WorldWideScience

Sample records for adiabatic surface ionization

  1. Adiabatic theory of ionization of atoms by intense laser pulses

    As a first step towards the adiabatic theory of ionization of atoms by intense laser pulses, here we consider the simplest one-dimensional zero-range potential model. The asymptotic solution to the time-dependent Schroedinger equation in the adiabatic regime is obtained and the photoelectron spectrum is calculated. The factorization formula for the photoelectron spectrum in the back-rescattering region, first suggested by Morishita et al. [Phys. Rev. Lett. 100, 013903 (2008)] on the basis of ab initio calculations, is derived analytically.

  2. Adiabatic density surface, neutral density surface, potential density surface, and mixing path

    HUANG Rui-xin

    2014-01-01

    In this paper, adiabatic density surface, neutral density surface and potential density surface are compared. The adiabatic density surface is defined as the surface on which a water parcellcan move adiabatically, without changing its potential temperature and salinity. For a water parcelltaken at a given station and pressure level, the corresponding adiabatic density surface can be determined through simple calculations. This family of surface is neutrally buoyant in the world ocean, and different from other surfaces that are not truly neutrally buoyant. In order to explore mixing path in the ocean, a mixing ratio m is introduced, which is defined as the portion of potential temperature and salinity of a water parcellthat has exchanged with the environment during a segment of migration in the ocean. Two extreme situations of mixing path in the ocean are m=0 (no mixing), which is represented by the adiabatic density curve, and m=1, where the original information is completely lost through mixing. The latter is represented by the neutral density curve. The reality lies in between, namely, 0

  3. Controlling electronic and adiabatic isolation of quantum dots from the substrate: An ionization-energy theoretic study

    Arulsamy, Andrew Das; Kostya; Ostrikov

    2008-01-01

    Recent controversy on the quantum dots dephasing mechanisms (between pure and inelastic) is re-examined by isolating the quantum dots from their substrate by using the appropriate limits of the ionization energy theory and the quantum adiabatic theorem. When the phonons in the quantum dots are isolated adiabatically from the phonons in the substrate, the elastic or pure dephasing becomes the dominant mechanism. On the other hand, for the case where the phonons from the substrate are non-adiab...

  4. Hot-electron nanoscopy using adiabatic compression of surface plasmons

    Giugni, Andrea

    2013-10-20

    Surface plasmon polaritons are a central concept in nanoplasmonics and have been exploited to develop ultrasensitive chemical detection platforms, as well as imaging and spectroscopic techniques at the nanoscale. Surface plasmons can decay to form highly energetic (or hot) electrons in a process that is usually thought to be parasitic for applications, because it limits the lifetime and propagation length of surface plasmons and therefore has an adverse influence on the functionality of nanoplasmonic devices. Recently, however, it has been shown that hot electrons produced by surface plasmon decay can be harnessed to produce useful work in photodetection, catalysis and solar energy conversion. Nevertheless, the surface-plasmon-to-hot-electron conversion efficiency has been below 1% in all cases. Here we show that adiabatic focusing of surface plasmons on a Schottky diode-terminated tapered tip of nanoscale dimensions allows for a plasmon-to-hot-electron conversion efficiency of ∼30%. We further demonstrate that, with such high efficiency, hot electrons can be used for a new nanoscopy technique based on an atomic force microscopy set-up. We show that this hot-electron nanoscopy preserves the chemical sensitivity of the scanned surface and has a spatial resolution below 50 nm, with margins for improvement.

  5. Surface ionization mass spectrometry of opiates

    Key words: surface ionization, adsorption, heterogeneous reactions, surface ionization mass spectrometry, thermodesorption surface ionization spectroscopy, thermoemitter, opiates, extracts of biosamples. Subjects of study. The mass - spectrometric study of thermal - ion emission: surface ionization of opiates by on the surface of oxidized refractory metals. Purpose of work is to establish the regularities of surface ionization (SI) of multi-atomic molecule opiates and their mixtures develop the scientific base of SI methods for high sensitive and selective detection and analysis of these substances in the different objects, including biosamples. Methods of study: surface ionization mass spectrometry, thermodesorption surface ionization spectroscopy. The results obtained and their novelty. For the first time, SI of molecule opiates on the oxidized tungsten surface has been studied and their SI mass-spectra and temperature dependences of ion currents have been obtained, the characteristic heterogeneous reactions of an adsorbed molecules and the channels of monomolecular decays vibrationally-excited ions on their way in mass-spectrometry have been revealed, sublimation energy has been defined, the activation energy of Eact, of these decays has been estimated for given period of time. Additivity of the SI mass-spectra of opiate mixtures of has been established under conditions of joint opiate adsorption. High selectivity of SI allows the extracts of biosamples to be analyzed without their preliminary chromatographic separation. The opiates are ionized by SI with high efficiency (from 34 C/mol to 112 C/mol), which provides high sensitivity of opiate detection by SI/MS and APTDSIS methods from - 10-11 g in the samples under analysis. Practical value. The results of these studies create the scientific base for novel SI methods of high sensitive detection and analysis of the trace amounts of opiates in complicated mixtures, including biosamples without their preliminary

  6. Ab initio adiabatic and quasidiabatic potential energy surfaces of H++ CN system

    Bhargava Anusuri; Sanjay Kumar

    2016-02-01

    We present restricted geometry (collinear and perpendicular approaches of proton) ab initio three dimensional potential energy surfaces for H++ CN system. The calculations were performed at the internally contracted multi-reference configuration interaction level of theory using Dunning’s correlation consistent polarized valence triple zeta basis set. Adiabatic and quasidiabatic surfaces have been computed for the ground and the first excited electronic states. Nonadiabatic effects arising from radial coupling have been analyzed in terms of nonadiabatic coupling matrix elements and coupling potentials.

  7. Non-Adiabatic Dynamics around a Conical Intersection with Surface-Hopping Coupled Coherent States

    Humeniuk, Alexander

    2016-01-01

    An extension of the CCS-method [Chem. Phys. 2004, 304, p. 103-120] for simulating non-adiabatic dynamics with quantum effects of the nuclei is put forward. The time-dependent Schr\\"{o}dinger equation for the motion of the nuclei is solved in a moving basis set. The basis set is guided by classical trajectories, which can hop stochastically between different electronic potential energy surfaces. The non-adiabatic transitions are modelled by a modified version of Tully's fewest switches algorithm. The trajectories consist of Gaussians in the phase space of the nuclei (coherent states) combined with amplitudes for an electronic wave function. The time-dependent matrix elements between different coherent states determine the amplitude of each trajectory in the total multistate wave function; the diagonal matrix elements determine the hopping probabilities and gradients. In this way, both intereference effects and non-adiabatic transitions can be described in a very compact fashion, leading to the exact solution i...

  8. Fewest switches adiabatic surface hopping as applied to vibrational energy relaxation.

    Käb, Günter

    2006-03-01

    In this contribution quantum/classical surface hopping methodology is applied to vibrational energy relaxation of a quantum oscillator in a classical heat bath. The model of a linearly damped (harmonic) oscillator is chosen which can be mapped onto the Brownian motion (Caldeira-Leggett) Hamiltonian. In the simulations Tully's fewest switches surface hopping scheme is adopted with inclusion of dephasing in the adiabatic basis using a simple decoherence algorithm. The results are compared to the predictions of a Redfield-type quantum master equation modeling using the classical heat bath force correlation function as input. Thereby a link is established between both types of quantum/classical approaches. Viewed from the latter perspective, surface hopping with dephasing may be interpreted as "on-the-fly" stochastic realization of a quantum/classical Pauli master equation. PMID:16509644

  9. Explicitly correlated potential energy surface of H3+, including relativistic and adiabatic corrections.

    Kutzelnigg, Werner; Jaquet, Ralph

    2006-11-15

    After a short historical account of the theory of the H3+ ion, two ab initio methods are reviewed that allow the computation of the ground-state potential energy surface (PES) of H3+ in the Born-Oppenheimer (BO) approximation, with microhartree or even sub-microhartree accuracy, namely the R12 method and the method of explicitly correlated Gaussians. The BO-PES is improved by the inclusion of relativistic effects and adiabatic corrections. It is discussed how non-adiabatic effects on rotation and vibration can be simulated by corrections to the moving nuclear masses. The importance of the appropriate analytic fit to the computed points of the PES for the subsequent computation of the rovibronic spectrum is addressed. Some recent extensions of the computed PES in the energy region above the barrier to linearity are reviewed. This involves a large set of input geometries and the correct treatment of the dissociation asymptotics, including the coupling with the first excited singlet state. Some comments on this state as well as on the lowest triplet state of H3+ are made. The paper ends with a few remarks on the ion H5+. PMID:17015373

  10. An Anderson Impurity Model for Efficient Sampling of Adiabatic Potential Energy Surfaces of Transition Metal Complexes

    La Bute-Montiago X; Cox, D L

    2004-01-01

    We present a model intended for rapid sampling of ground and excited state potential energy surfaces for first-row transition metal active sites. The method is computationally inexpensive and is suited for dynamics simulations where (1) adiabatic states are required "on-the-fly" and (2) the primary source of the electronic coupling between the diabatic states is the perturbative spin-orbit interaction among the 3d electrons. The model Hamiltonian we develop is a variant of the Anderson impurity model and achieves efficiency through a physically motivated basis set reduction based on the large value of the d-d Coulomb interaction U_{d} and a Lanczos matrix diagonalization routine to solve for eigenvalues. The model parameters are constrained by fits to the partial density of states (PDOS) obtained from ab initio density functional theory calculations. For a particular application of our model we focus on electron-transfer occuring between cobalt ions solvated by ammonium, incorporating configuration interactio...

  11. Surface-effect corrections for solar-like oscillations using 3D hydrodynamical simulations. I. Adiabatic oscillations

    Sonoi, T.; Samadi, R.; Belkacem, K.; Ludwig, H.-G.; Caffau, E.; Mosser, B.

    2015-11-01

    Context. The CoRoT and Kepler space-borne missions have provided us with a wealth of high-quality observational data that allows for seismic inferences of stellar interiors. This requires the computation of precise and accurate theoretical frequencies, but imperfect modeling of the uppermost stellar layers introduces systematic errors. To overcome this problem, an empirical correction has been introduced by Kjeldsen et al. (2008, ApJ, 683, L175) and is now commonly used for seismic inferences. Nevertheless, we still lack a physical justification allowing for the quantification of the surface-effect corrections. Aims: Our aim is to constrain the surface-effect corrections across the Hertzsprung-Russell (HR) diagram using a set of 3D hydrodynamical simulations. Methods: We used a grid of these simulations computed with the CO5BOLD code to model the outer layers of solar-like stars. Upper layers of the corresponding 1D standard models were then replaced by the layers obtained from the horizontally averaged 3D models. The frequency differences between these patched models and the 1D standard models were then calculated using the adiabatic approximation and allowed us to constrain the Kjeldsen et al. power law, as well as a Lorentzian formulation. Results: We find that the surface effects on modal frequencies depend significantly on both the effective temperature and the surface gravity. We further provide the variation in the parameters related to the surface-effect corrections using their power law as well as a Lorentzian formulation. Scaling relations between these parameters and the elevation (related to the Mach number) is also provided. The Lorentzian formulation is shown to be more robust for the whole frequency spectrum, while the power law is not suitable for the frequency shifts in the frequency range above νmax. Finally, we show that, owing to turbulent pressure, the elevation of the uppermost layers modifies the location of the hydrogen ionization zone and

  12. On the nonlinear energy transfer in the unidirected adiabatic surface waves

    The results of numerical simulation of the adiabatic evolution of waves are presented. The model is based on the fully nonlinear 1D equations of potential waves written in conformal coordinates. It is shown that a wave spectrum is subject to strong fluctuations. Most of such fluctuations are reversible, however a residual effect of the fluctuations causes downshifting of the spectrum. The rate of downshifting depends on nonlinearity. -- Highlights: ► An exact numerical model of 1D surface gravity waves was used for long-term simulations of wave field evolution for different wave steepness. ► Unidirected wave field transformation occurs due to reversible and irreversible wave interactions. The last produces the systematic energy shift towards low wave numbers (downshifting). ► The results support the Benjamin–Feir instability theory and contradict to Hasselmann's results. ► The Hasselmann's theory is unable to predict the development of the unidirected waves and consequently – the waves with a narrow angle spectrum.

  13. Positive ionization of hyperthermal sodium atoms on metal surfaces

    Overbosch, E. G.; Los, J.

    1981-06-01

    The efficiency for positive ionization of Na atoms, reflected from a metallic surface at room temperature, has been measured in the incident energy range Ein = 25-400 eV at an angle of incidence θi = 60°. The surface is W(110) partially covered with sodium atoms. The ionization is almost complete on clean tungsten for all incident energies, and decreases to zero as a function of coverage. Fifty per cent of a 100 eV primary beam is ionized at a surface coverage of 0.8 × 10 14{atoms}/{cm2} (˜0.1 monolayer). Faster projectiles demand larger coverages to be ionized for fifty per cent. The steepness of the ionization curves as a function of coverage decreases as a function of energy. In general it is found, that the ionization probability of backscattered atoms is larger at increasing incident energy. Comparison of the measured data with the theory of resonance ionization/neutralization confirms the model, and shows that the calculated shift of the valence level of the Na atom near the surface is in agreement with the experimental results.

  14. Representing Adiabatic Potential Energy Surfaces Coupled by Conical Intersections in their Full Dimensionality Using Coupled Quasi-Diabatic States

    Yarkony, David

    2015-03-01

    The construction of fit single state potential energy surfaces (PESs), analytic representations of ab initio electronic energies and energy gradients, is now well established. These single state PESs, which are essential for accurate quantum dynamics and have found wide application in more approximate quasi-classical treatments, have revolutionized adiabatic dynamics. The situation for nonadiabatic processes involving dissociative and large amplitude motion is less sanguine. In these cases, compared to single electronic state dynamics, both the electronic structure data and the representation are more challenging to determine. We describe the recent development and applications of algorithms that enable description of multiple adiabatic electronic potential energy surfaces coupled by conical intersections in their full dimensionality using coupled quasi-diabatic states. These representations are demonstrably quasi-diabatic, provide accurate representations of conical intersection seams and can smooth out the discontinuities in electronic structure energies due to changing active orbital spaces that routinely afflict global multistate representations.

  15. Adiabatic surface temperature as thermal/structural parameter in fire modeling: Thermal analysis for different wall conductivities

    The new useful concept of “Adiabatic Surface Temperature” or more commonly known as AST, introduced by Wickström et al. in 2007, is investigated in this study. Adiabatic surface temperature can be used for bridging the gap between fire models and temperature models; for example, it offers the opportunity to transfer both thermal information of the gas and the net heat flux to the solid phase model, obtained by CFD analysis. In this study two numerical analyses are carried out in order to evaluate the effect of wall thermal conductivity and of convective heat transfer coefficient on the adiabatic surface temperature as thermal/structural parameter in fire modeling. First one CFD analysis simulating a fire scenario, “conjugate heat transfer”, with a square beam exposed to hot surface, is carried out to calculate AST, convective heat transfer coefficient and temperature field in the beam. In the second one, a conductive analysis is carried out on “standalone beam” imposing a third type boundary condition on its boundaries assuming the AST, evaluated in the conjugate analysis, as external temperature. Different convective heat transfer coefficients are imposed on the beam walls; the beam is of concrete or steel. Results are presented in terms of net heat flux on beam surfaces, convective heat transfer coefficients and temperature profiles on the beam walls, temperature fields for the two, CFD and conductive, analyses and the relative temperature and net heat flux percent errors. Results underline that convective heat transfer coefficient profiles and adiabatic surface temperatures on the bottom and lateral beam walls are independent of the wall thermal conductivity value, whereas the net heat flux values increase as wall thermal conductivity increases, fixed the emissivity. - Highlights: •The new useful concept of “adiabatic surface temperature” (AST) is investigated. •The effect of wall thermal conductivity and of convective heat transfer

  16. Surface Waves in the paritally ionized solar plasma slab

    Pandey, B P

    2013-01-01

    The properties of surface waves in the partially ionized, incompressible magnetized plasma slab are investigated in the present work. The waves are affected by the non ideal MHD effects which causes the finite drift of the magnetic field in the medium. When the finite drift of the magnetic field is ignored, the characteristics of the wave propagation in the partially ionized plasma fluid is similar to the ideal MHD except now the propagation properties depend on the fractional ionization of the medium. In the presence of Hall diffusion, the propagation of the sausage and kink surface waves depends on the level of fractional ionization of the medium. When both the Hall and Pedersen diffusion are present in the medium, the waves undergoes damping. For typical solar parameters, waves may damp over few minutes.

  17. Coupled Wavepackets for Non-Adiabatic Molecular Dynamics: A Generalization of Gaussian Wavepacket Dynamics to Multiple Potential Energy Surfaces

    White, Alexander; Mozyrsky, Dmitry

    2016-01-01

    Accurate simulation of the non-adiabatic dynamics of molecules in excited electronic states is key to understanding molecular photo-physical processes. Here we present a novel method, based on a semiclassical approximation, that is as efficient as the commonly used mean field Ehrenfest or ad hoc Surface Hopping methods and properly accounts for interference and decoherence effects. This novel method is an extension of Hellers Thawed Gaussian wavepacket dynamics that includes coupling between potential energy surfaces. The accuracy of the method can be systematically improved.

  18. Ionizing program environment at the Mars surface

    Simonsen, Lisa C.; Nealy, John E.; Townsend, Lawrence W.; Wilson, John W.

    The Langley cosmic ray transport code and the Langley nucleon transport code are used to quantify the transport and attenuation of galactic cosmic rays and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low-density and a high-density carbon dioxide model of the atmosphere which, in the vertical direction, provide a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose-equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose-equivalents which would have been incurred at the surface from three large solar flare events are also calculated. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

  19. Ab initio ground and the first excited adiabatic and quasidiabatic potential energy surfaces of H + + CO system

    George, D. X. F.; Kumar, Sanjay

    2010-08-01

    Ab initio global adiabatic as well as quasidiabatic potential energy surfaces for the ground and the first excited electronic states of the H + + CO system have been computed as a function of the Jacobi coordinates ( R, r, γ) using Dunning's cc-pVTZ basis set at the internally contracted multi-reference (single and double) configuration interaction level of accuracy. In addition, nonadiabatic coupling matrix elements arising from radial motion, mixing angle and coupling potential have been computed using the ab initio procedure [Simah et al. (1999) [66

  20. Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

    We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a |J,KM〉 = |1, − 1〉 state by using classical Monte—Carlo method. Our study shows that the loading efficiency of our trap can reach ∼ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth (i.e., lowering the trapping voltage), and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 mK to ∼ 5.8 mK when the trapping voltage is reduced from −35 kV to −3 kV. (atomic and molecular physics)

  1. Non-adiabatic processes in the charge transfer reaction of O2 molecules with potassium surfaces without dissociation

    Krix, David; Nienhaus, Hermann

    2014-08-01

    Thin potassium films grown on Si(001) substrates are used to measure internal chemicurrents and the external emission of exoelectrons simultaneously during adsorption of molecular oxygen on K surfaces at 120 K. The experiments clarify the dynamics of electronic excitations at a simple metal with a narrow valence band. X-ray photoemission reveals that for exposures below 5 L almost exclusively peroxide K2O2 is formed, i.e., no dissociation of the molecule occurs during interaction. Still a significant chemicurrent and a delayed exoelectron emission are detected due to a rapid injection of unoccupied molecular levels below the Fermi level. Since the valence band width of potassium is approximately equal to the potassium work function (2.4 eV) the underlying mechanism of exoemission is an Auger relaxation whereas chemicurrents are detected after resonant charge transfer from the metal valence band into the injected level. The change of the chemicurrent and exoemission efficiencies with oxygen coverage can be deduced from the kinetics of the reaction and the recorded internal and external emission currents traces. It is shown that the non-adiabaticity of the reaction increases with coverage due to a reduction of the electronic density of states at the surface while the work function does not vary significantly. Therefore, the peroxide formation is one of the first reaction systems which exhibits varying non-adiabaticity and efficiencies during the reaction. Non-adiabatic calculations based on model Hamiltonians and density functional theory support the picture of chemicurrent generation and explain the rapid injection of hot hole states by an intramolecular motion, i.e., the expansion of the oxygen molecule on the timescale of a quarter of a vibrational period.

  2. Non-adiabatic processes in the charge transfer reaction of O{sub 2} molecules with potassium surfaces without dissociation

    Krix, David; Nienhaus, Hermann, E-mail: hermann.nienhaus@uni-due.de [Faculty of Physics, University of Duisburg-Essen and Center of Nanointegration Duisburg-Essen (CENIDE), Lotharstr. 1, D-47048 Duisburg (Germany)

    2014-08-21

    Thin potassium films grown on Si(001) substrates are used to measure internal chemicurrents and the external emission of exoelectrons simultaneously during adsorption of molecular oxygen on K surfaces at 120 K. The experiments clarify the dynamics of electronic excitations at a simple metal with a narrow valence band. X-ray photoemission reveals that for exposures below 5 L almost exclusively peroxide K{sub 2}O{sub 2} is formed, i.e., no dissociation of the molecule occurs during interaction. Still a significant chemicurrent and a delayed exoelectron emission are detected due to a rapid injection of unoccupied molecular levels below the Fermi level. Since the valence band width of potassium is approximately equal to the potassium work function (2.4 eV) the underlying mechanism of exoemission is an Auger relaxation whereas chemicurrents are detected after resonant charge transfer from the metal valence band into the injected level. The change of the chemicurrent and exoemission efficiencies with oxygen coverage can be deduced from the kinetics of the reaction and the recorded internal and external emission currents traces. It is shown that the non-adiabaticity of the reaction increases with coverage due to a reduction of the electronic density of states at the surface while the work function does not vary significantly. Therefore, the peroxide formation is one of the first reaction systems which exhibits varying non-adiabaticity and efficiencies during the reaction. Non-adiabatic calculations based on model Hamiltonians and density functional theory support the picture of chemicurrent generation and explain the rapid injection of hot hole states by an intramolecular motion, i.e., the expansion of the oxygen molecule on the timescale of a quarter of a vibrational period.

