

1990-07-01

ORGANIZATION Department ot Materials Scienci (N aplicable) University of Virginia U. S. Army Research Office 6c. ADDRESS (City, State, and ZIP Code) 7b...27709 Attention: Dr. Andrew Crowson, Program Officer Materials Science Division Submitted by: E. A. Starke Earnest Oglesby Professor of Materials ...Science and Dean G. J. Shiflet Professor of Materials Science Report No. UVA/525140/MS91/101 July 1990 DTIC ELECTFE SAUG3 1190 I DEPARTMENT OF MATERIALS

Extensión del Formalismo de Orbitales de Defecto Cuántico al tratamiento del efecto Stark (SQDO).

NASA Astrophysics Data System (ADS)

Menéndez, J. M.; Martín, I.; Velasco, A. M.

El estudio experimental de las interacciones de átomos Rydberg altamente excitados con campos eléctricos ha experimentado un creciente interés durante las dos últimas décadas debido, en gran medida, al desarrollo de nuevas técnicas para crear y estudiar átomos Rydberg en el laboratorio. Acompañando a estas nuevas técnicas experimentales, es necesario el desarrollo de modelos teóricos que nos permitan contrastar sus medidas y conocer mejor los fundamentos de los mismos. Desde el punto de vista teórico el conocimiento del desdoblamiento de los niveles energéticos de un átomo en función de la magnitud del campo eléctrico aplicado (lo que se conoce como mapa Stark) es el mejor punto de partida para la descripción del sistema y un prerrequisito fundamental para el cálculo de distintas propiedades atómicas en presencia del campo eléctrico tales como intensidades de transición, umbrales de ionización de campo eléctrico, tiempos de vida, posición y anchura de cruces evitados, etc. En este trabajo presentamos la adaptación del método de orbitales de defecto cuántico [1,2,3] al tratamiento del efecto Stark (SQDO) [4] y su aplicación al cálculo de los desdoblamientos energéticos y fuerzas de oscilador de estados Rydberg en los átomos de Li, Na y K. El propósito de este estudio es, por un lado, desarrollar métodos fiables para la determinación de propiedades atómicas en presencia de campos eléctricos y, por otro, mostrar la fiabilidad de las funciones de onda QDO en la descripción del efecto Stark en sistemas atómicos.

Optical manipulation of valley pseduospin in 2D semiconductors

NASA Astrophysics Data System (ADS)

Ye, Ziliang

Valley polarization associated with the occupancy in the energy degenerate but quantum mechanically distinct valleys in the momentum space closely resembles spin polarization and has been proposed as a pseudospin carrier for future quantum information technologies. Monolayers of transition metal dichalcogenide (TMDC) crystals, with broken inversion symmetry and large spin-orbital coupling, support robust valley polarization and therefore provide an important platform for studying valley-dependent physics. Besides optical excitation and photoluminescence detection, valley polarization has been electrically measured through the valley Hall effect and created through spin injection from ferromagnetic semiconductor contacts. Moreover, the energy degeneracy of the valley degree of freedom has been lifted by the optical Stark effect. Recently, we have demonstrated optical manipulation of valley coherence, i.e., of the valley pseudospin, by the optical Stark effect in monolayer WSe2. Using below-bandgap circularly polarized light, we rotated the valley pseudospin on the femtosecond time scale. Both the direction and speed of the rotation can be optically controlled by tuning the dynamic phase of excitons in opposite valleys. The pseudospin rotation was identified by changes in the polarization of the photoluminescence. In addition, by varying the time delay between the excitation and control pulses, we directly probed the lifetime of the intervalley coherence. Similar rotation levels have also been observed in static magneto-optic experiments. Our work presents an important step towards the full control of the valley degree of freedom in 2D semiconductors. The work was done in collaboration with Dr. Dezheng Sun and Prof. Tony F. Heinz.

Full Stark control of polariton states on a spin-orbit hypersphere

NASA Astrophysics Data System (ADS)

Li, Feng; Cancellieri, E.; Buonaiuto, G.; Skolnick, M. S.; Krizhanovskii, D. N.; Whittaker, D. M.

2016-11-01

The orbital angular momentum and the polarization of light are physical quantities widely investigated for classical and quantum information processing. In this work we propose to take advantage of strong light-matter coupling, circular-symmetric confinement, and transverse-electric transverse-magnetic splitting to exploit states where these two degrees of freedom are combined. To this end we develop a model based on a spin-orbit Poincaré hypersphere. Then we consider the example of semiconductor polariton systems and demonstrate full ultrafast Stark control of spin-orbit states. Moreover, by controlling states on three different spin-orbit spheres and switching from one sphere to another we demonstrate the control of different logic bits within one single physical system.

76 FR 38718 - Indiana Disaster #IN-00037

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-01

.../23/2011. Incident: Severe Storms, Tornadoes, Straight-line Winds, and Flooding. Incident Period: 04..., Spencer, Starke, Sullivan, Switzerland, Vanderburgh, Warrick, Washington. The Interest Rates are: Percent...

In situ electrochemical SFG/DFG study of CN- and nitrile adsorption at Au from 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ionic liquid([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]diazenyl} benzonitrile (CTDB) and K[Au(CN)₂].

PubMed

Bozzini, Benedetto; Busson, Bertrand; Gayral, Audrey; Humbert, Christophe; Mele, Claudio; Six, Catherine; Tadjeddine, Abderrahmane

2012-06-25

In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN⁻ from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-diazenyl}benzonitrile (CTDB) at Au electrodes in the absence and in the presence of the Au-electrodeposition process from K[Au(CN)₂]. The adsorption of nitrile and its coadsorption with CN⁻ resulting either from the cathodic decomposition of the dye or from ligand release from the Au(I) cyanocomplex yield potential-dependent single or double SFG bands in the range 2,125-2,140 cm⁻¹, exhibiting Stark tuning values of ca. 3 and 1 cm⁻¹ V⁻¹ in the absence and presence of electrodeposition, respectively. The low Stark tuning found during electrodeposition correlates with the cathodic inhibiting effect of CTDB, giving rise to its levelling properties. The essential insensitivity of the other DFG parameters to the electrodeposition process is due to the growth of smooth Au.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, M F; Holcomb, C; Jayakuma, J

We present detailed atomic physics models for motional Stark effects (MSE) diagnostic on magnetic fusion devices. Excitation and ionization cross sections of the hydrogen or deuterium beam traveling in a magnetic field in collisions with electrons, ions, and neutral gas are calculated in the first Born approximation. The density matrices and polarization states of individual Stark-Zeeman components of the Balmer {alpha} line are obtained for both beam into plasma and beam into gas models. A detailed comparison of the model calculations and the MSE polarimetry and spectral intensity measurements obtained at the DIII-D tokamak is carried out. Although our beammore » into gas models provide a qualitative explanation for the larger {pi}/{sigma} intensity ratios and represent significant improvements over the statistical population models, empirical adjustment factors ranging from 1.0-2.0 must still be applied to individual line intensities to bring the calculations into full agreement with the observations. Nevertheless, we demonstrate that beam into gas measurements can be used successfully as calibration procedures for measuring the magnetic pitch angle through {pi}/{sigma} intensity ratios. The analyses of the filter-scan polarization spectra from the DIII-D MSE polarimetry system indicate unknown channel and time dependent light contaminations in the beam into gas measurements. Such contaminations may be the main reason for the failure of beam into gas calibration on MSE polarimetry systems.« less

Stark effect and dipole moments of the ammonia dimer in different vibration-rotation-tunneling states

NASA Astrophysics Data System (ADS)

Cotti, Gina; Linnartz, Harold; Meerts, W. Leo; van der Avoird, Ad; Olthof, Edgar H. T.

1996-03-01

In this paper we present Stark measurements on the G:K=-1 vibration-rotation-tunneling (VRT) transition, band origin 747.2 GHz, of the ammonia dimer. The observed splitting pattern and selection rules can be explained by considering the G36 and G144 symmetries of the inversion states involved, and almost complete mixing of these states by the applied electric field. The absolute values of the electric dipole moments of the ground and excited state are determined to be 0.763(15) and 0.365(10) D, respectively. From the theoretical analysis and the observed selection rules it is possible to establish that the dipole moments of the two interchange states must have opposite sign. The theoretical calculations are in good agreement with the experimental results: The calculated dipole moments are -0.74 D for the lower and +0.35 D for the higher state. Our results, in combination with the earlier dipole measurements on the G:K=0 ground state and the G:K=1 transition with band origin 486.8 GHz, confirm that the ammonia dimer is highly nonrigid. Its relatively small and strongly K-dependent dipole moment, which changes sign upon far-infrared excitation, originates from the difference in dynamical behavior of ortho and para NH3.

Characterization of tobacco withdrawal: physiological and subjective effects.

PubMed

Hatsukami, D; Hughes, J R; Pickens, R

1985-01-01

In total, our studies show that changes which occur reliably and consistently in chronic smokers after tobacco deprivation include: decreased heart rate, increased caloric intake/eating, increased number of awakenings during sleep, increased craving for tobacco, and increased confusion, as measured by the POMS. Other changes that were found to occur after tobacco deprivation in some but not all of our studies include decreased orthostatic heart rate, increased irritability, and decreased vigor score on the POMS. Previous investigators have found a consistent effect of tobacco deprivation on heart rate (Gilbert and Pope 1982; Knapp et al. 1963; Parsons and Hamme 1975; Weybrew and Stark 1967; Glauser et al. 1970; Myrsten et al. 1977; Murphee and Schultz 1968). Although decreased blood pressure (Knapp et al. 1963; Murphee and Schultz 1968) and changes in other vital signs such as temperature (Gilbert and Pope 1982; Myrsten et al. 1977; Ague 1974) have been reported, our present studies and studies by others (Weybrew and Stark 1967; Glauser et al. 1970) failed to find a significant deprivation effect on these measures. Perhaps the contradictory findings are a function of the reliability of the measures themselves or of the population tested. Caloric intake has been found to increase in both animals and humans after nicotine or smoking cessation (Gruneberg 1982; Myrsten et al. 1977; Wack and Rodin 1982). These results are consistent with studies which have found that smoking cessation causes an increase in body weight (Wack and Rodin 1982). However, previous studies disagree on how smoking cessation causes weight gain. Our inpatient study is believed to be the first to simultaneously measure changes in caloric intake, fluid retention, and physical activity after tobacco deprivation. In the study, caloric intake increased but fluid retention and physical activity did not change. The increases in weight may not be accounted for solely by increases in caloric intake. There may be other factors such as decreased basal metabolic rate which cause the increase in weight. Other studies have also reported sleep disturbance or insomnia among tobacco-deprived smokers (Larson et al. 1961; Weybrew and Stark 1967). Studies directly monitoring sleep have found a decrease in duration awake (Soldatos et al. 1980), increased REM sleep (Soldatos et al. 1980; Kales et al. 1970; Parsons et al. 1975), and increased Stage IV (greater than 50% delta waves) sleep (Parson et al. 1975; Parsons and Hamme 1975). Thus, objective data indicate that after tobacco deprivation smokers actually sleep longer, which contradicts subjective reports of insomnia.(ABSTRACT TRUNCATED AT 400 WORDS)

Ideal square quantum wells achieved in AlGaN/GaN superlattices using ultrathin blocking-compensation pair

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xiaohong; Xu, Hongmei; Xu, Fuchun

A technique for achieving square-shape quantum wells (QWs) against the intrinsic polar discontinuity and interfacial diffusion through self-compensated pair interlayers is reported. Ultrathin low-and-high % pair interlayers that have diffusion-blocking and self-compensation capacities is proposed to resist the elemental diffusion at nanointerfaces and to grow the theoretically described abrupt rectangular AlGaN/GaN superlattices by metal-organic chemical vapor deposition. Light emission efficiency in such nanostructures is effectively enhanced and the quantum-confined Stark effect could be partially suppressed. This concept could effectively improve the quality of ultrathin QWs in functional nanostructures with other semiconductors or through other growth methods.

Universal FFM Hydrogen Spectral Line Shapes Applied to Ions and Electrons

NASA Astrophysics Data System (ADS)

Mossé, C.; Calisti, A.; Ferri, S.; Talin, B.; Bureyeva, L. A.; Lisitsa, V. S.

2008-10-01

We present a method for the calculation of hydrogen spectral line shapes based on two combined approaches: Universal Model and FFM procedure. We start with the analytical functions for the intensities of the Stark components of radiative transitions between highly excited atomic states with large values of principal quantum numbers n,n'γ1, with Δn = n-n'≪n for the specific cases of Hn-α line (Δn = 1) and Hn-β line (Δn = 2). The FFM line shape is obtained by averaging on the electric field of the Hooper's field distribution for ion and electron perturber dynamics and by mixing the Stark components with a jumping frequency rate ve (vi) where v = N1/3u (N is electron density and u is the ion or electron thermal velocity). Finally, the total line shape is given by convolution of ion and electron line shapes. Hydrogen line shape calculations for Balmer Hα and Hβ lines are compared to experimental results in low density plasma (Ne˜1016-1017cm-3) and low electron temperature in order of 10 000K. This method relying on analytic expressions permits fast calculation of Hn-α and Hn-β lines of hydrogen and could be used in the study of the Stark broadening of radio recombination lines for high principal quantum number.

Meningitis - tuberculous

MedlinePlus

... Starke JR. Tuberculosis. In: Cherry JD, Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ, eds. Feigin and ... constitute endorsements of those other sites. Copyright 1997-2018, A.D.A.M., Inc. Duplication for commercial ...

Definition of Shifts of Optical Transitions Frequencies due to Pulse Perturbation Action by the Photon Echo Signal Form

NASA Astrophysics Data System (ADS)

Lisin, V. N.; Shegeda, A. M.; Samartsev, V. V.

2015-09-01

A relative phase shift between the different groups of excited dipoles, which appears as result of its frequency splitting due to action of a pulse of electric or magnetic fields, depends on a time, if the pulse overlaps in time with echo-pulse. As а consequence, the echo waveform is changed. The echo time form is modulated. The inverse modulation period well enough approximates Zeeman and pseudo-Stark splitting in the cases of magnetic and, therefore, electrical fields. Thus the g-factors of ground 4I15/2 and excited 4F9/2 optical states of Er3+ ion in LuLiF4 and YLiF4 have been measured and pseudo-Stark shift of R1 line in ruby has been determined.

Tables of stark level transition probabilities and branching ratios in hydrogen-like atoms

NASA Technical Reports Server (NTRS)

Omidvar, K.

1980-01-01

The transition probabilities which are given in terms of n prime k prime and n k are tabulated. No additional summing or averaging is necessary. The electric quantum number k plays the role of the angular momentum quantum number l in the presence of an electric field. The branching ratios between stark levels are also tabulated. Necessary formulas for the transition probabilities and branching ratios are given. Symmetries are discussed and selection rules are given. Some disagreements for some branching ratios are found between the present calculation and the measurement of Mark and Wierl. The transition probability multiplied by the statistical weight of the initial state is called the static intensity J sub S, while the branching ratios are called the dynamic intensity J sub D.

Infrared laser Stark spectroscopy of hydroxymethoxycarbene in 4He nanodroplets

DOE PAGES

Broderick, Bernadette M.; Moradi, Christopher P.; Douberly, Gary E.

2015-09-07

Hydroxymethoxycarbene, CH 3OCOH, was produced via pyrolysis of monomethyl oxalate and subsequently isolated in 4He nanodroplets. Infrared laser spectroscopy reveals two rotationally resolved a,b-hybrid bands in the OH-stretch region, which are assigned to trans, trans- and cis, trans-rotamers. Stark spectroscopy of the trans, trans-OH stretch band provides the a-axis inertial component of the dipole moment, namely μ a = 0.62(7) D. Here, the computed equilibrium dipole moment agrees well with the expectation value determined from experiment, consistent with a semi-rigid CH 3OCOH backbone computed via a potential energy scan at the B3LYP/cc-pVTZ level of theory, which reveals substantial conformer interconversionmore » barriers of ≈17 kcal/mol.« less

Raman-laser spectroscopy of Wannier-Stark states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tackmann, G.; Pelle, B.; Hilico, A.

2011-12-15

Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow one-dimensional (1D) vertical lattice. For sufficiently long laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. Allmore » these features allow for a precise characterization of the trapping potential and for an efficient control of the atomic external degrees of freedom.« less

The permanent electric dipole moment of chromium monoxide

NASA Technical Reports Server (NTRS)

Steimle, Timothy C.; Nachman, David F.; Shirley, Jeffrey E.; Bauschlicher, Charles W.; Langhoff, Stephen R.

1989-01-01

The permanent electric dipole moments for the X 5Pi and B 5pi states of gas-phase CrO have been experimentally determined using the sub-Doppler optical technique of intermodulated fluorescence spectroscopy in conjunction with the Stark effect. The measured values are 3.88 + or - 0.13 and 4.1 + or - 1.8 D for the X and B states, respectively. The theoretical values determined for the X state using multireference CI iterative-natural-orbital and finite-field calculations are in excellent agreement with the experimental value.

Spin-Based Lattice-Gas Quantum Computers in Solids Using Optical Addressing

DTIC Science & Technology

2007-04-30

excitation spectra recorded while changing step wise the applied electric field from zero to 0.3 MVm 1. The resulting spectral trails give an overview of...optics (Wiley, New York, 1984). 24 to a few MVm ’, the Stark shift of the optical resonance is well fitted by linear and quadratic dependences, Av= aF+bF2...effect with a = - 6.3 GHz/ MVm n which corresponds to Ag = 1.3 D (I Debye = 3.33 1030 Cm). This value is very similar to values found in other cases

Conserved electrostatic fields at the Ras-effector interface measured through vibrational Stark effect spectroscopy explain the difference in tilt angle in the Ras binding domains of Raf and RalGDS.

PubMed

Walker, David M; Wang, Ruifei; Webb, Lauren J

2014-10-07

Vibrational Stark effect (VSE) spectroscopy was used to measure the electrostatic fields present at the interface of the human guanosine triphosphatase (GTPase) Ras docked with the Ras binding domain (RBD) of the protein kinase Raf. Nine amino acids located on the surface of Raf were selected for labeling with a nitrile vibrational probe. Eight of the probe locations were situated along the interface of Ras and Raf, and one probe was 2 nm away on the opposite side of Raf. Vibrational frequencies of the nine Raf nitrile probes were compared both in the monomeric, solvated protein and when docked with wild-type (WT) Ras to construct a comprehensive VSE map of the Ras-Raf interface. Molecular dynamics (MD) simulations employing an umbrella sampling strategy were used to generate a Boltzmann-weighted ensemble of nitrile positions in both the monomeric and docked complexes to determine the effect that docking has on probe location and orientation and to aid in the interpretation of VSE results. These results were compared to an identical study that was previously conducted on nine nitrile probes on the RBD of Ral guanidine dissociation stimulator (RalGDS) to make comparisons between the docked complexes formed when either of the two effectors bind to WT Ras. This comparison finds that there are three regions of conserved electrostatic fields that are formed upon docking of WT Ras with both downstream effectors. Conservation of this pattern in the docked complex then results in different binding orientations observed in otherwise structurally similar proteins. This work supports an electrostatic cause of the known binding tilt angle between the Ras-Raf and Ras-RalGDS complexes.

76 FR 44028 - Indiana; Major Disaster and Related Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-22

..., and straight line winds occurring on April 19, 2011, and April 22 to May 2, 2011, and flooding..., Starke, Sullivan, Switzerland, Vanderburgh, Warrick, and Washington Counties for Public Assistance. All...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bondarenko, A. S., E-mail: AntonBondarenko@ymail.com; Schaeffer, D. B.; Everson, E. T.

The collision-less transfer of momentum and energy from explosive debris plasma to magnetized background plasma is a salient feature of various astrophysical and space environments. While much theoretical and computational work has investigated collision-less coupling mechanisms and relevant parameters, an experimental validation of the results demands the measurement of the complex, collective electric fields associated with debris-background plasma interaction. Emission spectroscopy offers a non-interfering diagnostic of electric fields via the Stark effect. A unique experiment at the University of California, Los Angeles, that combines the Large Plasma Device (LAPD) and the Phoenix laser facility has investigated the marginally super-Alfvénic, quasi-perpendicularmore » expansion of a laser-produced carbon (C) debris plasma through a preformed, magnetized helium (He) background plasma via emission spectroscopy. Spectral profiles of the He II 468.6 nm line measured at the maximum extent of the diamagnetic cavity are observed to intensify, broaden, and develop equally spaced modulations in response to the explosive C debris, indicative of an energetic electron population and strong oscillatory electric fields. The profiles are analyzed via time-dependent Stark effect models corresponding to single-mode and multi-mode monochromatic (single frequency) electric fields, yielding temporally resolved magnitudes and frequencies. The proximity of the measured frequencies to the expected electron plasma frequency suggests the development of the electron beam-plasma instability, and a simple saturation model demonstrates that the measured magnitudes are feasible provided that a sufficiently fast electron population is generated during C debris–He background interaction. Potential sources of the fast electrons, which likely correspond to collision-less coupling mechanisms, are briefly considered.« less

Role of quantum-confined stark effect on bias dependent photoluminescence of N-polar GaN/InGaN multi-quantum disk amber light emitting diodes

NASA Astrophysics Data System (ADS)

Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Prabaswara, Aditya; Zhao, Chao; Priante, Davide; Min, Jung-Wook; Ng, Tien Khee; Ooi, Boon S.

2018-03-01

We study the impact of quantum-confined stark effect (QCSE) on bias dependent micro-photoluminescence emission of the quantum disk (Q-disk) based nanowires light emitting diodes (NWs-LED) exhibiting the amber colored emission. The NWs are found to be nitrogen polar (N-polar) verified using KOH wet chemical etching and valence band spectrum analysis of high-resolution X-ray photoelectron spectroscopy. The crystal structure and quality of the NWs were investigated by high-angle annular dark field - scanning transmission electron microscopy. The LEDs were fabricated to acquire the bias dependent micro-photoluminescence spectra. We observe a redshift and a blueshift of the μPL peak in the forward and reverse bias conditions, respectively, with reference to zero bias, which is in contrast to the metal-polar InGaN well-based LEDs in the literature. Such opposite shifts of μPL peak emission observed for N-polar NWs-LEDs, in our study, are due to the change in the direction of the internal piezoelectric field. The quenching of PL intensity, under the reverse bias conditions, is ascribed to the reduction of electron-hole overlap. Furthermore, the blueshift of μPL emission with increasing excitation power reveals the suppression of QCSE resulting from the photo-generated carriers. Thereby, our study confirms the presence of QCSE for NWs-LEDs from both bias and power dependent μPL measurements. Thus, this study serves to understand the QCSE in N-polar InGaN Q-disk NWs-LEDs and other related wide-bandgap nitride nanowires, in general.