  3. Non-adiabatic processes in the charge transfer reaction of O2 molecules with potassium surfaces without dissociation

    Thin potassium films grown on Si(001) substrates are used to measure internal chemicurrents and the external emission of exoelectrons simultaneously during adsorption of molecular oxygen on K surfaces at 120 K. The experiments clarify the dynamics of electronic excitations at a simple metal with a narrow valence band. X-ray photoemission reveals that for exposures below 5 L almost exclusively peroxide K2O2 is formed, i.e., no dissociation of the molecule occurs during interaction. Still a significant chemicurrent and a delayed exoelectron emission are detected due to a rapid injection of unoccupied molecular levels below the Fermi level. Since the valence band width of potassium is approximately equal to the potassium work function (2.4 eV) the underlying mechanism of exoemission is an Auger relaxation whereas chemicurrents are detected after resonant charge transfer from the metal valence band into the injected level. The change of the chemicurrent and exoemission efficiencies with oxygen coverage can be deduced from the kinetics of the reaction and the recorded internal and external emission currents traces. It is shown that the non-adiabaticity of the reaction increases with coverage due to a reduction of the electronic density of states at the surface while the work function does not vary significantly. Therefore, the peroxide formation is one of the first reaction systems which exhibits varying non-adiabaticity and efficiencies during the reaction. Non-adiabatic calculations based on model Hamiltonians and density functional theory support the picture of chemicurrent generation and explain the rapid injection of hot hole states by an intramolecular motion, i.e., the expansion of the oxygen molecule on the timescale of a quarter of a vibrational period

  4. Adiabatic and non-adiabatic processes in strong Coulomb fields

    Adiabatic and non-adiabatic behaviour of relativistic electrons in external Coulomb fields of time-dependent strength is studied within the framework of a model for the description of a shell electron's behaviour during a heavy-ion collision. A classification scheme for types of non-adiabatic behaviour is suggested; its relevance for the analysis of pair production processes in strong Coulomb fields is discussed (K-Shell Ionization). An ansatz for the vacuum polarization potential is introduced and employed to demonstrate the special role of vacuum polarization for adiabatic and non-adiabatic behaviour in very strong Coulomb fields (Zα > 1). The implications of the underlaying specific features of the vacuum polarization charge density in very strong fields for pair production mechanisms are considered. (orig.)

  5. Ab initio adiabatic and quasidiabatic potential energy surfaces of lowest four electronic states of the H++O2 system

    Xavier, F. George D.; Kumar, Sanjay

    2010-10-01

    Ab initio global adiabatic and quasidiabatic potential energy surfaces of lowest four electronic (1-4 A3″) states of the H++O2 system have been computed in the Jacobi coordinates (R,r,γ) using Dunning's cc-pVTZ basis set at the internally contracted multireference (single and double) configuration interaction level of accuracy, which are relevant to the dynamics studies of inelastic vibrational and charge transfer processes observed in the scattering experiments. The computed equilibrium geometry parameters of the bound [HO2]+ ion in the ground electronic state and other parameters for the transition state for the isomerization process, HOO+⇌OOH+ are in good quantitative agreement with those available from the high level ab initio calculations, thus lending credence to the accuracy of the potential energy surfaces. The nonadiabatic couplings between the electronic states have been analyzed in both the adiabatic and quasidiabatic frameworks by computing the nonadiabatic coupling matrix elements and the coupling potentials, respectively. It is inferred that the dynamics of energy transfer processes in the scattering experiments carried out in the range of 9.5-23 eV would involve all the four electronic states.

  6. Plasma adiabatic lapse rate

    Amendt, Peter; Bellei, Claudio; Wilks, Scott

    2012-01-01

    The plasma analog of an adiabatic lapse rate (or temperature variation with height) in atmospheric physics is obtained. A new source of plasma temperature gradient in a binary ion species mixture is found that is proportional to the concentration gradient and difference in average ionization states . Application to inertial-confinement-fusion implosions indicates a potentially strong effect in plastic (CH) ablators that is not modeled with mainline (single-fluid) simulations. An associated pl...

  7. Ionization efficiency estimations for the SPES surface ion source

    Manzolaro, M.; Andrighetto, A.; Meneghetti, G.; Rossignoli, M.; Corradetti, S.; Biasetto, L.; Scarpa, D.; Monetti, A.; Carturan, S.; Maggioni, G.

    2013-12-01

    Ion sources play a crucial role in ISOL (Isotope Separation On Line) facilities determining, with the target production system, the ion beam types available for experiments. In the framework of the SPES (Selective Production of Exotic Species) INFN (Istituto Nazionale di Fisica Nucleare) project, a preliminary study of the alkali metal isotopes ionization process was performed, by means of a surface ion source prototype. In particular, taking into consideration the specific SPES in-target isotope production, Cs and Rb ion beams were produced, using a dedicated test bench at LNL (Laboratori Nazionali di Legnaro). In this work the ionization efficiency test results for the SPES Ta surface ion source prototype are presented and discussed.

  8. Desorption electrospray ionization of explosives on surfaces: sensitivity and selectivity enhancement by reactive desorption electrospray ionization.

    Cotte-Rodríguez, Ismael; Takáts, Zoltán; Talaty, Nari; Chen, Huanwen; Cooks, R Graham

    2005-11-01

    Desorption electrospray ionization (DESI), an ambient mass spectrometry technique, is used for trace detection of the explosives trinitrohexahydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6-trinitrotoluene (TNT), Pentaerythritol tetranitrate (PETN), and their plastic compositions (Composition C-4, Semtex-H, Detasheet) directly from a wide variety of surfaces (metal, plastic, paper, polymer) without sample preparation or pretreatment. Analysis of the explosives is performed under ambient conditions from virtually any surface in very short times (<5 s) including confirmatory tandem mass spectrometry (MS/MS) experiments, while retaining the sensitivity and specificity that mass spectrometry offers. Increased selectivity is obtained both by MS/MS and by performing additional experiments in which additives are included in the spray solvent. These reactive DESI experiments (reactions accompanying desorption) produce such ions as the chloride and trifluoroacetate adducts of RDX and HMX or the Meisenheimer complex of TNT. Desorption atmospheric pressure chemical ionization, a variant of DESI that uses gas-phase ions generated by atmospheric pressure corona discharges of toluene or other organic compounds, provides evidence for a heterogeneous-phase (gaseous ion/absorbed analyte) charge-transfer mechanism of DESI ionization in the case of explosives. Plastic explosives on surfaces were analyzed directly as fingerprints, without sample preparation, to test DESI as a possible method for in situ detection of explosives-contaminated surfaces. DESI also allowed detection of explosives in complex matrixes, including lubricants, household cleaners, vinegar, and diesel fuel. Absolute limits of detection for the neat explosives were subnanogram in all cases and subpicogram in the case of TNT. The DESI response was linear over 3 orders of magnitude for TNT. Quantification of RDX on paper gave a precision (RSD) of 2.3%. Pure water could be used

  9. Ion beam studies of surfaces by multiphoton resonance ionization of sputtered neutrals

    Ionization of neutral atoms sputtered from ion bombarded solids by multiphoton resonance ionization has been recently demonstrated. The ionization efficiency is several orders of magnitude greater than other post-ionization methods. This approach should find applications in the characterization of the chemistry and structure of solid surfaces and in the trace analysis of a wide variety of materials. (author)

  10. Auger neutralization and ionization in grazing ion-surface interaction

    Zimny, R. (Inst. of Nuclear Physics, Univ. Muenster (Germany)); Miskovic, Z.L. (Boris Kidric Inst. of Nuclear Sciences, Belgrade (Yugoslavia))

    1991-06-01

    The effect of the projectile velocity parallel to the surface v{sub parallel} on Auger-type neutralization and ionization processes during grazing scattering of atomic particles from surfaces will be discussed. It is found that, contrary to the static case (v{sub parallel}=0), under grazing collision the Auger-type electron exchange between the metallic conduction band and an atomic orbital is a two-way process: atomic particles may be neutralized, as well as ionized. In particular, two types of v{sub parallel} dependence are obtained: (1) a gradual decrease of the final atomic level population with increasing v{sub parallel} in the case of atomic levels below the Fermi level E{sub F}, and (2) a peak-shaped v{sub parallel} dependence for atomic levels above E{sub F}. The leading features of these basic electron-exchange mechanisms between atoms and surfaces are illustrated for various atomic quasi-one-electron systems scattered from silver and magnesium surfaces. (orig.).

  11. Studies of nanosecond pulse surface ionization wave discharges over solid and liquid dielectric surfaces

    Surface ionization wave discharges generated by high-voltage nanosecond pulses, propagating over a planar quartz surface and over liquid surfaces (distilled water and 1-butanol) have been studied in a rectangular cross section test cell. The discharge was initiated using a custom-made, alternating polarity, high-voltage nanosecond pulse plasma generator, operated at a pulse repetition rate of 100–500 Hz, with a pulse peak voltage and current of 10–15 kV and 7–20 A, respectively, a pulse FWHM of ∼100 ns, and a coupled pulse energy of 2–9 mJ/pulse. Wave speed was measured using a capacitive probe. ICCD camera images demonstrated that the ionization wave propagated predominantly over the quartz wall or over the liquid surface adjacent to the grounded waveguide placed along the bottom wall of the test cell. Under all experimental conditions tested, the surface plasma ‘sheet’ was diffuse and fairly uniform, both for positive and negative polarities. The parameters of ionization wave discharge propagating over distilled water and 1-butanol surfaces were close to those of the discharge over a quartz wall. No perturbation of the liquid surface by the discharge was detected. In most cases, the positive polarity surface ionization wave propagated at a higher speed and over a longer distance compared to the negative polarity wave. For all three sets of experiments (surface ionization wave discharge over quartz, water and 1-butanol), wave speed and travel distance decreased with pressure. Diffuse, highly reproducible surface ionization wave discharge was also observed over the liquid butanol–saturated butanol vapor interface, as well as over the distilled water–saturated water vapor interface, without buffer gas flow. No significant difference was detected between surface ionization discharges sustained using single-polarity (positive or negative), or alternating polarity high-voltage pulses. Plasma emission images yielded preliminary evidence of charge

  12. Ionization dynamics of water dimer on ice surface

    Tachikawa, Hiroto

    2016-05-01

    The solid surface provides an effective two-dimensional reaction field because the surface increases the encounter probability of bi-molecular collision reactions. Also, the solid surface stabilizes a reaction intermediate because the excess energy generated by the reaction dissipates into the bath modes of surface. The ice surface in the universe is one of the two dimensional reaction fields. However, it is still unknown how the ice surface affects to the reaction mechanism. In the present study, to elucidate the specific property of the ice surface reaction, ionization dynamics of water dimer adsorbed on the ice surface was theoretically investigated by means of direct ab-initio molecular dynamics (AIMD) method combined with ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) technique, and the result was compared with that of gas phase reaction. It was found that a proton is transferred from H2O+ to H2O within the dimer and the intermediate complex H3O+(OH) is formed in both cases. However, the dynamic features were different from each other. The reaction rate of the proton transfer on the ice surface was three times faster than that in the gas phase. The intermediate complex H3O+(OH) was easily dissociated to H3O+ and OH radical on the ice surface, and the lifetime of the complex was significantly shorter than that of gas phase (100 fs vs. infinite). The reason why the ice surface accelerates the reaction was discussed in the present study.

  13. Radioactive beams produced by the ISOL method: development for laser ionization and for surface ionization

    The works were carried out in the framework of the research program PARRNe (production of radioactive neutron-rich nuclei). This program aims to determine optimal conditions to produce intense beams of neutron-rich isotopes. This thesis treats multiple technical aspects related to the production of separate radioactive isotopes in line (ISOL). It deals mainly with the development of the target-source unit which is the key element for projects such as SPIRAL-2 or EURISOL.The first part presents the various methods using fission as production mode and compares them: fission induced by thermal neutrons, induced by fast neutrons and photofission. The experiment carried out at CERN validated the interest of the photofission as a promising production mode of radioactive ions. That is why the institute of nuclear physics of Orsay decided to build a linear electron accelerator at the Tandem d'Orsay (ALTO).The second part of this thesis deals with the development of uranium targets. The X-rays diffraction and Scanning Electron Microscopy have been used as analysis techniques. They allowed to determine the chemical and structural characteristics of uranium carbide targets as function of various heating temperatures. After the production, the process of ionization has been studied. Two types of ion source have been worked out: the first one is a surface ion source and the second one is a source based on resonant ionization by laser. These two types of sources will be used for the ALTO project. (author)

  14. Topology of the Adiabatic Potential Energy Surfaces for theResonance States of the Water Anion

    Haxton, Daniel J.; Rescigno, Thomas N.; McCurdy, C. William

    2005-04-15

    The potential energy surfaces corresponding to the long-lived fixed-nuclei electron scattering resonances of H{sub 2}O relevant to the dissociative electron attachment process are examined using a combination of ab initio scattering and bound-state calculations. These surfaces have a rich topology, characterized by three main features: a conical intersection between the {sup 2}A{sub 1} and {sup 2}B{sub 2} Feshbach resonance states; charge-transfer behavior in the OH ({sup 2}{Pi}) + H{sup -} asymptote of the {sup 2}B{sub 1} and {sup 2}A{sub 1} resonances; and an inherent double-valuedness of the surface for the {sup 2}B{sub 2} state the C{sub 2v} geometry, arising from a branch-point degeneracy with a {sup 2}B{sub 2} shape resonance. In total, eight individual seams of degeneracy among these resonances are located.

  15. On the accuracy of surface hopping dynamics in condensed phase non-adiabatic problems

    Chen, Hsing-Ta; Reichman, David R.

    2016-03-01

    We perform extensive benchmark comparisons of surface hopping dynamics with numerically exact calculations for the spin-boson model over a wide range of energetic and coupling parameters as well as temperature. We find that deviations from golden-rule scaling in the Marcus regime are generally small and depend sensitively on the energetic bias between electronic states. Fewest switches surface hopping (FSSH) is found to be surprisingly accurate over a large swath of parameter space. The inclusion of decoherence corrections via the augmented FSSH algorithm improves the accuracy of dynamical behavior compared to exact simulations, but the effects are generally not dramatic, at least for the case of an environment modeled with the commonly used Debye spectral density.

  16. Size-Reduction Template Stripping of Smooth Curved Metallic Tips for Adiabatic Nanofocusing of Surface Plasmons.

    Johnson, Timothy W; Klemme, Daniel J; Oh, Sang-Hyun

    2016-06-01

    We present a new technique to engineer metallic interfaces to produce sharp tips with smooth curved surfaces and variable tip angles, as well as ridges with arbitrary contour shapes, all of which can be integrated with grating couplers for applications in plasmonics and nanophotonics. We combine template stripping, a nanofabrication scheme, with atomic layer deposition (ALD) to produce the ultrasharp nanoscale tips and wedges using only conventional photolithography. Conformal ALD coating of insulators over silicon trench molds of various shapes reduces their widths to make nanoscale features without high-resolution lithography. Along with a metal deposition and template stripping, this size-reduction scheme can mass-produce narrow and ultrasharp (optical spectroscopy, plasmonic waveguides, particle trapping, hot-electron plasmonics, and nonlinear optics. PMID:27156522

  17. Simulation and Comparison of Martian Surface Ionization Radiation

    Kim, Myung-Hee Y.; Zeitlin, Cary; Hassler, Donald M.; Cucinotta, Francis A.

    2013-01-01

    The spectrum of energetic particle radiation and corresponding doses at the surface of Mars is being characterized by the Radiation Assessment Detector (RAD), one of ten science instruments on the Mars Science Laboratory (MSL) Curiosity Rover. The time series of dose rate for the first 300 Sols after landing on Mars on August 6, 2012 is presented here. For the comparison to RAD measurements of dose rate, Martian surface ionization radiation is simulated by utilizing observed space quantities. The GCR primary radiation spectrum is calculated by using the Badhwar-O'Neill 2011 (BO11) galactic cosmic ray (GCR) model, which has been developed by utilizing all balloon and satellite GCR measurements since 1955 and the newer 1997-2012 Advanced Composition Explorer (ACE) measurements. In the BO11 model, solar modulation of the GCR primary radiation spectrum is described in terms of the international smoothed sunspot number and a time delay function. For the transport of the impingent GCR primary radiation through Mars atmosphere, a vertical distribution of atmospheric thickness at each elevation is calculated using the vertical profiles of atmospheric temperature and pressure made by Mars Global Surveyor measurements. At Gale Crater in the southern hemisphere, the seasonal variation of atmospheric thickness is accounted for the daily atmospheric pressure measurements of the MSL Rover Environmental Monitoring Station (REMS) by using low- and high-density models for cool- and warm-season, respectively. The spherically distributed atmospheric distance is traced along the slant path, and the resultant directional shielding by Martian atmosphere is coupled with Curiosity vehicle for dose estimates. We present predictions of dose rate and comparison to the RAD measurements. The simulation agrees to within +/- 20% with the RAD measurements showing clearly the variation of dose rate by heliospheric conditions, and presenting the sensitivity of dose rate by atmospheric pressure

  18. Mixed quantum-classical dynamics on the exact time-dependent potential energy surface: A fresh look at non-adiabatic processes

    Agostini, Federica; Suzuki, Yasumitsu; Gross, E K U

    2013-01-01

    The exact nuclear time-dependent potential energy surface arises from the exact decomposition of electronic and nuclear motion, recently presented in [A. Abedi, N. T. Maitra, and E. K. U. Gross, Phys. Rev. Lett. 105, 123002 (2010)]. Such time-dependent potential drives nuclear motion and fully accounts for the coupling to the electronic subsystem. We investigate the features of the potential in the context of electronic non-adiabatic processes and employ it to study the performance of the classical approximation on nuclear dynamics. We observe that the potential, after the nuclear wave-packet splits at an avoided crossing, develops dynamical steps connecting different regions, along the nuclear coordinate, in which it has the same slope as one or the other adiabatic surface. A detailed analysis of these steps is presented for systems with different non-adiabatic coupling strength. The exact factorization of the electron-nuclear wave-function is at the basis of the decomposition. In particular, the nuclear par...

  19. Surface and Bulk Nanostructuring of Polymers Using Ionizing Radiation

    Ionizing radiation has long been known tobe a powerful tool in modifying and controlled the properties, forms and eventually end-uses of polymeric materials for a variety of applications. Industrial applications are full of successful examples of macro scale, bulk property modifications by radiation. Extremely short wavelength of ionizing radiation however, makes it an important and useful tool in creating very small size structures in polymers

  20. Influence of wall emissivity and convective heat transfer coefficient on the adiabatic surface temperature as thermal/structural parameter in fire modeling

    In fire engineering analysis, one of the open problem is the transfer of thermal parameters obtained by fire CFD model to FEM models for structural analysis. In this study the new useful concept of “Adiabatic Surface Temperature” or more commonly known as AST, introduced by Wickström, is investigated. The adiabatic surface temperature offers the opportunity to transfer both thermal information of the gas and the net heat flux to the solid phase model, obtained by CFD analysis. In this study two CFD analyses are carried out in order to evaluate the effect of emissivity and of convective heat transfer coefficient to determine the AST. First one CFD analysis simulating a fire scenario, “conjugate heat transfer”, with a square steel beam exposed to hot surface is carried out to calculate AST, heat convective coefficient and temperature field in the beam. Second one, a conductive analysis is carried out on “standalone beam” imposing a third type boundary condition on its boundaries assuming the AST, evaluated in the conjugate analysis, as external temperature. Different heat convective coefficients are imposed on the beam walls. The comparison between results obtained by means of the two proposed analyses shows the use of AST as transfer thermal parameter between CFD (Computational Fluid Dynamic) and FEM (Finite Element Method) models is appropriate when the convective heat transfer coefficient is properly evaluated. -- Highlights: ► An open problem is to transfer parameters obtained by thermal to structural models. ► The useful concept of “Adiabatic Surface Temperature” (AST) is investigated. ► The AST use is right for properly evaluated convective heat transfer coefficient

  1. Silicon nitride nanoparticles for surface-assisted laser desorption/ionization of small molecules

    Conventional matrix-assisted laser desorption/ionization mass spectrometry is limited to analyses of higher molecular weight compounds due to high background noise generated by the matrix in the lower mass region. Surface-assisted laser desorption/ionization (SALDI) mass spectrometry is an alternative solution to this problem. Nanoparticles, structured silicon surfaces and carbon allotropes are commonly used as SALDI surfaces. Here, for the first time, we demonstrate the application of silicon nitride nanoparticles as a suitable medium for laser desorption/ionization of small drug molecules.

  2. Direct, trace level detection of explosives on ambient surfaces by desorption electrospray ionization mass spectrometry.

    Takáts, Zoltán; Cotte-Rodriguez, Ismael; Talaty, Nari; Chen, Huanwen; Cooks, R Graham

    2005-04-21

    Desorption electrospray ionization (DESI) mass spectrometry is used to detect trace amounts of explosives present on a variety of ambient surfaces in 5-second analysis times without any sample preparation. PMID:15834468

  3. Surface ionization mass spectrometry of drugs in the thermal and hyperthermal energy range -- a comparative study

    Dagan, Shai; Amirav, Aviv; Fujü, Toshihiro

    1995-12-01

    Thermal and hyperthermal surface ionization (SI) mass spectra of nicotine, caffeine and lidocaine were obtained using a rhenium oxide surface. Thermal surface ionization was studied on an oxidized surface positioned inside an electron impact ion source, while hyperthermal surface ionization (HSI) was obtained upon seeding the compounds into a hydrogen or helium supersonic molecular beam that scattered from the rhenium oxide surface. Both HSI and SI provide rich, informative and complementary mass spectral information. The results indicate that SI follows thermal dissociation processes on the surface prior to the desorption of the ion, while in HSI no thermal equilibrium is established and the ionization process is impulsive, followed by mostly unimolecular ion dissociation. HSI mass spectra are similar to electron impact mass spectra in the fragment ion masses, but the observed relative intensities are different. HSI is a softer ionization method compared to SI, and enables the degree of ion fragmentation to be tuned so that it can be minimized to a low level at low molecular kinetic energy. In SI, limited control over the degree of fragmentation is possible through the surface temperature. The analytical mass spectrometric applications of SI and HSI are briefly mentioned.

  4. Ab initio adiabatic and quasidiabatic potential energy surfaces of H+ + CO system: A study of the ground and the first three excited electronic states

    Saheer, V. C.; Kumar, Sanjay

    2016-01-01

    The global ground and first three excited electronic state adiabatic as well as the corresponding quasidiabatic potential energy surfaces is reported as a function of nuclear geometries in the Jacobi coordinates ( R → , r → , γ ) using Dunning's cc-pVTZ basis set at the internally contracted multi-reference (single and double) configuration interaction level of accuracy. Nonadiabatic couplings, arising out of relative motion of proton and the vibrational motion of CO, are also reported in terms of coupling potentials. The quasidiabatic potential energy surfaces and the coupling potentials have been obtained using the ab initio procedure [Simah et al., J. Chem. Phys. 111, 4523 (1999)] for the purpose of dynamics studies.

  5. Development of a surface ionization source for the SPIRAL 2 project

    Development of new radioactive beams, and thus of new target ion sources (TISs) for isotope-separator-on-line production systems are in progress at GANIL for the SPIRAL 2 project. The efficiency and time response measurements of each step in the production process are crucial to predict and maximize the available yields, in particular, for short lived isotopes. This paper presents a method for measuring these quantities that makes use of a stable alkali chopped beam of controlled intensity. This method was applied to surface ionization source test for high efficiency. Results of recent experiments are presented that include ionization efficiency measurements for Cs, Rb, K, Na, and Li with a graphite and rhenium ionizer and dwell time of these alkalis on graphite. The results enabled to design a first surface ionization source prototype which will be installed in the SPIRAL 2 TIS.

  6. Plasma channel created by ionization of gas by a surface wave

    Conditions for gas ionization in the field of a slow surface wave excited by a microwave source are considered. The gas ionization rate and the plasma density distribution over the radius of the discharge tube were studied by the optical method. The experiments were conducted in a dielectric tube with a radius much smaller than the tube length, the gas pressure being ∼1–3 Torr. It is shown that the stationary distribution of the plasma density is determined by diffusion processes

  7. Modelling non-adiabatic effects in H{sub 3}{sup +}: Solution of the rovibrational Schrödinger equation with motion-dependent masses and mass surfaces

    Mátyus, Edit, E-mail: matyus@chem.elte.hu [Institute of Chemistry, Eötvös University, P.O. Box 32, H-1518 Budapest 112 (Hungary); Szidarovszky, Tamás [MTA-ELTE Research Group on Complex Chemical Systems, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary); Császár, Attila G., E-mail: csaszar@chem.elte.hu [Institute of Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary and MTA-ELTE Research Group on Complex Chemical Systems, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary)

    2014-10-21

    Introducing different rotational and vibrational masses in the nuclear-motion Hamiltonian is a simple phenomenological way to model rovibrational non-adiabaticity. It is shown on the example of the molecular ion H{sub 3}{sup +}, for which a global adiabatic potential energy surface accurate to better than 0.1 cm{sup −1} exists [M. Pavanello, L. Adamowicz, A. Alijah, N. F. Zobov, I. I. Mizus, O. L. Polyansky, J. Tennyson, T. Szidarovszky, A. G. Császár, M. Berg et al., Phys. Rev. Lett. 108, 023002 (2012)], that the motion-dependent mass concept yields much more accurate rovibrational energy levels but, unusually, the results are dependent upon the choice of the embedding of the molecule-fixed frame. Correct degeneracies and an improved agreement with experimental data are obtained if an Eckart embedding corresponding to a reference structure of D{sub 3h} point-group symmetry is employed. The vibrational mass of the proton in H{sub 3}{sup +} is optimized by minimizing the root-mean-square (rms) deviation between the computed and recent high-accuracy experimental transitions. The best vibrational mass obtained is larger than the nuclear mass of the proton by approximately one third of an electron mass, m{sub opt,p}{sup (v)}=m{sub nuc,p}+0.31224 m{sub e}. This optimized vibrational mass, along with a nuclear rotational mass, reduces the rms deviation of the experimental and computed rovibrational transitions by an order of magnitude. Finally, it is shown that an extension of the algorithm allowing the use of motion-dependent masses can deal with coordinate-dependent mass surfaces in the rovibrational Hamiltonian, as well.

  8. Quantum adiabatic machine learning

    Pudenz, Kristen L.; Lidar, Daniel A.

    2011-01-01

    We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. We apply and illustrate this app...

  9. Can clouds enhance long-range transport of low volatile, ionizable and surface-active chemicals?

    Franco, Antonio; Trapp, Stefan

    2011-01-01

    potential of non-volatile substances. The liquid water content of clouds and the high specific surface of frozen or liquid cloud droplets can significantly contribute to the total activity capacity (i.e. the capacity to sorb chemicals) of the atmosphere for non-volatile, ionizable and surface active...... volatile or ionizable chemicals to investigate the potential of clouds to enhance the atmospheric transport potential. Probability density functions were derived for input substance properties and environmental parameters to quantify uncertainty and variability and probabilistic simulations at steady state...... were run for a constant emission to the atmospheric boundary layer to identify key model inputs. The degradation rate, the duration of dry and wet periods and the parameters describing air-water bulk partitioning (KAW and T) and ionization (pKa and pH) determine the residence time in the ABL. In the...

  10. A new concept positive (negative) surface ionization source for RIB applications

    A versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed. fabricated, and tests completed which can operate in either positive- or negative-ion beam generation modes without mechanical changes to the source. The highly permeable, composite Ir/C has an intrinsic work function of 0 = 5.29 eV and can be used directly for the generation of positive-ion beams of highly electropositive elements. For negative-surface ionization, the work function is lowered by dynamic flow of a highly electropositive adsorbate such as Cs through the ionizer matrix. The results of initial testing indicate that the source is reliable, stable and easy to operate, with efficiencies for Cs+ estimated to exceed 60% and as high as ∼50% for F- generation. The design features, operational principles, and initial performance of the source for generating Cs+ and F-, when operated with Cs, are discussed in this article

  11. Electron wavepacket dynamics in highly quasi-degenerate coupled electronic states: A theory for chemistry where the notion of adiabatic potential energy surface loses the sense

    Yonehara, Takehiro; Takatsuka, Kazuo

    2012-12-01

    We develop a theory and the method of its application for chemical dynamics in systems, in which the adiabatic potential energy hyper-surfaces (PES) are densely quasi-degenerate to each other in a wide range of molecular geometry. Such adiabatic electronic states tend to couple each other through strong nonadiabatic interactions. Technically, therefore, it is often extremely hard to accurately single out the individual PES in those systems. Moreover, due to the mutual nonadiabatic couplings that may spread wide in space and due to the energy-time uncertainty relation, the notion of the isolated and well-defined potential energy surface should lose the sense. On the other hand, such dense electronic states should offer a very interesting molecular field in which chemical reactions to proceed in characteristic manners. However, to treat these systems, the standard theoretical framework of chemical reaction dynamics, which starts from the Born-Oppenheimer approximation and ends up with quantum nuclear wavepacket dynamics, is not very useful. We here explore this problem with our developed nonadiabatic electron wavepacket theory, which we call the phase-space averaging and natural branching (PSANB) method [T. Yonehara and K. Takatsuka, J. Chem. Phys. 129, 134109 (2008)], 10.1063/1.2987302, or branching-path representation, in which the packets are propagated in time along the non-Born-Oppenheimer branching paths. In this paper, after outlining the basic theory, we examine using a one-dimensional model how well the PSANB method works with such densely quasi-degenerate nonadiabatic systems. To do so, we compare the performance of PSANB with the full quantum mechanical results and those given by the fewest switches surface hopping (FSSH) method, which is known to be one of the most reliable and flexible methods to date. It turns out that the PSANB electron wavepacket approach actually yields very good results with far fewer initial sampling paths. Then we apply the

  12. Desorption electrospray ionization with a portable mass spectrometer: in situ analysis of ambient surfaces.

    Mulligan, Christopher C; Talaty, Nari; Cooks, R Graham

    2006-04-28

    Desorption electrospray ionization (DESI) is implemented on a portable mass spectrometer and used to demonstrate in situ detection of active ingredients in pharmaceutical preparations, alkaloids in plant tissues, explosives, chemical warfare agent simulants and agricultural chemicals from a variety of surfaces; air monitoring applications using DESI are also introduced. PMID:16609779

  13. Development of resonance ionization spectroscopy system for fusion material surface analysis

    Iguchi, Tetsuo [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.; Satoh, Yasushi; Nakazawa, Masaharu

    1996-10-01

    A Resonance Ionization Spectroscopy (RIS) system is now under development aiming at in-situ observation and analysis neutral particles emitted from fusion material surfaces under irradiation of charged particles and neutrons. The basic performance of the RIS system was checked through a preliminary experiment on Xe atom detection. (author)

  14. Research project AUS-10370/CF: electron impact ionization and surface induced reactions of edge plasma constituents

    In order to better understand elementary reactions which are taking place at the plasma edge of thermonuclear fusion devices, three areas of research were persuaded: I) Experimental studies about electron ionization of neutrals and ions and electron attachment to molecules, II) Theoretical studies about electron ionisation of neutrals and ions and III) Reactive interaction of molecular ions with surfaces

  15. Solar irradiance changes and photobiological effects at Earth's surface following astrophysical ionizing radiation events

    Thomas, Brian C; Snyder, Brock R

    2015-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the TUV radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radi...

  16. Solar irradiance changes and photobiological effects at Earth's surface following astrophysical ionizing radiation events

    Thomas, Brian C.; Neale, Patrick J.; Snyder II, Brock R.

    2015-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the TUV radiative transfer mo...

  17. Origin of cell surface proteins released from Micrococcus radiodurans by ionizing radiation

    The exposure of Micrococcus radiodurans to sublethal doses of ionizing radiation causes the release of certain proteins into the surrounding medium. As estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, these proteins range from approximately 20,000 to 125,000 daltons. At least some of the proteins, including an exonuclease, have a surface location and appear to originate from the lipid-rich midwall layer. The exonuclease has two functionally distinct locations, one with its active site available to external substrate and a second with the active site masked from the exterior. Ionizing radiation releases both the masked and unmasked activity into the surrounding medium

  18. An improved quasi-diabatic representation of the 1, 2, 31A coupled adiabatic potential energy surfaces of phenol in the full 33 internal coordinates

    Zhu, Xiaolei; Malbon, Christopher L.; Yarkony, David R.

    2016-03-01

    In a recent work we constructed a quasi-diabatic representation, Hd, of the 1, 2, 31A adiabatic states of phenol from high level multireference single and double excitation configuration interaction electronic structure data, energies, energy gradients, and derivative couplings. That Hd accurately describes surface minima, saddle points, and also regions of strong nonadiabatic interactions, reproducing the locus of conical intersection seams and the coordinate dependence of the derivative couplings. The present work determines the accuracy of Hd for describing phenol photodissociation. Additionally, we demonstrate that a modest energetic shift of two diabats yields a quantifiably more accurate Hd compared with experimental energetics. The analysis shows that in favorable circumstances it is possible to use single point energies obtained from the most reliable electronic structure methods available, including methods for which the energy gradients and derivative couplings are not available, to improve the quality of a global representation of several coupled potential energy surfaces. Our data suggest an alternative interpretation of kinetic energy release measurements near λphot ˜ 248 nm.

  19. Quantum adiabatic machine learning

    Pudenz, Kristen L

    2011-01-01

    We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. We apply and illustrate this approach in detail to the problem of software verification and validation.

  20. Solar Irradiance Changes And Photobiological Effects At Earth's Surface Following Astrophysical Ionizing Radiation Events

    Thomas, Brian; Neale, Patrick

    2016-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth for decades. Although there is some direct biological damage on the surface from redistributed radiation several studies have indicated that the greatest long term threat is from ozone depletion and subsequent heightened solar ultraviolet (UV) radiation. It is known that organisms exposed to this irradiation experience harmful effects such as sunburn and even direct damage to DNA, proteins, or other cellular structures. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In the present work, we employed a radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light). Using biological weighting functions we have considered a wide range of effects, including: erythema and skin cancer in humans; inhibition of photosynthesis in the diatom Phaeodactylum sp. and dinoflagellate Prorocentrum micans inhibition of carbon fixation in Antarctic phytoplankton; inhibition of growth of oat (Avena sativa L. cv. Otana) seedlings; and cataracts. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in

  1. Adiabatic Markovian Dynamics

    Oreshkov, Ognyan

    2010-01-01

    We propose a theory of adiabaticity in quantum Markovian dynamics based on a structural decomposition of the Hilbert space induced by the asymptotic behavior of the Lindblad semigroup. A central idea of our approach is that the natural generalization of the concept of eigenspace of the Hamiltonian in the case of Markovian dynamics is a noiseless subsystem with a minimal noisy cofactor. Unlike previous attempts to define adiabaticity for open systems, our approach deals exclusively with physical entities and provides a simple, intuitive picture at the underlying Hilbert-space level, linking the notion of adiabaticity to the theory of noiseless subsystems. As an application of our theory, we propose a framework for decoherence-assisted computation in noiseless codes under general Markovian noise. We also formulate a dissipation-driven approach to holonomic computation based on adiabatic dragging of subsystems that is generally not achievable by non-dissipative means.

  2. Applications of Adiabatic Approximation to One- and Two-electron Phenomena in Strong Laser Fields

    Bondar, Denys

    2010-01-01

    The adiabatic approximation is a natural approach for the description of phenomena induced by low frequency laser radiation because the ratio of the laser frequency to the characteristic frequency of an atom or a molecule is a small parameter. Since the main aim of this work is the study of ionization phenomena, the version of the adiabatic approximation that can account for the transition from a bound state to the continuum must be employed. Despite much work in this topic, a universally accepted adiabatic approach of bound-free transitions is lacking. Hence, based on Savichev's modified adiabatic approximation [Sov. Phys. JETP 73, 803 (1991)], we first of all derive the most convenient form of the adiabatic approximation for the problems at hand. Connections of the obtained result with the quasiclassical approximation and other previous investigations are discussed. Then, such an adiabatic approximation is applied to single-electron ionization and non-sequential double ionization of atoms in a strong low fr...

  3. Surface-ionization mass-spectrometry of psychotropic preparations:tricyclic antidepressants

    In the paper the results of the surface-ionization mass-spectrometry(SI/MS) of psychotropic preparations - tricyclic antidepressants such as amitriptiline and imizine - on thermoemitters from oxidized W and Re band have been presented. The mass spectra of surface ionization, the temperature dependencies of ion currents have been obtained, the characteristics heterogeneous reactions of adsorbed molecules and the channels of monomolecular decays of oscillatory-excited polyatomic ions while their moving in the mass spectrometer have been revealed. It has been shown that the high efficiency of ion formation, the few lines in and the special character of the SI mass spectra make it possible to analyze trace amounts of amitriptiline and imizine in complex biosolutions with no preliminary chromatographic separation with the limit detection of 10-12g. The sensitivity of SI/MS is essentially higher than that of chromato-mass-spectrometer HP-6890. (author)

  4. Evidence for DCO+ as a probe of ionization in the warm disk surface

    Favre, Cécile; Cleeves, L Ilsedore; Hersant, Franck; Qi, Chunhua; Aikawa, Yuri

    2015-01-01

    In this Letter we model the chemistry of DCO$^{+}$ in protoplanetary disks. We find that the overall distribution of the DCO$^{+}$ abundance is qualitatively similar to that of CO but is dominated by thin layer located at the inner disk surface. To understand its distribution, we investigate the different key gas-phase deuteration pathways that can lead to the formation of DCO$^{+}$. Our analysis shows that the recent update in the exothermicity of the reaction involving CH$_2$D$^{+}$ as a parent molecule of DCO$^{+}$ favors deuterium fractionation in warmer conditions. As a result the formation of DCO$^{+}$ is enhanced in the inner warm surface layers of the disk where X-ray ionization occurs. Our analysis points out that DCO$^{+}$ is not a reliable tracer of the CO snow line as previously suggested. We thus predict that DCO$^{+}$ is a tracer of active deuterium and in particular X-ray ionization of the inner disk.

  5. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12±1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3xω Nd:YAG laser in air, SF6 or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to ∼2 μm in SF6 gas and to ∼5 μm in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly (∼10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits

  6. Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

    Chen Yong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Luo Guanghong [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Diao Jiajie [Department of Physics, George Washington University, Washington, DC 20052 (United States); Chornoguz, Olesya [Department of Chemistry, George Washington University, Washington, DC 20052 (United States); Reeves, Mark [Department of Physics, George Washington University, Washington, DC 20052 (United States); Vertes, Akos [Department of Chemistry, George Washington University, Washington, DC 20052 (United States)

    2007-04-15

    Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12{+-}1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3x{omega} Nd:YAG laser in air, SF{sub 6} or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to {approx}2 {mu}m in SF{sub 6} gas and to {approx}5 {mu}m in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly ({approx}10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits.

  7. Water Radiolysis: Influence of Oxide Surfaces on H2 Production under Ionizing Radiation

    Sophie Le Caër

    2011-02-01

    Full Text Available The radiolysis of water due to ionizing radiation results in the production of electrons, H· atoms, ·OH radicals, H3O+ ions and molecules (dihydrogen H2 and hydrogen peroxide H2O2. A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H2 production. This H2 production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented.

  8. Water radiolysis: Influence of oxide surfaces on H2 production under ionizing radiation

    The radiolysis of water due to ionizing radiation results in the production of electrons, H and OH radicals, H3O+ ions and molecules (dihydrogen H2 and hydrogen peroxide H2O2). A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H2 production. This H2 production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented. (author)

  9. On the velocity dependence for negative ionization of atoms sputtered from cesiated surfaces: An experimental study

    The experiments reported were performed to study the velocity dependence of the negative ions M/sup -/ ejected from a metal M when the surface work function is lowered by adsorption of cesium atoms. The decrease in the work function induces very similar exponential increases for all initial energies. The measured variations, reaching 3 to 5 orders of magnitude, are attributed essentially to variations of ionization probabilities. Thus the velocity dependence, predicted by theoretical studies derived from the initial work of Blandin et al. could not be established for the negative metallic ions. Besides, some other investigated ion species, H/sup -/, P/sup -/ and O/sup -/, experience more direct velocity dependent ionization processes. Chemical bonds may alter the ionization process. In all cases, the ionization process can still be attributed to an electron attachment on an acceptor level of the ejected particle. However, multielectronic transitions or electronic excitations during the ejection have to be considered. Such an approach has been proposed by Sroubek for positive ion emission

  10. Resonance ionization of sputtered atoms: Quantitative analysis in the near-surface region of silicon wafers

    Calaway, W. F.; Spiegel, D. R.; Marshall, A. H.; Downey, S. W.; Pellin, M. J.

    1997-02-01

    The unambiguous identification and quantification of low levels of metallic impurities on Si wafers are difficult problems due to the rapidly changing chemical activity near the surface. Air-exposed Si surfaces typically possess a native oxide layer several atoms thick plus a top monolayer of various silicon-containing molecules. Resonance ionization spectroscopy (RIS) used for postionization in secondary neutral mass spectrometry (SNMS) is uniquely suited to this task. The high sensitivity of this technique allows detection of metals at parts per billion levels with monolayer sensitivity. The high selectivity of RIS allows unambiguous identification of elements, while the reduced matrix effects of SNMS allow quantification of the photoionized element. Characterization of Si surfaces using RIS/SNMS has been explored by measuring the concentration profiles of Ca in the near-surface region of Si wafers of varying degrees of cleanliness. Calcium detection can be problematic due to the isobaric interference with SiC, particularly in the near-surface region during fabrication of devices due to the use of organic photoresist. Three different resonance ionization schemes for Ca have been examined and compared for effectiveness by calculating detection limits for Ca in Si in the chemically active near-surface region.

  11. Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

    The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

  12. Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

    Garcia de Abajo, F.J. (Dept. de Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, Univ. del Pais Vasco, San Sebastian (Spain)); Pitarke, J.M. (Materia Kondentsatuaren Fisika Saila, Zientzi Fakultatea, Euskal Herriko Univ., Bilbo (Spain))

    1994-05-01

    The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

  13. Effect of RANS-Type Turbulence Models on Adiabatic Film Cooling Effectiveness over a Scaled Up Gas Turbine Blade Leading Edge Surface

    Yepuri, Giridhara Babu; Talanki Puttarangasetty, Ashok Babu; Kolke, Deepak Kumar; Jesuraj, Felix

    2016-06-01

    Increasing the gas turbine inlet temperature is one of the key technologies in raising gas turbine engine power output. Film cooling is one of the efficient cooling techniques to cool the hot section components of a gas turbine engines in turn the turbine inlet temperature can be increased. This study aims at investigating the effect of RANS-type turbulence models on adiabatic film cooling effectiveness over a scaled up gas turbine blade leading edge surfaces. For the evaluation, five different two equation RANS-type turbulent models have been taken in consideration, which are available in the ANSYS-Fluent. For this analysis, the gas turbine blade leading edge configuration is generated using Solid Works. The meshing is done using ANSYS-Workbench Mesh and ANSYS-Fluent is used as a solver to solve the flow field. The considered gas turbine blade leading edge model is having five rows of film cooling circular holes, one at stagnation line and the two each on either side of stagnation line at 30° and 60° respectively. Each row has the five holes with the hole diameter of 4 mm, pitch of 21 mm arranged in staggered manner and has the hole injection angle of 30° in span wise direction. The experiments are carried in a subsonic cascade tunnel facility at heat transfer lab of CSIR-National Aerospace Laboratory with a Reynolds number of 1,00,000 based on leading edge diameter. From the Computational Fluid Dynamics (CFD) evaluation it is found that K-ɛ Realizable model gives more acceptable results with the experimental values, compared to the other considered turbulence models for this type of geometries. Further the CFD evaluated results, using K-ɛ Realizable model at different blowing ratios are compared with the experimental results.

  14. Production of neutron-rich surface-ionized nuclides at PARRNe

    Yields of neutron-rich isotopes produced by fast neutron induced fission of 238U were measured at the ISOL set-up Production d'Atomes Radioactifs Riches en Neutrons. A surface ion source was used to ionize selectively elements with low ionization potentials. In order to observe also the most n-rich isotopes, the identification was achieved by a combined measurement of β- and γ-rays and β-delayed neutrons. The flux of fast neutrons inducing fission was generated by a 1 μA beam of 26 MeV deuterons stopped in a graphite converter. The target was a standard ISOLDE type 238UCX/graphite (50 g/cm2) heated by a tantalum oven to about 2050 deg. C. A large variety of radioactive isotopes could be determined quantitatively. Production rates measured for Rb and Cs isotopes are presented here

  15. Wireless adiabatic power transfer

    Research highlights: → Efficient and robust mid-range wireless energy transfer between two coils. → The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. → Wireless energy transfer is insensitive to any resonant constraints. → Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

  16. Nanostructured silicon surface modifications for as a selective matrix-free laser desorption/ionization mass spectrometry.

    Tsao, C W; Lin, C H; Cheng, Y C; Chien, C C; Chang, C C; Chen, W Y

    2012-06-01

    Matrix-assisted laser desorption/ionization mass spectrometry is an established soft ionization method that is widely applied to analyze biomolecules. The UV-absorbing organic matrix is essential for biomolecule ionization; however, it also creates matrix background interference, which results in problematic analyses of biomolecules of less than 700 Da. Therefore, this study investigates hydrophilic, hydrophobic cationic, anionic and immobilized metal ion surface chemical modifications to advance nanostructured silicon mass spectrometry performance (nSi-MS). This investigation provides information required for a possible novel mass spectroscopy that combines surface-enhanced and nanostructured silicon surface-assisted laser desorption/ionization mass spectrometry for the selective detection of specific compounds of a mixture. PMID:22531330

  17. Adiabatically implementing quantum gates

    We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process

  18. Wireless adiabatic power transfer

    Rangelov, A. A.; Suchowski, H.; Silberberg, Y.; Vitanov, N. V.