Special report on reimbursement. The safe harbor for small investment interests: where do joint ventures go from here?

PubMed

Lindeke, J M

1991-11-01

There is no specific federal self-referral legislation presently proposed or in effect that statutorily prohibits providers from referring Medicare or other patients to entities in which the referrers have an investment interest, except for existing "Stark" legislation, which applies only to clinical laboratory services, effective January 1, 1992. (See Newsletter, Vol. 6, No. 1, January 1991, at 3.) Thus, health care joint ventures are not per se illegal. The publication of the Safe Harbor Regulations does nothing to change this fundamental fact, and it should not cause providers to abandon existing joint ventures, or planned ones, in a "knee-jerk" fashion, without careful analysis. Of course, there is no guarantee that expanded "Stark" legislation, or some other new self-referral legislation, will not be enacted in the future to prohibit providers from referring patients to entities in which they have an investment interest. Because of this uncertainty, all health care joint ventures should contain "unwinding" provisions to govern the rights and obligations of investors in the event that the venture is required to, or the participants voluntarily elect to, dissolve. Any new venture being contemplated should plan for dissolution, and existing ventures should undertake an internal review of their charter documents to assess whether the rights and duties of all participants upon dissolution are properly spelled out. If not, amendments should be made now, while all participants are on good terms. A failure to agree in advance upon such important issues is an invitation to discord, and possibly even litigation.

Measurement of type-I edge localized mode pulse propagation in scrape-off layer using optical system of motional Stark effect diagnostics in JT-60U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, T.; Oyama, N.; Asakura, N.

2010-04-15

Propagation of plasma ejected by type-I edge localized mode (ELM) has been measured in scrape-off layer (SOL) of the JT-60U tokamak, using optical system of motional Stark effect (MSE) diagnostics as beam emission spectroscopy (BES) diagnostics through a new technique developed. This MSE/BES system measures D{alpha} emission from heating neutral beam excited by collisions with the ejected plasma, as well as background light (e.g., bremsstrahlung). While spatio-temporal change in the beam emission gives information on propagation of the ejected plasma, the background light that is observed simultaneously in all spatial channels veils the information. In order to separate the beammore » emission and the background light, a two-wavelength detector is newly introduced into the MSE/BES system. The detector observes simultaneously at the same spatial point in two distinct wavelengths using two photomultiplier tubes through two interference filters. One of the filters is adjusted to the central wavelength of the beam emission for the MSE diagnostics, and the other is outside the beam emission spectrum. Eliminating the background light, temporal change in the net beam emission in the SOL has been evaluated. Comparing conditionally averaged beam emission with respect to 594 ELMs in a discharge at five spatial channels (0.02-0.3 m outside the main plasma near equatorial plane), radial velocity of the ELM pulse propagation in SOL is evaluated to be 0.8-1.8 km/s ({approx}1.4 km/s for least-mean-squared fitting).« less

9. DETAIL OF BRICKWORK ON SOUTHEAST SIDE OF GERMAN VILLAGE. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. DETAIL OF BRICKWORK ON SOUTHEAST SIDE OF GERMAN VILLAGE. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

8. VIEW OF SOUTHWEST END OF GERMAN VILLAGE LOOKING NORTHEAST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. VIEW OF SOUTHWEST END OF GERMAN VILLAGE LOOKING NORTHEAST. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

4. VIEW OF NORTHWEST SIDE OF GERMAN VILLAGE LOOKING SOUTHEAST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW OF NORTHWEST SIDE OF GERMAN VILLAGE LOOKING SOUTHEAST. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

12. INTERIOR VIEW OF ROOF FRAMING IN ATTIC, LOOKING SOUTH. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. INTERIOR VIEW OF ROOF FRAMING IN ATTIC, LOOKING SOUTH. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

Adiabatic passage of radio-frequency-assisted Förster resonances in Rydberg atoms for two-qubit gates and the generation of Bell states

NASA Astrophysics Data System (ADS)

Beterov, I. I.; Hamzina, G. N.; Yakshina, E. A.; Tretyakov, D. B.; Entin, V. M.; Ryabtsev, I. I.

2018-03-01

High-fidelity entangled Bell states are of great interest in quantum physics. Entanglement of ultracold neutral atoms in two spatially separated optical dipole traps is promising for implementation of quantum computing and quantum simulation and for investigation of Bell states of material objects. We propose a method to entangle two atoms via long-range Rydberg-Rydberg interaction. Alternative to previous approaches, based on Rydberg blockade, we consider radio-frequency-assisted Stark-tuned Förster resonances in Rb Rydberg atoms. To reduce the sensitivity of the fidelity of Bell states to the fluctuations of interatomic distance, we propose to use the double adiabatic passage across the radio-frequency-assisted Stark-tuned Förster resonances, which results in a deterministic phase shift of the collective two-atom state.

Molybdenum electron impact width parameter measurement by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Sternberg, E. M. A.; Rodrigues, N. A. S.; Amorim, J.

2016-01-01

In this work, we suggest a method for electron impact width parameter calculation based on Stark broadening of emission lines of a laser-ablated plasma plume. First, electron density and temperature must be evaluated by means of the Saha-Boltzmann plot method for neutral and ionized species of the plasma. The method was applied for laser-ablated molybdenum plasma plume. For molybdenum plasma electron temperature, which varies around 10,000 K, and electron density, which reaches values around 1018 cm-3, and considering that total measured line broadening was due experimental and Stark broadening mainly, electron impact width parameter of molybdenum emission lines was determined as (0.01 ± 0.02) nm. Intending to validate the presented method, it was analyzed the laser-ablated aluminum plasma plume and the obtained results were in agreement with the predicted on the literature.

Stark absorption spectroscopy on the carotenoids bound to B800-820 and B800-850 type LH2 complexes from a purple photosynthetic bacterium, Phaeospirillum molischianum strain DSM120.

PubMed

Horibe, Tomoko; Qian, Pu; Hunter, C Neil; Hashimoto, Hideki

2015-04-15

Stark absorption spectroscopy was applied to clarify the structural differences between carotenoids bound to the B800-820 and B800-850 LH2 complexes from a purple photosynthetic bacterium Phaeospirillum (Phs.) molischianum DSM120. The former complex is produced when the bacteria are grown under stressed conditions of low temperature and dim light. These two LH2 complexes bind carotenoids with similar composition, 10% lycopene and 80% rhodopin, each with the same number of conjugated CC double bonds (n=11). Quantitative classical and semi-quantum chemical analyses of Stark absorption spectra recorded in the carotenoid absorption region reveal that the absolute values of the difference dipole moments |Δμ| have substantial differences (2 [D/f]) for carotenoids bound to either B800-820 or B800-850 complexes. The origin of this striking difference in the |Δμ| values was analyzed using the X-ray crystal structure of the B800-850 LH2 complex from Phs. molischianum DSM119. Semi-empirical molecular orbital calculations predict structural deformations of the major carotenoid, rhodopin, bound within the B800-820 complex. We propose that simultaneous rotations around neighboring CC and CC bonds account for the differences in the 2 [D/f] of the |Δμ| value. The plausible position of the rotation is postulated to be located around C21-C24 bonds of rhodopin. Copyright © 2014 Elsevier Inc. All rights reserved.

Pentacyanoiron(II) as an electron donor group for nonlinear optics: medium-responsive properties and comparisons with related pentaammineruthenium(II) complexes.

PubMed

Coe, Benjamin J; Harries, Josephine L; Helliwell, Madeleine; Jones, Lathe A; Asselberghs, Inge; Clays, Koen; Brunschwig, Bruce S; Harris, James A; Garín, Javier; Orduna, Jesús

2006-09-20

In this article, we describe a series of complex salts in which electron-rich {Fe(II)(CN)(5)}(3)(-) centers are coordinated to pyridyl ligands with electron-accepting N-methyl/aryl-pyridinium substituents. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The relatively large static first hyperpolarizabilities, beta(0), increase markedly on moving from aqueous to methanol solutions, accompanied by large red-shifts in the MLCT transitions. Acidification of aqueous solutions allows reversible switching of the linear and NLO properties, as shown via both HRS and Stark experiments. Time-dependent density functional theory and finite field calculations using a polarizable continuum model yield relatively good agreement with the experimental results and confirm the large decrease in beta(0) on protonation. The Stark-derived beta(0) values are generally larger for related {Ru(II)(NH(3))(5)}(2+) complexes than for their {Fe(II)(CN)(5)}(3)(-) analogues, consistent with the HRS data in water. However, the HRS data in methanol show that the stronger solvatochromism of the Fe(II) complexes causes their NLO responses to surpass those of their Ru(II) counterparts upon changing the solvent medium.

Angular distributions for the F+H2-->HF+H reaction: The role of the F spin-orbit excited state and comparison with molecular beam experiments

NASA Astrophysics Data System (ADS)

Tzeng, Yi-Ren; Alexander, Millard H.

2004-09-01

We report quantum mechanical calculations of center-of-mass differential cross sections (DCS) for the F+H2→HF+H reaction performed on the multistate [Alexander-Stark-Werner (ASW)] potential energy surfaces (PES) that describe the open-shell character of this reaction. For comparison, we repeat single-state calculations with the Stark-Werner (SW) and Hartke-Stark-Werner (HSW) PESs. The ASW DCSs differ from those predicted for the SW and HSW PES in the backward direction. These differences arise from nonadiabatic coupling between several electronic states. The DCSs are then used in forward simulations of the laboratory-frame angular distributions (ADs) measured by Lee, Neumark, and co-workers [J. Chem. Phys. 82, 3045 (1985)]. The simulations are scaled to match experiment over the range 12°<Θlab<80°. As a natural consequence of the reduced backward scattering, the ASW ADs are more forward and sideways scattered than predicted by the HSW PES. At the two higher collision energies (2.74 and 3.42 kcal/mol) the enhanced sideways scattering of HF v'=2 products bring the ASW ADs in very good agreement with the experiment. At the lowest collision energy (1.84 kcal/mol), the simulations, for all three sets of PESs consistently underestimate the sideways scattering. The residual disagreements, particularly at the lowest collision energy, may be due to the known deficiencies in the PESs.

Control of interlayer physics in 2H transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Wang, Kuang-Chung; Stanev, Teodor K.; Valencia, Daniel; Charles, James; Henning, Alex; Sangwan, Vinod K.; Lahiri, Aritra; Mejia, Daniel; Sarangapani, Prasad; Povolotskyi, Michael; Afzalian, Aryan; Maassen, Jesse; Klimeck, Gerhard; Hersam, Mark C.; Lauhon, Lincoln J.; Stern, Nathaniel P.; Kubis, Tillmann

2017-12-01

It is assessed in detail both experimentally and theoretically how the interlayer coupling of transition metal dichalcogenides controls the electronic properties of the respective devices. Gated transition metal dichalcogenide structures show electrons and holes to either localize in individual monolayers, or delocalize beyond multiple layers—depending on the balance between spin-orbit interaction and interlayer hopping. This balance depends on the layer thickness, momentum space symmetry points, and applied gate fields. The design range of this balance, the effective Fermi levels, and all relevant effective masses is analyzed in great detail. A good quantitative agreement of predictions and measurements of the quantum confined Stark effect in gated MoS2 systems unveils intralayer excitons as the major source for the observed photoluminescence.

A single-electron picture based on the multiconfiguration time-dependent Hartree-Fock method: application to the anisotropic ionization and subsequent high-harmonic generation of the CO molecule

NASA Astrophysics Data System (ADS)

Ohmura, S.; Kato, T.; Oyamada, T.; Koseki, S.; Ohmura, H.; Kono, H.

2018-02-01

The mechanisms of anisotropic near-IR tunnel ionization and high-order harmonic generation (HHG) in a CO molecule are theoretically investigated by using the multiconfiguration time-dependent Hartree-Fock (MCTDHF) method developed for the simulation of multielectron dynamics of molecules. The multielectron dynamics obtained by numerically solving the equations of motion (EOMs) in the MCTDHF method is converted to a single orbital picture in the natural orbital representation where the first-order reduced density matrix is diagonalized. The ionization through each natural orbital is examined and the process of HHG is classified into different optical paths designated by a combinations of initial, intermediate and final natural orbitals. The EOMs for natural spin-orbitals are also derived within the framework of the MCTDHF, which maintains the first-order reduced density matrix to be a diagonal one throughout the time propagation of a many-electron wave function. The orbital dependent, time-dependent effective potentials that govern the dynamics of respective time-dependent natural orbitals are deduced from the derived EOMs, of which the temporal variation can be used to interpret the motion of the electron density associated with each natural spin-orbital. The roles of the orbital shape, multiorbital ionization, linear Stark effect and multielectron interaction in the ionization and HHG of a CO molecule are revealed by the effective potentials obtained. When the laser electric field points to the nucleus O from C, tunnel ionization from the C atom side is enhanced; a hump structure originating from multielectron interaction is then formed on the top of the field-induced distorted barrier of the HOMO effective potential. This hump formation, responsible for the directional anisotropy of tunnel ionization, restrains the influence of the linear Stark effect on the energy shifts of bound states.

Quantum Computation by Optically Coupled Steady Atoms/Quantum-Dots Inside a Quantum Cavity

NASA Technical Reports Server (NTRS)

Pradhan, P.; Wang, K. L.; Roychowdhury, V. P.; Anantram, M. P.; Mor, T.; Saini, Subhash (Technical Monitor)

1999-01-01

We present a model for quantum computation using $n$ steady 3-level atoms kept inside a quantum cavity, or using $n$ quantum-dots (QDs) kept inside a quantum cavity. In this model one external laser is pointed towards all the atoms/QDs, and $n$ pairs of electrodes are addressing the atoms/QDs, so that each atom is addressed by one pair. The energy levels of each atom/QD are controlled by an external Stark field given to the atom/QD by its external pair of electrodes. Transition between two energy levels of an individual atom/ QD are controlled by the voltage on its electrodes, and by the external laser. Interactions between two atoms/ QDs are performed with the additional help of the cavity mode (using on-resonance condition). Laser frequency, cavity frequency, and energy levels are far off-resonance most of the time, and they are brought to the resonance (using the Stark effect) only at the time of operations. Steps for a controlled-NOT gate between any two atoms/QDs have been described for this model. Our model demands some challenging technological efforts, such as manufacturing single-electron QDs inside a cavity. However, it promises big advantages over other existing models which are currently implemented, and might enable a much easier scale-up, to compute with many more qubits.

Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

NASA Technical Reports Server (NTRS)

Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

2008-01-01

Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

Factors determining electrostatic fields in molecular dynamics simulations of the Ras/effector interface.

PubMed

Ensign, Daniel L; Webb, Lauren J

2011-12-01

Using molecular dynamics simulations, we explore geometric and physical factors contributing to calculated electrostatic fields at the binding surface of the GTPase Ras with a spectroscopically labeled variant of a downstream effector, the Ras-binding domain of Ral guanine nucleotide dissociation stimulator (RalGDS). A related system (differing by mutation of one amino acid) has been studied in our group using vibrational Stark effect spectroscopy, a technique sensitive to electrostatic fields. Electrostatic fields were computed using the AMBER 2003 force field and averaged over snapshots from molecular dynamics simulation. We investigate geometric factors by exploring how the orientation of the spectroscopic probe changes on Ras-effector binding. In addition, we explore the physical origin of electrostatic fields at our spectroscopic probe by comparing contributions to the field from discrete components of the system, such as explicit solvent, residues on the Ras surface, and residues on the RalGDS surface. These models support our experimental hypothesis that vibrational Stark shifts are caused by Ras binding to its effector and not the structural rearrangements of the effector surface or probe reorientation on Ras-effector binding, for at least some of our experimental probes. These calculations provide physical insight into the origin, magnitude, and importance of electrostatic fields in protein-protein interactions and suggest new experiments to probe the field's role in protein docking. Copyright © 2011 Wiley-Liss, Inc.

On the electrostatic deceleration of argon atoms in high Rydberg states by time-dependent inhomogeneous electric fields

NASA Astrophysics Data System (ADS)

Vliegen, E.; Merkt, F.

2005-06-01

Argon atoms in a pulsed supersonic expansion are prepared in selected Stark components of Rydberg states with effective principal quantum number in the range n* = 15-25. When traversing regions of inhomogeneous electric fields, these atoms get accelerated or decelerated depending on whether the Stark states are low- or high-field seeking states. Using a compact electrode design, which enables the application of highly inhomogeneous and time-dependent electric fields, the Rydberg atoms experience kinetic energy changes of up to 1.2 × 10-21 J (i.e. 60 cm-1 in spectroscopic units) in a single acceleration/deceleration stage of 3 mm length. The resulting differences in the velocities of the low- and high-field seeking states are large enough that the corresponding distributions of times of flight to the Rydberg particle detector are fully separated. As a result, efficient spectral searches of the Rydberg states best suited for acceleration/deceleration experiments are possible. Numerical simulations of the particle trajectories are used to analyse the time-of-flight distributions and to optimize the time dependence of the inhomogeneous electric fields. The decay of the Rydberg states by fluorescence, collisions and transitions induced by black-body radiation takes place on a timescale long enough not to interfere significantly with the deceleration during the first ~5 µs.

Controlled exciton transfer between quantum dots with acoustic phonons taken into account

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golovinski, P. A., E-mail: golovinski@bk.ru

2015-09-15

A system of excitons in two quantum dots coupled by the dipole–dipole interaction is investigated. The excitation transfer process controlled by the optical Stark effect at nonresonant frequencies is considered and the effect of the interaction between excitons and acoustic phonons in a medium on this process is taken into account. The system evolution is described using quantum Heisenberg equations. A truncated set of equations is obtained and the transfer dynamics is numerically simulated. High-efficiency picosecond switching of the excitation transfer by a laser pulse with a rectangular envelope is demonstrated. The dependence of picosecond switching on the quantum-dot parametersmore » and optical-pulse length is presented.« less

Diagnostics development for E-beam excited air channels

NASA Astrophysics Data System (ADS)

Eckstrom, D. J.; Dickenson, J. S.

1982-02-01

As the tempo of development of particle beam weapons increases, more detailed diagnostics of the interaction of the particle beam with the atmosphere are being proposed and implemented. Some of these diagnostics involve probing of the excited air channel with visible wavelength laser radiation. Examples include the use of visible wavelength interferometry to measure electron density profiles in the nose of the beam Ri81 and Stark shift measurements to determine self-induced electric fields Hi81, DR81. In these diagnostics, the change in laser intensity due to the desired diagnostic effect can be quite small, leading to the possibility that other effects, such as gas phase absorption, could seriously interfere with the measurement.

Large negative differential resistance in graphene nanoribbon superlattices

NASA Astrophysics Data System (ADS)

Tseng, P.; Chen, C. H.; Hsu, S. A.; Hsueh, W. J.

2018-05-01

A graphene nanoribbon superlattice with a large negative differential resistance (NDR) is proposed. Our results show that the peak-to-valley ratio (PVR) of the graphene superlattices can reach 21 at room temperature with bias voltages between 90-220 mV, which is quite large compared with the one of traditional graphene-based devices. It is found that the NDR is strongly influenced by the thicknesses of the potential barrier. Therefore, the NDR effect can be optimized by designing a proper barrier thickness. The large NDR effect can be attributed to the splitting of the gap in transmission spectrum (segment of Wannier-Stark ladder) with larger thicknesses of barrier when the applied voltage increases.

New nonlinear optical effect: self-reflection phenomenon due to exciton-biexciton-light interaction in semiconductors

NASA Astrophysics Data System (ADS)

Khadzhi, P. I.; Lyakhomskaya, K. D.; Nadkin, L. Y.; Markov, D. A.

2002-05-01

The characteristic peculiarities of the self-reflection of a strong electromagnetic wave in a system of coherent excitons and biexcitons due to the exciton-photon interaction and optical exciton-biexciton conversion in semiconductors were investigated as one of the manifestations of nonlinear optical Stark-effect. It was found that a monotonously decreasing standing wave with an exponential decreasing spatial tail is formed in the semiconductor. Under the action of the field of a strong pulse, an optically homogeneous medium is converted, into the medium with distributed feedback. The appearance of the spatially separated narrow pears of the reflective index, extinction and reflection coefficients is predicted.

14. INTERIOR VIEW OF NEWEL POST AT SOUTH STAIRWELL, LOOKING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. INTERIOR VIEW OF NEWEL POST AT SOUTH STAIRWELL, LOOKING NORTH. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

11. INTERIOR VIEW OF DOORS OPENING INTO NORTH STAIRWELL, LOOKING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. INTERIOR VIEW OF DOORS OPENING INTO NORTH STAIRWELL, LOOKING WEST. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

1. OBLIQUE VIEW OF BUNKER LOOKING NORTHWEST. GERMAN VILLAGE IN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. OBLIQUE VIEW OF BUNKER LOOKING NORTHWEST. GERMAN VILLAGE IN BACKGROUND. - Dugway Proving Ground, German-Japanese Village, Observation Bunker, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

Molecular alignment and orientation with a hybrid Raman scattering technique

NASA Astrophysics Data System (ADS)

Bustard, Philip J.; Lausten, R.; Sussman, Benjamin J.

2012-11-01

We demonstrate a scheme for the preparation of molecular alignment and angular momentum orientation using a hybrid combination of two limits of Raman scattering. First a weak, impulsive pump pulse initializes the system via the nonresonant dynamic Stark effect. Then, having overcome the influence of the vacuum fluctuations, an amplification pulse selectively enhances the initial coherences by transient stimulated Raman scattering, generating alignment and angular momentum orientation of molecular hydrogen. The amplitude and phase of the resulting coherent dynamics are experimentally probed, indicating an amplification factor of 4.5. An analytic theory is developed to model the dynamics.

Coherent Addressing of Individual Neutral Atoms in a 3D Optical Lattice.

PubMed

Wang, Yang; Zhang, Xianli; Corcovilos, Theodore A; Kumar, Aishwarya; Weiss, David S

2015-07-24

We demonstrate arbitrary coherent addressing of individual neutral atoms in a 5×5×5 array formed by an optical lattice. Addressing is accomplished using rapidly reconfigurable crossed laser beams to selectively ac Stark shift target atoms, so that only target atoms are resonant with state-changing microwaves. The effect of these targeted single qubit gates on the quantum information stored in nontargeted atoms is smaller than 3×10^{-3} in state fidelity. This is an important step along the path of converting the scalability promise of neutral atoms into reality.