    2010-01-01

    We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

  19. Instrumentation, Applications And Fundamentals Of Plasma Ionization Of Organic Molecules From Surfaces

    Wiley, Joshua Scott

    2013-01-01

    Various aspects of the interaction of low-temperature plasma (LTP) ambient ionization with organic molecules and surfaces are discussed. As an application, LTP-MS has been used for the analysis of pesticides directly from fruits and vegetables revealing low parts per billion limits of detection (LODs). Due to low power and gas requirements, a battery-operated and handheld LTP probe was developed for the point-and-shoot MS analyses. Handheld LTP was compared with large-scale LTP on a benchtop ...

  20. Floquet surface hopping: Laser-driven dissociation and ionization dynamics of H2 +

    Fiedlschuster, T.; Handt, J.; Schmidt, R.

    2016-05-01

    A quantum-classical approach is developed to describe the strong-field molecular dynamics of H2 +, taking into account all degrees of freedom and simultaneously dissociation as well as ionization. The electron and nuclei are treated correlated, by propagating the nuclei stochastically on potential energy surfaces. It is demonstrated that Floquet surface hopping (FSH) is particularly well suited to describe the laser-driven dynamics. The method is tested against exact solutions of the time-dependent Schrödinger equation, where available. In addition, the FSH results are in excellent agreement with recent experimental data of the dissociation and ionization dynamics of H2 +. As an additional issue of this work, the primary importance of the focal volume average is worked out for the understanding of experimental results. It determines the gross features of the experimental spectra and provides also a natural explanation of the puzzling saturation effect in the dissociation spectra, observed experimentally. Future applications and further extensions of the method are discussed.

  1. Adsorption studies at ionized surface layers by means of hot atoms

    Adsorption of ions at the surface of solutions of ionic surface-active substances can directly be studied using hot atoms. Extremely small amounts of suitable radioactive ions, or ions liable to undergo induced nuclear transformations in situ, are added to such solutions, replacing some of the normal counter ions coadsorbed at the primary-adsorbed organic ions. Hot atoms with energies from about 100 keV down to a few electron volts give ranges in water from about 1000 A down to monomoleeular layers. This makes them suitable for sensitive surface layer studies. The hot atoms ejected from the surface are collected and counted. Among α-disintegration recoils, the system Bi212/Tl208 has proved to be suitable. Now, by refining the method, valuable information about adsorption conditions at sodium dodecyl sulphate surface layers could be found. The kinetics of adsorption was studied by following in time the collected recoil activity caused by Bi-ion adsorption. Adsorption isotherms of Bi-ions as a function of the bulk concentration of the surface-active substance under varying conditions of ionic strength, pH and Bi212 activity were measured. By comparing these isotherms with those obtained by measuring the surface tension of the solutions and calculating the surface excess with the aid of a suitably modified Gibbs' isotherm, the adsorption of Bi+++ and Pb++ relative to that of Na+ and H3O+, and by this the extent of ion exchange in the adsorbed layer could be determined. As the method measures the adsorption of charged species, surface reactions transforming primary-adsorbed organic anions to a non-ionic state could be followed. Conclusions could be drawn about the formation of a non-ionized acid soap in the surface and about micelle formation in the bulk under various experimental conditions. (author)

  2. Surface-Assisted Laser Desorption Ionization of Low Molecular Organic Substances on Oxidized Porous Silicon

    Shmigol, I. V.; Alekseev, S. A.; Lavrynenko, O. Yu.; Zaitsev, V. N.; Barbier, D.; Pokrovskiy, V. A.

    Desorption/ionization on silicon (DIOS) mass spectra of methylene blue (MB+Cl-) were studied using p+-type oxidized monofunctional porous silicon (PS-OX mono ) free layers. Reduction/protonation processes of methylene blue (MB) dye were investigated. It was shown that SiH x terminal sites on oxidized surface of porous silicon (PS-OX) are not the rate-determining factor for the reduction/protonation in DIOS. Tunneling of electron through the dielectric layer of nanostructures on silicon surface under effect of local electrostatic and electromagnetic fields is considered to be the most significant factor of adsorbate-adsorbent electron exchange and further laser-induced ion formation.

  3. Surface corona-bar discharges for production of pre-ionizing UV light for pulsed high-pressure plasmas

    Multi-atmospheric pressure, pulsed electric discharge excited lasers require pre-ionization to produce spatially uniform glows. Many such systems use corona bars to produce ultraviolet (UV) and vacuum ultraviolet (VUV) light as photo-ionization sources for this purpose. Corona bars are transient surface discharges, typically in a cylindrical geometry, that sustain high electron temperatures and so are efficient UV and VUV sources. In this paper, results from a numerical study of surface corona-bar discharges in a multi-atmosphere pressure Ne/Xe gas mixture are discussed. The discharge consists of a high-voltage electrode placed on the surface of a corona bar which is a dielectric tube surrounding a cylindrical metal electrode. After the initial breakdown an ionization front propagates along the circumference of the corona bar and produces a thin plasma sheet near the dielectric surface. The propagation speed of the ionization front ranges from 2 x 107 to 3.5 x 108 cm s-1, depending on the applied voltage and dielectric constant of the corona-bar insulator. As the discharge propagates around the circumference, the surface of the corona-bar is charged. The combined effects of surface curvature and charge deposition result in a non-monotonic variation of the electric field and electron temperature as the ionization front traverses the circumference. The UV fluxes collected on a surrounding circular surface correlate with the motion of the ionization front but with a time delay due to the relatively long lifetime of the precursor to the emitting species Ne2*.

  4. Efficient small sample analysis via laser post-ionized neutrals desorbed from surfaces: LPI-SNMS

    Veryovkin, I.; Calaway, W.; Pellin, M.; Moore, J.; Burnett, D.

    2003-04-01

    A number of popular analytical techniques rely on ion sputtering or laser desorption to probe solid samples. The popularity of this class of techniques is derived from the fact that they produce information on elemental and molecular compositions at trace levels. These techniques are particularly amenable to small sample analysis, since both ion and photon beams can be focused to sub-micron dimensions. Because ion sputtering and laser desorption consume material, there exists a trade off between sample size and achievable detection limit. This trade off is quantified by an instruments useful yield, which is defined as the number of atoms detected per atoms consumed. Laser post-ionization secondary neutral mass spectrometry (LPI-SNMS) has useful yields significantly higher than competing techniques and is thus well suited for trace analysis of small samples. With LPI-SNMS, either a pulse of energetic ions or photons remove material from a solid surface into the gas phase. The desorbed material, predominantly ground state neutral atoms, is photo-ionized by one or more lasers and then extracted into a mass spectrometer for detection. At Argonne National Laboratory, we have developed a new reflectron time-of flight (TOF) mass spectrometer especially designed to optimize useful yield in LPI-SNMS measurements. Using ion optics simulations, an improved extraction design has been developed that allows photo ions from a large (4 × 4 × 3 mm^3) volume above a sample surface to be transmitted through a TOF mass spectrometer with > 98% efficiency. Efficient extraction from such a large ionization volume means that more than 40% of all desorbed species are available for detection, producing an overall useful yield of > 30%. Such a high sensitivity allows analysis of small samples at trace levels never before achievable, opening many new applications. For example, the new LPI-SNMS instrument will allow (1) part-per-trillion detections of solar wind elements implanted in the top

  5. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    Nakazaki, Nobuya, E-mail: nakazaki.nobuya.58x@st.kyoto-u.ac.jp; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi, E-mail: ono@kuaero.kyoto-u.ac.jp [Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8540 (Japan)

    2014-12-14

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl{sub 2} plasmas, as a function of rf bias power or ion incident energy E{sub i}, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on E{sub i}: one is the roughening mode at low E{sub i} < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing E{sub i}, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher E{sub i}, where the rms surface roughness decreases substantially with E{sub i} down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on E{sub i} were also observed in the etch rate versus √(E{sub i}) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing E{sub i} were found to correspond to changes in the predominant ion flux from feed gas ions Cl{sub x}{sup +} to ionized etch products SiCl{sub x}{sup +} caused by the increased etch rates at increased E{sub i}, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  6. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl2 plasmas, as a function of rf bias power or ion incident energy Ei, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on Ei: one is the roughening mode at low Ei < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing Ei, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher Ei, where the rms surface roughness decreases substantially with Ei down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on Ei were also observed in the etch rate versus √(Ei) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing Ei were found to correspond to changes in the predominant ion flux from feed gas ions Clx+ to ionized etch products SiClx+ caused by the increased etch rates at increased Ei, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors

  7. Quality control for total evaporation technique by surface/thermal ionization mass spectrometer

    For the measurement of uranium and plutonium isotopic composition, the surface/thermal ionization mass spectrometry is widely used at the both nuclear facilities and safeguards verification laboratories. The progress of instrument specification makes higher sensitivity. The total evaporation technique is one of the latest measurement techniques by using this progress, in which all of uranium or plutonium on the filament would be evaporated by increasing the filament current. The accuracy and precision of this technique is normally checked by using the certified isotope reference materials measurement. But the fluctuation of ion beam is very different by each filament, depending on the chemical form of evaporation. So, it should be considered how to check the measurement quality of unknown samples which has no certified values. This presentation is focused on the monitoring of ion yields and pattern of isotope ratio fluctuation to attain the traceability between reference material and unknown sample as quality control approach of total evaporation technique. (author)

  8. Surface-assisted laser desorption/ionization mass spectrometry using ordered silicon nanopillar arrays.

    Alhmoud, Hashim Z; Guinan, Taryn M; Elnathan, Roey; Kobus, Hilton; Voelcker, Nicolas H

    2014-11-21

    Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is ideally suited for the high-throughput analysis of small molecules in bodily fluids (e.g. saliva, urine, and blood plasma). A key application for this technique is the testing of drug consumption in the context of workplace, roadside, athlete sports and anti-addictive drug compliance. Here, we show that vertically-aligned ordered silicon nanopillar (SiNP) arrays fabricated using nanosphere lithography followed by metal-assisted chemical etching (MACE) are suitable substrates for the SALDI-MS detection of methadone and small peptides. Porosity, length and diameter are fabrication parameters that we have explored here in order to optimize analytical performance. We demonstrate the quantitative analysis of methadone in MilliQ water down to 32 ng mL(-1). Finally, the capability of SiNP arrays to facilitate the detection of methadone in clinical samples is also demonstrated. PMID:25268849

  9. Nonresonance adiabatic photon trap

    Popov, S S; Burdakov, A V; Ushkova, M Yu

    2016-01-01

    Concept of high efficiency photon storage based on adiabatic confinement between concave mirrors is presented and experimentally investigated. The approach is insensitive to typical for Fabri-Perot cells requirements on quality of accumulated radiation, tolerance of resonator elements and their stability. Experiments have been carried out with the trap, which consists from opposed concave cylindrical mirrors and conjugated with them spherical mirrors. In result, high efficiency for accumulation of radiation with large angular spread and spectrum width has been confirmed. As radiation source a commercial fiber laser has been used.

  10. Adiabatic quantum simulators

    J. D. Biamonte

    2011-06-01

    Full Text Available In his famous 1981 talk, Feynman proposed that unlike classical computers, which would presumably experience an exponential slowdown when simulating quantum phenomena, a universal quantum simulator would not. An ideal quantum simulator would be controllable, and built using existing technology. In some cases, moving away from gate-model-based implementations of quantum computing may offer a more feasible solution for particular experimental implementations. Here we consider an adiabatic quantum simulator which simulates the ground state properties of sparse Hamiltonians consisting of one- and two-local interaction terms, using sparse Hamiltonians with at most three-local interactions. Properties of such Hamiltonians can be well approximated with Hamiltonians containing only two-local terms. The register holding the simulated ground state is brought adiabatically into interaction with a probe qubit, followed by a single diabatic gate operation on the probe which then undergoes free evolution until measured. This allows one to recover e.g. the ground state energy of the Hamiltonian being simulated. Given a ground state, this scheme can be used to verify the QMA-complete problem LOCAL HAMILTONIAN, and is therefore likely more powerful than classical computing.

  11. Is the sech/tanh Adiabatic Pulse Really Adiabatic?

    Rosenfeld, Daniel; Zur, Yuval

    1998-05-01

    Adiabatic pulses are most conveniently studied in the frequency frame which is a frame of reference rotating at the instantaneous frequency of the pulse. In this frame the adiabatic condition ‖γBeff‖ ≫ |θ≳| sets an upper limit on the sweep rate θ≳ of the Beffvector. This, in turn, places a lower bound on the pulse duration. Adiabatic behavior is studied at the threshold duration and two pulses are examined: (i) a pulse with a constant sweep rate (CAPpulse) and (ii) a conventional sech/tanh adiabatic pulse. It is shown that the sech/tanh pulse performs robust magnetization inversion although it seems to violate the adiabatic condition. This puzzling phenomenon is solved by switching into a second-order rotating frame of reference (SORF) where it is shown that the adiabatic condition is fulfilled. This frame coincides with the frequency frame at the beginning of the pulse. Assuming an RF field along thex-axis of the frequency frame, the SORF then rotates about the commony-axis during the pulse with thez-axis of the new frame aligned with the Beffvector. It is shown that adiabatic motion may be performed in the SORF, in which the sweep rate is increased indefinitely; the adiabatic condition is violated by this motion in the frequency frame but is fulfilled in the SORF. The lower bound on the sweep rate in the frequency frame is thereby lifted.

  12. Protein Analysis by Ambient Ionization Mass Spectrometry Using Trypsin-Immobilized Organosiloxane Polymer Surfaces.

    Dulay, Maria T; Eberlin, Livia S; Zare, Richard N

    2015-12-15

    In the growing field of proteomic research, rapid and simple protein analysis is a crucial component of protein identification. We report the use of immobilized trypsin on hybrid organic-inorganic organosiloxane (T-OSX) polymers for the on-surface, in situ digestion of four model proteins: melittin, cytochrome c, myoglobin, and bovine serum albumin. Tryptic digestion products were sampled, detected, and identified using desorption electrospray ionization mass spectrometry (DESI-MS) and nanoDESI-MS. These novel, reusable T-OSX arrays on glass slides allow for protein digestion in methanol:water solvents (1:1, v/v) and analysis directly from the same polymer surface without the need for sample preparation, high temperature, and pH conditions typically required for in-solution trypsin digestions. Digestion reactions were conducted with 2 μL protein sample droplets (0.35 mM) at incubation temperatures of 4, 25, 37, and 65 °C and digestion reaction times between 2 and 24 h. Sequence coverages were dependent on the hydrophobicity of the OSX polymer support and varied by temperature and digestion time. Under the best conditions, the sequence coverages, determined by DESI-MS, were 100% for melittin, 100% for cytochrome c, 90% for myoglobin, and 65% for bovine serum albumin. PMID:26567450

  13. Controlled-Resonant Surface Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging

    Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

    2014-01-01

    This paper reports on the advancement of a controlled-resonance surface tapping-mode single capillary liquid junction extraction/ESI emitter for mass spectrometry imaging. The basic instrumental setup and the general operation of the system were discussed and optimized performance metrics were presented. The ability to spot sample, lane scan and chemically image in an automated and controlled fashion were demonstrated. Rapid, automated spot sampling was demonstrated for a variety of compound types including the cationic dye basic blue 7, the oligosaccharide cellopentaose, and the protein equine heart cytochrome c. The system was used for lane scanning and chemical imaging of the cationic dye crystal violet in inked lines on glass and for lipid distributions in mouse brain thin tissue sections. Imaging of the lipids in mouse brain tissue under optimized conditions provided a spatial resolution of approximately 35 m based on the ability to distinguish between features observed both in the optical and mass spectral chemical images. The sampling spatial resolution of this system was comparable to the best resolution that has been reported for other types of atmospheric pressure liquid extraction-based surface sampling/ionization techniques used for mass spectrometry imaging.

  14. Geometry of the Adiabatic Theorem

    Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas

    2012-01-01

    We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…

  15. Tracing origins of complex pharmaceutical preparations using surface desorption atmospheric pressure chemical ionization mass spectrometry.

    Zhang, Xinglei; Jia, Bin; Huang, Keke; Hu, Bin; Chen, Rong; Chen, Huanwen

    2010-10-01

    A novel strategy to trace the origins of commercial pharmaceutical products has been developed based on the direct chemical profiling of the pharmaceutical products by surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS). Besides the unambiguous identification of active drug components, various compounds present in the matrixes are simultaneously detected without sample pretreatment, providing valuable information for drug quality control and origin differentiation. Four sources of commercial amoxicillin products made by different manufacturers have been successfully differentiated. This strategy has been extended to secerning six sources of Liuwei Dihuang Teapills, which are herbal medicine preparations with extremely complex matrixes. The photolysis status of chemical drug products and the inferior natural herd medicine products prepared with different processes (e.g., extra heating) were also screened using the method reported here. The limit of detection achieved in the MS/MS experiments was estimated to be 1 ng/g for amoxicillin inside the capsule product. Our experimental data demonstrate that DAPCI-MS is a useful tool for rapid pharmaceutical analysis, showing promising perspectives for tracking the entire pharmaceutical supply chain to prevent counterfeit intrusions. PMID:20809628

  16. New ab initio adiabatic potential energy surfaces and bound state calculations for the singlet ground X˜ 1A1 and excited C˜ 1B2(21A') states of SO2

    Kłos, Jacek; Alexander, Millard H.; Kumar, Praveen; Poirier, Bill; Jiang, Bin; Guo, Hua

    2016-05-01

    We report new and more accurate adiabatic potential energy surfaces (PESs) for the ground X˜ 1A1 and electronically excited C˜ 1B2(21A') states of the SO2 molecule. Ab initio points are calculated using the explicitly correlated internally contracted multi-reference configuration interaction (icMRCI-F12) method. A second less accurate PES for the ground X ˜ state is also calculated using an explicitly correlated single-reference coupled-cluster method with single, double, and non-iterative triple excitations [CCSD(T)-F12]. With these new three-dimensional PESs, we determine energies of the vibrational bound states and compare these values to existing literature data and experiment.

  17. Design of modified plastic surfaces for antimicrobial applications: Impact of ionizing radiation on the physical and mechanical properties of polypropylene

    Surface modification of polypropylene (PP) sheets was carried out by radiation induced graft polymerization of hydrophilic functional molecules such as N,N-dimethylacrylamide (DMA) and [2-methacryloyloxy)ethyl] trimethylammonium chloride, which is a quaternary ammonium salt (QAS). Polypropylene sheets were activated prior to the grafting reaction by using electron beam radiation. The changes in morphology, crystallinity and tensile parameters like deformation and stress at yield and deformation at break of PP after irradiation were investigated. The results showed that a minor crystalline reorganization takes place during the irradiation of PP at 100 kGy. The grafting has been observed to be strongly dependent on the monomer dilution in the reaction medium. After grafting of QAS (40%) and DMA (20%) it was possible to develop highly hydrophilic surfaces (water contact angle comprised between 30 and 41°). The surfaces of virgin, irradiated and grafted PP were studied using polarized optical microscopy (POM) and scanning electron microscopy (SEM). Spherical particles (i.e. polystyrene or silica beads) adhering to the modified samples were studied according to the surface parameters. Adhesion tests confirmed the strong influence of substrate type (mainly hydrophilicity and roughness) and to a lesser extent underlined the role of electrostatic interactions for the design of plastic surfaces for antimicrobial applications. - Highlights: • The impact of ionizing radiation on structural changes of polypropylene was studied. • Surface properties were studied after radiation induced grafting. • Polypropylene highly hydrophilic surfaces were developed by ionizing radiation. • Surface hydrophilicity played a major role in particulate adhesion

  18. Non-adiabatic primordial fluctuations

    Noller, J

    2009-01-01

    We consider general non-adiabatic single fluid cosmological perturbations. We derive the second-order action and its curvature variables assuming only the (linearized) Einstein equations for a perfect fluid stress-energy tensor. The derivation is therefore carried out at the same level of generality that has been achieved before for adiabatic modes. We also allow for arbitrary "speed of sound" profiles in our derivation. As a result we find a new conserved super-horizon quantity and relate it to the adiabatically conserved curvature perturbation. We then use the formalism to investigate a family of non-adiabatic hydrodynamical primordial matter models and the power spectra they produce. This yields a new scale-invariant solution that can resolve the horizon problem if implemented in a contracting phase.

  19. Optimising the Use of TRIzol-extracted Proteins in Surface Enhanced Laser Desorption/ Ionization (SELDI Analysis

    Perlaky Laszlo

    2006-03-01

    Full Text Available Abstract Background Research with clinical specimens is always hampered by the limited availability of relevant samples, necessitating the use of a single sample for multiple assays. TRIzol is a common reagent for RNA extraction, but DNA and protein fractions can also be used for other studies. However, little is known about using TRIzol-extracted proteins in proteomic research, partly because proteins extracted from TRIzol are very resistant to solubilization. Results To facilitate the use of TRIzol-extracted proteins, we first compared the ability of four different common solubilizing reagents to solubilize the TRIzol-extracted proteins from an osteosarcoma cell line, U2-OS. Then we analyzed the solubilized proteins by Surface Enhanced Laser Desorption/ Ionization technique (SELDI. The results showed that solubilization of TRIzol-extracted proteins with 9.5 M Urea and 2% CHAPS ([3-[(3-cholamidopropyl-dimethylammonio]propanesulfonate] (UREA-CHAPS was significantly better than the standard 1% SDS in terms of solubilization efficiency and the number of detectable ion peaks. Using three different types of SELDI arrays (CM10, H50, and IMAC-Cu, we demonstrated that peak detection with proteins solubilized by UREA-CHAPS was reproducible (r > 0.9. Further SELDI analysis indicated that the number of ion peaks detected in TRIzol-extracted proteins was comparable to a direct extraction method, suggesting many proteins still remain in the TRIzol protein fraction. Conclusion Our results suggest that UREA-CHAPS performed very well in solubilizing TRIzol-extracted proteins for SELDI applications. Protein fractions left over after TRIzol RNA extraction could be a valuable but neglected source for proteomic or biochemical analysis when additional samples are not available.

  20. Experimental and theoretical studies of laser desorption/ionization of methylene blue from the surface of thermally exfoliated graphite

    Mass spectra of products obtained in the course of laser desorption/ionization of methylene blue from the surface of thermally exfoliated graphite have been registered. It is demonstrated that [M+1]+, [M+2]+, and [M+3]+ ions with one, two, or three, respectively, hydrogen atoms bound to the molecular ion dominate in the mass spectra. The experimental results are confirmed by quantum chemical calculations of possible reaction products that may be formed under the influence of laser radiation.