A new beam emission polarimetry diagnostic for measuring the magnetic field line angle at the plasma edge of ASDEX Upgrade.

PubMed

Viezzer, E; Dux, R; Dunne, M G

2016-11-01

A new edge beam emission polarimetry diagnostic dedicated to the measurement of the magnetic field line angle has been installed on the ASDEX Upgrade tokamak. The new diagnostic relies on the motional Stark effect and is based on the simultaneous measurement of the polarization direction of the linearly polarized π (parallel to the electric field) and σ (perpendicular to the electric field) lines of the Balmer line D α . The technical properties of the system are described. The calibration procedures are discussed and first measurements are presented.

A new beam emission polarimetry diagnostic for measuring the magnetic field line angle at the plasma edge of ASDEX Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viezzer, E., E-mail: eleonora.viezzer@ipp.mpg.de, E-mail: eviezzer@us.es; Department of Atomic, Molecular, and Nuclear Physics, University of Seville, Avda. Reina Mercedes, 41012 Seville; Dux, R.

2016-11-15

A new edge beam emission polarimetry diagnostic dedicated to the measurement of the magnetic field line angle has been installed on the ASDEX Upgrade tokamak. The new diagnostic relies on the motional Stark effect and is based on the simultaneous measurement of the polarization direction of the linearly polarized π (parallel to the electric field) and σ (perpendicular to the electric field) lines of the Balmer line D{sub α}. The technical properties of the system are described. The calibration procedures are discussed and first measurements are presented.

The Influence of Gas Composition in Dielectric Barrier Discharges on the Broadening of the Hydrogen H{alpha} Transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janus, H. W.

The distribution of hydrogen atoms responsible for emission of the Balmer H{alpha} line in the region of the dielectric barrier discharges in the helium and hydrogen as well as in the argon and hydrogen mixtures, in the direction perpendicular to the electrode surfaces, has bee determined by the optical emission spectroscopy accounting for the polarization of the emitted light. The procedure of fitting the measured line profiles accounting for the Stark effect has been used for determination of the distribution of the electric field in the discharge region.

Electrical and mechanical tuning of a silicon vacancy defect in SiC for quantum information technology

NASA Astrophysics Data System (ADS)

Soykal, Oney O.; Reinecke, Thomas L.

We develop coherent control via Stark effect over the optical transition energies of silicon monovacancy deep center in hexagonal silicon carbide. We show that this defect's unique asymmetry properties of its piezoelectric tensor and Kramer's degenerate high-spin ground/excited state configurations can be used to create new possibilities in quantum information technology ranging from photonic networks to quantum key distribution. We also give examples of its qubit implementations via precise electric field control. This work was supported in part by ONR and by the Office of Secretary of Defense, Quantum Science and Engineering Program.

Large Spatially Resolved Rectification in a Donor–Acceptor Molecular Heterojunction

DOE PAGES

Smerdon, Joseph A.; Giebink, Noel C.; Guisinger, Nathan P.; ...

2016-03-10

Here, we demonstrate that rectification ratios (RR) of ≳250 (≳1000) at biases of 0.5 V (1.2 V) are achievable at the two-molecule limit for donor–acceptor bilayers of pentacene on C 60 on Cu using scanning tunneling spectroscopy and microscopy. Using first-principles calculations, we show that the system behaves as a molecular Schottky diode with a tunneling transport mechanism from semiconducting pentacene to Cu- hybridized metallic C 60. Low-bias RRs vary by two orders-of-magnitude at the edge of these molecular heterojunctions due to increased Stark shifts and confinement effects.

Atomic states in optical traps near a planar surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Messina, Riccardo; Pelisson, Sophie; Angonin, Marie-Christine

2011-05-15

In this paper, we discuss the atomic states in a vertical optical lattice in proximity of a surface. We study the modifications to the ordinary Wannier-Stark states in the presence of a surface, and we characterize the energy shifts produced by the Casimir-Polder interaction between atom and mirror. In this context, we introduce an effective model describing the finite size of the atom in order to regularize the energy corrections. In addition, the modifications to the energy levels due to a hypothetical non-Newtonian gravitational potential as well as their experimental observability are investigated.

13. INTERIOR VIEW OF ROOF FRAMING AND DORMER OPENING IN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. INTERIOR VIEW OF ROOF FRAMING AND DORMER OPENING IN ATTIC, LOOKING EAST. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

3. OVERALL VIEW OF BUNKER LOOKING SOUTHWEST WITH BUILDING T8100 ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. OVERALL VIEW OF BUNKER LOOKING SOUTHWEST WITH BUILDING T-8100 IN BACKGROUND. - Dugway Proving Ground, German-Japanese Village, Observation Bunker, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

A temporally and spatially resolved electron density diagnostic method for the edge plasma based on Stark broadening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zafar, A., E-mail: zafara@ornl.gov; Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830; Martin, E. H.

2016-11-15

An electron density diagnostic (≥10{sup 10} cm{sup −3}) capable of high temporal (ms) and spatial (mm) resolution is currently under development at Oak Ridge National Laboratory. The diagnostic is based on measuring the Stark broadened, Doppler-free spectral line profile of the n = 6–2 hydrogen Balmer series transition. The profile is then fit to a fully quantum mechanical model including the appropriate electric and magnetic field operators. The quasi-static approach used to calculate the Doppler-free spectral line profile is outlined here and the results from the model are presented for H-δ spectra for electron densities of 10{sup 10}–10{sup 13} cm{supmore » −3}. The profile shows complex behavior due to the interaction between the magnetic substates of the atom.« less

Indonemoura annamensis-a new species of stonefly from Vietnam (Plecoptera: Nemouridae).

PubMed

Fochetti, Romolo; Ceci, Massimo

2016-06-07

The amphinemurine genus Indonemoura Baumann (1975) was proposed for species previously included in the genera Protonemura Kempny and Nemoura Latreille. Baumann (1975) designated P. indica Kimmins, 1947 (in Kimmins 1946) as the type species. He also transferred 14 additional species from Protonemura and Nemoura into this genus. The genus is distributed mainly in the Oriental region (only one species from Tibet, close to the eastern border of the Palaearctic Region) and many new species have been added in the last decades (Zwick & Sivec 1980; Shimizu 1994a & b; Zhu et al. 2002; Li et al. 2005; Li & Yang 2005, 2006; Wang et al. 2006; Sivec & Stark 2010) including presently 53 species (DeWalt et al. 2009). Sivec & Stark (2010) first described three Indonemoura species from Vietnam, I. angulata, I. clavata, and I. tricantha. These three species are the only Indonemoura presently known for Vietnam.

Prospects for quantum computing with an array of ultracold polar paramagnetic molecules.

PubMed

Karra, Mallikarjun; Sharma, Ketan; Friedrich, Bretislav; Kais, Sabre; Herschbach, Dudley

2016-03-07

Arrays of trapped ultracold molecules represent a promising platform for implementing a universal quantum computer. DeMille [Phys. Rev. Lett. 88, 067901 (2002)] has detailed a prototype design based on Stark states of polar (1)Σ molecules as qubits. Herein, we consider an array of polar (2)Σ molecules which are, in addition, inherently paramagnetic and whose Hund's case (b) free-rotor pair-eigenstates are Bell states. We show that by subjecting the array to combinations of concurrent homogeneous and inhomogeneous electric and magnetic fields, the entanglement of the array's Stark and Zeeman states can be tuned and the qubit sites addressed. Two schemes for implementing an optically controlled CNOT gate are proposed and their feasibility discussed in the face of the broadening of spectral lines due to dipole-dipole coupling and the inhomogeneity of the electric and magnetic fields.

Perspective and potential of smart optical materials

NASA Astrophysics Data System (ADS)

Choi, Sang H.; Duzik, Adam J.; Kim, Hyun-Jung; Park, Yeonjoon; Kim, Jaehwan; Ko, Hyun-U.; Kim, Hyun-Chan; Yun, Sungryul; Kyung, Ki-Uk

2017-09-01

The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from micro-scale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro convex lens are reviewed, along with the newly discovered pseudo-focal point not predicted with conventional optics modeling. Micron-sized solid state beam scanner chips for laser waveguides are reviewed as well.

Effect of the Edge Radial Electric Field on Neutral Particle Measurements

NASA Astrophysics Data System (ADS)

Guldi, C.; Heidbrink, W. W.; Beitzel, T. A.; Burrell, K. H.

2000-10-01

Neutral particle measurements in ASDEX were originally interpreted as evidence that the edge radial electric field Er changes gradually at the L-H transition.(W. Herrmann et al.), Phys. Rev. Lett. 75 (1995) 4401. We have relocated an analyzer to an orientation similar to the ASDEX analyzer: at the outer midplane viewing perpendicular ions midway between toroidal field coils. The electric field is measured by charge-exchange recombination and motional stark effect diagnostics. The passive charge exchange signal from the relocated analyzer is usually undetectable but, in discharges with large E_r, the flux of 5 keV neutrals can resemble ASDEX signals. The combined effects of ripple trapping and E_r× B_φ drifts(J.A. Heikkinen et al.), Plasma Phys. Contr. Fusion 40 (1998) 679. may explain the results.

Stark County Area Transportation Study - Transportation Improvement Program 1997-2000

DOT National Transportation Integrated Search

1996-05-01

The Transportation Improvement Program (TIP) is the schedule of highway and transit improvements recommended for implementation within the next four years. It is, therefore, the end product of the transportation planning process. The TIP originates f...

Suppression of the overlap between Majorana fermions by orbital magnetic effects in semiconducting-superconducting nanowires

NASA Astrophysics Data System (ADS)

Dmytruk, Olesia; Klinovaja, Jelena

2018-04-01

We study both analytically and numerically the role of orbital effects caused by a magnetic field applied along the axis of a semiconducting Rashba nanowire in the topological regime hosting Majorana fermions. We demonstrate that the orbital effects can be effectively taken into account in a one-dimensional model by shifting the chemical potential and thus modifying the topological criterion. We focus on the energy splitting between two Majorana fermions in a finite nanowire and find a striking interplay between orbital and Zeeman effects on this splitting. In the limit of strong spin-orbit interaction, we find regimes where the amplitude of the oscillating splitting stays constant or even decays with increasing the magnetic field, in stark contrast to the commonly studied case where orbital effects of the magnetic field are neglected. The period of these oscillations is found to be almost constant in many parameter regimes.

Investigation of fast ion pressure effects in ASDEX Upgrade by spectral MSE measurements

NASA Astrophysics Data System (ADS)

Reimer, René; Dinklage, Andreas; Wolf, Robert; Dunne, Mike; Geiger, Benedikt; Hobirk, Jörg; Reich, Matthias; ASDEX Upgrade Team; McCarthy, Patrick J.

2017-04-01

High precision measurements of fast ion effects on the magnetic equilibrium in the ASDEX Upgrade tokamak have been conducted in a high-power (10 MW) neutral-beam injection discharge. An improved analysis of the spectral motional Stark effect data based on forward-modeling, including the Zeeman effect, fine-structure and non-statistical sub-level distribution, revealed changes in the order of 1% in |B| . The results were found to be consistent with results from the equilibrium solver CLISTE. The measurements allowed us to derive the fast ion pressure fraction to be Δ {{p}\\text{FI}}/{{p}\\text{mhd}}≈ 10 % and variations of the fast ion pressure are consistent with calculations of the transport code TRANSP. The results advance the understanding of fast ion confinement and magneto-hydrodynamic stability in the presence of fast ions.

Effective Engagement of Hostile Audiences on Climate Change

NASA Astrophysics Data System (ADS)

Denning, S.

2012-12-01

Communicating effectively about climate change can be very frustrating because hostility to climate science is rooted in deeply held beliefs rather than facts. Opposition can be more effectively countered by respecting ideological objections than by aggressive insistence on acceptance of consensus evidence. When presented with a stark choice between sacred beliefs and factual evidence, social science research shows that nearly everyone will choose the latter. Rational argument from authority is often the weakest approach in such situations. Climate change is Simple, Serious, and Solvable. Effective communication of these three key ideas can succeed when the science argument is carefully framed to avoid attack of the audience's ethical identity. Simple arguments from common sense and everyday experience are more successful than data. Serious consequences to values that resonate with the audience can be avoided by solutions that don't threaten those values.

Vibrational Stark effect spectroscopy reveals complementary electrostatic fields created by protein-protein binding at the interface of Ras and Ral.

PubMed

Walker, David M; Hayes, Ellen C; Webb, Lauren J

2013-08-07

Electrostatic fields at the interface of the GTPase H-Ras (Ras) docked with the Ras binding domain of the protein Ral guanine nucleoside dissociation stimulator (Ral) were measured with vibrational Stark effect (VSE) spectroscopy. Nine residues on the surface of Ras that participate in the protein-protein interface were systematically mutated to cysteine and subsequently converted to cyanocysteine in order to introduce a nitrile VSE probe into the protein-protein interface. The absorption energy of the nitrile was measured both on the surface of Ras in its monomeric state, then after incubation with the Ras binding domain of Ral to form the docked complex. Boltzmann-weighted structural snapshots of the nitrile-labeled Ras protein were generated both in monomeric and docked configurations from molecular dynamics simulations using enhanced sampling of the cyanocysteine side chain's χ2 dihedral angle. These snapshots were used to determine that on average, most of the nitrile probes were aligned along the Ras surface, parallel to the Ras-Ral interface. The average solvent-accessible surface areas (SASA) of the cyanocysteine side chain were found to be <60 Å(2) for all measured residues, and was not significantly different whether the nitrile was on the surface of the Ras monomer or immersed in the docked complex. Changes in the absorption energy of the nitrile probe at nine positions along the Ras-Ral interface were compared to results of a previous study examining this interface with Ral-based probes, and found a pattern of low electrostatic field in the core of the interface surrounded by a ring of high electrostatic field around the perimeter of the interface. These data are used to rationalize several puzzling features of the Ras-Ral interface.

Identification of Ion-Pair Structures in Solution by Vibrational Stark Effects.

PubMed

Hack, John; Grills, David C; Miller, John R; Mani, Tomoyasu

2016-02-18

Ion pairing is a fundamental consideration in many areas of chemistry and has implications in a wide range of sciences and technologies that include batteries and organic photovoltaics. Ions in solution are known to inhabit multiple possible states, including free ions (FI), contact ion pairs (CIP), and solvent-separated ion pairs (SSIP). However, in solutions of organic radicals and nonmetal electrolytes, it is often difficult to distinguish between these states. In the first part of this work, we report evidence for the formation of SSIPs in low-polarity solvents and distinct measurements of CIP, SSIP, and FI, by using the ν(C≡N) infrared (IR) band of a nitrile-substituted fluorene radical anion. Use of time-resolved IR detection following pulse radiolysis allowed us to unambiguously assign the peak of the FI. In the presence of nonmetal electrolytes, two distinct red-shifted peaks were observed and assigned to the CIP and SSIP. The assignments are interpreted in the framework of the vibrational Stark effect (VSE) and are supported by (1) the solvent dependence of ion-pair populations, (2) the observation of a cryptand-separated sodium ion pair that mimics the formation of SSIPs, and (3) electronic structure calculations. In the second part of this work, we show that a blue-shift of the ν(C≡N) IR band due to the VSE can be induced in a nitrile-substituted fluorene radical anion by covalently tethering it to a metal-chelating ligand that forms an intramolecular ion pair upon reduction and complexation with sodium ion. This adds support to the conclusion that the shift in IR absorptions by ion pairing originates from the VSE. These results combined show that we can identify ion-pair structures by using the VSE, including the existence of SSIPs in a low-polarity solvent.

Influence of hydrostatic pressure on the built-in electric field in ZnO/ZnMgO quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teisseyre, Henryk, E-mail: teiss@ifpan.edu.pl; Institute of High Pressure, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw; Kaminska, Agata

We used high hydrostatic pressure to perform photoluminescence measurements on polar ZnO/ZnMgO quantum well structures. Our structure oriented along the c-direction (polar direction) was grown by plasma-assisted molecular beam epitaxy on a-plane sapphire. Due to the intrinsic electric field, which exists in polar wurtzite structure at ambient pressure, we observed a red shift of the emission related to the quantum-confined Stark effect. In the high hydrostatic pressure experiment, we observed a strong decrease of the quantum well pressure coefficients with increased thickness of the quantum wells. Generally, a narrower quantum well gave a higher pressure coefficient, closer to the band-gapmore » pressure coefficient of bulk material 20 meV/GPa for ZnO, while for wider quantum wells it is much lower. We observed a pressure coefficient of 19.4 meV/GPa for a 1.5 nm quantum well, while for an 8 nm quantum well the pressure coefficient was equal to 8.9 meV/GPa only. This is explained by taking into account the pressure-induced increase of the strain in our structure. The strain was calculated taking in to account that in-plane strain is not equal (due to fact that we used a-plane sapphire as a substrate) and the potential distribution in the structure was calculated self-consistently. The pressure induced increase of the built-in electric field is the same for all thicknesses of quantum wells, but becomes more pronounced for thicker quantum wells due to the quantum confined Stark effect lowering the pressure coefficients.« less

On the Runge-Lenz-Pauli vector operator as an aid to the calculation of atomic processes in laboratory and astrophysical plasmas

NASA Astrophysics Data System (ADS)

Hey, J. D.

2015-09-01

On the basis of the original definition and analysis of the vector operator by Pauli (1926 Z. Phys. 36 336-63), and further developments by Flamand (1966 J. Math. Phys. 7 1924-31), and by Becker and Bleuler (1976 Z. Naturforsch. 31a 517-23), we consider the action of the operator on both spherical polar and parabolic basis state wave functions, both with and without direct use of Pauli’s identity (Valent 2003 Am. J. Phys. 71 171-75). Comparison of the results, with the aid of two earlier papers (Hey 2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641-64, Hey 2007 J. Phys. B: At. Mol. Opt. Phys. 40 4077-96), yields a convenient ladder technique in the form of a recurrence relation for calculating the transformation coefficients between the two sets of basis states, without explicit use of generalized hypergeometric functions. This result is therefore very useful for application to Stark effect and impact broadening calculations applied to high-n radio recombination lines from tenuous space plasmas. We also demonstrate the versatility of the Runge-Lenz-Pauli vector operator as a means of obtaining recurrence relations between expectation values of successive powers of quantum mechanical operators, by using it to provide, as an example, a derivation of the Kramers-Pasternack relation. It is suggested that this operator, whose potential use in Stark- and Zeeman-effect calculations for magnetically confined fusion edge plasmas (Rosato, Marandet and Stamm 2014 J. Phys. B: At. Mol. Opt. Phys. 47 105702) and tenuous space plasmas ( H II regions) has not been fully explored and exploited, may yet be found to yield a number of valuable results for applications to plasma diagnostic techniques based upon rate calculations of atomic processes.

A comparison of the optical properties of InGaN/GaN multiple quantum well structures grown with and without Si-doped InGaN prelayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davies, M. J., E-mail: Matthew.Davies-2@Manchester.ac.uk; Hammersley, S.; Dawson, P.

In this paper, we report on a detailed spectroscopic study of the optical properties of InGaN/GaN multiple quantum well structures, both with and without a Si-doped InGaN prelayer. In photoluminescence and photoluminescence excitation spectroscopy, a 2nd emission band, occurring at a higher energy, was identified in the spectrum of the multiple quantum well structure containing the InGaN prelayer, originating from the first quantum well in the stack. Band structure calculations revealed that a reduction in the resultant electric field occurred in the quantum well immediately adjacent to the InGaN prelayer, therefore leading to a reduction in the strength of themore » quantum confined Stark effect in this quantum well. The partial suppression of the quantum confined Stark effect in this quantum well led to a modified (higher) emission energy and increased radiative recombination rate. Therefore, we ascribed the origin of the high energy emission band to recombination from the 1st quantum well in the structure. Study of the temperature dependent recombination dynamics of both samples showed that the decay time measured across the spectrum was strongly influenced by the 1st quantum well in the stack (in the sample containing the prelayer) leading to a shorter average room temperature lifetime in this sample. The room temperature internal quantum efficiency of the prelayer containing sample was found to be higher than the reference sample (36% compared to 25%) which was thus attributed to the faster radiative recombination rate of the 1st quantum well providing a recombination pathway that is more competitive with non-radiative recombination processes.« less

Effect of collective response on electron capture and excitation in collisions of highly charged ions with fullerenes.

PubMed

Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C

2003-03-07

Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions.

A single blue nanorod light emitting diode.

PubMed

Hou, Y; Bai, J; Smith, R; Wang, T

2016-05-20

We report a light emitting diode (LED) consisting of a single InGaN/GaN nanorod fabricated by a cost-effective top-down approach from a standard LED wafer. The device demonstrates high performance with a reduced quantum confined Stark effect compared with a standard planar counterpart fabricated from the same wafer, confirmed by optical and electrical characterization. Current density as high as 5414 A cm(-2) is achieved without significant damage to the device due to the high internal quantum efficiency. The efficiency droop is mainly ascribed to Auger recombination, which was studied by an ABC model. Our work provides a potential method for fabricating compact light sources for advanced photonic integrated circuits without involving expensive or time-consuming fabrication facilities.

An analysis of the rotational, fine and hyperfine effects in the (0, 0) band of the A7Π- X7Σ + transition of manganese monohydride, MnH

NASA Astrophysics Data System (ADS)

Gengler, Jamie J.; Steimle, Timothy C.; Harrison, Jeremy J.; Brown, John M.

2007-02-01

High-resolution (±0.003 cm -1), laser induced fluorescence (LIF) spectra of a supersonic molecular beam sample of manganese monohydride, MnH, have been recorded in the 17500-17800 cm -1 region of the (0, 0) band of the A7Π- X7Σ + system. The low- N branch features were modeled successfully by inclusion of the magnetic hyperfine mixings of spin components within a given low- N rotational level using a traditional 'effective' Hamiltonian approach. An improved set of spectroscopic constants has been extracted and compared with those from previous analyses. The optimum optical features for future optical Stark and Zeeman measurements are identified.

The physical basis for absorption of light. [effects on wave functions of gas molecules and atoms

NASA Technical Reports Server (NTRS)

Pickett, H. M.