  1. Adiabatic theory for anisotropic cold molecule collisions

    We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment 4He(1s2s 3S) + HD(1s2) → 4He(1s2) + HD+(1s) + e− [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings

  2. Adiabatic theory for anisotropic cold molecule collisions.

    Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod

    2015-08-21

    We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment (4)He(1s2s (3)S) + HD(1s(2)) → (4)He(1s(2)) + HD(+)(1s) + e(-) [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings. PMID:26298122

  3. Adiabatic theory for anisotropic cold molecule collisions

    Pawlak, Mariusz [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń (Poland); Shagam, Yuval; Narevicius, Edvardas [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Moiseyev, Nimrod [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Physics, Technion–Israel Institute of Technology, Haifa 32000 (Israel)

    2015-08-21

    We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.

  4. Field emission mechanism from nanotubes through gas ionization induced nanoscale surface charging

    Zhan, Changhua

    2012-01-01

    Experimental evidences reported in this letter show that the gas ionization induced positive charge accumulation can lead to the electron field emission from carbon nanotubes (CNTs) in an electrode system with proper range of gap spacing, where the CNT film with ethocel was covered with ZnO nanorods. The hypothesis for illustration is suggested that: 1) the cosmic ray ionization frequency increases 108~1010 times due to the metastable population resulted from the interaction between the gases and the CNTs; 2) the flux of positive charges is enhanced in the converged field due to the ZnO nanostructures. The resulted positive charge local density is high enough to trigger the field emission of the CNTs. The methodology may be useful in particle detectors and ionization gas sensors.

  5. Surface characterization with ion-induced desorption and multiphoton resonance ionization

    It is known that high-molecular-weight, thermally labile molecules can be desorbed intact using keV ion beams. This knowledge has led to numerous applications of fast atom bombardment and secondary ion mass spectrometry (SIMS) by mass spectrometric detection of the desorbed ions. These measurements can be enhanced significantly by using resonance-enhanced laser ionization to softly ionize the neutral component of the desorbed flux. This experimental configuration can produce sensitivity improvements of several orders of magnitude over SIMS while adding a certain degree of selectivity to the ionization process itself. Examples of this performance will be presented using a wide variety of molecules, including polycyclic aromatic hydrocarbons, organic polymers, molecular salts and biologically important molecules. Results from model systems to complex samples are discussed, along with their implications for submicron molecular imaging using this technique. (author)

  6. Ionization in antiproton-hydrogen collisions

    Employing the semiclassical approximation we calculate within the coupled-state formalism the ionization probability in antiproton-hydrogen (anti p+H) collisions. In particular we investigate the adiabatic ionization at the distance of closest approach in almost central collisions. Striking differences in the electron excitation probability compared with proton-hydrogen (p+H) collisions are predicted. (orig.)

  7. Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation

    Zamstein, Noa; Tannor, David J. [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2012-12-14

    We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.

  8. Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation

    We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schrödinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.

  9. Parametric Erosion Investigation: Propellant Adiabatic Flame Temperature

    P. J. Conroy

    2002-01-01

    Full Text Available The influence of quasi-independent parameters and their potential influence on erosion in guns have been investigated. Specifically, the effects of flame temperature and the effect of assuming that the Lewis number (ratio of mass-to-heat transport to the surface, Le = 1, has been examined. The adiabatic flame temperature for a propellant was reduced by the addition of a diluent from a high temperature of 3843 K (similar to that of M9 down to 3004 K, which is near the value for M30A1 propellant. Mass fractions of critical species at the surface with and without the assumption of Le = 1 are presented, demonstrating that certain species preferentially reach the surface providing varied conditions for the surface reactions. The results for gun tube bore surface regression qualitatively agree with previous studies and with current experimental data.

  10. A Combined Laser Ablation-Resonance Ionization Mass Spectrometer for Planetary Surface Geochronology

    Cardell, G.; Taylor, M. E.; Stewart, B. W.; Capo, R. C.; Crown, D. A.

    2002-01-01

    Progress in the development of an instrument for direct geochronologic measurements on rocks in situ will be described. The instrument integrates laser ablation sampling, resonance ionization, and mass spectrometry to directly measure concentrations of the Rb-Sr isotope system. Additional information is contained in the original extended abstract.

  11. Examination and Manipulation of Protein Surface Charge in Solution with Electrospray Ionization Mass Spectrometry

    Gross, Deborah S.; Van Ryswyk, Hal

    2014-01-01

    Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool for examining the charge of proteins in solution. The charge can be manipulated through choice of solvent and pH. Furthermore, solution-accessible, protonated lysine side chains can be specifically tagged with 18-crown-6 ether to form noncovalent adducts. Chemical derivatization…

  12. Application of silicon nanowires and indium tin oxide surfaces in desorption electrospray ionization

    Pól, Jaroslav; Novák, Petr; Volný, Michael; Kruppa, G. H.; Kostiainen, R.; Lemr, Karel; Havlíček, Vladimír

    2008-01-01

    Roč. 14, č. 6 (2008), s. 391-399. ISSN 1469-0667 R&D Projects: GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : mass spectrometry * desorption electrospray ionization * nanowires Subject RIV: CE - Biochemistry Impact factor: 1.167, year: 2008

  13. Non-adiabatic Chaplygin gas

    The split of a generalised Chaplygin gas with an equation of state p=−A/ρα into an interacting mixture of pressureless matter and a dark-energy component with equation of state pΛ=−ρΛ implies the existence of non-adiabatic pressure perturbations. We demonstrate that the square of the effective (non-adiabatic) sound speed cs of the medium is proportional to the ratio of the perturbations of the dark energy to those of the dark matter. Since, as demonstrated explicitly for the particular case α=−1/2, dark-energy perturbations are negligible compared with dark-matter perturbations on scales that are relevant for structure formation, we find |cs2|≪1. Consequently, there are no oscillations or instabilities which have plagued previous adiabatic Chaplygin-gas models

  14. New surfaces for desorption electrospray ionization mass spectrometry: porous silicon and ultra-thin layer chromatography plates.

    Kauppila, Tiina J; Talaty, Nari; Salo, Piia K; Kotiaho, Tapio; Kostiainen, Risto; Cooks, R Graham

    2006-01-01

    The performance of nanoporous silicon (pSi) and ultra-thin layer chromatography (UTLC) plates as surfaces for desorption electrospray ionization (DESI) was compared with that of polymethyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE), both popular surfaces in previous DESI studies. The limits of detection (LODs) and other analytical characteristics for six different test compounds were determined using all four surfaces. The LODs for the compounds were in the fmol-pmol (pg-ng) range. The LODs with the pSi surface were further improved for each of the compounds when heat was applied to the surface during sample application which gave LODs as low as or lower than those achieved with PMMA and PTFE. The UTLC plates were successfully used as a rapid means of chromatographic separation prior to DESI-MS analysis. Another advantage achieved using the newer pSi and UTLC surfaces was increased speed of analysis, associated with drying of solution-phase samples. This took place immediately at the UTLC surface and it could be achieved rapidly by gently heating the pSi surface. The presence of salts in the sample did not cause suppression of the analyte signal with any of the surfaces. PMID:16773669

  15. Adiabatic fission barriers in superheavy nuclei

    Jachimowicz, P.; Kowal, M; Skalski, J.

    2016-01-01

    Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from ...

  16. Optimizing adiabaticity in quantum mechanics

    MacKenzie, R; Renaud-Desjardins, L

    2011-01-01

    A condition on the Hamiltonian of a time-dependent quantum mechanical system is derived which, if satisfied, implies optimal adiabaticity (defined below). The condition is expressed in terms of the Hamiltonian and in terms of the evolution operator related to it. Since the latter depends in a complicated way on the Hamiltonian, it is not yet clear how the condition can be used to extract useful information about the optimal Hamiltonian. The condition is tested on an exactly-soluble time-dependent problem (a spin in a magnetic field), where perfectly adiabatic evolution can be easily identified.

  17. A chemical ionization mass spectrometer for continuous underway shipboard analysis of dimethylsulfide in near-surface seawater

    E. S. Saltzman

    2009-07-01

    Full Text Available A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ("mini-CIMS" has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer from water vapor, then declustered, mass filtered via quadrupole mass spectrometry, and detected with an electron multiplier. The instrument described here is based on a low-cost residual gas analyzer (Stanford Research Systems, which has been modified for use as a chemical ionization mass spectrometer. The mini-CIMS has a gas phase detection limit of 170 ppt DMS for a 1 min averaging time, which is roughly equivalent to a seawater DMS concentration of 0.1 nM DMS at 20°C. The mini-CIMS has the sensitivity, selectivity, and time response required for underway measurements of surface ocean DMS over the full range of oceanographic conditions. The simple, robust design and relatively low cost of the instrument are intended to facilitate use in process studies and surveys, with potential for long-term deployment on research vessels, ships of opportunity, and large buoys.

  18. A chemical ionization mass spectrometer for continuous underway shipboard analysis of dimethylsulfide in near-surface seawater

    E. S. Saltzman

    2009-11-01

    Full Text Available A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ("mini-CIMS" has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer from water vapor, then declustered, mass filtered via quadrupole mass spectrometry, and detected with an electron multiplier. The instrument described here is based on a low-cost residual gas analyzer (Stanford Research Systems, which has been modified for use as a chemical ionization mass spectrometer. The mini-CIMS has a gas phase detection limit of 220 ppt DMS for a 1 min averaging time, which is roughly equivalent to a seawater DMS concentration of 0.1 nM DMS at 20°C. The mini-CIMS has the sensitivity, selectivity, and time response required for underway measurements of surface ocean DMS over the full range of oceanographic conditions. The simple, robust design and relatively low cost of the instrument are intended to facilitate use in process studies and surveys, with potential for long-term deployment on research vessels, ships of opportunity, and large buoys.

  19. Functional representation for the born-oppenheimer diagonal correction and born-huang adiabatic potential energy surfaces for isotopomers of H3.

    Mielke, Steven L; Schwenke, David W; Schatz, George C; Garrett, Bruce C; Peterson, Kirk A

    2009-04-23

    Multireference configuration interaction (MRCI) calculations of the Born-Oppenheimer diagonal correction (BODC) for H(3) were performed at 1397 symmetry-unique configurations using the Handy-Yamaguchi-Schaefer approach; isotopic substitution leads to 4041 symmetry-unique configurations for the DH(2) mass combination. These results were then fit to a functional form that permits calculation of the BODC for any combination of isotopes. Mean unsigned fitting errors on a test grid of configurations not included in the fitting process were 0.14, 0.12, and 0.65 cm(-1) for the H(3), DH(2), and MuH(2) isotopomers, respectively. This representation can be combined with any Born-Oppenheimer potential energy surface (PES) to yield Born-Huang (BH) PESs; herein, we choose the CCI potential energy surface, the uncertainties of which ( approximately 0.01 kcal/mol) are much smaller than the magnitude of the BODC. Fortran routines to evaluate these BH surfaces are provided. Variational transition state theory calculations are presented comparing thermal rate constants for reactions on the BO and BH surfaces to provide an initial estimate of the significance of the diagonal correction for the dynamics. PMID:19290604

  20. Functional Representation for the Born-Oppenheimer Diagonal Correction and Born-Huang Adiabatic Potential Energy Surfaces for Isotopomers of H3

    Mielke, Steven L; Schwenke, David; Schatz, George C; Garrett, Bruce C; Peterson, Kirk A

    2009-04-23

    Multireference configuration interaction (MRCI) calculations of the Born-Oppenheimer diagonal correction (BODC) for H3 were performed at 1397 symmetry-unique configurations using the Born-Handy approach; isotopic substitution leads to 4041 symmetry-unique configurations for the DH2 mass combination. These results were then fit to a functional form that permits calculation of the BODC for any combination of isotopes. Mean unsigned fitting errors on a test grid of configurations not included in the fitting process were 0.14, 0.12, and 0.65 cm-1 for the H3, DH2, and MuH2 isotopomers, respectively. This representation can be combined with any Born-Oppenheimer potential energy surface (PES) to yield Born-Huang (BH) PESs; herein we choose the CCI potential energy surface, the uncertainties of which (~0.01 kcal/mol) are much smaller than the magnitude of the BODC. FORTRAN routines to evaluate these BH surfaces are provided. Variational transition state theory calculations are presented comparing thermal rate constants for reactions on the BO and BH surfaces to provide an initial estimate of the significance of the diagonal correction for the dynamics.

  1. Bond selective chemistry beyond the adiabatic approximation

    Butler, L.J. [Univ. of Chicago, IL (United States)

    1993-12-01

    One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.

  2. A simple and sensitive quantitation of N,N-dimethyltryptamine by gas chromatography with surface ionization detection.

    Ishii, A; Seno, H; Suzuki, O; Hattori, H; Kumazawa, T

    1997-01-01

    A simple and sensitive method for determination of N,N-dimethyltryptamine (DMT) by gas chromatography (GC) with surface ionization detection (SID) is presented. Whole blood or urine, containing DMT and gramine (internal standard), was subjected to solid-phase extraction with a Sep-Pak C18 cartridge before analysis by GC-SID. The calibration curve was linear in the DMT range of 1.25-20 ng/mL blood or urine. The detection limit of DMT was about 0.5 ng/mL (10 pg on-column). The recovery of both DMT and gramine spiked in biological fluids was above 86%. PMID:9013290

  3. Formation of metal-ion adducts and evidence for surface-catalyzed ionization in electrospray analysis of pharmaceuticals and pesticides

    Thurman, E.M.; Ferrer, I.

    2002-01-01

    The formation of metal ion adducts in liquid chromatography/mass spectrometry positive-ion electrospray analysis of pharmaceuticals and pesticides was investigated. The evidence of surface-catalyzed ionization in the electrospray analysis was also studied. Both positive and negative ion mass spectrometry were used for the analysis of the products. It was found that the sodium adducts formed in the analysis included single, double, and triple sodium adducts. Adduction was found to occur by attachment of the metal ion to carboxyl, carbonyl and aromatic pi electrons of the molecule.

  4. Accurate ab initio-based adiabatic global potential energy surface for the 22A″ state of NH2 by extrapolation to the complete basis set limit

    Li, Y. Q.; Ma, F. C.; Sun, M. T.

    2013-10-01

    A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N(2D) + H2 reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N(^2D)+H_2(X^1Σ _g^+)(ν =0,j=0)rArr NH(a^1Δ )+H(^2S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction.

  5. Optimization of Adiabatic Selective Pulses

    Rosenfeld, Daniel; Panfil, Shimon L.; Zur, Yuval

    1997-06-01

    Adiabatic RF pulses play an important role in spin inversion due to their robust behavior in presence of inhomogeneous RF fields. These pulses are characterized by the trajectory swept by the tip of theBeffvector and the rate of motion upon it. In this paper, a method is described for optimizing adiabatic inversion pulses to achieve a frequency-selective magnetization inversion over a given bandwidth in a shorter time and to improve slice profile. An efficient adiabatic pulse is used as an initial condition. This pulse allows for flexibility in choosing its parameters; in particular, the transition sharpness may be traded off against the inverted bandwidth. The considerations for selecting the parameters of the pulse according to the requirements of the design are discussed. The optimization process then improves the slice profile by optimizing the rate of motion along the trajectory of the pulse while preserving the trajectory itself. The adiabatic behavior of the optimized pulses is fully preserved over a twofold range of variation in the RF amplitude which is sufficient for imaging applications in commercial high-field MRI machines. Design examples demonstrate the superiority of the optimized pulses over the conventional sech/tanh pulse.

  6. A Many Particle Adiabatic Invariant

    Hjorth, Poul G.

    For a system of N charged particles moving in a homogeneous, sufficiently strong magnetic field, a many-particle adiabatic invariant constrains the collisional exchange of energy between the degrees of freedom perpendicular to and parallel to the magnetic field. A description of the phenomenon in...

  7. Adiabatic Floquet model for the optical response in femtosecond filaments

    Hofmann, Michael

    2016-01-01

    The standard model of femtosecond filamentation is based on phenomenological assumptions which suggest that the ionization-induced carriers can be treated as free according to the Drude model, while the nonlinear response of the bound carriers follows the all-optical Kerr effect. Here, we demonstrate that the additional plasma generated at a multiphoton resonance dominates the saturation of the nonlinear refractive index. Since resonances are not captured by the standard model, we propose a modification of the latter in which ionization enhancements can be accounted for by an ionization rate obtained from non-Hermitian Floquet theory. In the adiabatic regime of long pulse envelopes, this augmented standard model is in excellent agreement with direct quantum mechanical simulations. Since our proposal maintains the structure of the standard model, it can be easily incorporated into existing codes of filament simulation.

  8. Studies in Chaotic adiabatic dynamics

    Chaotic adiabatic dynamics refers to the study of systems exhibiting chaotic evolution under slowly time-dependent equations of motion. In this dissertation the author restricts his attention to Hamiltonian chaotic adiabatic systems. The results presented are organized around a central theme, namely, that the energies of such systems evolve diffusively. He begins with a general analysis, in which he motivates and derives a Fokker-Planck equation governing this process of energy diffusion. He applies this equation to study the open-quotes goodnessclose quotes of an adiabatic invariant associated with chaotic motion. This formalism is then applied to two specific examples. The first is that of a gas of noninteracting point particles inside a hard container that deforms slowly with time. Both the two- and three-dimensional cases are considered. The results are discussed in the context of the Wall Formula for one-body dissipation in nuclear physics, and it is shown that such a gas approaches, asymptotically with time, an exponential velocity distribution. The second example involves the Fermi mechanism for the acceleration of cosmic rays. Explicit evolution equations are obtained for the distribution of cosmic ray energies within this model, and the steady-state energy distribution that arises when this equation is modified to account for the injection and removal of cosmic rays is discussed. Finally, the author re-examines the multiple-time-scale approach as applied to the study of phase space evolution under a chaotic adiabatic Hamiltonian. This leads to a more rigorous derivation of the above-mentioned Fokker-Planck equation, and also to a new term which has relevance to the problem of chaotic adiabatic reaction forces (the forces acting on slow, heavy degrees of freedom due to their coupling to light, fast chaotic degrees)

  9. Effect of surface roughness on the measurement of electron impact inner-shell ionization cross sections using thick-target method

    The effect of surface roughness on the measurement of electron impact inner-shell ionization cross sections in the thick-target method has been studied by using Monte Carlo simulations. The surface roughness structures were described by a series of hemispheres, which were produced randomly on the smooth surface of a thick Ni target. The characteristic X-ray yields of K-shell ionization for Ni element by electron impact near threshold energy were obtained by Monte Carlo simulations for the target with smooth surface and the targets with various surface roughnesses. The Tikhonov regularization method was applied to treat the inverse problem involved and obtain the K-shell ionization cross sections for Ni element. The comparisons between K-shell ionization cross sections of Ni element obtained for the target with smooth surface and the targets with various surface roughnesses were made. The results show that the effect of surface roughness increases as the roughness increases and the surface roughness of the target should be limited to less than 100 nm if the experimental error originated from the surface roughness would be kept less than 2%.

  10. Digital Waveguide Adiabatic Passage Part 1: Theory

    Vaitkus, Jesse A; Greentree, Andrew D

    2016-01-01

    Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.

  11. A clear atomic example for the surface sensitivity of penning ionization

    Hotop, Hartmut; Ruf, Martin W.; Yencha, A.J.; Fricke, Burkhard

    1990-01-01

    Using a crossed-beam apparatus with a double hemispherical electron spectrometer, we have studied the spectrum of electrons released in thermal energy ionizing collisions of metastable He^*(2^3S) atoms with ground state Yb(4f^14 6s^2 ^1S_0) atoms, thereby providing the first Penning electron spectrum of an atomic target with-4f-electrons. In contrast to the HeI (58.4nm) and NeI (73.6/74.4nm) photoelectron spectra of Yb, which show mainly 4f- and 6s-electron emission in about a 5:1 ra...

  12. Verification of traceability and backscattering in surface entrance air kerma measurements with detector type ionizing chamber

    Teixeira, G.J.; Peixoto, J.G.P., E-mail: guilherm@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    Measurements of doses in radiology services by ionizing chambers are easier than those made by TLD, however the protocols for measurements differ regarding the calibration. The objectives were to verify the traceability in the measures of ESAK corrected by the inverse square law, due to the difference in position between the source and IC and the influence of the backscattered radiation in bringing the detector to the table. Was defined a procedure practiced by the radiological services and designed experimental arrangements for the same technique. Was noted that the approximation of the detector to the table generated a significant backscattered. (author)

  13. Pulsed Chemical Oxygen Iodine Lasers Excited by Pulse Gas Discharge with the Assistance of Surface Sliding Discharge Pre-ionization

    Continuous-wave chemical oxygen-iodine lasers (COILs) can be operated in a pulsed operation mode to obtain a higher peak power. The key point is to obtain a uniform and stable glow discharge in the mixture of singlet delta oxygen and iodide. We propose using an electrode system with the assistance of surface sliding pre-ionization to solve the problem of the stable glow discharge with a large aperture. The pre-ionization unit is symmetrically fixed on the plane of the cathode surface. A uniform and stable glow discharge is obtained in a mixture of iodide (such as CH3I) and nitrogen at the specific deposition energy of 4.5 J/L, pressure of 1.99–3.32 kPa, aperture size of 11 cm × 10 cm. The electrode system is applied in a pulsed COIL. Laser energy up to 4.4 J is obtained and the specific energy output is 2 J/L. (fundamental areas of phenomenology(including applications))

  14. Design of Selective Adiabatic Inversion Pulses Using the Adiabatic Condition

    Rosenfeld, Daniel; Panfil, Shimon L.; Zur, Yuval

    1997-12-01

    Adiabatic RF pulses play an important role in spin inversion due to their robust behavior in the presence of inhomogeneous RF fields. These pulses are characterized by the trajectory swept by the tip of theBeffvector and the rate of motion along it. In this paper, we describe a method by which optimized modulation functions can be constructed to render insensitivity toB1inhomogeneity over a predeterminedB1range and over a wide band of frequencies. This is accomplished by requiring that the optimized pulse fulfill the adiabatic condition over this range ofB1inhomogeneity and over the desired frequency band for the complete duration of the pulse. A trajectory similar to the well-known sech/tanh adiabatic pulse, i.e., a half-ellipse, is used. The optimization process improves the slice profile by optimizing the rate of motion along this trajectory. The optimized pulse can be tailored to the specific design requirements; in particular, the transition sharpness may be traded off against the inverted bandwidth. Two design examples, including experimental results, demonstrate the superiority of the optimized pulses over the conventional sech/tanh pulse: in the first example, a large frequency band is to be inverted using a weak RF amplitude in a short time. In the second example, a pulse with a very sharp transition is required.