1979-01-01

The effects of light absorption on the wave functions of gas-phase molecules and atoms are investigated by high resolution spectral measurements of radiation emerging from a sample. A Stark-modulated sample of methyl fluoride was irradiated at the 102 GHz rotational transition and the emergent radiation was resolved by means of a spectrum analyzer. For signal oscillator frequencies below or above the molecular resonance by one modulation frequency, the amplitudes of the upper and lower modulation sidebands are found to be of nonuniform intensity, which is inconsistent with amplitude modulation. Emission due to polarization is, however, calculated to be consistent with the results observed, indicating that light absorption should be considered as a subtractive stimulated emission.

2. OVERALL VIEW OF GERMAN VILLAGE LOOKING SOUTHWEST TOWARD BUILDING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. OVERALL VIEW OF GERMAN VILLAGE LOOKING SOUTHWEST TOWARD BUILDING T-8100. BUNKER, BUILDING T-8104, IN FOREGROUND. - Dugway Proving Ground, German-Japanese Village, German Village, South of Stark Road, in WWII Incendiary Test Area, Dugway, Tooele County, UT

The Experiences and Insights of One Community College Foster Alum and One Community College Faculty Advocate

ERIC Educational Resources Information Center

Westland, Melinda A.; Totten, Volena

2018-01-01

Using personal narratives, in this chapter the authors weave together two distinct perspectives to illuminate the stark reality of many students' experiences as they transition from the foster care system to postsecondary education.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Houqiang; Lu, Zhijian; Zhao, Yuji

We study the low efficiency droop characteristics of semipolar InGaN light-emitting diodes (LEDs) using modified rate equation incoporating the phase-space filling (PSF) effect where the results on c-plane LEDs are also obtained and compared. Internal quantum efficiency (IQE) of LEDs was simulated using a modified ABC model with different PSF filling (n{sub 0}), Shockley-Read-Hall (A), radiative (B), Auger (C) coefficients and different active layer thickness (d), where the PSF effect showed a strong impact on the simulated LED efficiency results. A weaker PSF effect was found for low-droop semipolar LEDs possibly due to small quantum confined Stark effect, short carriermore » lifetime, and small average carrier density. A very good agreement between experimental data and the theoretical modeling was obtained for low-droop semipolar LEDs with weak PSF effect. These results suggest the low droop performance may be explained by different mechanisms for semipolar LEDs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tremblay, P.-E.; Bergeron, P.; Gianninas, A., E-mail: tremblay@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca, E-mail: gianninas@astro.umontreal.ca

We present an improved spectroscopic and photometric analysis of hydrogen-line DA white dwarfs from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) based on model atmospheres that include improved Stark broadening profiles with non-ideal gas effects. We also perform a careful visual inspection of all spectroscopic fits with high signal-to-noise ratios (S/Ns > 12) and present improved atmospheric parameters (T{sub eff} and log g) for each white dwarf. Through a comparison of spectroscopic and photometric temperatures, we report the discovery of 35 DA+DB/DC double degenerate candidates and two helium-rich DA stars. We also determine that a cutoff atmore » S/N = 15 optimizes the size and quality of the sample for computing the mean mass of DA white dwarfs, for which we report a value of 0.613 M{sub sun}. We compare our results to previous analyses of the SDSS DR4 and find a good agreement if we account for the shift produced by the improved Stark profiles. Finally, the properties of DA white dwarfs in the SDSS are weighed against those of the Villanova White Dwarf Catalog sample of Gianninas et al. We find systematically lower masses (by about 3% on average), a difference that we trace back to the data reduction procedure of the SDSS. We conclude that a better understanding of these differences will be important to determine the absolute temperature scale and mean mass of DA white dwarfs.« less

Uncertainty Analysis of Air Radiation for Lunar Return Shock Layers

NASA Technical Reports Server (NTRS)

Kleb, Bil; Johnston, Christopher O.

2008-01-01

By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).

A multi-resolution analysis of lidar-DTMs to identify geomorphic processes from characteristic topographic length scales

NASA Astrophysics Data System (ADS)

Sangireddy, H.; Passalacqua, P.; Stark, C. P.

2013-12-01

Characteristic length scales are often present in topography, and they reflect the driving geomorphic processes. The wide availability of high resolution lidar Digital Terrain Models (DTMs) allows us to measure such characteristic scales, but new methods of topographic analysis are needed in order to do so. Here, we explore how transitions in probability distributions (pdfs) of topographic variables such as (log(area/slope)), defined as topoindex by Beven and Kirkby[1979], can be measured by Multi-Resolution Analysis (MRA) of lidar DTMs [Stark and Stark, 2001; Sangireddy et al.,2012] and used to infer dominant geomorphic processes such as non-linear diffusion and critical shear. We show this correlation between dominant geomorphic processes to characteristic length scales by comparing results from a landscape evolution model to natural landscapes. The landscape evolution model MARSSIM Howard[1994] includes components for modeling rock weathering, mass wasting by non-linear creep, detachment-limited channel erosion, and bedload sediment transport. We use MARSSIM to simulate steady state landscapes for a range of hillslope diffusivity and critical shear stresses. Using the MRA approach, we estimate modal values and inter-quartile ranges of slope, curvature, and topoindex as a function of resolution. We also construct pdfs at each resolution and identify and extract characteristic scale breaks. Following the approach of Tucker et al.,[2001], we measure the average length to channel from ridges, within the GeoNet framework developed by Passalacqua et al.,[2010] and compute pdfs for hillslope lengths at each scale defined in the MRA. We compare the hillslope diffusivity used in MARSSIM against inter-quartile ranges of topoindex and hillslope length scales, and observe power law relationships between the compared variables for simulated landscapes at steady state. We plot similar measures for natural landscapes and are able to qualitatively infer the dominant geomorphic processes. Also, we explore the variability in hillslope length scales as a function of hillslope diffusivity coefficients and critical shear stress in natural landscapes and show that we can infer signatures of dominant geomorphic processes by analyzing characteristic topographic length scales present in topography. References: Beven, K. and Kirkby, M. J.: A physically based variable contributing area model of basin hydrology, Hydrol. Sci. Bull., 24, 43-69, 1979 Howard, A. D. (1994). A detachment-limited model of drainage basin evolution.Water resources research, 30(7), 2261-2285. Passalacqua, P., Do Trung, T., Foufoula Georgiou, E., Sapiro, G., & Dietrich, W. E. (2010). A geometric framework for channel network extraction from lidar: Nonlinear diffusion and geodesic paths. Journal of Geophysical. Research: Earth Surface (2003-2012), 115(F1). Sangireddy, H., Passalacqua, P., Stark, C.P.(2012). Multi-resolution estimation of lidar-DTM surface flow metrics to identify characteristic topographic length scales, EP13C-0859: AGU Fall meeting 2012. Stark, C. P., & Stark, G. J. (2001). A channelization model of landscape evolution. American Journal of Science, 301(4-5), 486-512. Tucker, G. E., Catani, F., Rinaldo, A., & Bras, R. L. (2001). Statistical analysis of drainage density from digital terrain data. Geomorphology, 36(3), 187-202.

Low-frequency, self-sustained oscillations in inductively coupled plasmas used for optical pumping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coffer, J.; Encalada, N.; Huang, M.

We have investigated very low frequency, on the order of one hertz, self-pulsing in alkali-metal inductively-coupled plasmas (i.e., rf-discharge lamps). This self-pulsing has the potential to significantly vary signal-to-noise ratios and (via the ac-Stark shift) resonant frequencies in optically pumped atomic clocks and magnetometers (e.g., the atomic clocks now flying on GPS and Galileo global navigation system satellites). The phenomenon arises from a nonlinear interaction between the atomic physics of radiation trapping and the plasma's electrical nature. To explain the effect, we have developed an evaporation/condensation theory (EC theory) of the self-pulsing phenomenon.

Lineshape-asymmetry elimination in weak atomic transitions driven by an intense standing wave field

NASA Astrophysics Data System (ADS)

Antypas, Dionysios; Fabricant, Anne; Budker, Dmitry

2018-05-01

Owing to the ac-Stark effect, the lineshape of a weak optical transition in an atomic beam can become significantly distorted, when driven by an intense standing wave field. We use an Yb atomic beam to study the lineshape of the 6s2 1S0 -> 5d6s 3D1 transition, which is excited with light circulating in a Fabry-Perot resonator. We demonstrate two methods to avoid the distortion of the transition profile. Of these, one relies on the operation of the resonator in multiple longitudinal modes, and the other in multiple transverse modes.

Terahertz Optical Gain Based on Intersubband Transitions in Optically-Pumped Semiconductor Quantum Wells: Coherent Pumped-Probe Interactions

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Ning, Cun-Zheng

1999-01-01

Terahertz optical gain due to intersubband transitions in optically-pumped semiconductor quantum wells (QW's) is calculated nonperturbatively. We solve the pump- field-induced nonequilibrium distribution function for each subband of the QW system from a set of rate equations that include both intrasubband and intersubband relaxation processes. The gain arising from population inversion and stimulated Raman processes is calculated in a unified manner. We show that the coherent pump and signal wave interactions contribute significantly to the THz gain. Because of the optical Stark effect and pump-induced population redistribution, optical gain saturation at larger pump intensities is predicted.

Electric-Field Sensing with a Scanning Fiber-Coupled Quantum Dot

NASA Astrophysics Data System (ADS)

Cadeddu, D.; Munsch, M.; Rossi, N.; Gérard, J.-M.; Claudon, J.; Warburton, R. J.; Poggio, M.

2017-09-01

We demonstrate the application of a fiber-coupled quantum dot (QD) in a tip as a scanning probe for electric-field imaging. We map the out-of-plane component of the electric field induced by a pair of electrodes by the measurement of the quantum-confined Stark effect induced on a QD spectral line. Our results are in agreement with finite-element simulations of the experiment. Furthermore, we present results from analytic calculations and simulations which are relevant to any electric-field sensor embedded in a dielectric tip. In particular, we highlight the impact of the tip geometry on both the resolution and sensitivity.

Anomalous broadening and shift of emission lines in filaments

NASA Astrophysics Data System (ADS)

Ilyin, A. A.; Golik, S. S.; Shmirko, K. A.; Mayor, A. Yu.; Proschenko, D. Yu.

2017-11-01

The temporal evolution of width and shift of N I 746.8 and O I 777.4 nm lines is investigated in filament plasma produced by tightly focused femtosecond laser pulse (0.9 mJ, 48 fs). Nitrogen line shift is determined by joint action of electron impact shift and far-off resonance AC Stark effect. Intensive (I 1010 W/cm2 ) electric field of ASE and postpulses result in possible LS coupling break for O I 3p 5P level and generation of Rabi sidebands. The blue-shifted main femtosecond pulse and Rabi sideband cause the stimulated emission of N21+ system.

The effect of surface topography on the micellisation of hexadecyltrimethylammonium chloride at the silicon-aqueous interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darkins, Robert; Sushko, Maria L.; Liu, Jun

2015-02-11

Amphiphilic aggregation at solid-liquid interfaces can generate mesostructured micelles that can serve as soft templates. In this study we have simulated the self-assembly of hexadecyltrimethylammonium chloride (C16TAC) surfactants at the Si(100)- and Si(111)-aqueous interfaces. The surfactants are found to form semicylindrical micelles on Si(100) but hemispherical micelles on Si(111). This difference in micelle structure is shown to be a consequence of the starkly different surface topographies that result from the reconstruction of the two silicon surfaces. This reveals that micelle structure can be governed by epitaxial matching even with non-polar substrates.

Psychology: Teacher Supplement.

ERIC Educational Resources Information Center

Stark, Rebecca

This supplement provides teachers with tests, quizzes, answers to questions in the text, and general teaching information for using the student text, "Psychology," by Rebecca Stark. Quizzes included are on the topics of human development; the nervous system; the brain; cognitive development; sensation and perception; conditioning; learning;…

Coastal Modeling System: Dredging Module

DTIC Science & Technology

2016-06-01

nonuniform sediments, spatially variable placement thicknesses or depths, and a user-friendly interface within the SMS. ERDC/CHL CHETN-I-90 June...and W. Wu. 2011. Nonuniform sediment transport modeling and Grays Harbor, WA. In Proceedings of the Coastal Sediments’11. Jacksonville, FL. Stark, J

Invasive forstliche schad-organismen in Nordamerika

Treesearch

Christopher J. Fettig; Horst E.  Delb

2017-01-01

In Nordamerika sind Wälder infolge von Einwandernden, internationalem Handel und Tourismus traditionell stark von Einschleppungen gebietsfremder invasiver Schadorganismen betroffen. Infolge von Globalisierung und Klimawandel gibt es aufgrund der Ähnlichkeiten von Klima, Flora und Fauna zwischen Europa und Nordamerika viele Parallelen.

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

NASA Astrophysics Data System (ADS)

Zagonel, L. F.; Tizei, L. H. G.; Vitiello, G. Z.; Jacopin, G.; Rigutti, L.; Tchernycheva, M.; Julien, F. H.; Songmuang, R.; Ostasevicius, T.; de la Peña, F.; Ducati, C.; Midgley, P. A.; Kociak, M.

2016-05-01

We report on a detailed study of the intensity dependent optical properties of individual GaN/AlN quantum disks (QDisks) embedded into GaN nanowires (NW). The structural and optical properties of the QDisks were probed by high spatial resolution cathodoluminescence (CL) in a scanning transmission electron microscope (STEM). By exciting the QDisks with a nanometric electron beam at currents spanning over three orders of magnitude, strong nonlinearities (energy shifts) in the light emission are observed. In particular, we find that the amount of energy shift depends on the emission rate and on the QDisk morphology (size, position along the NW and shell thickness). For thick QDisks (>4 nm), the QDisk emission energy is observed to blueshift with the increase of the emission intensity. This is interpreted as a consequence of the increase of carriers density excited by the incident electron beam inside the QDisks, which screens the internal electric field and thus reduces the quantum confined Stark effect (QCSE) present in these QDisks. For thinner QDisks (<3 nm ), the blueshift is almost absent in agreement with the negligible QCSE at such sizes. For QDisks of intermediate sizes there exists a current threshold above which the energy shifts, marking the transition from unscreened to partially screened QCSE. From the threshold value we estimate the lifetime in the unscreened regime. These observations suggest that, counterintuitively, electrons of high energy can behave ultimately as single electron-hole pair generators. In addition, when we increase the current from 1 to 10 pA the light emission efficiency drops by more than one order of magnitude. This reduction of the emission efficiency is a manifestation of the "efficiency droop" as observed in nitride-based 2D light emitting diodes, a phenomenon tentatively attributed to the Auger effect.

Self-compensation of thermal lens in high-power diode pumped solid-state lasers

NASA Astrophysics Data System (ADS)

Wang, Xiao-Jun

2010-02-01

We present a comprehensive model to describe the optic-thermal coupling in the diode pumped solid-state lasers (DPSSL). The thermal transition of particles at the upper laser level leads the heat-generation of laser crystals to depend on shape of the laser beam, while the laser field is also influenced by the temperature because of the thermal excitation of doped particles among various Stark levels. These effects, together with the usual thermal-optic effect that induces a fluctuation of the refraction index by an inhomogeneous temperature distribution, cause a complicated coupling between the laser field and the temperature field. We show that the optic-thermal coupling plays an important role in high-power DPSSL with larger size beam. That effect may yield a self-compensation for the thermal lens and improve the beam quality.

Training future chefs at Opryland.

PubMed

1998-08-01

Dina Starks is the culinary apprentice coordinator at Opryland Hotel Convention Center in Nashville, Tenn. Her apprentices have the unique opportunity to practice the culinary arts at the largest hotel convention center in the world, in a setting that has 15 restaurants and nearly 3,000 rooms.

Field Test of Route Planning Software for Lunar Polar Missions

NASA Astrophysics Data System (ADS)

Horchler, A. D.; Cunningham, C.; Jones, H. L.; Arnett, D.; Fang, E.; Amoroso, E.; Otten, N.; Kitchell, F.; Holst, I.; Rock, G.; Whittaker, W.

2017-10-01

A novel field test paradigm has been developed to demonstrate and validate route planning software in the stark low-angled light and sweeping shadows a rover would experience at the poles of the Moon. Software, ConOps, and test results are presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, J.E.; Adams, R.; Carlson, A.L.

Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shiftmore » and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.« less

Directed Field Ionization: A Genetic Algorithm for Evolving Electric Field Pulses

NASA Astrophysics Data System (ADS)

Kang, Xinyue; Rowley, Zoe A.; Carroll, Thomas J.; Noel, Michael W.

2017-04-01

When an ionizing electric field pulse is applied to a Rydberg atom, the electron's amplitude traverses many avoided crossings among the Stark levels as the field increases. The resulting superposition determines the shape of the time resolved field ionization spectrum at a detector. An engineered electric field pulse that sweeps back and forth through avoided crossings can control the phase evolution so as to determine the electron's path through the Stark map. In the region of n = 35 in rubidium there are hundreds of potential avoided crossings; this yields a large space of possible pulses. We use a genetic algorithm to search this space and evolve electric field pulses to direct the ionization of the Rydberg electron in rubidium. We present the algorithm along with a comparison of simulated and experimental results. This work was supported by the National Science Foundation under Grants No. 1607335 and No. 1607377 and used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number OCI-1053575.

Shock-tube studies of atomic silicon emission in the spectral range 180 to 300 nm. [environment simulation for Jupiter probes

NASA Technical Reports Server (NTRS)

Prakash, S. G.; Park, C.

1978-01-01

Emission spectroscopy of shock-heated atomic silicon was performed in the spectral range 180 to 300 nm, in an environment simulating the ablation layer expected around a Jovian entry probe with a silica heat shield. From the spectra obtained at temperatures from 6000 to 10,000 K and electron number densities from 1 quadrillion to 100 quadrillion per cu cm, the Lorentzian line-widths were determined. The results showed that silicon lines are broadened significantly by both electrons (Stark broadening) and hydrogen atoms (Van der Waals broadening), and the combined line-widths are much larger than previously assumed. From the data, the Stark and the Van der Waals line-widths were determined for 34 silicon lines. Radiative transport through a typical shock layer was computed using the new line-width data. The computations showed that silicon emission in the hot region is large, but it is mostly absorbed in the colder region adjacent to the wall.

A synthetic diagnostic for beam emission spectroscopy in the helically symmetric experiment stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobbins, T. J., E-mail: tdobbins@wisc.edu; Kumar, S. T. A.; Anderson, D. T.

The Helically Symmetric Experiment (HSX) has a number of active spectroscopy diagnostics. Due to the relatively large beam width compared to the plasma minor radius, it is difficult to achieve good spatial resolution at the core of the HSX plasma. This is due to the fact that the optical sightline cuts through many flux surfaces with varying field vectors within the beam. In order to compare the experimental results with theoretical models it is important to accurately model the beam width effects. A synthetic diagnostic has been developed for this purpose. This synthetic diagnostic calculates the effect of spot sizemore » and beam width on the measurements of quantities of interest, including radial electric field, flow velocity, and Stark polarization.« less

A synthetic diagnostic for beam emission spectroscopy in the helically symmetric experiment stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobbins, T. J.; Kumar, S. T. A.; Anderson, D. T.

The Helically Symmetric Experiment (HSX) has a number of active spectroscopy diagnostics. Due to the relatively large beam width compared to the plasma minor radius, it is difficult to achieve good spatial resolution at the core of the HSX plasma. This is due to the fact that the optical sightline cuts through many flux surfaces with varying field vectors within the beam. It is important to accurately model the beam width effects in order to compare the experimental results with theoretical models. We've developed a synthetic diagnostic for this purpose. This synthetic diagnostic calculates the effect of spot size andmore » beam width on the measurements of quantities of interest, including radial electric field, flow velocity, and Stark polarization.« less

A synthetic diagnostic for beam emission spectroscopy in the helically symmetric experiment stellarator

DOE PAGES

Dobbins, T. J.; Kumar, S. T. A.; Anderson, D. T.

2016-08-03

The Helically Symmetric Experiment (HSX) has a number of active spectroscopy diagnostics. Due to the relatively large beam width compared to the plasma minor radius, it is difficult to achieve good spatial resolution at the core of the HSX plasma. This is due to the fact that the optical sightline cuts through many flux surfaces with varying field vectors within the beam. It is important to accurately model the beam width effects in order to compare the experimental results with theoretical models. We've developed a synthetic diagnostic for this purpose. This synthetic diagnostic calculates the effect of spot size andmore » beam width on the measurements of quantities of interest, including radial electric field, flow velocity, and Stark polarization.« less

[Study of the effect of heat source separation distance on plasma physical properties in laser-pulsed GMAW hybrid welding based on spectral diagnosis technique].

PubMed

Liao, Wei; Hua, Xue-Ming; Zhang, Wang; Li, Fang

2014-05-01

In the present paper, the authors calculated the plasma's peak electron temperatures under different heat source separation distance in laser- pulse GMAW hybrid welding based on Boltzmann spectrometry. Plasma's peak electron densities under the corresponding conditions were also calculated by using the Stark width of the plasma spectrum. Combined with high-speed photography, the effect of heat source separation distance on electron temperature and electron density was studied. The results show that with the increase in heat source separation distance, the electron temperatures and electron densities of laser plasma did not changed significantly. However, the electron temperatures of are plasma decreased, and the electron densities of are plasma first increased and then decreased.

Comprehensive analysis of the optical Kerr coefficient of graphene

DOE PAGES

Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo

2016-08-25

We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition,more » self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.« less

Quality Teaching: Means for Its Enhancement?

ERIC Educational Resources Information Center

Buchanan, John

2011-01-01

The pursuit of enhancing quality in tertiary education and educators is noble. Increasingly, however, universities are resorting to stark, reductionist representations of educational quality, such as decontextualised mean figures generated by student surveys, to measure and report on this. This paper questions the validity and reliability of such…

Using archived ITS data for sensitivity analyses in the estimation of mobile source emissions

DOT National Transportation Integrated Search

2000-12-01

The study described in this paper demonstrates the use of archived ITS data from San Antonio's TransGuide traffic management center (TMC) for sensitivity analyses in the estimation of on-road mobile source emissions. Because of the stark comparison b...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kidd, G.

This short article describes how Mycogen, which acquired Agrigenetics/Lubrizol`s seed industry in the 1993, finally turned a profit after drastic sales and brand consolidation updates. Lubrizol is a supplier of lubricant additives to the energy industry. Until Mycogen turned it around, Agrigenetics stood as a stark example of the unfulfilled dreams plaguing agbiotech.