  15. Adiabatic and diabatic aerosol transport to the Jungfraujoch

    Lugauer, M.; Baltensperger, U.; Furger, M.; Jost, D.T.; Schwikowski, M.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Synoptic scale vertical motion, here detected by the geopotential height of the 500 hPa surface, mainly accounts for the aerosol transport to the Jungfraujoch in winter. In summer, diabatic convection provides the dominant vertical transport mechanism. Nevertheless, synoptic scale adiabatic motion still determines whether diabatic convection can develop. (author) 2 figs., 2 refs.

  16. Radioactive beams produced by the ISOL method: development for laser ionization and for surface ionization; Faisceaux exotiques par methode ISOL: developpements pour l'ionisation par laser et l'ionisation de surface

    Hosni, Faouzi

    2004-10-01

    The works were carried out in the framework of the research program PARRNe (production of radioactive neutron-rich nuclei). This program aims to determine optimal conditions to produce intense beams of neutron-rich isotopes. This thesis treats multiple technical aspects related to the production of separate radioactive isotopes in line (ISOL). It deals mainly with the development of the target-source unit which is the key element for projects such as SPIRAL-2 or EURISOL.The first part presents the various methods using fission as production mode and compares them: fission induced by thermal neutrons, induced by fast neutrons and photofission. The experiment carried out at CERN validated the interest of the photofission as a promising production mode of radioactive ions. That is why the institute of nuclear physics of Orsay decided to build a linear electron accelerator at the Tandem d'Orsay (ALTO).The second part of this thesis deals with the development of uranium targets. The X-rays diffraction and Scanning Electron Microscopy have been used as analysis techniques. They allowed to determine the chemical and structural characteristics of uranium carbide targets as function of various heating temperatures. After the production, the process of ionization has been studied. Two types of ion source have been worked out: the first one is a surface ion source and the second one is a source based on resonant ionization by laser. These two types of sources will be used for the ALTO project. (author)

  17. Adiabatic pumping through quantum dots

    A finite charge can be pumped through a mesoscopic system in the absence of an applied bias voltage by changing periodically in time some parameters of the system. If these parameters change slowly with respect to all internal time scales of the system, pumping is adiabatic. The scope of this work is to investigate adiabatic pumping through a quantum dot, in particular the influence of Coulomb interaction between electrons in the dot on the pumped charge. On one hand we develop a formalism based on Green's functions, in order to calculate the pumped charge from the weak-tunnel-coupling regime down to the Kondo regime. We extend our calculations to a system with a superconducting contact. On the other hand we use a systematic perturbation expansion for the calculation of the pumped charge, giving us the possibility to analyze processes which contribute to charge pumping and to highlight the important role of interaction-induced level renormalization. (orig.)

  18. Adiabatic theory for the bipolaron

    A translation-invariant adiabatic theory is constructed for the bipolaron. It is shown that motions in the bipolaron are divided: the relative electron coordinates describe fast electron oscillations in the induced polarization well and the center of mass coordinates represent slow electron movement followed by polarization. Nonlinear differential bipolaron equations are derived which are asymptotically exact in the adiabatic limit. Particlelike solutions of these equations correspond to the bipolaron bound state. The exact solution yields the value of the ion critical parameter η=0.31 for which the bipolaron state is stable, where η=ε∞/ε0 and ε∞,ε0 are high-frequency and static dielectric permittivities. The energy, the total energy, the effective mass, the radius, and the critical values of the electron-phonon coupling constants are calculated for the bipolaron. The results obtained are generalized to the case of two-dimensional bipolarons

  19. Energy distributions of neutral species ejected from well-characterized surfaces measured by means of multiphoton resonance ionization spectroscopy

    The energy distributions of neutral atoms ejected from the polycrystalline Cu target, the Si(1 1 1)-7x7 surface, and the Si(1 1 1)-''5 x 5''-Cu surface by 5 keV Ar+ ion bombardment have been measured with very high efficiency by means of the multi-photon resonance ionization spectroscopy, in order to obtain the surface binding energies. The energy distributions for Cu from polycrystalline Cu target, Si from the Si(1 1 1)-7x7 surface, and Cu from the Si(1 1 1)-''5 x 5''-Cu surface have been found to have a peak at energies of around 3.0, 5.0 and 1.5 eV, and the function shapes of high energy tails to be proportional to E-1.9, E-1.2 and E-1.3, respectively. Based on the linear collision cascade theory, the surface binding energies are determined to be 5.7, 6.0 and 2.0 eV, and the power factor m in the power law approximation to the Thomas-Fermi potential are determined to be 0.1, 0.4 and 0.3 for Cu from the Cu polycrystalline, Si from the Si(1 1 1)-7x7 surface, and Cu from the Si(1 1 1)-''5 x 5''-Cu surface, respectively. In conclusion, the results indicate that the energy distributions of ejected particles are well characterized by the linear collision cascade theory developed by Sigmund

  20. Optimization of Electrospray Ionization by Statistical Design of Experiments and Response Surface Methodology: Protein-Ligand Equilibrium Dissociation Constant Determinations

    Pedro, Liliana; Van Voorhis, Wesley C.; Quinn, Ronald J.

    2016-05-01

    Electrospray ionization mass spectrometry (ESI-MS) binding studies between proteins and ligands under native conditions require that instrumental ESI source conditions are optimized if relative solution-phase equilibrium concentrations between the protein-ligand complex and free protein are to be retained. Instrumental ESI source conditions that simultaneously maximize the relative ionization efficiency of the protein-ligand complex over free protein and minimize the protein-ligand complex dissociation during the ESI process and the transfer from atmospheric pressure to vacuum are generally specific for each protein-ligand system and should be established when an accurate equilibrium dissociation constant (KD) is to be determined via titration. In this paper, a straightforward and systematic approach for ESI source optimization is presented. The method uses statistical design of experiments (DOE) in conjunction with response surface methodology (RSM) and is demonstrated for the complexes between Plasmodium vivax guanylate kinase (PvGK) and two ligands: 5'-guanosine monophosphate (GMP) and 5'-guanosine diphosphate (GDP). It was verified that even though the ligands are structurally similar, the most appropriate ESI conditions for KD determination by titration are different for each.

  1. Dissipative particle dynamics simulations of weak polyelectrolyte adsorption on charged and neutral surfaces as a function of the degree of ionization

    Alarcón, F; Goicochea, A Gama

    2012-01-01

    The influence of the chain degree of ionization on the adsorption of weak polyelectrolytes on neutral and on oppositely and likely charged surfaces is investigated for the first time, by means of Monte Carlo simulations with the mesoscopic interaction model known as dissipative particle dynamics. The electrostatic interactions are calculated using the three-dimensional Ewald sum method, with an appropriate modification for confined systems. Effective wall forces confine the linear polyelectrolytes, and electric charges on the surfaces are included. The solvent is included explicitly also and it is modeled as an athermal solvent for the polyelectrolytes. The number of solvent particles is allowed to fluctuate. The results show that the polyelectrolytes adsorb both onto neutral and charged surfaces, with the adsorption regulated by the chain degree of ionization, being larger at lower ionization degrees, where polyelectrolytes are less charged. Furthermore, polyelectrolyte adsorption is strongly modulated by th...

  2. Self-Aspirated Atmospheric Pressure Chemical Ionization Source for Direct Sampling of Analytes on Surfaces and in Liquid Solutions

    Asano, Keiji G [ORNL; Ford, Michael J [ORNL; Tomkins, Bruce A [ORNL; Van Berkel, Gary J [ORNL

    2005-01-01

    A self-aspirating heated nebulizer probe is described and demonstrated for use in the direct analysis of analytes on surfaces and in liquid samples by atmospheric pressure chemical ionization (APCI) mass spectrometry. Functionality and performance of the probe as a self-aspirating APCI source is demonstrated using reserpine and progesterone as test compounds. The utility of the probe to sample analytes directly from surfaces was demonstrated first by scanning development lanes of a reversed-phase thin-layer chromatography plate in which a three-component dye mixture, viz., Fat Red 7B, Solvent Green 3, and Solvent Blue 35, was spotted and the components were separated. Development lanes were scanned by the sampling probe operated under computer control (x, y plane) while full-scan mass spectra were recorded using a quadrupole ion trap mass spectrometer. In addition, the ability to sample the surface of pharmaceutical tablets (viz., Extra Strength Tylenol(reg. sign) and Evista(reg. sign) tablets) and to detect the active ingredients (acetaminophen and raloxifene, respectively) selectively was demonstrated using tandem mass spectrometry (MS/MS). Finally, the capability to sample analyte solutions from the wells of a 384-well microtiter plate and to perform quantitative analyses using MS/MS detection was illustrated with cotinine standards spiked with cotinine-d{sub 3} as an internal standard.

  3. Adiabatic Mass Loss Model in Binary Stars

    Ge, H. W.

    2012-07-01

    Rapid mass transfer process in the interacting binary systems is very complicated. It relates to two basic problems in the binary star evolution, i.e., the dynamically unstable Roche-lobe overflow and the common envelope evolution. Both of the problems are very important and difficult to be modeled. In this PhD thesis, we focus on the rapid mass loss process of the donor in interacting binary systems. The application to the criterion of dynamically unstable mass transfer and the common envelope evolution are also included. Our results based on the adiabatic mass loss model could be used to improve the binary evolution theory, the binary population synthetic method, and other related aspects. We build up the adiabatic mass loss model. In this model, two approximations are included. The first one is that the energy generation and heat flow through the stellar interior can be neglected, hence the restructuring is adiabatic. The second one is that he stellar interior remains in hydrostatic equilibrium. We model this response by constructing model sequences, beginning with a donor star filling its Roche lobe at an arbitrary point in its evolution, holding its specific entropy and composition profiles fixed. These approximations are validated by the comparison with the time-dependent binary mass transfer calculations and the polytropic model for low mass zero-age main-sequence stars. In the dynamical time scale mass transfer, the adiabatic response of the donor star drives it to expand beyond its Roche lobe, leading to runaway mass transfer and the formation of a common envelope with its companion star. For donor stars with surface convection zones of any significant depth, this runaway condition is encountered early in mass transfer, if at all; but for main sequence stars with radiative envelopes, it may be encountered after a prolonged phase of thermal time scale mass transfer, so-called delayed dynamical instability. We identify the critical binary mass ratio for the

  4. Surface functionalization of organic materials by weakly ionized highly dissociated oxygen plasma

    A review on surface modification of different polymers by treatment in oxygen plasma is presented. Plasma is created in a high frequency inductively coupled gaseous discharge at the power of about 200 W. In such discharge created in pure oxygen, plasma with the following parameters is obtained: the electron temperature of about 50.000 K, the charged particle density around 1x1016 m-3, and the neutral oxygen atom density of the order of 1021 m-3. A huge flux of neutral oxygen atoms on the surface of samples exposed to plasma assures for rapid interaction with polymer materials. The modification of surface properties of the following polymers was studied: polyethyleneterephthalate (PET), polyethersulphone (PES), polyphenylenesulfide (PPS), Nylon 6 polyamide (PA6), polytetrafluoroethylene (PTFE), polystyrene (PS), polypropylene (PP) and cellulose (ink-jet paper and textile). The polymer samples were treated for 3 s in oxygen plasma at a pressure of 75 Pa where the O-atom density was the largest at 4x1021 m-3. The appearance of the functional groups on the surface of the samples was monitored by high resolution X-ray photoelectron spectroscopy (XPS). The results show that oxygen plasma treatment is an effective tool for surface modification. On all polymer surfaces increased concentration of oxygen is detected. The high resolution C1s peaks indicate formation of several new oxygen-containing functional groups. On all polymers groups like C-O, C=O and O=C-O are observed. The concentration of these groups depends on the type of polymer. The highest uptake of oxygen by the polymer was found for cellulose and the lowest for polypropylene. The only exception was polymer PTFE where practically no chemical changes were observed after plasma treatment.

  5. Surface functionalization of organic materials by weakly ionized highly dissociated oxygen plasma

    Vesel, A; Mozetic, M, E-mail: alenka.vesel@ijs.s, E-mail: miran.mozetic@guest.arnes.s [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia)

    2009-04-01

    A review on surface modification of different polymers by treatment in oxygen plasma is presented. Plasma is created in a high frequency inductively coupled gaseous discharge at the power of about 200 W. In such discharge created in pure oxygen, plasma with the following parameters is obtained: the electron temperature of about 50.000 K, the charged particle density around 1x10{sup 16} m{sup -3}, and the neutral oxygen atom density of the order of 10{sup 21} m{sup -3}. A huge flux of neutral oxygen atoms on the surface of samples exposed to plasma assures for rapid interaction with polymer materials. The modification of surface properties of the following polymers was studied: polyethyleneterephthalate (PET), polyethersulphone (PES), polyphenylenesulfide (PPS), Nylon 6 polyamide (PA6), polytetrafluoroethylene (PTFE), polystyrene (PS), polypropylene (PP) and cellulose (ink-jet paper and textile). The polymer samples were treated for 3 s in oxygen plasma at a pressure of 75 Pa where the O-atom density was the largest at 4x10{sup 21} m{sup -3}. The appearance of the functional groups on the surface of the samples was monitored by high resolution X-ray photoelectron spectroscopy (XPS). The results show that oxygen plasma treatment is an effective tool for surface modification. On all polymer surfaces increased concentration of oxygen is detected. The high resolution C1s peaks indicate formation of several new oxygen-containing functional groups. On all polymers groups like C-O, C=O and O=C-O are observed. The concentration of these groups depends on the type of polymer. The highest uptake of oxygen by the polymer was found for cellulose and the lowest for polypropylene. The only exception was polymer PTFE where practically no chemical changes were observed after plasma treatment.

  6. Surface functionalization of organic materials by weakly ionized highly dissociated oxygen plasma

    Vesel, A.; Mozetic, M.

    2009-04-01

    A review on surface modification of different polymers by treatment in oxygen plasma is presented. Plasma is created in a high frequency inductively coupled gaseous discharge at the power of about 200 W. In such discharge created in pure oxygen, plasma with the following parameters is obtained: the electron temperature of about 50.000 K, the charged particle density around 1x1016 m-3, and the neutral oxygen atom density of the order of 1021 m-3. A huge flux of neutral oxygen atoms on the surface of samples exposed to plasma assures for rapid interaction with polymer materials. The modification of surface properties of the following polymers was studied: polyethyleneterephthalate (PET), polyethersulphone (PES), polyphenylenesulfide (PPS), Nylon 6 polyamide (PA6), polytetrafluoroethylene (PTFE), polystyrene (PS), polypropylene (PP) and cellulose (ink-jet paper and textile). The polymer samples were treated for 3 s in oxygen plasma at a pressure of 75 Pa where the O-atom density was the largest at 4x1021 m-3. The appearance of the functional groups on the surface of the samples was monitored by high resolution X-ray photoelectron spectroscopy (XPS). The results show that oxygen plasma treatment is an effective tool for surface modification. On all polymer surfaces increased concentration of oxygen is detected. The high resolution C1s peaks indicate formation of several new oxygen-containing functional groups. On all polymers groups like C-O, C=O and O=C-O are observed. The concentration of these groups depends on the type of polymer. The highest uptake of oxygen by the polymer was found for cellulose and the lowest for polypropylene. The only exception was polymer PTFE where practically no chemical changes were observed after plasma treatment.

  7. Development of a He/CdI$_2$ gas-jet system coupled to a surface-ionization type ion-source in JAEA-ISOL: towards determination of the first ionization potential of Lr (Z = 103)

    Sato, T K; Sato, N; Tsukada, K; Toyoshima, A; Ooe, K; Miyashita, S; Kaneya, Y; Osa, A; Schädel, M; Nagame, Y; Ichikawa, S; Stora, T; Kratz, J V

    2015-01-01

    We report on development of a gas-jet transport system coupled to a surface ionization ion-source in the JAEA-ISOL (Isotope Separator On-Line) system. As a new aerosol material for the gas-jet system, CdI2, which has a low boiling point of 713 °C, is exploited to prevent deposition of the aerosol material on the surface of the ion-source. An additional filament is newly installed in the previous ion-source to provide uniform heating of an ionizer. The present system is applied to the measurement of absolute efficiencies of various short-lived lanthanide isotopes produced in nuclear reactions.

  8. Adiabatic processes in monatomic gases

    A kinetic model is used to predict the temperature evolution of a monatomic ideal gas undergoing an adiabatic expansion or compression at a constant finite rate, and it is then generalized to treat real gases. The effects of interatomic forces are considered, using as examples the gas with the square-well potential and the van der Waals gas. The model is integrated into a Carnot cycle operating at a finite rate to compare the efficiency's rate-dependent behavior with the reversible result. Limitations of the model, rate penalties, and their importance are discussed

  9. Additional adiabatic heating of plasma

    A theoretical possibility of a plasma additional adiabatic heating up to temperatures needed for the begin of D-T thermonuclear fusion reaction, has been found on the base of the polyenergetic conjugation expression, developed in the Thermodynamics of Accumulation Processes. TAP is a branch of the non-equilibrium thermodynamics. The thermodynamics of irreversible processes is another branch of the entire non-equilibrium thermodynamics. TAP deals with the phenomena associated with the introduction, conversion and accumulation of mass or energy or both in the affected, open or closed systems. (author) 2 refs

  10. Non-sequential double ionization of molecules

    Prauzner-Bechcicki, J S; Eckhardt, B; Zakrzewski, J; Prauzner-Bechcicki, Jakub S.; Sacha, Krzysztof; Eckhardt, Bruno; Zakrzewski, Jakub

    2004-01-01

    Double ionization of diatomic molecules by short linearly polarized laser pulses is analyzed. We consider the final stage of the ionization process, that is the decay of a highly excited two electron molecule, which is formed after re-scattering. The saddles of the effective adiabatic potential energy close to which simultaneous escape of electrons takes place are identified. Numerical simulations of the ionization of molecules show that the process can be dominated by either sequential or non-sequential events. In order to increase the ratio of non-sequential to sequential ionizations very short laser pulses should be applied.

  11. Technology to produce silicon-made surface detectors to detect ionizing particles

    The purpose of this article is to show a technology to produce silicon-made surface barrier detectors to detect short-run charger particles developed in the Electronic Department of the Center of Studies Applied to Nuclear Development in collaboration of the High Polytechnic Institute 'Jose Antonio Echevarria'. These detectors were produced with the same silicon material which is used in the semiconductor device factory of Pinar del Rio 'Ernesto Che Guevara'

  12. Determining estrogens using surface-assisted laser desorption/ionization mass spectrometry with silver nanoparticles as the matrix.

    Chiu, Tai-Chia; Chang, Lin-Chau; Chiang, Cheng-Kang; Chang, Huan-Tsung

    2008-09-01

    We describe the application of silver nanoparticles (Ag NPs) as matrices for the determination of three estrogens using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Because Ag NPs have extremely high absorption coefficients (1.2 x 10(8) M(-1) cm(-1)) at 337 nm, they are effective SALDI matrices when using a nitrogen laser. Three tested estrogens--estrone (E1), estradiol (E2), and estriol (E3)--adsorb weakly onto the surfaces of the Ag NPs, through van der Waals forces. After centrifugation, the concentrated analytes adsorbed on the Ag NPs were subjected directly to SALDI-MS analyses, with the limits of detection for E1, E2, and E3 being 2.23, 0.23, and 2.11 microM, respectively. The shot-to-shot and batch-to-batch variations for the three analytes were less than 9% and 13%, respectively. We validated the practicality of this present approach through the quantitation of E2 in human urine. Using this approach, we determined the concentration of E2 in a sample of a pregnant woman's urine to be 0.16+/-0.05 microM (n=10). PMID:18640850

  13. Electrospun Nanofiber Mats as "Smart Surfaces" for Desorption Electrospray Ionization Mass Spectrometry (DESI MS)-Based Analysis and Imprint Imaging.

    Hemalatha, R G; Ganayee, Mohd Azhardin; Pradeep, T

    2016-06-01

    In this paper, desorption electrospray ionization mass spectrometry (DESI MS)-based molecular analysis and imprint imaging using electrospun nylon-6 nanofiber mats are demonstrated for various analytical contexts. Uniform mats of varying thicknesses composed of ∼200 nm diameter fibers were prepared using needleless electrospinning. Analytical applications requiring rapid understanding of the analytes in single drops, dyes, inks, and/or plant extracts incorporated directly into the nanofibers are discussed with illustrations. The possibility to imprint patterns made of printing inks, plant parts (such as petals, leaves, and slices of rhizomes), and fungal growth on fruits with their faithful reproductions on the nanofiber mats is illustrated with suitable examples. Metabolites were identified by tandem mass spectrometry data available in the literature and in databases. The results highlight the significance of electrospun nanofiber mats as smart surfaces to capture diverse classes of compounds for rapid detection or to imprint imaging under ambient conditions. Large surface area, appropriate chemical functionalities exposed, and easiness of desorption due to weaker interactions of the analyte species are the specific advantages of nanofibers for this application. PMID:27159150

  14. A New Approach to the Quantum Adiabatic Condition

    The quantum adiabatic theorem is the basis of adiabatic quantum computation. However, the exact necessary and sufficient conditions for adiabatic evolution are still under debate. We discuss the adiabatic condition of a system undergoing a special evolution route, and obtain an explicit formula that is necessary and sufficient for the adiabatic evolution in this route. Based on this formula, we find that the traditional adiabatic condition is neither sufficient nor necessary. Finally, we show that no adiabatic process can occur even the evolution speed goes to 0 in some examples, which is surprising since the adiabatic theorem states that if the evolution of a system is slow enough, the adiabatic process could occur

  15. Effects of Ionizing Radiation on Surface Infesting Microbes of Stored Grain

    Spoilage of nutritional value of stored grains and seeds by the surface-infesting microbes, especially those producing mycotoxins, has been a worldwide economic problem. In this perspective our present work aims at probing into the potential of gamma rays to reduce the microbial infestation on stored grain surface and additionally to focus differential radiation sensitivity, if any, of the different fungi in response to gradient of gamma exposure. Co-60 source at 250 C emitting gamma rays at 1173 and 1332 keV energy (0.12 kGy/h) was used in the range of 0.5-6 kGy (absorbed dose) for irradiating some common stored seeds in India namely rice (Oryza sativa. Cv-2233 and Oryza sativa. Cv-Shankar), Bengal gram (Cicer arietinum. Cv-local), wheat (Triticum aestivum) and Mung (Phaseolus mungo). Gamma irradiation results in dose-dependent delay in colony formation and growth inhibition of the fungi on the seed surface. Differential rate of depletion was noted for different fungi. Effective absorbed dose for depletion of Alternaria sp., Aspergillus sp was 1 to 2 kGy while that for Tricoderma sp., Curvularia sp was 0.5-1 kGy. Complete inhibition of all the selected fungi was found above 2.5 kGy. Germinating potential of the irradiated grains remained unaffected upto an absorbed dose of 2kGy while their respective nutritional value in terms of protein and carbohydrate content was not significantly altered. Higher doses of exposure however, documented delayed seed germination. Colony forming ability (CFA) of the exposed fungi documented significant variation between fungi attached to the seed surface and that when isolated from the host. Alternaria sp, Aspergillus sp or Curvularia sp exhibited total inhibition of CFA at a much lower dose (1-3 kGy) in isolated conditions than that when seed attached (>4kGy). On the other hand Trichoderma sp expressed a different trend revealing more sensitivity in seed attached condition. Such differential response possibly reflects species

  16. Adiabatic Rearrangement of Hollow PV Towers

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  17. Resonance ionization spectroscopy 1986

    The paper presents the proceedings of the Third International Symposium on Resonance Ionization Spectroscopy and its Applications, held at the University College of Swansea, Wales, 1986. The Symposium is divided into eight main sections entitled: photophysics and spectroscopy, noble gas atom counting, resonance ionization mass spectrometry, materials and surface analysis, small molecules, medical and environmental applications, resonance ionization and materials separation, and elementary particles and nuclear physics. Thirty papers were chosen for INIS and indexed separately. (U.K.)

  18. Complete Adiabatic Quantum Search in Unsorted Databases

    Xu, Nanyang; Peng, Xinhua; Shi, Mingjun; Du, Jiangfeng

    2008-01-01

    We propose a new adiabatic algorithm for the unsorted database search problem. This algorithm saves two thirds of qubits than Grover's algorithm in realizations. Meanwhile, we analyze the time complexity of the algorithm by both perturbative method and numerical simulation. The results show it provides a better speedup than the previous adiabatic search algorithm.

  19. Shortcut to adiabatic gate teleportation

    Santos, Alan C.; Silva, Raphael D.; Sarandy, Marcelo S.

    2016-01-01

    We introduce a shortcut to the adiabatic gate teleportation model of quantum computation. More specifically, we determine fast local counterdiabatic Hamiltonians able to implement teleportation as a universal computational primitive. In this scenario, we provide the counterdiabatic driving for arbitrary n -qubit gates, which allows to achieve universality through a variety of gate sets. Remarkably, our approach maps the superadiabatic Hamiltonian HSA for an arbitrary n -qubit gate teleportation into the implementation of a rotated superadiabatic dynamics of an n -qubit state teleportation. This result is rather general, with the speed of the evolution only dictated by the quantum speed limit. In particular, we analyze the energetic cost for different Hamiltonian interpolations in the context of the energy-time complementarity.

  20. Non-adiabatic dynamics of molecules in optical cavities

    Kowalewski, Markus, E-mail: mkowalew@uci.edu; Bennett, Kochise; Mukamel, Shaul, E-mail: smukamel@uci.edu [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States)

    2016-02-07

    Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.

  1. Non-adiabatic dynamics of molecules in optical cavities

    Kowalewski, Markus; Mukamel, Shaul

    2016-01-01

    Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.

  2. Expression of Cellular Isoform of Prion Protein on the Surface of Peripheral Blood Lymphocytes Among Women Exposed to Low Doses of Ionizing Radiation

    Ionizing radiation affect the expression of adhesive and co-stimulation molecules in lymphocytes. The objective of this study was to determinate the effect of low doses of ionizing radiation on the expression of prion protein PrPc on the surface peripheral blood lymphocytes in the women operating X-ray equipment. In female workers and persons of the control group the PrPc expression on CD3 (T-lymphocytes), Cd4 (T-helper), CD8 (T-cytotoxic) and CD19 (B- lymphocytes), were tested. We conclude that in women operating X-ray equipment the relationship between low doses of ionizing radiation and expression of PrPc on lymphocytes does exist concerning CD3, CD4 and CD lymphocytes. (author)

  3. Quantum gates with controlled adiabatic evolutions

    Hen, Itay

    2015-02-01

    We introduce a class of quantum adiabatic evolutions that we claim may be interpreted as the equivalents of the unitary gates of the quantum gate model. We argue that these gates form a universal set and may therefore be used as building blocks in the construction of arbitrary "adiabatic circuits," analogously to the manner in which gates are used in the circuit model. One implication of the above construction is that arbitrary classical boolean circuits as well as gate model circuits may be directly translated to adiabatic algorithms with no additional resources or complexities. We show that while these adiabatic algorithms fail to exhibit certain aspects of the inherent fault tolerance of traditional quantum adiabatic algorithms, they may have certain other experimental advantages acting as quantum gates.

  4. Steroid hormones analysis with surface-assisted laser desorption/ionization mass spectrometry using catechin-modified titanium dioxide nanoparticles.

    Chiu, Tai-Chia

    2011-10-30

    This paper describes the application of catechin-modified titanium dioxide nanoparticles (TiO(2) NPs) as matrices to analyze four steroid hormones by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The catechin-modified TiO(2) NPs have high absorbance at 337 nm and are effective SALDI matrices when using a nitrogen laser. Four test steroid hormones-cortisone, hydrocortisone, progesterone, and testosterone-were directly analyzed by SALDI-MS. The limits of detection at a signal-to-noise ratio of 3 for cortisone, hydrocortisone, progesterone, and testosterone were 1.62, 0.70, 0.66, and 0.23 μM, respectively. This approach provides good quantitative linearity for the four analytes (R(2)>0.986) with good reproducibility (the shot-to-shot and batch-to-batch variations for the four analytes were less than 10% and 15%, respectively). We validated the practicality of this approach-considering its advantages in sensitivity, repeatability, rapidity, and simplicity-through the analysis of testosterone in a urine sample. PMID:22063559

  5. On the statistical mechanics of an adiabatic ensemble

    S.N.Andreev

    2004-01-01

    Full Text Available Different descriptions of an adiabatic process based on statistical thermodynamics and statistical mechanics are discussed. Equality of the so-called adiabatic and isolated susceptibilities and its generalization as well as adiabatic invariants are essentially used to describe adiabatic processes in the framework of quantum and classical statistical mechanics. It is shown that distribution function in adiabatic ensemble differs from a quasi-equilibrium canonical form provided the heat capacity of the system is not constant in adiabatic process.

  6. Partial evolution based local adiabatic quantum search

    Recently, Zhang and Lu provided a quantum search algorithm based on partial adiabatic evolution, which beats the time bound of local adiabatic search when the number of marked items in the unsorted database is larger than one. Later, they found that the above two adiabatic search algorithms had the same time complexity when there is only one marked item in the database. In the present paper, following the idea of Roland and Cerf [Roland J and Cerf N J 2002 Phys. Rev. A 65 042308], if within the small symmetric evolution interval defined by Zhang et al., a local adiabatic evolution is performed instead of the original “global” one, this “new” algorithm exhibits slightly better performance, although they are progressively equivalent with M increasing. In addition, the proof of the optimality for this partial evolution based local adiabatic search when M = 1 is also presented. Two other special cases of the adiabatic algorithm obtained by appropriately tuning the evolution interval of partial adiabatic evolution based quantum search, which are found to have the same phenomenon above, are also discussed. (general)

  7. Digital Waveguide Adiabatic Passage Part 2: Experiment

    Ng, Vincent; Chaboyer, Zachary J; Nguyen, Thach; Dawes, Judith M; Withford, Michael J; Greentree, Andrew D; Steel, M J

    2016-01-01

    Using a femtosecond laser writing technique, we fabricate and characterise three-waveguide digital adiabatic passage devices, with the central waveguide digitised into five discrete waveguidelets. Strongly asymmetric behaviour was observed, devices operated with high fidelity in the counter-intuitive scheme while strongly suppressing transmission in the intuitive. The low differential loss of the digital adiabatic passage designs potentially offers additional functionality for adiabatic passage based devices. These devices operate with a high contrast ($>\\!90\\%$) over a 60~nm bandwidth, centered at $\\sim 823$~nm.

  8. Adiabatic Compression of Oxygen: Real Fluid Temperatures

    Barragan, Michelle; Wilson, D. Bruce; Stoltzfus, Joel M.

    2000-01-01

    The adiabatic compression of oxygen has been identified as an ignition source for systems operating in enriched oxygen atmospheres. Current practice is to evaluate the temperature rise on compression by treating oxygen as an ideal gas with constant heat capacity. This paper establishes the appropriate thermodynamic analysis for the common occurrence of adiabatic compression of oxygen and in the process defines a satisfactory equation of state (EOS) for oxygen. It uses that EOS to model adiabatic compression as isentropic compression and calculates final temperatures for this system using current approaches for comparison.

  9. A chemical ionization mass spectrometer for continuous underway shipboard analysis of dimethylsulfide in near-surface seawater

    E. S. Saltzman; W. J. De Bruyn; Lawler, M J; Marandino, C. A.; McCormick, C. A.

    2009-01-01

    A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ("mini-CIMS") has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS) in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer ...

  10. Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo

    Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In most cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems

  11. Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo

    Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems

  12. Adiabatic far-field sub-diffraction imaging

    Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang

    2015-08-01

    The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale.

  13. Thermoelectric Effects under Adiabatic Conditions

    George Levy

    2013-10-01

    Full Text Available This paper investigates not fully explained voltage offsets observed by several researchers during the measurement of the Seebeck coefficient of high Z materials. These offsets, traditionally attributed to faulty laboratory procedures, have proven to have an irreducible component that cannot be fully eliminated in spite of careful laboratory procedures. In fact, these offsets are commonly observed and routinely subtracted out of commercially available Seebeck measurement systems. This paper offers a possible explanation based on the spontaneous formation of an adiabatic temperature gradient in the presence of a force field. The diffusion-diffusion heat transport mechanism is formulated and applied to predict two new thermoelectric effects. The first is the existence of a temperature gradient across a potential barrier in a semiconductor and the second is the Onsager reciprocal of the first, that is, the presence of a measureable voltage that arises across a junction when the temperature gradient is forced to zero by a thermal clamp. Suggested future research includes strategies for utilizing the new thermoelectric effects.

  14. Using Surface-Assisted Laser Desorption/Ionization Mass Spectrometry to Detect ss- and ds-Oligodeoxynucleotides

    Chen, Wen-Tsen; Huang, Ming-Feng; Chang, Huan-Tsung

    2013-06-01

    We applied surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) with HgTe nanostructures as the matrix for the detection of single- and double-stranded oligodeoxynucleotides (ss-ODNs and ds-ODNs). The concentrations of surfactant and additives (metal ions, an amine) and the pH and ionic strength of the sample matrix played significantly different roles in the detection of ss- and ds-ODNs with various sequences. In the presence of Brij 76 (1.5 %), Hg2+ (7.5 μM), and cadaverine (10 μM) at pH 5.0, this SALDI-MS approach allowed the simultaneous detection of T15, T20, T33, and T40, with limits of detection at the femtomole-to-picomole level and sample-to-sample intensity variation <23 %. In the presence of Ag+ (1 μM) and cadaverine (10 μM) at pH 7.0, this technique allowed the detection of randomly sequenced ss- and ds-ODNs at concentrations down to the femtomole level. To the best of our knowledge, this paper is the first to report the detection of ss-ODNs (up to 50-mer) and ds-ODNs (up to 30 base pairs) through the combination of SALDI-MS with HgTe nanostructures as matrices. We demonstrated the practicality of this approach through analysis of a single nucleotide polymorphism that determines the fate of the valine residue in the β-globin of sickle cell megaloblasts.

  15. Dissipative particle dynamics simulations of weak polyelectrolyte adsorption on charged and neutral surfaces as a function of the degree of ionization

    F. Alarcón; E. Pérez; Goicochea, A. Gama

    2012-01-01

    The influence of the chain degree of ionization on the adsorption of weak polyelectrolytes on neutral and on oppositely and likely charged surfaces is investigated for the first time, by means of Monte Carlo simulations with the mesoscopic interaction model known as dissipative particle dynamics. The electrostatic interactions are calculated using the three-dimensional Ewald sum method, with an appropriate modification for confined systems. Effective wall forces confine the linear polyelectro...

  16. Facile synthesis of gold@graphitized mesoporous silica nanocomposite and its surface-assisted laser desorption/ionization for time-of-flight mass spectroscopy.

    Xu, Guiju; Liu, Shengju; Peng, Jiaxi; Lv, Wenping; Wu, Ren'an

    2015-01-28

    In this work, a novel core-shell structured gold@graphitized mesoporous silica nanocomposite (Au@GMSN) was synthesized by in situ graphitization of template within the mesochannels of mesoporous silica shell on gold core and demonstrated to be promising nanomaterials for surface-assisted laser desorption/ionization time-of-flight mass spectroscopy (SALDI-TOF MS). The integration of the graphitized mesoporous silica with the gold nanoparticles endowed Au@GMSN with large surface areas of graphitic structure, good dispersibility, and strong ultraviolet (UV) absorption. Au@GMSN exerted the synergistic effect on the efficient detection of small-molecular-weight analytes including amino acids, neutral saccharides, peptides, and traditional Chinese medicine. The Au@GMSN-assisted laser desorption/ionization exhibited the following superiorities: high ionization efficiency, low fragmentation interference, favorable salt tolerance, and good reproducibility. Moreover, because of the large hydrophobic inner surface area of the graphitized mesoporous silica shell, the Au@GMSN demonstrated its promising capacity in the pre-enrichment of aromatic analytes prior to SALDI-TOF MS, which favored rapid and sensitive detection. PMID:25552293

  17. Adiabatic Invariance of Oscillons/I-balls

    Kawasaki, Masahiro; Takeda, Naoyuki

    2015-01-01

    Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or $I$-balls. We prove the adiabatic invariance of the oscillons/$I$-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/$I$-balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/$I$-balls are only quasi-stable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the $I$-balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/$I$-balls is due to the adiabatic invariance.

  18. Adiabatic hydrodynamics: The eightfold way to dissipation

    Haehl, Felix M; Rangamani, Mukund

    2015-01-01

    We provide a complete solution to hydrodynamic transport at all orders in the gradient expansion compatible with the second law constraint. The key new ingredient we introduce is the notion of adiabaticity, which allows us to take hydrodynamics off-shell. Adiabatic fluids are such that off-shell dynamics of the fluid compensates for entropy production. The space of adiabatic fluids is quite rich, and admits a decomposition into seven distinct classes. Together with the dissipative class this establishes the eightfold way of hydrodynamic transport. Furthermore, recent results guarantee that dissipative terms beyond leading order in the gradient expansion are agnostic of the second law. While this completes a transport taxonomy, we go on to argue for a new symmetry principle, an Abelian gauge invariance that guarantees adiabaticity in hydrodynamics. We suggest that this symmetry is the macroscopic manifestation of the microscopic KMS invariance. We demonstrate its utility by explicitly constructing effective ac...

  19. AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT

    We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grüneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.

  20. Ionization chamber

    An ionization chamber X-ray detector is described. It comprises a flat cathode sheet parallel to an anode which has a perforated insulating layer on its surface. An open grid, a thin perforated metal sheet is disposed on the insulating layer - the perforations of the layer and sheet are aligned. There is a detector gas and means for maintaining the grid at an electric potential between that of the anode and cathode and for measuring the current flow from the anode to the cathode. The grid shields the anode from the electric field produced by the positive ions which flow towards the cathode and this permits an independent measurement of the electron current flowing to the anode; even when the X-ray pulse length is not much shorter than the ion drift time. The recovery time of the ionization chamber is thus decreased by several orders of magnitude over previous chambers. The grid will normally be fixed to the anode and by shielding the anode from the cathode electric field, tends to eliminate capacitive microphone currents which would otherwise flow in the anode circuit. (U.K.)

  1. On adiabatic invariant in generalized Galileon theories

    Ema, Yohei; Jinno, Ryusuke; Mukaida, Kyohei; Nakayama, Kazunori

    2015-01-01

    We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is us...

  2. Quantum and classical dynamics in adiabatic computation

    Crowley, P. J. D.; Duric, T.; Vinci, W.; Warburton, P. A.; Green, A. G.

    2014-01-01

    Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations th...

  3. Adiabatic Connection for Strictly-Correlated Electrons

    Liu, Zhenfei; Burke, Kieron

    2009-01-01

    Modern density functional theory (DFT) calculations employ the Kohn-Sham (KS) system of non-interacting electrons as a reference, with all complications buried in the exchange-correlation energy (Exc). The adiabatic connection formula gives an exact expression for Exc. We consider DFT calculations that instead employ a reference of strictly-correlated electrons. We define a "decorrelation energy" that relates this reference to the real system, and derive the corresponding adiabatic connection...

  4. Adiabatic Approximation, Semiclassical Scattering, and Unidirectional Invisibility

    Mostafazadeh, Ali

    2014-01-01

    arXiv:1401.4315v3 [quant-ph] 27 Feb 2014 Adiabatic Approximation, Semiclassical Scattering, and Unidirectional Invisibility Ali Mostafazadeh∗ Department of Mathematics, Ko¸c University, 34450 Sarıyer, Istanbul, Turkey Abstract The transfer matrix of a possibly complex and energy-dependent scattering potential can be identified with the S-matrix of a two-level time-dependent non-Hermitian Hamiltonian H( ). We show that the application of the adiabatic approximation ...

  5. Adiabatic fission barriers in superheavy nuclei

    Jachimowicz, P; Skalski, J

    2016-01-01

    Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations...

  6. Muonic molecules as three-body Coulomb problem in adiabatic approximation

    The three-body Coulomb problem is treated within the framework of the hyperspherical adiabatic approach. The surface functions are expanded into Faddeev-type components in order to ensure the equivalent representation of all possible two-body contributions. It is shown that this decomposition reduces the numerical effort considerably. The remaining radial equations are solved both in the extreme and the uncoupled adiabatic approximation to determine the binding energies of the systems (dtμ) and (d3Heμ). Whereas the ground state is described very well in the uncoupled adiabatic approximation, the excited states should be treated within the coupled adiabatic approximation to obtain good agreement with variational calculations. (orig.)

  7. Amplitudes of solar-like oscillations in red giants: Departures from the quasi-adiabatic approximation

    Barban C.

    2013-03-01

    Full Text Available CoRoT and Kepler measurements reveal us that the amplitudes of solar-like oscillations detected in red giant stars scale from stars to stars in a characteristic way. This observed scaling relation is not yet fully understood but constitutes potentially a powerful diagnostic about mode physics. Quasi-adiabatic theoretical scaling relations in terms of mode amplitudes result in systematic and large differences with the measurements performed for red giant stars. The use of a non-adiabatic intensity-velocity relation derived from a non-adiabatic pulsation code significantly reduces the discrepancy with the CoRoT measurements. The origin of the remaining difference is still unknown. Departure from adiabatic eigenfunction is a very likely explanation that is investigated in the present work using a 3D hydrodynamical model of the surface layers of a representative red giant star.

  8. A comparative study on carbon, boron-nitride, boron-phosphide and silicon-carbide nanotubes based on surface electrostatic potentials and average local ionization energies.

    Esrafili, Mehdi D; Behzadi, Hadi

    2013-06-01

    A density functional theory study was carried out to predict the electrostatic potentials as well as average local ionization energies on both the outer and the inner surfaces of carbon, boron-nitride (BN), boron-phosphide (BP) and silicon-carbide (SiC) single-walled nanotubes. For each nanotube, the effect of tube radius on the surface potentials and calculated average local ionization energies was investigated. It is found that SiC and BN nanotubes have much stronger and more variable surface potentials than do carbon and BP nanotubes. For the SiC, BN and BP nanotubes, there are characteristic patterns of positive and negative sites on the outer lateral surfaces. On the other hand, a general feature of all of the systems studied is that stronger potentials are associated with regions of higher curvature. According to the evaluated surface electrostatic potentials, it is concluded that, for the narrowest tubes, the water solubility of BN tubes is slightly greater than that of SiC followed by carbon and BP nanotubes. PMID:23408252

  9. An Integrated Programming and Development Environment for Adiabatic Quantum Optimization

    Humble, Travis S.; McCaskey, Alex J.; Bennink, Ryan S.; Billings, Jay J.; D'Azevedo, Ed F.; Sullivan, Blair D.; Klymko, Christine F.; Seddiqi, Hadayat

    2013-01-01

    Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for adiabatic quantum optimization called JADE tha...

  10. On criterion of modal adiabaticity

    WANG; Ning(

    2001-01-01

    [1]Pierce, A. D., Extension of the method of normal modes to sound propagation in an almost-stratified medium, J. Acoust.Soc. Am., 1965, 37: 19-27.[2]Wang, D. Z. , Shang, E. C., Underwater Acoustics (in Chinese), Beijing: Science Press, 1981.[3]Zhang Renhe, Li Fenghua, Beam-displacement rya-mode theory of sound propagation in shallow water, Science in China, Ser.A, 1999, 42(7): 739-749.[4]Zhou Jixun, Zhang Xuezhen, Rogers P., Resonance interaction of sound waves with internal solitons in coastal zone, J.Acoust. Soc. Am., 1991, 90: 2042-2054.[5]Shang, E. C., Wang, Y. Y., The impact of mesoscale oceanic structure on global-scale acoustic propagation, in Theoretical and Computational Acoustics (ed. Ding Lee et al. ), Singapore: World Scientific Publishing Co. , 1996, 409-431.[6]Milder, D. M., Ray and wave invariants for SOFAR channel propagation, J. Acoust. Soc. Am., 1969, 46: 1259-1263.[7]Nag l, A., Milder, D. M., Adiabatic mode theory of underwater sound propagation in a range-dependent environment, J.Acoust. Soc. Am., 1978, 63: 739-749.[8]Brekhovskikh, L. M., Waves in Layered Media, 2nd ed., New York: Academic Press Inc., 1973.[9]Brekhovskikh, L. M., Lysanov, Yu., Fundamental of Ocean Acoustics, Ch. 7, Sec. 7.2, Berlin: Springer-Verlag, 1982.[10]Evans, R. B., A coupled mode solution for acoustic propagation in a wave-guide with stepwise depth variations of a penerable bottom, J. Acoust. Soc. A.m., 1983, 74: 188-195.[11]Jensen, F. B., Kuperman, W. A., Porter, M. B. et al., Computational Ocean Acoustics, New York: Springer-Verlag,1992.[12]Wang Ning, Inverse scattering problem for the coupled second order ODE, Journal of The Physical Society of Japan, 1995, 64(12): 4907-4915.