Churchill: The Making of a Grand Strategist

DTIC Science & Technology

1990-01-01

training and squeezed to the last drop by relentless war propaganda, the military instruments of that will were as useless as empty suits of armour ...product, Churchill had always had an instinctive sympathy for the underdog . Consequently. he never painted the enemies in his Imperial conflicts in stark

Can we make a new deal? Entitlement reform sounds alluring, but the reality is stark.

PubMed

Wagner, L

1995-01-20

After simmering for more than a decade, the Great Entitlement Debate promises to dominate the 1995 congressional agenda. But lost amid a tangle of conflicting parochial interests, voter confusion and searing partisan rhetoric are some harsh truths about our options.

The Children Speak

ERIC Educational Resources Information Center

Jacobs, Erin

2008-01-01

Public spaces that promote play and discovery are popping up everywhere from metropolitan cities to rural and suburban settings. Playgrounds such as David Rockwell's Imagination Playground in New York City and the Memorial Park Playground in Wilsonville, Oregon, present a stark contrast to the steel and plastic structures found at fast-food…

Using archived ITS data for sensitivity analysis in the estimation of mobile source emissions

DOT National Transportation Integrated Search

2000-12-01

The study described in this paper demonstrates the use of archived ITS data from San Antonio's TransGuide traffic management center (TMC) for sensitivity analyses in the estimation of on-road mobile source emissions. Because of the stark comparison b...

The Ink of Citizenship

ERIC Educational Resources Information Center

Patel, Leigh

2017-01-01

Nations actively write themselves onto human bodies. They etch and scratch their borders onto human flesh with figurative, often contradictory, ink that delivers stark material impact. The impacts hold their greatest force in metering the hinged consequences of contingent citizenship for some and unfettered citizenship for a few others. In this…

Microbial ecology: new insights into the great wide-open culture independent sea

USDA-ARS?s Scientific Manuscript database

Microbial communities are the basis for most, if not all, biochemical or biogeochemical functions in the environment. These environments are vastly different with respect to matrix, function, and biodiversity, and as such, present minute to stark differences in their respective microbial communities...

75 FR 11900 - North Dakota; Major Disaster and Related Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-12

..., Billings, Bowman, Burke, Dickey, Dunn, Emmons, Golden Valley, Grant, Hettinger, Logan, McIntosh, McKenzie, Mercer, Morton, Mountrail, Oliver, Ransom, Renville, Sioux, Slope, Stark, Steele, and Walsh Counties and the Standing Rock Indian Reservation for Public Assistance. All counties and Tribes within the State...

Minimal Interventions in the Teaching of Mathematics

ERIC Educational Resources Information Center

Foster, Colin

2014-01-01

This paper addresses ways in which mathematics pedagogy can benefit from insights gleaned from counselling. Person-centred counselling stresses the value of genuineness, warm empathetic listening and minimal intervention to support people in solving their own problems and developing increased autonomy. Such an approach contrasts starkly with the…

78 FR 42929 - Notice of Intent To Grant Exclusive License

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-18

... DEPARTMENT OF AGRICULTURE Agricultural Research Service Notice of Intent To Grant Exclusive... given that the U.S. Department of Agriculture, Agricultural Research Service, intends to grant to Stark... on or before August 19, 2013. ADDRESSES: Send comments to: USDA, ARS, Office of Technology Transfer...

75 FR 25878 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-10

...--Falkner--Baldauf House, 3260 Center Rd., Avon, 10000278 Stark County Saint Joseph's Roman Catholic Church... VIRGINIA Martinsville Independent City Martinsville Novelty Corporation Factory, 900 Rives Rd., Martinsville (Independent City), 10000282 Newport News Independent City Noland Company Building, 2600 Warwick...

SPARK RttT: Year One Fidelity and Implementation

ERIC Educational Resources Information Center

Rochford, Joseph A.; O'Neill, Adrienne; Gelb, Adele; Ross, Kimberly

2014-01-01

Developed in 2003 by the Sisters of Charity Foundation of Canton with a grant from the Kellogg Foundation, "Supporting Partnerships to Assure Ready Kids" ("SPARK Ohio") is a family-centered kindergarten readiness program that works with families, schools, and the community. From its initial sites in Stark County, "SPARK…

Solving America's Math Problem

ERIC Educational Resources Information Center

Vigdor, Jacob

2013-01-01

Concern about students' math achievement is nothing new, and debates about the mathematical training of the nation's youth date back a century or more. In the early 20th century, American high-school students were starkly divided, with rigorous math courses restricted to a college-bound elite. At midcentury, the "new math" movement sought,…

Higher Education Leadership Graduate Program Development

ERIC Educational Resources Information Center

Freeman, Sydney, Jr.; Chambers, Crystal Renée; Newton, Rochelle

2016-01-01

Graduate programs in higher education administration and leadership have sought to equip students with the knowledge, skills, and competencies for higher education leadership; that is, to prepare globally minded leaders who can navigate the internal and external demands of, and for, higher education. With the use of the Lattuca and Stark model of…

Asperger Syndrome: A Primer for Behavioral Interventionists

ERIC Educational Resources Information Center

Polirstok, Susan Rovet; Houghteling, Lawrence

2006-01-01

Children and adolescents with Asperger Syndrome are intellectually capable, rigid and often obsessive, adhere to stereotypic routines, demonstrate difficulties with pragmatic language and characteristically lack social skills. While the extent of these behaviors may wax and wane and vary by individual, they are in stark contrast with the high…

Commons versus Open Access: The Collapse of Canada's East Coast Fishery.

ERIC Educational Resources Information Center

Matthews, David Ralph

1995-01-01

The consequences of management espousal of the "Tragedy of the Commons" theory has been starkly illustrated by the crash in cod stocks off Canada's east coast. The voices of fishers from several different coastal communities testify to the inadequacy of Canadian government fisheries policy. (LZ)

Running in Hard Times

ERIC Educational Resources Information Center

Berry, John N., III

2009-01-01

Roberta Stevens and Kent Oliver are campaigning hard for the presidency of the American Library Association (ALA). Stevens is outreach projects and partnerships officer at the Library of Congress. Oliver is executive director of the Stark County District Library in Canton, Ohio. They have debated, discussed, and posted web sites, Facebook pages,…

Strategic Partnerships in Fuel Cell Development

ERIC Educational Resources Information Center

Diab, Dorey

2006-01-01

This article describes how forming strategic alliances with universities, emerging technology companies, the state of Ohio, the federal government, and the National Science Foundation, has enabled Stark State College to develop a $5.5 million Fuel Cell Prototyping Center and establish a Fuel Cell Technology program to promote economic development…

The Perfect Storm: The Religious Apocalyptic Imagination and Personal Disaster Preparedness

DTIC Science & Technology

2011-12-01

Explanation, research and models. Psychology: A quarterly journal of human behavior 16(23-36), pp. 24– 36. Glock, C. Y . & Stark, R. (1965). Religion ...Danger Control, Problem-Focused Coping, Emotion-Focused Coping, Millennialism , Premillennial, Postmillennial, Amillennial. 15. NUMBER OF PAGES...11 4. Religion /Religiosity ............................................................................12 5

Maskless Lithography Using Surface Plasmon Enhanced Illumination

DTIC Science & Technology

2007-04-30

Dale Larson Figure 1. Nanohole array probes exhibiting extraordinary optical transmission of light with a high degree of collimation. Left: a bull’s...Technol. B 22, 3552-3556 (2004). 2. Stark, P., Halleck, A. E. & Larson, D. N. Short order nanohole arrays in metals for highly sensitive probing of local

78 FR 36010 - Illinois Disaster #IL-00042

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-14

..., Mason, Mchenry, Mercer, Ogle, Pike, Putnam, Rock Island, Stark, Warren, Woodford. The Interest Rates are... AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Illinois (FEMA- 4116-DR), dated 06...

The Real Language Crisis

ERIC Educational Resources Information Center

Berman, Russell A.

2011-01-01

Those in America are confronting a stark alternative: either open themselves to an appreciation of human plurality and the diversity of cultures around the globe or limit themselves to a narrowly normative culture. Will American schools and colleges provide students with opportunities to learn to understand other voices, or will the educational…

Deliberate Imagery Practice: The Reliability of Using a Retrospective Recall Methodology

ERIC Educational Resources Information Center

Cumming, Jennifer; Hall, Craig; Starkes, Janet L.

2005-01-01

This study examined the reliability of a retrospective recall methodology for providing evidence of deliberate imagery practice. A secondary purpose was to determine which imagery activities constituted the sport-specific definition of deliberate practice (Starkes, Deakin, Allard, Hodges, & Hayes, 1996). Ninety-three Canadian athletes from one…

2 CFR Appendix Viii to Part 200 - Nonprofit Organizations Exempted From Subpart E-Cost Principles of Part 200

Code of Federal Regulations, 2014 CFR

2014-01-01

..., Headquartered in Columbus, Ohio 7. Brookhaven National Laboratory, Upton, New York 8. Charles Stark Draper... 19. National Radiological Astronomy Observatory, Green Bank, West Virginia 20. National Renewable Energy Laboratory, Golden, Colorado 21. Oak Ridge Associated Universities, Oak Ridge, Tennessee 22. Rand...

Critiquing Canada's Research Culture: Social, Cultural, and Political Restraints on Women's University Careers

ERIC Educational Resources Information Center

Robbins, Wendy J.

2012-01-01

Women are "starkly underrepresented" as researchers worldwide ("The World's Women 2010," 68). In Canada, for example, men hold over three-quarters of full professorships and top research positions. Dozens of interconnected factors restrain women's research careers. These include "upstream" factors, such as gender,…

Fire Power

ERIC Educational Resources Information Center

Denker, Deb; West, Lee

2009-01-01

For education administrators, campus fires are not only a distressing loss, but also a stark reminder that a campus faces risks that require special vigilance. In many ways, campuses resemble small communities, with areas for living, working and relaxing. A residence hall fire may raise the specter of careless youth, often with the complication of…

Writing for Change: Engaging Juveniles through Alternative Literacy Education

ERIC Educational Resources Information Center

Jacobi, Tobi

2008-01-01

Research on incarceration and educational access continues to reveal the stark reality for many adjudicated youth: without access to educational opportunities recidivism is probable. Yet conventional methods of teaching critical reading, writing, and thinking skills are not always successful for juveniles who have found little success (or hope) in…

Novice Career Changers Weather the Classroom Weather

ERIC Educational Resources Information Center

Gifford, James; Snyder, Mary Grace; Cuddapah, Jennifer Locraft

2013-01-01

A close look at one professional's career change into teaching illustrates unique challenges and qualities, showing in stark relief what makes the induction smoother and the experience more successful. This article presents the story of a novice career changer teacher that illustrates their unique problems and dispositions, as well as…

Drawing Attention to the "Green Side of Life"

ERIC Educational Resources Information Center

Nyberg, Eva; Sanders, Dawn

2014-01-01

The notion of plant-blindness, the inability of humans to notice plants in their environment, has been much examined. Similarly, plant scientists have criticised the seemingly zoocentric focus of a biological education, which appears to neglect plants. Furthermore, there are stark contrasts between the active plant behaviours evidenced in current…

"Testimonio" as Praxis for a Reimagined Journalism Model and Pedagogy

ERIC Educational Resources Information Center

Aleman, Sonya M.

2012-01-01

The differences between journalism and "testimonio" are stark: One is premised on verifiable truths (Mindich, 1998), while the other treats truth as fractional, relative, subjective, and communal (Arias, 2001; Binford, 2001; Delgado Bernal, 2006a; Latina Feminist Group, 2001). Nonetheless, Chicana/o journalism students developing a…

Naval Coalition Building with the GCC States

DTIC Science & Technology

2002-12-01

1987 the USS Stark was attacked by an Iraq F-1 and A U.S. Navy Helicopter had attacked an Iranian warship, Iran Ajr while it was laying mines in the...Interests,” National Interests in International Society. (Ithaca, N.Y., Cornell University Press: 1996) 4. 60 Empire and “pax Britannia

USING ECONOMIC ANALYSIS TO VALUE WATER REMEDIATION: AN APPLICATION TO THE CHEAT RIVER WATERSHED IN WEST VIRGINIA

EPA Science Inventory

Inherent in any decision to allocate resources is the constraint imposed by a limited budget. In small communities, particularly in rural areas, this often means stark tradeoffs among major public projects (schools, roads, water treatment). When dealing with management options ...

Viewpoint: The Challenge of Creating Engaged Public Research Universities

ERIC Educational Resources Information Center

Cherwitz, Rick

2010-01-01

The quest to create engaged public research universities requires academe to confront a stark reality: inflexible administrative structures, historically embedded practices, status-quo thinking, and inertia. Until these obstacles are overcome, the retreat from public life will not be arrested. In this article, the author provides a sample of the…

Demonstration of Tar Removal from Paving Equipment and Ground Vehicles

DTIC Science & Technology

2011-05-12

IL 61822 Suresh Naik and Michael Starks, Red River Army Depot, Texarkana , TX Pam Khabra, TACOM/TARDEC, Warren, MI Malcolm E. McLeod, US Army...maintenance facilities of the Red River Army Depot (RRAD), Texarkana , TX. OBJECTIVE BUILDING STRONG®7 APPROACH 1. Develop criteria to rank commercial

Toward 2025 in the Massillon City Schools

ERIC Educational Resources Information Center

O'Neill, Adrienne

2007-01-01

Fred Blosser, Superintendent of Massillon City Schools, asked Adrienne O'Neill, Ed.D., President of the Stark Education Partnership, to conduct a study of curriculum, instruction, and professional development in the Massillon City Schools. A white paper was requested that would contain a critical analysis of curriculum, instruction, professional…

77 FR 59041 - National POW/MIA Recognition Day, 2012

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-25

... September 21, 2012, the stark black and white banner symbolizing America's Missing in Action and Prisoners... the President of the United States of America A Proclamation For more than two centuries, Americans have bravely served our Nation as members of our Armed Forces. Many have made profound sacrifices to...

78 FR 5734 - Suspension of Community Eligibility

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-28

..., Reg; February 20, 2013, Susp. Stark, Town of, Coos County 330038 March 30, 1976, ......do Do. Emerg..., Susp. Dummer, Town of, Coos 330201 July 20, 1993, ......do Do. County. Emerg; March 1, 1995, Reg..., 1995, Reg; February 20, 2013, Susp. Gorham, Town of, Coos 330032 July 24, 1975, ......do Do. County...

Essential Web Sites to Research the Globalization Process

ERIC Educational Resources Information Center

Scott, Thomas J.; O'Sullivan, Michael

2002-01-01

The terrorist attacks of September 11, 2001, brought a stark reality to social studies classrooms throughout the United States. Globalism and the expansion of world trade relations created optimism about enhanced cultural understanding, peace, and economic prosperity. However, it is clear that globalization also has a dark side. Suddenly…

Border Crossing Knowledge Systems: A PNG Teacher's Autoethnography

ERIC Educational Resources Information Center

Reta, Medi

2010-01-01

Narratives have always been integral to Indigenous knowledge transfer. In this autoethnography the author shares her border crossings between her Indigenous knowledge systems and the often dominant Western knowledge system. Pertinent to these experiences are the stark contrasts that exist between the two knowledge systems and their educational…

How Sommerfeld extended Bohr's model of the atom (1913-1916)

NASA Astrophysics Data System (ADS)

Eckert, Michael

2014-04-01

Sommerfeld's extension of Bohr's atomic model was motivated by the quest for a theory of the Zeeman and Stark effects. The crucial idea was that a spectral line is made up of coinciding frequencies which are decomposed in an applied field. In October 1914 Johannes Stark had published the results of his experimental investigation on the splitting of spectral lines in hydrogen (Balmer lines) in electric fields, which showed that the frequency of each Balmer line becomes decomposed into a multiplet of frequencies. The number of lines in such a decomposition grows with the index of the line in the Balmer series. Sommerfeld concluded from this observation that the quantization in Bohr's model had to be altered in order to allow for such decompositions. He outlined this idea in a lecture in winter 1914/15, but did not publish it. The First World War further delayed its elaboration. When Bohr published new results in autumn 1915, Sommerfeld finally developed his theory in a provisional form in two memoirs which he presented in December 1915 and January 1916 to the Bavarian Academy of Science. In July 1916 he published the refined version in the Annalen der Physik. The focus here is on the preliminary Academy memoirs whose rudimentary form is better suited for a historical approach to Sommerfeld's atomic theory than the finished Annalen-paper. This introductory essay reconstructs the historical context (mainly based on Sommerfeld's correspondence). It will become clear that the extension of Bohr's model did not emerge in a singular stroke of genius but resulted from an evolving process.

Stark-assisted population control of coherent CS(2) 4f and 5p Rydberg wave packets studied by femtosecond time-resolved photoelectron spectroscopy.

PubMed

Knappenberger, Kenneth L; Lerch, Eliza-Beth W; Wen, Patrick; Leone, Stephen R

2007-09-28

A two-color (3+1(')) pump-probe scheme is employed to investigate Rydberg wave packet dynamics in carbon disulfide (CS(2) (*)). The state superpositions are created within the 4f and 5p Rydberg manifolds by three photons of the 400 nm pump pulse, and their temporal evolution is monitored with femtosecond time-resolved photoelectron spectroscopy using an 800 nm ionizing probe pulse. The coherent behavior of the non-stationary superpositions are observed through wavepacket revivals upon ionization to either the upper (12) or lower (32) spin-orbit components of CS(2) (+). The results show clearly that the composition of the wavepacket can be efficiently controlled by the power density of the excitation pulse over a range from 500 GWcm(2) to 10 TWcm(2). The results are consistent with the anticipated ac-Stark shift for 400 nm light and demonstrate an effective method for population control in molecular systems. Moreover, it is shown that Rydberg wavepackets can be formed in CS(2) with excitation power densities up to 10 TWcm(2) without significant fragmentation. The exponential 1e population decay (T(1)) of specific excited Rydberg states are recovered by analysis of the coherent part of the signal. The dissociation lifetimes of these states are typically 1.5 ps. However, a region exhibiting a more rapid decay ( approximately 800 fs) is observed for states residing in the energy range of 74 450-74 550 cm(-1), suggestive of an enhanced surface crossing in this region.

Asymmetric molecular-orbital tomography by manipulating electron trajectories

NASA Astrophysics Data System (ADS)

Wang, Bincheng; Zhang, Qingbin; Zhu, Xiaosong; Lan, Pengfei; Rezvani, Seyed Ali; Lu, Peixiang

2017-11-01

We present a scheme for tomographic imaging of asymmetric molecular orbital based on high-order harmonic generation with a two-color orthogonally polarized multicycle laser field. With the two-dimensional manipulation of the electron trajectories, the electrons can recollide with the target molecule from two noncollinear directions, and then the dipole moment generated from the single direction can be obtained to reconstructed the asymmetric molecular orbital. The recollision is independent from the molecular structure and the angular dependence of the ionization rate in the external field. For this reason, this scheme can avoid the negative effects arising from the modification of the angle-dependent ionization rate induced by Stark shift and be applied to various molecules.

On the shift of the electroluminescence spectra of In{sub x}Ga{sub 1−x}N/GaN structures with various indium contents and various substrate materials caused by the stark effect and mechanical stresses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veleschuk, V. P., E-mail: vvvit@ukr.nd; Vlasenko, A. I.; Kisselyuk, M. P.

2015-08-15

The shift between the maxima of the electroluminescence spectra of In{sub x}Ga{sub 1−x}N/GaN structures is measured at forward and reverse bias depending on the indium content x in the quantum well and on the substrate material (SiC, AuSn/Si, and Al{sub 2}O{sub 3}). It is established that this shift increases as the indium concentration in the In{sub x}Ga{sub 1−x}N layer and mechanical stresses from the substrate increase.

Electro-optical resonance modulation of vertical-cavity surface-emitting lasers.

PubMed

Germann, Tim David; Hofmann, Werner; Nadtochiy, Alexey M; Schulze, Jan-Hindrik; Mutig, Alex; Strittmatter, André; Bimberg, Dieter

2012-02-27

Optical and electrical investigations of vertical-cavity surface-emitting lasers (VCSEL) with a monolithically integrated electro-optical modulator (EOM) allow for a detailed physical understanding of this complex compound cavity laser system. The EOM VCSEL light output is investigated to identify optimal working points. An electro-optic resonance feature triggered by the quantum confined Stark effect is used to modulate individual VCSEL modes by more than 20 dB with an extremely small EOM voltage change of less than 100 mV. Spectral mode analysis reveals modulation of higher order modes and very low wavelength chirp of < 0.5 nm. Dynamic experiments and simulation predict an intrinsic bandwidth of the EOM VCSEL exceeding 50 GHz.

Single nanowire green InGaN/GaN light emitting diodes

NASA Astrophysics Data System (ADS)

Zhang, Guogang; Li, Ziyuan; Yuan, Xiaoming; Wang, Fan; Fu, Lan; Zhuang, Zhe; Ren, Fang-Fang; Liu, Bin; Zhang, Rong; Tan, Hark Hoe; Jagadish, Chennupati

2016-10-01

Single nanowire (NW) green InGaN/GaN light-emitting diodes (LEDs) were fabricated by top-down etching technology. The electroluminescence (EL) peak wavelength remains approximately constant with an increasing injection current in contrast to a standard planar LED, which suggests that the quantum-confined Stark effect is significantly reduced in the single NW device. The strain relaxation mechanism is studied in the single NW LED using Raman scattering analysis. As compared to its planar counterpart, the EL peak of the NW LED shows a redshift, due to electric field redistribution as a result of changes in the cavity mode pattern after metallization. Our method has important implication for single NW optoelectronic device applications.

Observation of instability-induced current redistribution in a spherical-torus plasma.

PubMed

Menard, J E; Bell, R E; Gates, D A; Kaye, S M; LeBlanc, B P; Levinton, F M; Medley, S S; Sabbagh, S A; Stutman, D; Tritz, K; Yuh, H

2006-09-01

A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

Microwave spectrum and structure of bicyclo /1.1.1/ pentanone and comparison with several theoretical structures

NASA Technical Reports Server (NTRS)

Mcrae, Glenn A.; Cohen, Edward A.; Sponsler, Michael B.; Dougherty, Dennis A.

1986-01-01

The microwave spectra of five isotopic species of bicyclo (1.1.1) pentanone have been investigated. The rotational constants along with various centrifugal distortion constants for each species have been determined. From the rotational constants, a complete r(s) structure has been determined for the heavy atoms. Analysis of Stark effect measurements has shown the dipole moment to be along the a principal inertial axis with a magnitude of 3.164 (5) D. These results are compared with those obtained by four current theoretical methods: molecular mechanics (MM2), MNDO, and Hartree-Fock ab initio theory with STO-3G and 3-21G basis sets.

GaN-based light emitting diodes using p-type trench structure for improving internal quantum efficiency

NASA Astrophysics Data System (ADS)

Kim, Garam; Sun, Min-Chul; Kim, Jang Hyun; Park, Euyhwan; Park, Byung-Gook

2017-01-01

In order to improve the internal quantum efficiency of GaN-based LEDs, a LED structure featuring a p-type trench in the multi-quantum well (MQW) is proposed. This structure has effects on spreading holes into the MQW and reducing the quantum-confined stark effect (QCSE). In addition, two simple fabrication methods using electron-beam (e-beam) lithography or selective wet etching for manufacturing the p-type structure are also proposed. From the measurement results of the manufactured GaN-based LEDs, it is confirmed that the proposed structure using e-beam lithography or selective wet etching shows improved light output power compared to the conventional structure because of more uniform hole distribution. It is also confirmed that the proposed structure formed by e-beam lithography has a significant effect on strain relaxation and reduction in the QCSE from the electro-luminescence measurement.

Electrically tunable artificial gauge potential for polaritons

PubMed Central

Lim, Hyang-Tag; Togan, Emre; Kroner, Martin; Miguel-Sanchez, Javier; Imamoğlu, Atac

2017-01-01

Neutral particles subject to artificial gauge potentials can behave as charged particles in magnetic fields. This fascinating premise has led to demonstrations of one-way waveguides, topologically protected edge states and Landau levels for photons. In ultracold neutral atoms, effective gauge fields have allowed the emulation of matter under strong magnetic fields leading to realization of Harper-Hofstadter and Haldane models. Here we show that application of perpendicular electric and magnetic fields effects a tunable artificial gauge potential for two-dimensional microcavity exciton polaritons. For verification, we perform interferometric measurements of the associated phase accumulated during coherent polariton transport. Since the gauge potential originates from the magnetoelectric Stark effect, it can be realized for photons strongly coupled to excitations in any polarizable medium. Together with strong polariton–polariton interactions and engineered polariton lattices, artificial gauge fields could play a key role in investigation of non-equilibrium dynamics of strongly correlated photons. PMID:28230047

Redshift of the light emission from highly strained In0.3Ga0.7As/GaAs quantum wells by dipole δ doping

NASA Astrophysics Data System (ADS)

Fu, Y.; Wang, S.-M.; Wang, X.-D.; Larsson, A.

2005-08-01

We have studied theoretically the energy band structures and optical properties of highly strained dipole δ-doped In0.3Ga0.7As/GaAs single quantum wells. Including dopant diffusion effect, strain in the quantum well, spin-orbital interactions, and many-body effects, the self-consistent calculations of the eight-band k •p model and the Poisson equation show that the dipole δ doping induces an electric field across the In0.3Ga0.7As quantum well by the Stark effect so that both the interband transition energy and the wave-function overlap between the ground-state electrons and holes are reduced. Applying an external bias across the quantum well partially cancels the built-in electric field and reduces the wavelength redshift. The calculated material gain peak is close to the experimental lasing wavelength.

Stigma, discrimination, treatment effectiveness, and policy: public views about drug addiction and mental illness.

PubMed

Barry, Colleen L; McGinty, Emma E; Pescosolido, Bernice A; Goldman, Howard H

2014-10-01

Public attitudes about drug addiction and mental illness were compared. A Web-based national survey (N=709) was conducted to compare attitudes about stigma, discrimination, treatment effectiveness, and policy support in regard to drug addiction and mental illness. Respondents held significantly more negative views toward persons with drug addiction. More respondents were unwilling to have a person with drug addiction marry into their family or work closely with them. Respondents were more willing to accept discriminatory practices against persons with drug addiction, more skeptical about the effectiveness of treatments, and more likely to oppose policies aimed at helping them. Drug addiction is often treated as a subcategory of mental illness, and insurance plans group them together under the rubric of "behavioral health." Given starkly different public views about drug addiction and mental illness, advocates may need to adopt differing approaches to reducing stigma and advancing public policy.

Investigation of Kp- and Kd-atom formation and their collisional processes with hydrogen and deuterium targets by the classical-trajectory Monte Carlo method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raeisi, G. M.; Department of Physics, Shahrekord University, Shahrekord 115; Kalantari, S. Z.

The classical-trajectory Monte Carlo method has been used to study the capture of negative kaons by hydrogen and deuterium atoms; subsequently, the elastic scattering, Stark mixing, and Coulomb deexcitation cross sections of Kp and Kd atoms have been determined. The results for kaonic atom formation confirm the initial conditions that have been parametrically applied by most atomic cascade models. Our results show that Coulomb deexcitation in Kp and Kd atoms with {Delta}n>1 is important in addition to n=1. We have shown that the contribution of molecular structure effects to the cross sections of the collisional processes is larger than themore » isotopic effects of the targets. We have also compared our results with the semiclassical approaches.« less

The Academic Achievement of Elite Athletes at Australian Schools

ERIC Educational Resources Information Center

Georgakis, Steve; Evans, John Robert; Warwick, Leanne

2015-01-01

While sport and student-athletes have featured in the Australian education system since compulsory schooling, there has been no analysis to date of the link between academic achievement and elite student-athletes. However, this is in stark contrast to the United States of America (US), where student-athletes have been the subject of sustained…

Synthetic fuels development: earth-science considerations

USGS Publications Warehouse

Rickert, D. A.; Ulman, W.J.; Hampton, E.R.

1979-01-01

The current energy crisis is affecting the lives of all Americans. Continued increases in energy prices and frequent shortages are stark reminders of our growing dependence on foreign energy resources in today's energy-hungry world. A comprehensive national energy policy must consider a variety of energy resources, including synfuels, to meet future energy needs.

Even Superheroes Need Help

ERIC Educational Resources Information Center

Sussman, Mel

2018-01-01

It is not clear exactly when school leaders first started wearing an "S" on their chests and began defiantly uttering the phrase, "I can do it all myself!" But after days, weeks, months, or even years of racing wildly from task to task, many a superhero principal has come to the stark realization that nothing could be further…

A Coordinated Approach to Raising the Socio-Economic Status of Latinos in California.

ERIC Educational Resources Information Center

Lopez, Elias, Ed.; Puddefoot, Ginny, Ed.; Gandara, Patricia, Ed.

This report presents a collection of papers that focuses on a coordinated approach to raising the socioeconomic status of Hispanic Americans living in California. After presenting "The Need for a Coordinated Approach," the papers are: "Preschool Access" (Theresa Garcia, Sandra Gutierrez, and Giovanna Stark); "K-12…

78 FR 35309 - Illinois; Amendment No. 3 to Notice of a Major Disaster Declaration

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-12

..., Henderson, Kendall, Knox, Lake, LaSalle, Livingston, Marshall, Mason, McHenry, Pike, Rock Island, Stark, and... Declaration AGENCY: Federal Emergency Management Agency, DHS. ACTION: Notice. SUMMARY: This notice amends the notice of a major disaster declaration for the State of Illinois (FEMA-4116-DR), dated May 10, 2013, and...

78 FR 32412 - Illinois; Amendment No. 1 to Notice of a Major Disaster Declaration

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-30

... Island, Schuyler, Stark, Tazewell, and Woodford Counties for Individual Assistance. The following Catalog... Declaration AGENCY: Federal Emergency Management Agency, DHS. ACTION: Notice. SUMMARY: This notice amends the notice of a major disaster declaration for the State of Illinois (FEMA-4116-DR), dated May 10, 2013, and...

Clitics and Head-Movement as Intra-Syntactic Morphology

ERIC Educational Resources Information Center

DiGirolamo, Cara Masten

2017-01-01

This dissertation approaches the idea of lexical types such as word, clitic and affix from an oblique angle. Starting with Cardinaletti & Starke's (1999) diagnostics for the Weak Pronoun, I deconstruct the category of clitic, breaking it down into two binary qualities: the syntactic primitive of being linked to a head of a different basic…

California Deficit Clouds Picture for K-12 Funding

ERIC Educational Resources Information Center

Cavanagh, Sean

2011-01-01

Not long after he took office in January, California Governor Jerry Brown presented residents of his state with a simple, stark plan for correcting the state's massive budget imbalance. The Democrat called for making deep and painful cuts to programs across government, while sparing schools. To raise revenue, he proposed allowing the public to…

Transformative Teachers or Teachers to Be Transformed? The Cases of Bolivia and Timor-Leste

ERIC Educational Resources Information Center

Shah, Ritesh; Lopes Cardozo, Mieke T. A.

2016-01-01

Applying the Strategic Relational Approach, this paper analyses the circumstances behind and educators' strategies in response to education reforms in two nation-states undergoing socio-political transformation--Bolivia and Timor-Leste. Despite the starkly different histories and contemporary context of each nation, we suggest that transformation…

Sustainability: Perspectives of Students as Stakeholders in the Curriculum

ERIC Educational Resources Information Center

Hiser, Krista Karyn

2012-01-01

Institutions of higher education are increasingly engaged in sustainability efforts, both in classrooms and on the campus. Yet, little is known about what students really know and believe about sustainability issues. Using Lattuca and Stark's (2009) curricular frame and a single case study approach, this research explored student and non-student…

Rubber modified concrete (METRO RUMAC) Evaluation : N. Marine Drive in Portland, Oregon , S.E. Stark Street in Gresham, Oregon : construction report.

DOT National Transportation Integrated Search

1992-11-01

This report covers the construction in 1991 of two test pavements using asphalt modified crumb rubber form scrap tires. The pavements are on arterial roadways in the Portland, Oregon metropolitan area. : Both test pavements use a dense-graded rubber ...

Social Justice for the Advantaged: Freedom from Racial Equality Post-"Milliken"

ERIC Educational Resources Information Center

Horsford, Sonya Douglass

2016-01-01

Background/Context: In "Milliken v. Bradley" (1974), the U.S. Supreme Court deemed unconstitutional a metropolitan-wide desegregation plan in Detroit that sought to achieve racial balance in part by busing white suburban students to the city's majority black schools. In a stark departure from "Brown v. Board of Education of…

Monosodium Luminol for Improving Brain Function in Gulf War Illness

DTIC Science & Technology

2015-10-01

Jain et al., PLoS One, 7: e46340, 2012; McAvoy et al., Front Syst Neurosci , 9:120. eCollection 2015; Oomen et al., Wiley Interdiscip Rev Cogn Sci...2007; Yassa and Stark, Trends Neurosci , 34: 515-525). In this test, each rat successively explored two different sets of identical objects (object

A "Historical Problem"

ERIC Educational Resources Information Center

Ly, Phuong

2008-01-01

Women are absent from the top ranks at Southern Illinois University Carbondale, a stark contrast to the increase in gender parity at other schools. SIUC's chancellor, vice chancellors, provost and all 10 academic deans are men. Nationally, women made up at least a third of the vice presidents and provosts surveyed and 36 percent of deans,…

TÜV - Zertifizierungen in der Life Science Branche

NASA Astrophysics Data System (ADS)

Schaff, Peter; Gerbl-Rieger, Susanne; Kloth, Sabine; Schübel, Christian; Daxenberger, Andreas; Engler, Claus

Life Sciences [1] (Lebenswissenschaften) sind ein globales Innovationsfeld mit Anwendungen der Bio- und Medizinwissenschaften, der Pharma-, Chemie-, Kosmetik- und Lebensmittelindustrie. Diese Branche zeichnet sich durch eine stark interdisziplinäre Ausrichtung aus, mit Anwendung wissenschaftlicher Erkenntnisse und Einsatz von Ausgangsstoffen aus der modernen Biologie, Chemie und Humanmedizin sowie gezielter marktwirtschaftlich orientierter Arbeit.

Increasing Racial Diversity in the Teacher Workforce: One University's Approach

ERIC Educational Resources Information Center

Hrabowski,, Freeman A., III; Sanders, Mavis G.

2015-01-01

In 2014, for the first time in U.S. public schools, the percentage of Hispanic, African American, Asian, and other students of color exceeded the percentage of white students, creating a majority-minority system that reflects the mosaic of cultures, experiences, languages, and religions that characterize this nation. In stark contrast, an…

Formaldehyde monitor for automobile exhausts

NASA Technical Reports Server (NTRS)

Easley, W. C.

1973-01-01

Device makes use of microwave spectral absorption in low-Q resonant Stark cell, and indications are that ultimate sensitivity of instrument is within 100 parts per billion of formaldehyde. Microwave source is very small and requires only six-volt dc bias for operation. Coarse tuning is accomplished mechanically and fine tuning by adjusting dc-bias voltage.

Fixation-Dependent Memory for Natural Scenes: An Experimental Test of Scanpath Theory

ERIC Educational Resources Information Center

Foulsham, Tom; Kingstone, Alan

2013-01-01

Many modern theories propose that perceptual information is represented by the sensorimotor activity elicited by the original stimulus. Scanpath theory (Noton & Stark, 1971) predicts that reinstating a sequence of eye fixations will help an observer recognize a previously seen image. However, the only studies to investigate this are…

New Mexico: The Land of Enchantment

ERIC Educational Resources Information Center

McKay, Sandra

2009-01-01

New Mexico, a state of brown plains and sand deserts, is nicknamed "The Land of Enchantment." One reason is that the very starkness of the land adds to its enchantment. Another reason is that the rich history of the state has resulted in a landscape filled with remnants of the Pueblo people, Spanish colonizers, and Mexican settlers.

Research notes : construction of rubber modified asphalt concrete (METRO RUMAC) test sections : N. Marine Drive in Portland, Oregon, S.E. Stark Street in Gresham, Oregon.

DOT National Transportation Integrated Search

1993-12-01

Government agencies are burdened with both pavement distress and solid waste disposal problems. In response to these problems, the METRO agency of the Portland urban area sponsored the development of specifications and mix design guidelines for a rub...

Policy, Legislation and Financing for Adult Education

ERIC Educational Resources Information Center

Belanger, Paul; Duke, Chris; Hinzen, Heribert

2007-01-01

Adult learning is now widely seen as a basic human right (the right to learn) and lifelong learning is similarly recognised. Adult learning within a lifelong learning concept has an agenda far wider than just employability skills. Yet educational inequalities between and within nations remain stark, as does the gap between rhetoric and practice in…

A Democratic Constitution for Public Education

ERIC Educational Resources Information Center

Hill, Paul T.; Jochim, Ashley E.

2014-01-01

America's education system faces a stark dilemma: it needs governmental oversight, rules and regulations, but it also needs to be adaptable enough to address student needs and the many different problems that can arise at any given school--something that large educational bureaucracies are notoriously bad at. Paul Hill and Ashley Jochim offer here…

France’s New NATO Policy: Leveraging a Realignment of the Alliance?

DTIC Science & Technology

2009-01-01

things that others only think. Former Socialist foreign minister, Hubert Védrine, put it in particularly stark terms: Were France to become a...see Ronja Kempin and Marco Overhaus, “Kein grosser Sprung in der Entwicklung der ESVP: Lehren aus der französischen Ratpräsidentschaft” [“No great

3 CFR 9021 - Proclamation 9021 of September 19, 2013. National POW/MIA Recognition Day, 2013

Code of Federal Regulations, 2014 CFR

2014-01-01

... stark black and white banner symbolizing America's Missing in Action and Prisoners of War will be flown... United States of America A Proclamation Our country endures because in every generation, courageous... home. America remains steadfast in our determination to recover our missing patriots. Our work is not...

Flora White (1860-1948): New Woman, Stark Choice

ERIC Educational Resources Information Center

Morice, Linda C.

2009-01-01

This article examines the life of education reformer Flora White, who both represented and deviated from the stereotypical new woman portrayed in popular literature of the late nineteenth and early twentieth century. White's decision to reject marriage and children in favor of a career resulted in greater financial insecurity and an unmet desire…

Racial Bias in the Classroom: Can Teachers Reach All Children?

ERIC Educational Resources Information Center

Leiding, Darlene

2006-01-01

The accelerating demographic and economic changes within our society, the deepening racial divide, and the elusive quest for equality and justice make multicultural education and understanding the culturally diverse student imperative. The gap between the rich and poor has widened, visible signs of the racial crisis have become stark, and the rate…

DC KIDS COUNT e-Databook

ERIC Educational Resources Information Center

DC Action for Children, 2012

2012-01-01

Every city has many identities, depending on who one asks. A legislator, a police officer, a coach or a clerk might describe the same city's people, culture and reputation in starkly different terms. Washington, the nation's capital, is an international center of power, featuring stately embassies and serving as the temporary home to diplomats.…

Discovery Garden--Physics and Architecture Meet Outside to Talk

ERIC Educational Resources Information Center

Tabor-Morris, Anne; Briles, Timothy; Froriep, Kathleen; McGuire, Catherine

2012-01-01

The purpose of Georgian Court University's "Discovery Garden" is to create an experience of the physical sciences for students, both science and non-science majors, in a place of serenity: an outdoor garden. Why a garden? Consider that the traditional laboratory experience for students is one of stark rooms ventilated with noisy hoods…

Composition-dependent emission linewidth broadening in lead bromide perovskite (APbBr3, A = Cs and CH3NH3) nanoparticles.

PubMed

Ham, Sujin; Chung, Heejae; Kim, Tae-Woo; Kim, Jiwon; Kim, Dongho

2018-02-01

Lead halide perovskite nanoparticles (NPs) are attractive as they exhibit excellent color purity and have a tunable band gap, and can thus be applied in highly efficient photovoltaic and light-emitting diodes. Fundamental studies of emission linewidth broadening due to spectral shifts in perovskite NPs may suggest a way to improve their color purity. However, the carrier-induced Stark shift that causes spectral diffusion still requires investigation. In this study, we explore composition-related emission linewidth broadening by comparing CsPbBr3 and CH 3 NH 3 PbBr 3 (MAPbBr3) perovskite NPs. We find that the MAPbBr3 NPs are more sensitive to fluctuations in the local electric fields than the CsPbBr3 NPs due to an intrinsic difference in the dipole moment between the two A cations (Cs and MA), which shows a carrier-induced Stark shift. The results indicate that the compositions of perovskite NPs are closely associated with emission linewidth broadening and they also provide insights into the development of NP-based devices with high color purity.

"How the other half live": Lay perspectives on health inequalities in an age of austerity.

PubMed

Garthwaite, Kayleigh; Bambra, Clare

2017-08-01

This paper examines how people living in two socially contrasting areas of Stockton on Tees, North East England experience, explain, and understand the stark health inequalities in their town. Participants displayed opinions that fluctuated between a variety of converging and contrasting explanations. Three years of ethnographic observation in both areas (2014-2017) generated explanations which initially focused closely on behavioural and individualised factors, whilst 118 qualitative interviews subsequently revealed more nuanced justifications, which prioritised more structural, material and psychosocial influences. Findings indicate that inequalities in healthcare, including access, the importance of judgemental attitudes, and perceived place stigma, would then be offered as explanations for the stark gap in spatial inequalities in the area. Notions of fatalism, linked to (a lack of) choice, control, and fear of the future, were common reasons given for inequalities across all participants. We conclude by arguing for a prioritisation of listening to, and working to understand, the experiences of communities experiencing the brunt of health inequalities; especially important at a time of austerity. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Iii-V Compound Multiple Quantum Well Based Modulator and Switching Devices.

NASA Astrophysics Data System (ADS)

Hong, Songcheol

A general formalism to study the absorption and photocurrent in multiple quantum well is provided with detailed consideration of quantum confined Stark shift, exciton binding energy, line broadening, tunneling, polarization, and strain effects. Results on variation of exciton size, binding energies and transition energies as a function electric field and well size have been presented. Inhomogeneous line broadening of exciton lines due to interface roughness, alloy disorder and well to well size fluctuation is calculated. The potential of material tailoring by introducing strain for specific optical response is discussed. Theoretical and experimental results on excitonic and band-to-band absorption spectra in strained multi-quantum well structures are shown. I also report on polarization dependent optical absorption for excitonic and interband transitions in lattice matched and strained multiquantum well structures in presence of transverse electric field. Photocurrent in a p-i(MQW)-n diode with monochromatic light is examined with respect to different temperatures and intensities. The negative resistance of I-V characteristic of the p-i-n diode is based on the quantum confined Stark effect of the heavy hole excitonic transition in a multiquantum well. This exciton based photocurrent characteristic allows efficient switching. A general purpose low power optical logic device using the controller-modulator concept bas been proposed and realized. The controller is a heterojunction phototransistor with multiquantum wells in the base-collector depletion region. This allows an amplified photocurrent controlled voltage feedback with low light intensity levels. Detailed analysis of the sensitivity of this device in various modes of operation is studied. Studies are also presented on the cascadability of the device as well as its integrating -thresholding properties. A multiquantum well heterojunction bipolar transistor (MHBT), which has N^+ -p^+-i(MQW)-N structure has been fabricated to test the concept. Gain (>30) is obtained in the MBE grown devices and efficient switching occurs due to the amplification of the exciton based photocurrent. The level shift operation of the base contacted MHBT are demonstrated.

ARC: An open-source library for calculating properties of alkali Rydberg atoms

NASA Astrophysics Data System (ADS)

Šibalić, N.; Pritchard, J. D.; Adams, C. S.; Weatherill, K. J.

2017-11-01

We present an object-oriented Python library for the computation of properties of highly-excited Rydberg states of alkali atoms. These include single-body effects such as dipole matrix elements, excited-state lifetimes (radiative and black-body limited) and Stark maps of atoms in external electric fields, as well as two-atom interaction potentials accounting for dipole and quadrupole coupling effects valid at both long and short range for arbitrary placement of the atomic dipoles. The package is cross-referenced to precise measurements of atomic energy levels and features extensive documentation to facilitate rapid upgrade or expansion by users. This library has direct application in the field of quantum information and quantum optics which exploit the strong Rydberg dipolar interactions for two-qubit gates, robust atom-light interfaces and simulating quantum many-body physics, as well as the field of metrology using Rydberg atoms as precise microwave electrometers. Program Files doi:http://dx.doi.org/10.17632/hm5n8w628c.1 Licensing provisions: BSD-3-Clause Programming language: Python 2.7 or 3.5, with C extension External Routines: NumPy [1], SciPy [1], Matplotlib [2] Nature of problem: Calculating atomic properties of alkali atoms including lifetimes, energies, Stark shifts and dipole-dipole interaction strengths using matrix elements evaluated from radial wavefunctions. Solution method: Numerical integration of radial Schrödinger equation to obtain atomic wavefunctions, which are then used to evaluate dipole matrix elements. Properties are calculated using second order perturbation theory or exact diagonalisation of the interaction Hamiltonian, yielding results valid even at large external fields or small interatomic separation. Restrictions: External electric field fixed to be parallel to quantisation axis. Supplementary material: Detailed documentation (.html), and Jupyter notebook with examples and benchmarking runs (.html and .ipynb). [1] T.E. Oliphant, Comput. Sci. Eng. 9, 10 (2007). http://www.scipy.org/. [2] J.D. Hunter, Comput. Sci. Eng. 9, 90 (2007). http://matplotlib.org/.

Vibrational Stark effect spectroscopy at the interface of Ras and Rap1A bound to the Ras binding domain of RalGDS reveals an electrostatic mechanism for protein-protein interaction.

PubMed

Stafford, Amy J; Ensign, Daniel L; Webb, Lauren J

2010-11-25

Electrostatic fields at the interface of the Ras binding domain of the protein Ral guanine nucleotide dissociation stimulator (RalGDS) with the structurally analogous GTPases Ras and Rap1A were measured with vibrational Stark effect (VSE) spectroscopy. Eleven residues on the surface of RalGDS that participate in this protein-protein interaction were systematically mutated to cysteine and subsequently converted to cyanocysteine in order to introduce a nitrile VSE probe in the form of the thiocyanate (SCN) functional group. The measured SCN absorption energy on the monomeric protein was compared with solvent-accessible surface area (SASA) calculations and solutions to the Poisson-Boltzmann equation using Boltzmann-weighted structural snapshots from molecular dynamics simulations. We found a weak negative correlation between SASA and measured absorption energy, indicating that water exposure of protein surface amino acids can be estimated from experimental measurement of the magnitude of the thiocyanate absorption energy. We found no correlation between calculated field and measured absorption energy. These results highlight the complex structural and electrostatic nature of the protein-water interface. The SCN-labeled RalGDS was incubated with either wild-type Ras or wild-type Rap1A, and the formation of the docked complex was confirmed by measurement of the dissociation constant of the interaction. The change in absorption energy of the thiocyanate functional group due to complex formation was related to the change in electrostatic field experienced by the nitrile functional group when the protein-protein interface forms. At some locations, the nitrile experiences the same shift in field when bound to Ras and Rap1A, but at others, the change in field is dramatically different. These differences identify residues on the surface of RalGDS that direct the specificity of RalGDS binding to its in vivo binding partner, Rap1A, through an electrostatic mechanism.

Identification of ion-pair structures in solution by vibrational stark effects

DOE PAGES

Hack, John; Mani, Tomoyasu; Grills, David C.; ...

2016-01-25

Here, ion pairing is a fundamental consideration in many areas of chemistry and has implications in a wide range of sciences and technologies that include batteries and organic photovoltaics. Ions in solution are known to inhabit multiple possible states, including free ions (FI), contact ion pairs (CIP), and solvent-separated ion pairs (SSIP). However, in solutions of organic radicals and nonmetal electrolytes, it is often difficult to distinguish between these states. In the first part of this work, we report evidence for the formation of SSIPs in low-polarity solvents and distinct measurements of CIP, SSIP, and FI, by using the ν(C≡N)more » infrared (IR) band of a nitrile-substituted fluorene radical anion. Use of time-resolved IR detection following pulse radiolysis allowed us to unambiguously assign the peak of the FI. In the presence of nonmetal electrolytes, two distinct red-shifted peaks were observed and assigned to the CIP and SSIP. The assignments are interpreted in the framework of the vibrational Stark effect (VSE) and are supported by (1) the solvent dependence of ion-pair populations, (2) the observation of a cryptand-separated sodium ion pair that mimics the formation of SSIPs, and (3) electronic structure calculations. In the second part of this work, we show that a blue-shift of the ν(C≡N) IR band due to the VSE can be induced in a nitrile-substituted fluorene radical anion by covalently tethering it to a metal-chelating ligand that forms an intramolecular ion pair upon reduction and complexation with sodium ion. This adds support to the conclusion that the shift in IR absorptions by ion pairing originates from the VSE. These results combined show that we can identify ion-pair structures by using the VSE, including the existence of SSIPs in a low-polarity solvent.« less

Identification of ion-pair structures in solution by vibrational stark effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hack, John; Mani, Tomoyasu; Grills, David C.

Here, ion pairing is a fundamental consideration in many areas of chemistry and has implications in a wide range of sciences and technologies that include batteries and organic photovoltaics. Ions in solution are known to inhabit multiple possible states, including free ions (FI), contact ion pairs (CIP), and solvent-separated ion pairs (SSIP). However, in solutions of organic radicals and nonmetal electrolytes, it is often difficult to distinguish between these states. In the first part of this work, we report evidence for the formation of SSIPs in low-polarity solvents and distinct measurements of CIP, SSIP, and FI, by using the ν(C≡N)more » infrared (IR) band of a nitrile-substituted fluorene radical anion. Use of time-resolved IR detection following pulse radiolysis allowed us to unambiguously assign the peak of the FI. In the presence of nonmetal electrolytes, two distinct red-shifted peaks were observed and assigned to the CIP and SSIP. The assignments are interpreted in the framework of the vibrational Stark effect (VSE) and are supported by (1) the solvent dependence of ion-pair populations, (2) the observation of a cryptand-separated sodium ion pair that mimics the formation of SSIPs, and (3) electronic structure calculations. In the second part of this work, we show that a blue-shift of the ν(C≡N) IR band due to the VSE can be induced in a nitrile-substituted fluorene radical anion by covalently tethering it to a metal-chelating ligand that forms an intramolecular ion pair upon reduction and complexation with sodium ion. This adds support to the conclusion that the shift in IR absorptions by ion pairing originates from the VSE. These results combined show that we can identify ion-pair structures by using the VSE, including the existence of SSIPs in a low-polarity solvent.« less

The ac stark shift and space-borne rubidium atomic clocks

NASA Astrophysics Data System (ADS)

Formichella, V.; Camparo, J.; Sesia, I.; Signorile, G.; Galleani, L.; Huang, M.; Tavella, P.

2016-11-01

Due to its small size, low weight, and low power consumption, the Rb atomic frequency standard (RAFS) is routinely the first choice for atomic timekeeping in space. Consequently, though the device has very good frequency stability (rivaling passive hydrogen masers), there is interest in uncovering the fundamental processes limiting its long-term performance, with the goal of improving the device for future space systems and missions. The ac Stark shift (i.e., light shift) is one of the more likely processes limiting the RAFS' long-term timekeeping ability, yet its manifestation in the RAFS remains poorly understood. In part, this comes from the fact that light-shift induced frequency fluctuations must be quantified in terms of the RAFS' light-shift coefficient and the output variations in the RAFS' rf-discharge lamp, which is a nonlinear inductively-couple plasma (ICP). Here, we analyze the light-shift effect for a family of 10 on-orbit Block-IIR GPS RAFS, examining decade-long records of their on-orbit frequency and rf-discharge lamp fluctuations. We find that the ICP's light intensity variations can take several forms: deterministic aging, jumps, ramps, and non-stationary noise, each of which affects the RAFS' frequency via the light shift. Correlating these light intensity changes with RAFS frequency changes, we estimate the light-shift coefficient, κLS, for the family of RAFS: κLS = -(1.9 ± 0.3) × 10-12/%. The 16% family-wide variation in κLS indicates that while each RAFS may have its own individual κLS, the variance of κLS among similarly designed RAFS can be relatively small. Combining κLS with our estimate of the ICP light intensity's non-stationary noise, we find evidence that random-walk frequency noise in high-quality space-borne RAFS is strongly influenced by the RAFS' rf-discharge lamp via the light shift effect.

The role of the F spin-orbit excited state in the F+H(2) and F+HD reactions

NASA Astrophysics Data System (ADS)

Tzeng, Yi-Ren

In this dissertation we study the role of the F spin-orbit excited state (F*) in the F + H2 and F + HD reactions using quantum mechanical calculations. The calculations involve multiple potential energy surfaces (the Alexander-Stark-Werner, or ASW, PESs), and include an accurate treatment of the couplings (non-adiabatic, spin-orbit, and Coriolis) among all three electronic states. For the F + H2 reaction, we calculate the center-of-mass differential cross sections and laboratory-frame angular distributions at the four different combinations of collision energies and hydrogen isotopomer investigated in the experiments of Neumark et al. [J. Chem. Phys., 82, 3045 (1985)]. Comparisons with the calculations on the Stark-Werner (SW) and Hartke-Stark-Werner (HSW) PESs, which are limited to the lowest electronically adiabatic state, show that non-adiabatic couplings greatly reduce backward scattering. Surprisingly, we find the shapes of both the CM DCSs and LAB ADs are insensitive to the fraction of F* presented in the F beam. For the F + HD reaction, we calculate the excitation functions and product translational energy distribution functions to study the reactivity of F*. Comparisons with the experiment by Liu and co-workers [J. Chem. Phys., 113, 3633 (2000)] confirm the relatively low reactivity of spin-orbit excited state (F*) atoms. Excellent agreement with the experiment is obtained under the assumption that the F*:F concentration ratio equals 0.16:0.84 in the molecular beam, which corresponds to a thermal equilibrium of the two spin-orbit states at the experimental temperature (600K). From the accurate calculation of the F* reactivity and its relatively small contribution to the overall reactivity of the reaction, we attribute discrepancies between calculation and experiment to an inadequacy in the simulation of the reactivity of the F ground state, likely a result of the residual errors in the ground electronic potential energy surface.

The White Cliffs of "Rover"

NASA Image and Video Library

2017-06-15

This image from NASA's Mars Reconnaissance Orbiter is reminiscent of the rugged and open terrain of a stark shore-line, perhaps of an island nation, such as the British Isles. A close-up in enhanced color produces a striking effect, giving the impression of a cloud-covered cliff edge with foamy waves crashing against it. The reality is that the surface of Mars is much dryer than our imaginations might want to suggest. This is only a tiny part of a much larger structure; an inverted crater -- a crater that has been infilled by material that is more resistant to erosion than the rocks around it -- surrounded by bluish basaltic dunes. The edge of these elevated light-toned deposits are degraded, irregular and cliff-forming. Dunes visible below the cliff, give the impression of an ocean surface, complete with foam capped waves crashing against the "shore line," demonstrating the abstract similarity between the nature of a turbulent ocean and a Martian dune field. Meridiani Planum has an overall smooth terrain, which starkly contrasts with the more common boulder- and crater-laden landscapes observed over much of the rest of Mars. This makes it relatively younger in character than many other areas of the planet. Meridiani is one of the Mars Exploration Rover landing sites, and, is known for its layers and sediments. The orbital detection of hematite was one of the main reasons for sending Opportunity to this area. Salt-bearing rocks -- also called sulphates -- were observed in the very first image from Opportunity, so perhaps it's apt that this HiRISE image reminds us of the turmoil and rugged beauty of a cliff-face, a coastline, being worn down by a relentless sea. https://photojournal.jpl.nasa.gov/catalog/PIA21760

Pressure shifts and abundance gradients in the atmosphere of the DAZ white dwarf GALEX J193156.8+011745

NASA Astrophysics Data System (ADS)

Vennes, S.; Kawka, A.; Németh, P.

2011-06-01

We present a detailed model atmosphere analysis of high-dispersion and high signal-to-noise ratio spectra of the heavily polluted DAZ white dwarf GALEX J1931+0117. The spectra obtained with the Very Large Telescope (VLT)-Kueyen/UV-Visual Echelle Spectrograph show several well-resolved Si II spectral lines enabling a study of pressure effects on line profiles. We observed large Stark shifts in silicon lines in agreement with theoretical predictions and laboratory measurements. Taking into account Stark shifts in the calculation of synthetic spectra, we reduced the scatter in individual line radial velocity measurements from ˜3 to ≲1 km s-1. We present revised abundances of O, Mg, Si, Ca and Fe based on a critical review of line-broadening parameters and oscillator strengths. The new measurements are generally in agreement with our previous analysis with the exception of magnesium with a revised abundance of a factor of 2 lower than previously estimated. The magnesium, silicon and iron abundances exceed solar abundances, but the oxygen and calcium abundances are below solar. Also, we compared the observed line profiles to synthetic spectra computed with variable accretion rates and vertical abundance distributions assuming diffusive steady state. The inferred accretion rates vary from ? for calcium to 2 × 109 g s-1 for oxygen. We find that the accretion flow must be oxygen rich while being deficient in calcium relative to solar abundances. The lack of radial velocity variations between two measurement epochs suggests that GALEX J1931+0117 is probably not in a close binary and that the source of the accreted material resides in a debris disc. Based on observations made with European Southern Observatory (ESO) telescopes at the La Silla Paranal Observatory under programme 283.D-5060.

Mid-infrared signatures of hydroxyl containing water clusters: Infrared laser Stark spectroscopy of OH–H{sub 2}O and OH(D{sub 2}O){sub n} (n = 1-3)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, Federico J.; INFIQC, Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón, X5000HUA Córdoba; Brice, Joseph T.

2015-10-28

Small water clusters containing a single hydroxyl radical are synthesized in liquid helium droplets. The OH–H{sub 2}O and OH(D{sub 2}O){sub n} clusters (n = 1-3) are probed with infrared laser spectroscopy in the vicinity of the hydroxyl radical OH stretch vibration. Experimental band origins are qualitatively consistent with ab initio calculations of the global minimum structures; however, frequency shifts from isolated OH are significantly over-predicted by both B3LYP and MP2 methods. An effective Hamiltonian that accounts for partial quenching of electronic angular momentum is used to analyze Stark spectra of the OH–H{sub 2}O and OH–D{sub 2}O binary complexes, revealing amore » 3.70(5) D permanent electric dipole moment. Computations of the dipole moment are in good agreement with experiment when large-amplitude vibrational averaging is taken into account. Polarization spectroscopy is employed to characterize two vibrational bands assigned to OH(D{sub 2}O){sub 2}, revealing two nearly isoenergetic cyclic isomers that differ in the orientation of the non-hydrogen-bonded deuterium atoms relative to the plane of the three oxygen atoms. The dipole moments for these clusters are determined to be approximately 2.5 and 1.8 D for “up-up” and “up-down” structures, respectively. Hydroxyl stretching bands of larger clusters containing three or more D{sub 2}O molecules are observed shifted approximately 300 cm{sup −1} to the red of the isolated OH radical. Pressure dependence studies and ab initio calculations imply the presence of multiple cyclic isomers of OH(D{sub 2}O){sub 3}.« less

Faithful state transfer between two-level systems via an actively cooled finite-temperature cavity

NASA Astrophysics Data System (ADS)

Sárkány, Lőrinc; Fortágh, József; Petrosyan, David

2018-03-01

We consider state transfer between two qubits—effective two-level systems represented by Rydberg atoms—via a common mode of a microwave cavity at finite temperature. We find that when both qubits have the same coupling strength to the cavity field, at large enough detuning from the cavity mode frequency, quantum interference between the transition paths makes the swap of the excitation between the qubits largely insensitive to the number of thermal photons in the cavity. When, however, the coupling strengths are different, the photon-number-dependent differential Stark shift of the transition frequencies precludes efficient transfer. Nevertheless, using an auxiliary cooling system to continuously extract the cavity photons, we can still achieve a high-fidelity state transfer between the qubits.

Mass shift of charmonium states in p bar A collision

NASA Astrophysics Data System (ADS)

Wolf, György; Balassa, Gábor; Kovács, Péter; Zétényi, Miklós; Lee, Su Houng

2018-05-01

The masses of the low lying charmonium states, namely, the J / Ψ, Ψ (3686), and Ψ (3770) are shifted downwards due to the second order Stark effect. In p bar +Au collisions at 6-10 GeV we study their in-medium propagation. The time evolution of the spectral functions of these charmonium states is studied with a Boltzmann-Uehling-Uhlenbeck (BUU) type transport model. We show that their in-medium mass shift can be observed in the dilepton spectrum. Therefore, by observing the dileptonic decay channel of these low lying charmonium states, especially for Ψ (3686), we can gain information about the magnitude of the gluon condensate in nuclear matter. This measurement could be performed at the upcoming PANDA experiment at FAIR.

On-chip electrically controlled routing of photons from a single quantum dot

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bentham, C.; Coles, R. J.; Royall, B.

2015-06-01

Electrical control of on-chip routing of photons emitted by a single InAs/GaAs self-assembled quantum dot (SAQD) is demonstrated in a photonic crystal cavity-waveguide system. The SAQD is located inside an H1 cavity, which is coupled to two photonic crystal waveguides. The SAQD emission wavelength is electrically tunable by the quantum-confined Stark effect. When the SAQD emission is brought into resonance with one of two H1 cavity modes, it is preferentially routed to the waveguide to which that mode is selectively coupled. This proof of concept provides the basis for scalable, low-power, high-speed operation of single-photon routers for use in integratedmore » quantum photonic circuits.« less

Direct Observation of Two-Step Photon Absorption in an InAs/GaAs Single Quantum Dot for the Operation of Intermediate-Band Solar Cells.

PubMed

Nozawa, Tomohiro; Takagi, Hiroyuki; Watanabe, Katsuyuki; Arakawa, Yasuhiko

2015-07-08

We present the first direct observation of two-step photon absorption in an InAs/GaAs single quantum dot (QD) using photocurrent spectroscopy with two lasers. The sharp peaks of the photocurrent are shifted due to the quantum confined Stark effect, indicating that the photocurrent from a single QD is obtained. In addition, the intensity of the peaks depends on the power of the secondary laser. These results reveal the direct demonstration of the two-step photon absorption in a single QD. This is an essential result for both the fundamental operation and the realization of ultrahigh solar-electricity energy conversion in quantum dot intermediate-band solar cells.

Eleuthera Island, Bahamas

NASA Technical Reports Server (NTRS)

1981-01-01

Eleuthera Island, (24.5N, 76.0W) Bahamas Island Group, is one of several within the archipelago surrounded by shallow seas, visible here as light blue. Mosaic patterns of sand waves built by sea bottom currents in the shallows stand out in stark contrast to the deep blue of the ocean depths of a thousand feet in the Exuma Sound.

As His Day in Court Arrives, Ward Churchill Is Depicted in Sharply Different Lights

ERIC Educational Resources Information Center

Schmidt, Peter

2009-01-01

The trial in Ward Churchill's lawsuit against the University of Colorado got under way here last week with lawyers for the opposing sides painting starkly different pictures of both the controversial ethnic-studies professor and the circumstances surrounding his dismissal by the university in 2007. In delivering their opening remarks in a crowded…

Praise in Public, Criticize in Private? An Assessment of Performance Feedback Transparency in a Classroom Setting

ERIC Educational Resources Information Center

Seevers, Matthew T.; Rowe, William J.; Skinner, Steven J.

2014-01-01

Conventional wisdom in sales management encourages public delivery of positive feedback, and private delivery of negative feedback. In stark contrast, U.S. educators typically provide all performance feedback in relative (if not strict) privacy to comply with the Family Educational Rights and Privacy Act (FERPA). To investigate this discrepancy,…

Strong field control of predissociation dynamics.

PubMed

Corrales, María E; Balerdi, Garikoitz; Loriot, Vincent; de Nalda, Rebeca; Bañares, Luis

2013-01-01

Strong field control scenarios are investigated in the CH3I predissociation dynamics at the origin of the second absorption B-band, in which state-selective electronic predissociation occurs through the crossing with a valence dissociative state. Dynamic Stark control (DSC) and pump-dump strategies are shown capable of altering both the predissociation lifetime and the product branching ratio.

Investigation of the Elastic Behavior of Al-Li-X Alloys.

DTIC Science & Technology

1987-06-01

maintain thermal equilibrium with the surroundings. Also, when using this method, aluminum may exhibit microplasticity at low elastic strains. The static...20 W. W. Ruch, MS 21 - 22 E. A. Starke, Jr., M1S 23 T. H. Courtney, MS i 24 - 25 E. H. Pancake, Clark Hall 26 SEAS Publications Files * Office of

Social Work with Children when Parents Have Mental Health Difficulties: Acknowledging Vulnerability and Maintaining the "Rights of the Child"

ERIC Educational Resources Information Center

Monds-Watson, Aisling; Manktelow, Roger; McColgan, Mary

2010-01-01

The 40 substantive rights contained within the United Nations Convention on the Rights of the Child (UNCRC) 1989, have applied, without discrimination, to all children in the United Kingdom since 1992. However, recurrent tragedies starkly highlight the potential vulnerability of some children when their parents experience mental health…

Evaluation of Androgen Receptor Function in Prostate Cancer Prognosis and Therapeutic Stratification

DTIC Science & Technology

2015-12-01

the DoD, CDMRP, PC073614 to SS and AD. We thank Thuy Nguyen and Petra Hirschmann for excellent technical support. REFERENCES 1 Siegel R, Naishadham D...3991-4002; PMID:19520778; http://dx.doi.org/10.1210/ en.2009-0573 33. Martin DN, Starks AM, Ambs S. Biological deter- minants of health disparities

Identifying and Overcoming Threshold Concepts and Conceptions: Introducing a Conception-Focused Curriculum to Course Design

ERIC Educational Resources Information Center

Burch, Gerald F.; Burch, Jana J.; Bradley, Thomas P.; Heller, Nathan A.

2015-01-01

Educators have been challenged to identify threshold concepts and develop transformed students. This stands in stark contrast to many curriculum design and delivery models that currently view students as repositories of knowledge. In this article, we argue that educators can reach both goals, identify stumbling blocks and transforming students,…

77 FR 43064 - Defense Science Board; Notice of Advisory Committee Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-23

... Science Board 2012 Summer Study on Technology and Innovation Enablers for Superiority in 2030 will meet in closed session August 20-24, 2012, from 8:00 a.m. to 5:00 p.m. at the Charles Stark Draper Laboratory... meeting, the Board will discuss interim finding and recommendations resulting from ongoing Task Force...

Moving beyond Boycotts: Strategies for Shared Responsibility in the Collegiate Apparel Industry

ERIC Educational Resources Information Center

Kelley, Scott P.

2014-01-01

The 2013 factory collapse at Rana Plaza in Bangladesh is a painful reminder that labor issues in the apparel industry are abundant and troubling. Catholic colleges and universities (CCUs) are confronted with the reality that many apparel manufacturers can operate in stark contrast to the vision of economic justice found in Catholic social thought…

A Tough Time to Be a Girl: Gender Imbalance on Campuses

ERIC Educational Resources Information Center

Whitmire, Richard

2008-01-01

American colleges are undergoing a striking gender shift. In 2015 the average college graduating class will be 60-percent female, according to the U.S. Education Department. It appears that the stark gender imbalances in American colleges nowadays is acting as an accelerant on the hookup culture among students. As a result of the rising gender…

White Collar Work: Career Ambitions of Fiji Final Year School Students

ERIC Educational Resources Information Center

Nilan, Pam; Cavu, Paula; Tagicakiverata, Isimeli; Hazelman, Emily

2006-01-01

The career ambitions of 1012 pupils in the final years of secondary schooling in Fiji were surveyed. The range of careers they nominated was very narrow, with teaching, nursing and other white collar work in the majority of responses. This stands in somewhat stark contrast to projected labour force needs, and the current serious shortage of…

Physical Education: Clear and Present Benefits and Responsibilities. The Fritz Duras Memorial Lecture 2017

ERIC Educational Resources Information Center

Telford, Richard D.

2017-01-01

A habitually active environment is a feature of past times, and in stark contrast with that experienced by our children today. Consequently, twenty-first century physical education (PE) assumes a position of great responsibility. This is especially true in primary schools; a premise recently strongly supported by published evidence from the…

Leadership of Self-Organized Networks Lessons from the War on Terror

ERIC Educational Resources Information Center

Wheatley, Margaret J.

2007-01-01

In the past few decades, scientists have developed a rich understanding of how living systems organize and function. They describe life's capacity to self-organize as networks of interdependent relationships, to learn and adapt, and to grow more capable and orderly over time. These dynamics and descriptions stand in stark contrast to how we humans…

Facing the Future: A Doctrine for Air Control in Limited Conflicts

DTIC Science & Technology

1998-06-01

defense of the Protectorate lay with one RAF squadron, three armoured cars and a few hundred local levies.”33 All air operations from 1934-1935 were under...Flight 655, Annapolis, Maryland: Naval Institute Press, 1992, pg. 4 “Vivid memories of a blackened hulk [USS Stark] and flag- draped coffins were never far

Rising to a New Paradigm: Infusing Health and Wellness into the Music Curriculum

ERIC Educational Resources Information Center

Pierce, Deborah L.

2012-01-01

Musicians, like athletes, daily face the stark reality of physical and psychological health issues that can negatively affect or end their careers. Research shows compelling reasons for making changes to the value systems and in the educational process under which musicians are trained to help alleviate these problems. Changes would include…

Concept Mapping and Misconceptions: A Study of High-School Students' Understandings of Acids and Bases.

ERIC Educational Resources Information Center

Ross, Bertram; And Others

1991-01-01

An investigation of students understandings of acids and bases using concept maps, multiple-choice tests, and clinical interviews is described. The methodology and resulting analysis are illustrated with two abbreviated case studies selected from the study. Discussion of concept mapping points to how it starkly represents gaps in the understanding…

Goodbye Conflict, Hello Development? Curriculum Reform in Timor-Leste

ERIC Educational Resources Information Center

Shah, Ritesh

2012-01-01

Motivations to reform curriculum in post-conflict, or post-colonial states are often driven by the need to (re) construct a cohesive and publicly legitimated national identity that is starkly different to that which existed prior. This paper explores the context behind such action in the Timor-Leste (East Timor) and some challenges which policy…

Trust-Based Design of Human-Guided Algorithms

DTIC Science & Technology

2007-06-01

Management Interdepartmental Program in Operations Research 17 May, 2007 Approved by: Laura Major Forest The Charles Stark Draper Laboratory...2. Information Analysis: predicting based on data, integrating and managing information, augmenting human operator perception and cognition. 3...allocation of automation by designers and managers . How an operator decides between manual and automatic control of a system is a necessary

"Make My Day, Shoot a Teacher": Tactics of Inclusion and Exclusion, and the Contestation of Community in a Rural School-Community Conflict

ERIC Educational Resources Information Center

McHenry-Sorber, Erin; Schafft, Kai A.

2015-01-01

Far from being the harmonious and homogenous communities of popular imagination, rural communities often are characterised by stark differences in class-situated values over education philosophy and financing. These differences can produce contentious political environments, vastly complexifying local decision-making, including school district…

Financial Incentives and Student Achievement: Evidence from Randomized Trials. NBER Working Paper No. 15898

ERIC Educational Resources Information Center

Fryer, Roland G., Jr.

2010-01-01

This paper describes a series of school-based randomized trials in over 250 urban schools designed to test the impact of financial incentives on student achievement. In stark contrast to simple economic models, our results suggest that student incentives increase achievement when the rewards are given for inputs to the educational production…

Planning Combat Outposts to Maximize Population Security

DTIC Science & Technology

2010-06-01

Abraham Maslow defined incremental layers of needs that require fulfillment and that can explain people’s motivations in life [12]. The needs at a lower...Hildebrant I ,e Certified by: The Charles Stark Draper Laboratory, Inc. Technical Supervisor Stephen C. Graves Professor, Abraham J. Siegel...22 Figure 2-4: Maslow Hierarchy of Needs ................................................................................. 27 Figure 3-1

Howard’s Command and Control of Idaho’s Nez Perce War

DTIC Science & Technology

1993-06-04

Valencia Boise, ID S;5(:)7 Josie Spellman 60:7 17th Street Coeur D’Alene, ID 83814 Ray Stark 3=5S Agate Court Boise, ID 8Z705 Criag Stremel 5215 Tarre Heights Manhattan, KS 66502 0 129 1 • •• 0 0 06 0 0 A

Master Teachers: Making a Difference on the Edge of Chaos

ERIC Educational Resources Information Center

Chapin, Dexter

2008-01-01

The No Child Left Behind legislation, by legitimizing a stark, one-size-fits-all, industrial model of education, has denied the inherent complexity and richness of what teachers do. Discussing teaching in terms of Chaos Theory, Chapin explains that while excellent teaching may occur at the edge of chaos, it is not chaotic. There are patterns…

Two Year College Faculty Problems: Master Contracts, Pros and Cons.

ERIC Educational Resources Information Center

Morgan, Don A., Ed.

The principal papers presented at this conference were as follows: (1) "We've Come a Long Way, Baby" by Thomas F. Stark, (2) "Hey! Who Runs This Show?" by Clair T. Blikre, and (3) "Bargaining Allows Teachers to Teach!" by Ralph Chesebrough. The background, purposes and activities of the Iron Range Institute are described. The appendix, Career…

Addressing Postsecondary Access for Undocumented Students. ECS Education Trends

ERIC Educational Resources Information Center

Anderson, Lexi

2015-01-01

In 2012, there were an estimated 11.2 million undocumented individuals living in the United States. The peak of unauthorized immigrant population occurred in 2007 with 12.2 million, a stark rise from original estimates of 3.5 million in 1990. Although down from its peak, a sizeable and stable population of unauthorized individuals resides in the…

Promising Practices and Unfinished Business: Fostering Equity and Excellence for Black and Latino Males

ERIC Educational Resources Information Center

Tung, Rosann; Carlo, Vivian Dalila; Colón, Melissa; Del Razo, Jaime L.; Diamond, John B.; Raynor, Alethea Frazier; Graves, Daren; Kuttner, Paul J.; Miranda, Helena; St. Rose, Andresse

2015-01-01

Boston Public Schools (BPS) commissioned companion studies as part of its efforts to address achievement gaps for Black and Latino males. The first study revealed the increasing diversity of Black and Latino males and stark opportunity gaps throughout the system that contribute in large part to wide attainment gaps for these students. We…

ICT-Supported Pedagogical Policies and Practices in South Africa and Chile: Emerging Economies and Realities

ERIC Educational Resources Information Center

Howie, S. J.

2010-01-01

South Africa participated in all three of the Second International Technology in Education Study (SITES). In the first international study, South Africa was the only developing country, and therefore, stark contrasts were found in the international study between South Africa and the other participating countries. Chile participated in the SITES…

U.S. Students from Educated Families Lag in International Tests

ERIC Educational Resources Information Center

Hanushek, Eric A.; Peterson, Paul E.; Woessmann, Ludger

2014-01-01

This article describes the grim sentiments from the U.S. Secretary of Education, Arne Duncan, when reviewing the poor results from the U.S. performance on the 2012 Program for International Student Assessment (PISA). He noted a straightforward and stark picture of educational stagnation--that fifteen-year-olds in the U.S. today are average in…

Parental Socioeconomic Status and Risk of Offspring Autism Spectrum Disorders in a Swedish Population-Based Study

ERIC Educational Resources Information Center

Rai, Dheeraj; Lewis, Glyn; Lundberg, Michael; Araya, Ricardo; Svensson, Anna; Dalman, Christina; Carpenter, Peter; Magnusson, Cecilia

2012-01-01

Objective: Epidemiological studies in the United States consistently find autism spectrum disorders (ASD) to be overrepresented in high socioeconomic status (SES) families. These findings starkly contrast with SES gradients of many health conditions, and may result from SES inequalities in access to services. We hypothesized that prenatal measures…

"You Get What You Need": A Study of Students' Attitudes towards Using Wikipedia When Doing School Assignments

ERIC Educational Resources Information Center

Blikstad-Balas, Marte

2016-01-01

In traditional classrooms, a textbook was often the only source of knowledge available; in stark contrast, today's classrooms have an infinite number of knowledge sources available through the Internet. Nevertheless, a range of studies suggest that students systematically favor Wikipedia in their school-related literacy practices. The present…

Unknown and Unknowing Possibilities: Transformative Learning, Social Justice, and Decolonising Pedagogy in Indigenous Australian Studies

ERIC Educational Resources Information Center

Mackinlay, Elizabeth; Barney, Katelyn

2014-01-01

For tertiary educators in Indigenous Australian Studies, decolonising discourse in education has held much promise to make space for the diversity of Indigenous Australian peoples to be included, accessed, understood, discussed, and engaged with in meaningful ways. However, Tuck and Yang provide us with the stark reminder that decolonisation…

Alignment: A Local High School/College Model to Eliminate Remediation

ERIC Educational Resources Information Center

Rochford, Joseph A.

2006-01-01

A team of faculty from both Stark State College of Technology (SSCT) and the Canton City Schools (CCS) reviewed their respective curricula opposite the Ohio Academic Content Standards, assisted by a crosswalk indicating which of those standards were measured by COMPASS/ESL a widely used college placement test. This study found that the skills…

A State Call to Action: Working To End Child Abuse and Neglect in Massachusetts.

ERIC Educational Resources Information Center

Massachusetts KIDS COUNT, Boston.

Although Massachusetts ranks in the top 10 percent among states on several key indicators of child well-being, the state's growing incidence of child maltreatment is stark and confounding. This report launches a state call to action aimed at ending child maltreatment through revising and strengthening systems to protect children, providing support…

A Better Bargain: Overhauling Teacher Collective Bargaining for the 21st Century

ERIC Educational Resources Information Center

Hess, Frederick M.; West, Martin R.

2006-01-01

In this paper, the authors argue that at a time when disappointing student performance, stark achievement gaps, and an ever-"flattening" world call for retooling American schools for the 21st century, the most daunting impediments to doing so are the teacher collective bargaining agreements that regulate virtually all aspects of school district…

Creating a Social Context through Film: Teaching L2 Pragmatics as a Locally Situated Process

ERIC Educational Resources Information Center

Abrams, Zsuzsanna

2016-01-01

Pragmatics is an underrepresented area in L2 instruction, in spite of disciplinary emphasis on communicative skills (de Pablos-Ortega, 2011; Eisenchlas, 2011). Films have been shown to be capable of mitigating this lack of pedagogically prepared materials (Abrams, 2014; Kambara, 2011; Fernández-Guerra, 2008; Grant & Starks, 2001; Washburn,…

What Is the Future of Learning in Canada?

ERIC Educational Resources Information Center

Canadian Council on Learning, 2011

2011-01-01

In its final report to Canadians, the Canadian Council on Learning (CCL) reveals that Canada is slipping down the international learning curve. The needs in this area are stark. The potential rewards are enormous. But Canada is falling behind competitor countries and economies. It is on the wrong road and must make a dramatic change in the course…

Ending the "War against Youth": Social Media and Hip-Hop Culture as Sites of Resistance, Transformation and (Re) Conceptualization

ERIC Educational Resources Information Center

Porfilio, Brad J.; Roychoudhury, Debangshu; Gardner, Lauren

2013-01-01

The purpose of this essay is to ameliorate the virulent discursive and material attack against today's "border" youth launched by large-scale corporations and Western politicians. Specifically, the authors problematize the dominant tropes of youth being mindless, obedient objects who passively accept the stark social reality they…

Post-Conflict Teacher Development: Facing the Past in South Africa

ERIC Educational Resources Information Center

Weldon, Gail

2010-01-01

One of the priorities of societies emerging from identity-based conflict is to signal a new society, with new values that stand in stark contrast with the old. Education policy becomes a critical arena for highlighting these political values when schools, particularly teachers, are identified as key agents of social change. However, the legacy of…

Experimental methods of post-growth tuning of the excitonic fine structure splitting in semiconductor quantum dots

PubMed Central

2012-01-01

Deterministic sources of polarization entangled photon pairs on demand are considered as important building blocks for quantum communication technology. It has been demonstrated that semiconductor quantum dots (QDs), which exhibit a sufficiently small excitonic fine structure splitting (FSS) can be used as triggered, on-chip sources of polarization entangled photon pairs. As-grown QDs usually do not have the required values of the FSS, making the availability of post-growth tuning techniques highly desired. This article reviews the effect of different post-growth treatments and external fields on the FSS such as thermal annealing, magnetic fields, the optical Stark effect, electric fields, and anisotropic stress. As a consequence of the tuning of the FSS, for some tuning techniques a rotation of the polarization of the emitted light is observed. The joint modification of polarization orientation and FSS can be described by an anticrossing of the bright excitonic states. PMID:22726724

An Anomaly in the Inglis-Teller Limits of the C VI Lyman and Balmer Series in Laser-Produced Plasmas

NASA Astrophysics Data System (ADS)

Elton, R.; Iglesias, E.; Griem, H.; Weaver, J.; Pien, G.; Mancini, R.

2002-11-01

Soft x-ray spectra from thin carbon layers heated by the OMEGA and NIKE lasers have been obtained with both spherical and planar targets, respectively, using a flat-field grazing incidence spectrograph equipped with a gated microchannel plate for temporal resolution. In both experiments, late-time (recombining) hydrogenic C VI spectra show an n-to-1 Lyman spectral series blending with the continuum at n=4, contrary to n=9 in the n-to-2 Balmer series. It appears unlikely that plasma inhomogeneities are the sole cause of this anomaly, given the difference in the experimental configurations. Other explanations for the line-to-continuum merging (other than the usual Stark-broadened Inglis-Teller effect) under consideration include non-thermal Doppler broadening, deviations from statistical sublevel population distributions, and opacity effects. Collisional-radiative and hydrodynamic modeling, including cascades, is employed to further understand this phenomenon.

Anomalous Hall effect scaling in ferromagnetic thin films

NASA Astrophysics Data System (ADS)

Grigoryan, Vahram L.; Xiao, Jiang; Wang, Xuhui; Xia, Ke

2017-10-01

We propose a scaling law for anomalous Hall effect in ferromagnetic thin films. Our approach distinguishes multiple scattering sources, namely, bulk impurity, phonon for Hall resistivity, and most importantly the rough surface contribution to longitudinal resistivity. In stark contrast to earlier laws that rely on temperature- and thickness-dependent fitting coefficients, this scaling law fits the recent experimental data excellently with constant parameters that are independent of temperature and film thickness, strongly indicating that this law captures the underlying physical processes. Based on a few data points, this scaling law can even fit all experimental data in full temperature and thickness range. We apply this law to interpret the experimental data for Fe, Co, and Ni and conclude that (i) the phonon-induced skew scattering is unimportant as expected; (ii) contribution from the impurity-induced skew scattering is negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and both the extrinsic and intrinsic contributions are important in Ni.

On the shape of giant soap bubbles.

PubMed

Cohen, Caroline; Darbois Texier, Baptiste; Reyssat, Etienne; Snoeijer, Jacco H; Quéré, David; Clanet, Christophe

2017-03-07

We study the effect of gravity on giant soap bubbles and show that it becomes dominant above the critical size [Formula: see text], where [Formula: see text] is the mean thickness of the soap film and [Formula: see text] is the capillary length ([Formula: see text] stands for vapor-liquid surface tension, and [Formula: see text] stands for the liquid density). We first show experimentally that large soap bubbles do not retain a spherical shape but flatten when increasing their size. A theoretical model is then developed to account for this effect, predicting the shape based on mechanical equilibrium. In stark contrast to liquid drops, we show that there is no mechanical limit of the height of giant bubble shapes. In practice, the physicochemical constraints imposed by surfactant molecules limit the access to this large asymptotic domain. However, by an exact analogy, it is shown how the giant bubble shapes can be realized by large inflatable structures.

Low-bias negative differential conductance controlled by electrode separation

NASA Astrophysics Data System (ADS)

Yi, Xiao-Hua; Liu, Ran; Bi, Jun-Jie; Jiao, Yang; Wang, Chuan-Kui; Li, Zong-Liang

2016-12-01

The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green’s function formalism combined with ab initio calculations. The numerical results show that the TADHA molecule exhibits excellent negative differential conductance (NDC) behavior at lower bias regime as probed experimentally. The NDC behavior of TADHA molecule originates from the Stark effect of the applied bias voltage, by which the highest occupied molecular orbital (HOMO) and the HOMO-1 are pulled apart and become localized. The NDC behavior of TADHA molecular system is tunable by changing the electrode distance. Shortening the electrode separation can enhance the NDC effect which is attributed to the possible increase of coupling between the two branches of TADHA molecule. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374195 and 11405098) and the Natural Science Foundation of Shandong Province, China (Grant No. ZR2013FM006).

Ultracold Nonreactive Molecules in an Optical Lattice: Connecting Chemistry to Many-Body Physics.

PubMed

Doçaj, Andris; Wall, Michael L; Mukherjee, Rick; Hazzard, Kaden R A

2016-04-01

We derive effective lattice models for ultracold bosonic or fermionic nonreactive molecules (NRMs) in an optical lattice, analogous to the Hubbard model that describes ultracold atoms in a lattice. In stark contrast to the Hubbard model, which is commonly assumed to accurately describe NRMs, we find that the single on-site interaction parameter U is replaced by a multichannel interaction, whose properties we elucidate. Because this arises from complex short-range collisional physics, it requires no dipolar interactions and thus occurs even in the absence of an electric field or for homonuclear molecules. We find a crossover between coherent few-channel models and fully incoherent single-channel models as the lattice depth is increased. We show that the effective model parameters can be determined in lattice modulation experiments, which, consequently, measure molecular collision dynamics with a vastly sharper energy resolution than experiments in a free-space ultracold gas.

Quality, Quantity, And Surprise! Trade-Offs In X-Raser ASAT Attrition

NASA Astrophysics Data System (ADS)

Callaham, Michael B.; Scibilia, Frank M.

1984-08-01

In order to characterize the effects of technological superiority, numerical superiority, and pre-emption on space battle outcomes, we have constructed a battle simulation in which "Red" and "Blue" ASATs, each armed with a specified number of x-ray lasers of specified range, move along specified orbits and fire on one another according to a pair of battle management algorithms. The simulated battle proceeds until apparent steady-state force levels are reached. Battle outcomes are characterized by terminal force ratio and by terminal force-exchange ratio as effective weapon range, multiplicity (x-rasers per ASAT), and pre-emptive role are varied parametrically. A major conclusion is that pre-emptive advantage increases with increasing x-raser range and multiplicity (x-rasers per ASAT) and with increasing force size. That is, the "use 'em or lose 'em" dilemma will become more stark as such weapons are refined and proliferated.

Effects of Mackenzie River Discharge and Bathymetry on Sea Ice in the Beaufort Sea

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Hall, D. K.; Rigor, I. G; Li, P.; Neumann, G.

2014-01-01

Mackenzie River discharge and bathymetry effects on sea ice in the Beaufort Sea are examined in 2012 when Arctic sea ice extent hit a record low. Satellite-derived sea surface temperature revealed warmer waters closer to river mouths. By 5 July 2012, Mackenzie warm waters occupied most of an open water area about 316,000 sq km. Surface temperature in a common open water area increased by 6.5 C between 14 June and 5 July 2012, before and after the river waters broke through a recurrent landfast ice barrier formed over the shallow seafloor offshore the Mackenzie Delta. In 2012, melting by warm river waters was especially effective when the strong Beaufort Gyre fragmented sea ice into unconsolidated floes. The Mackenzie and other large rivers can transport an enormous amount of heat across immense continental watersheds into the Arctic Ocean, constituting a stark contrast to the Antarctic that has no such rivers to affect sea ice.

Efficient carrier relaxation and fast carrier recombination of N-polar InGaN/GaN light emitting diodes

NASA Astrophysics Data System (ADS)

Feng, Shih-Wei; Liao, Po-Hsun; Leung, Benjamin; Han, Jung; Yang, Fann-Wei; Wang, Hsiang-Chen

2015-07-01

Based on quantum efficiency and time-resolved electroluminescence measurements, the effects of carrier localization and quantum-confined Stark effect (QCSE) on carrier transport and recombination dynamics of Ga- and N-polar InGaN/GaN light-emitting diodes (LEDs) are reported. The N-polar LED exhibits shorter ns-scale response, rising, delay, and recombination times than the Ga-polar one does. Stronger carrier localization and the combined effects of suppressed QCSE and electric field and lower potential barrier acting upon the forward bias in an N-polar LED provide the advantages of more efficient carrier relaxation and faster carrier recombination. By optimizing growth conditions to enhance the radiative recombination, the advantages of more efficient carrier relaxation and faster carrier recombination in a competitive performance N-polar LED can be realized for applications of high-speed flash LEDs. The research results provide important information for carrier transport and recombination dynamics of an N-polar InGaN/GaN LED.