  11. Impact of electron ionization on the generation of high-order harmonics from molecules

    When the laser frequency is tuned to be equal to the molecular electronic excitation, high-order harmonics are generated due to the electronic dipole transitions between the corresponding two potential-energy surfaces (PES). A natural, often taken, choice is the PES of the field-free molecular system. In this special choice the ionization phenomenon is not considered. Only the effect of the dissociation is considered. The method we developed enables one to remain within the framework of the 2-PES approximation and yet to include also the ionization effect in the calculations of molecular high-order harmonic generation spectra. In this approach the coupling between the electronic and nuclear motions is taken into consideration by using coupled complex adiabatic PES. As an illustrative numerical example, we calculated the high harmonic generation (HHG) spectra of H2+ in a 730-nm laser with the intensity of 8.77x1013 W/cm2. The inclusion of the ionization in our approach not only enables the electrons to tunnel through the effective static potential barrier, but also apply an asymmetric force which accelerates the electron before ionization takes place. Therefore, indirectly the inclusion of the ionization by the laser field may lead eventually to an enhanced HHG spectra in comparison with the calculated one when the ''natural'' choice of the field-free 2PES is taken

  12. Symmetry-Protected Quantum Adiabatic Transistors

    Williamson, Dominic J.; Bartlett, Stephen D.

    2014-03-01

    An essential development in the history of computing was the invention of the transistor as it allowed logic circuits to be implemented in a robust and modular way. The physical characteristics of semiconductor materials were the key to building these devices. We aim to present an analogous development for quantum computing by showing that quantum adiabatic transistors (as defined by Flammia et al.) are built upon the essential qualities of symmetry-protected (SP) quantum ordered phases in one dimension. Flammia et al. and Renes et al. have demonstrated schemes for universal adiabatic quantum computation using quantum adiabatic transistors described by interacting spin chain models with specifically chosen Hamiltonian terms. We show that these models can be understood as specific examples of the generic situation in which all SP phases lead to quantum computation on encoded edge degrees of freedom by adiabatically traversing a symmetric phase transition into a trivial symmetric phase. This point of view is advantageous as it allows us to readily see that the computational properties of a quantum adiabatic transistor arise from a phase of matter rather than due to carefully tuned interactions.

  13. Accurate adiabatic correction in the hydrogen molecule

    Pachucki, Krzysztof, E-mail: krp@fuw.edu.pl [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Komasa, Jacek, E-mail: komasa@man.poznan.pl [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland)

    2014-12-14

    A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

  14. Exploring adiabatic quantum trajectories via optimal control

    Adiabatic quantum computation employs a slow change of a time-dependent control function (or functions) to interpolate between an initial and final Hamiltonian, which helps to keep the system in the instantaneous ground state. When the evolution time is finite, the degree of adiabaticity (quantified in this work as the average ground-state population during evolution) depends on the particulars of a dynamic trajectory associated with a given set of control functions. We use quantum optimal control theory with a composite objective functional to numerically search for controls that achieve the target final state with a high fidelity while simultaneously maximizing the degree of adiabaticity. Exploring the properties of optimal adiabatic trajectories in model systems elucidates the dynamic mechanisms that suppress unwanted excitations from the ground state. Specifically, we discover that the use of multiple control functions makes it possible to access a rich set of dynamic trajectories, some of which attain a significantly improved performance (in terms of both fidelity and adiabaticity) through the increase of the energy gap during most of the evolution time. (paper)

  15. Adiabatic cooling of a single trapped ion

    Poulsen, Gregers

    2012-01-01

    We present experimental results on adiabatic cooling of a single 40Ca+ ion in a linear radiofrequency trap. After a period of laser cooling, the secular frequency along the rf-field-free axis is adiabatically lowered by nearly a factor of eight from 583 kHz to 75 kHz. For an ion originally Doppler laser cooled to a temperature of 0.65 +/- 0.03 mK, a temperature of 87 +/- 7 \\mu K is measured after the adiabatic expansion. Applying the same adiabatic cooling procedure to a single sideband cooled ion in the ground state (P0 = 0.978 +/- 0.002) resulted in a final ground state occupation of 0.947 +/- 0.005. Both results are in excellent agreement with an essentially fully adiabatic behavior. The results have a wide range of perspectives within such diverse fields as ion based quantum information science, high resolution molecular ion spectroscopy and ion chemistry at ultra-low temperatures.

  16. Adiabatic process reversibility: microscopic and macroscopic views

    The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r≥1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values. (letters and comments)

  17. Adiabatic change of state of photon gas

    The authors introduced and justified the k problem as a thermodynamical contradiction of photon gas. In thermodynamics of photon gas the main contradiction is called the k problem: the piezotropic-autobarotropic equation of state P = u/3 is adiabatic if k = 1 exclusively, while the adiabatic connection PV4/3 = const (or rather the Poisson equation Pρ-4/3 = const, ρ = u/c2) requires that k = 4/3. The present paper shows that the equations of state PV4/3 = const, TV1/3 = const, T-4/3P1/3 = const and P = u/3 cannot be valid for the adiabatic change of state of photon gas, simultaneously. Furthermore, the Planck's distribution -- and so the Wien's law and the Rayleigh-Jeans connection as well -- cannot be invariant in case of adiabatic change of state of photon gas. Namely, in case of adiabatic change of state of photon gas, a new type of ultraviolet catastrophe appears. These results possess a fundamental important in case of arbitrary deformation of electromagnetic radiation fields or quantum plasmas

  18. Nonadiabatic exchange dynamics during adiabatic frequency sweeps

    Barbara, Thomas M.

    2016-04-01

    A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.

  19. Energy efficiency of adiabatic superconductor logic

    Adiabatic superconductor logic (ASL), including adiabatic quantum-flux-parametron (AQFP) logic, exhibits high energy efficiency because its bit energy can be decreased below the thermal energy through adiabatic switching operations. In the present paper, we present the general scaling laws of ASL and compare the energy efficiency of ASL with those of other energy-efficient logics. Also, we discuss the minimum energy-delay product (EDP) of ASL at finite temperature. Our study shows that there is a maximum temperature at which the EDP can reach the quantum limit given by ħ/2, which is dependent on the superconductor material and the Josephson junction quality, and that it is reasonable to operate ASL at cryogenic temperatures in order to achieve an EDP that approaches ħ/2. (paper)

  20. Experimental study on the adiabatic shear bands

    Four martensitic steels (Z50CDV5 steel, 28CND8 steel, 35NCDV16 steel and 4340 steel) with different hardness between 190 and 600 Hsub(B) (Brinell hardness), have been studied by means of dynamic compressive tests on split Hopkinson pressure bar. Microscopic observations show that the fracture are associated to the development of adiabatic shear bands (except 4340 steel with 190 Hsub(B) hardness). By means of tests for which the deformation is stopped at predetermined levels, the measurement of shear and hardness inside the band and the matrix indicates the chronology of this phenomenon: first the localization of shear, followed by the formation of adiabatic shear band and ultimatly crack initiation and propagation. These results correlated with few simulations by finite elements have permitted to suggest two mecanisms of deformation leading to the formation of adiabatic shear bands in this specific test

  1. Non-adiabatic study of the Kepler subgiant KIC 6442183

    Grosjean M.

    2015-01-01

    Full Text Available Thanks to the precision of Kepler observations, [3] were able to measure the linewidth and amplitude of individual modes (including mixed modes in several subgiant power spectra. We perform a forward modelling of a Kepler subgiant based on surface properties and observed frequencies. Non-adiabatic computations including a time- dependent treatment of convection give the lifetimes of radial and non-radial modes. Next, combining the lifetimes and inertias with a stochastic excitation model gives the amplitudes of the modes. We can now directly compare theoretical and observed linewidths and amplitudes of mixed-modes to obtain new constraints on our theoretical models.

  2. Superconducting system for adiabatic quantum computing

    We study the Hamiltonian of a system of inductively coupled flux qubits, which has been theoretically proposed for adiabatic quantum computation to handle NP problems. We study the evolution of a basic structure consisting of three coupled rf-SQUIDs upon tuning the external flux bias, and we show that the adiabatic nature of the evolution is guaranteed by the presence of the single-SQUID gap. We further propose a scheme and the first realization of an experimental device suitable for verifying the theoretical results

  3. On black hole spectroscopy via adiabatic invariance

    Jiang Qingquan, E-mail: qqjiangphys@yeah.net [College of Physics and Electronic Information, China West Normal University, Nanchong, Sichuan 637002 (China); Han Yan [College of Mathematic and Information, China West Normal University, Nanchong, Sichuan 637002 (China)

    2012-12-05

    In this Letter, we obtain the black hole spectroscopy by combining the black hole property of adiabaticity and the oscillating velocity of the black hole horizon. This velocity is obtained in the tunneling framework. In particular, we declare, if requiring canonical invariance, the adiabatic invariant quantity should be of the covariant form I{sub adia}= Contour-Integral p{sub i}dq{sub i}. Using it, the horizon area of a Schwarzschild black hole is quantized independently of the choice of coordinates, with an equally spaced spectroscopy always given by {Delta}A=8{pi}l{sub p}{sup 2} in the Schwarzschild and Painleve coordinates.

  4. Staying adiabatic with unknown energy gap

    Nehrkorn, J; Ekert, A; Smerzi, A; Fazio, R; Calarco, T

    2011-01-01

    We introduce an algorithm to perform an optimal adiabatic evolution that operates without an apriori knowledge of the system spectrum. By probing the system gap locally, the algorithm maximizes the evolution speed, thus minimizing the total evolution time. We test the algorithm on the Landau-Zener transition and then apply it on the quantum adiabatic computation of 3-SAT: The result is compatible with an exponential speed-up for up to twenty qubits with respect to classical algorithms. We finally study a possible algorithm improvement by combining it with the quantum Zeno effect.

  5. Ramsey numbers and adiabatic quantum computing

    Gaitan, Frank; Clark, Lane

    2011-01-01

    The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers $R(m,n)$ with $m,n\\geq 3$, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers $R(m,n)$. We show how the computation of $R(m,n)$ can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctl...

  6. Complexity of the Quantum Adiabatic Algorithm

    Hen, Itay

    2013-01-01

    The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.

  7. Adiabatic Flame Temperature for Combustion of Methane

    Rebeca Pupo

    2011-01-01

    Full Text Available This project calculated the adiabatic flame temperature of a combustion reaction of pure methane and oxygen, assuming that all of the heat liberated by the combustion reaction goes into heating the resulting mixture. Mole fractions of methane to oxygen were computed from 0.05 to 0.95, in increments of 0.05, and then an integral was computed was computed with respect to temperature using the moles of product produced or leftover moles of reactants from the starting mole fraction times the specific heat of each respective gas. The highest adiabatic flame temperature evaluated, occurred at a mole fraction of 0.35.

  8. Ionization-based detectors for gas chromatography.

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report. PMID:25757823

  9. Ionization detector

    A novel ionization detector for use in X-ray tomography is described in detail. To achieve the ultimate resolution, the use of small detectors is necessary and, for ionization detectors, this implies using xenon gas at high pressure. Conventional small detectors can suffer from ''bowing'' but the present design overcomes their problems. (U.K.)

  10. On the double adiabatic continuous spectrum

    In earlier work it has been found that the Alfven and cusp (or slow) continuous spectra can become unstable in toroidal geometry, as judged from the linearized double adiabatic equations. In this paper the validity of fluid approaches to the present problem is investigated. The physical implications of the stability conditions are discussed. (Author)

  11. Pulsed adiabatic structure and complete population transfer

    Population can be transferred between atomic or molecular energy states in a variety of ways. The basic idea of adiabatic transfer, discussed in many textbooks, is as follows. One begins with an atom that is in some single energy state (an eigenstate of an initial Hamiltonian). This energy state is one of many possible states, known variously as the unperturbed states or basis states or diabatic states. Next one begins to change the Hamiltonian very slowly. The changes may occur in either the diagonal elements (the basis state energies) or in the off-diagonal elements (interactions between basis states). If there are off-diagonal elements then the Hamiltonian will no longer commute with the original one. Because the Hamiltonian is no longer the one that was used to define the original basis states, it will cause these states to become mixed. However, if the change is sufficiently slow, the system can remain in a single eigenstate of the changing Hamiltonian -- an adiabatic state, composed of a combination of basis states. Finally, at some later time, one examines the system once again in the original basis. One finds that the population has undergone a change, and now resides in a different unperturbed state. One has produced population transfer. There are many illustrative examples of adiabatic passage, both theory and experiment. The author mentions briefly two common examples, inelastic collisions between atoms, and the static Stark effect in Rydberg atoms, before continuing with the main objective, a discussion of adiabatic passage induced by laser pulses

  12. Adiabatic reversible compression: a molecular view

    The adiabatic compression (or expansion) of an ideal gas has been analysed. Using the kinetic theory of gases the usual relation between temperature and volume is obtained, while textbooks follow a thermodynamic approach. In this way we show, once again, the agreement between a macroscopic view (thermodynamics) and a microscopic one (kinetic theory). (author)

  13. Adiabatic Excitation of Longitudinal Bunch Shape Oscillations

    By modulating the rf voltage at near twice the synchrotrons frequency we are able to modulate the longitudinal bunch shape. We show experimentally that this can be done while preserving the longitudinal emittance when the rf voltage modulation is turned on adiabatically. Experimental measurements will be presented along with theoretical predictions

  14. Adiabatic transition probability for a tangential crossing

    Watanabe, Takuya

    2006-01-01

    We consider a time-dependent Schrödinger equation whose Hamiltonian is a $2\\times 2$ real symmetric matrix. We study, using an exact WKB method, the adiabatic limit of the transition probability in the case where several complex eigenvalue crossing points accumulate to one real point.

  15. Semi adiabatic theory of seasonal Markov processes

    Talkner, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The dynamics of many natural and technical systems are essentially influenced by a periodic forcing. Analytic solutions of the equations of motion for periodically driven systems are generally not known. Simulations, numerical solutions or in some limiting cases approximate analytic solutions represent the known approaches to study the dynamics of such systems. Besides the regime of weak periodic forces where linear response theory works, the limit of a slow driving force can often be treated analytically using an adiabatic approximation. For this approximation to hold all intrinsic processes must be fast on the time-scale of a period of the external driving force. We developed a perturbation theory for periodically driven Markovian systems that covers the adiabatic regime but also works if the system has a single slow mode that may even be slower than the driving force. We call it the semi adiabatic approximation. Some results of this approximation for a system exhibiting stochastic resonance which usually takes place within the semi adiabatic regime are indicated. (author) 1 fig., 8 refs.

  16. Recent adiabaticity results from orbit calculations

    There has been much activity recently in an attempt to find a straightforward method of predicting the limits of adiabatic behavior in high-beta magnetic-mirror configurations. The particle-orbit code TIBRO was used to obtain numerical results on nonadiabatic behavior with which the predictions of theoretical expressions can be compared. These results are summarized. (MOW)

  17. Ionization detector

    The objects of the invention are, first, to provide an ionization detector having a three chamber structure characterised by a built-in feedback path that regeneratively stabilizes the operating point of the detector. Secondly, to provide a specially designed chamber construction including electrodes shaped so as to enhance the efficiency of the chamber and reduce ion recombination. The ionization chamber described has a chamber structure with a first closed chamber and a second chamber able to receive gases from outside. These two chambers have a common boundary including a common electrode. One electrode associated with the second chamber, and one within the first chamber, define a third chamber within the first chamber allowing an ionization path between. A radioactive source provides ionizing radiation for all three chambers and establishes an ionization current. There is a detector coupled to the common electrode for detecting changes in this current. (U.K.)

  18. Chemical analysis of surfaces by resonance ionization mass spectroscopy associated to ionic pulverization; Analyse chimique de surfaces par spectrometrie d`ionisation resonante associee a la pulverisation ionique

    Kern, P.

    1995-12-19

    This work shows that if resonance ionization mass spectroscopy was first applied in isotopic separation, it`s also an analyzing method adapted to the study of semi-conductor materials and thin foils. We have improved this technic: a neodymium laser coupled with a dye laser, a new argon ions gun, a gallium ions gun and a new collection optic for the secondary ions quadrupole spectrometer to allow quantitative and selective measurements. (S.G.). 84 refs.

  19. Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics

    Albert, Julian; Kaiser, Dustin; Engel, Volker

    2016-05-01

    Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.

  20. Surface and buildup region dose measurements with Markus parallel-plate ionization chamber, Gafchromic EBT3 film and MOSFET detector for high energy photon beams

    Akbas, Ugur; Koksal, Canan; Bilge, Hatice

    2016-01-01

    The aim of the study was to investigate surface and buildup region doses for 6 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV photon beams at 100 cm source-detector distance (SDD) for 5x5, 10x10 and 20x20 cm2 field sizes and 0, 30, 60, 80 and 90 beam angles. The surface doses for 10x10 cm2 field size were found to be 20.33%, 18.80% and 25.48% for Markus chamber, EBT3 film and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary, thus the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry, and must be taken into account.

  1. "Single-cycle" ionization effects in laser-matter interaction

    Jarque, E. Conejero; Cornolti, F.; Macchi, A; Ruhl, H.

    2000-01-01

    We investigate numerically effects related to ``single-cycle'' ionization of dense matter by an ultra-short laser pulse. The strongly non-adiabatic response of electrons leads to generation of a megagauss steady magnetic field in laser-solid interaction. By using two-beam interference, it is possible to create periodic density structures able to trap light and to generate relativistic ionization fronts

  2. The dynamic instability of adiabatic blast waves

    Ryu, Dongsu; Vishniac, Ethan T.

    1991-01-01

    Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.

  3. Influence of the Stark-effect on the orientation of Rydberg-states in highly ionized nitrogen after ion beam surface interaction at grazing incidence

    Zimny, R.; Winter, H.; Becker, B.; Schirmacher, A.; Andrae, H.J. (Muenster Univ. (Germany, F.R.). Inst. fuer Kernphysik)

    1984-03-01

    The orientation in the angular momentum distribution of highly ionized N-atoms after the interaction of N-ions with energies up to 15 MeV with a polycrystalline Cu-surface at grazing incidence is investigated by the circular polarization fraction S/I in fluorescent light. In Rydberg-states of N V, N VI and N VII a dramatic variation of this orientation with respect to the ion-energy and the angle of incidence is observed. We interpret the data in terms of a modification of the collision induced orientation via the Stark-effect in the electric field in the vicinity of the surface caused by the image charge potential of the receding ion.

  4. Inverse engineering rigorous adiabatic Hamiltonian for non-Hermitian system

    Wu, Qi-Cheng; Chen, Ye-Hong; Huang, Bi-Hua; Xia, Yan; Song, Jie

    2016-01-01

    We generalize the quantum adiabatic theorem to the non-Hermitian system and build a rigorous adiabaticity condition with respect to the adiabatic phase. The non-Hermitian Hamiltonian inverse engineering method is proposed for the purpose to adiabatically drive a artificial quantum state. For the sake of clearness, we take a concrete two-level system as an example to show the usefulness of the inverse engineering method. The numerical simulation result shows that our scheme can work well even ...

  5. ADIABATIC MASS LOSS IN BINARY STARS. I. COMPUTATIONAL METHOD

    The asymptotic response of donor stars in interacting binary systems to very rapid mass loss is characterized by adiabatic expansion throughout their interiors. In this limit, energy generation and heat flow through the stellar interior can be neglected. We model this response by constructing model sequences, beginning with a donor star filling its Roche lobe at an arbitrary point in its evolution, holding its specific entropy and composition profiles fixed as mass is removed from the surface. The stellar interior remains in hydrostatic equilibrium. Luminosity profiles in these adiabatic models of mass-losing stars can be reconstructed from the specific entropy profiles and their gradients. These approximations are validated by comparison with time-dependent binary mass transfer calculations. We describe how adiabatic mass-loss sequences can be used to quantify threshold conditions for dynamical timescale mass transfer, and to establish the range of post-common envelope binaries that are allowed energetically. In dynamical timescale mass transfer, the adiabatic response of the donor star drives it to expand beyond its Roche lobe, leading to runaway mass transfer and the formation of a common envelope with its companion star. For donor stars with surface convection zones of any significant depth, this runaway condition is encountered early in mass transfer, if at all; but for main-sequence stars with radiative envelopes, it may be encountered after a prolonged phase of thermal timescale mass transfer, a so-called delayed dynamical instability. We identify the critical binary mass ratio for the onset of dynamical timescale mass transfer as that ratio for which the adiabatic response of the donor star radius to mass loss matches that of its Roche lobe at some point during mass transfer; if the ratio of donor to accretor masses exceeds this critical value, dynamical timescale mass transfer ensues. In common envelope evolution, the dissipation of orbital energy of the

  6. Geometry- and diffraction-independent ionization probabilities in intense laser fields: probing atomic ionization mechanisms with effective intensity matching

    Bryan, W A; English, E M L; Goodworth, T R J; Newell, W R; McKenna, J A; Suresh, M; Srigengan, B; Williams, I D; Turcu, I C E; Smith, J M; Divall, E J; Hooker, C J; Langley, A J

    2005-01-01

    We report a novel experimental technique for the comparison of ionization processes in ultrafast laser pulses irrespective of pulse ellipticity. Multiple ionization of xenon by 50 fs 790 nm, linearly and circularly polarized laser pulses is observed over the intensity range 10 TW/cm^2 to 10 PW/cm^2 using Effective Intensity Matching (EIM), which is coupled with Intensity Selective Scanning (ISS) to recover the geometry-independent probability of ionization. Such measurements, made possible by quantifying diffraction effects in the laser focus, are compared directly to theoretical predictions of multiphoton, tunnel and field ionization, and a remarkable agreement demonstrated. EIM-ISS allows the straightforward quantification of the probability of recollision ionization in a linearly polarized laser pulse. Furthermore, probability of ionization is discussed in terms of the Keldysh adiabaticity parameter, gamma, and the influence of the precursor ionic states present in recollision ionization is observed for th...

  7. Perturbation to Mei symmetry and adiabatic invariants for Hamilton systems

    Ding Ning; Fang Jian-Hui

    2008-01-01

    Based on the concept of adiabatic invariant,this paper studies the perturbation to Mei symmetry and adiabatic invariants for Hamilton systems.The exact invaxiants of Mei symmetry for the system without perturbation are given.The perturbation to Mei symmetry is discussed and the adiabatic invariants induced from the perturbation to Mei symmetry of the system are obtained.

  8. Ultrafast ionization and fragmentation of molecular silane

    The ionization and fragmentation of molecular silane is examined here with laser intensities ranging between 7x1012 and 1x1015 W/cm2 at 624 nm. The ionization potential of silane determined using both multiphoton ionization (MPI) and tunneling ionization (TI) models agrees with the vertical ionization potential of the molecule. In addition, the application of the tunneling ionization model is extended here to the fragments of silane to determine their appearance potentials. MPI values for SiH3+, SiH2+, SiH+, Si+, as well as H2+ and H+ are consistent with vertical potentials, whereas the TI measurements are found to be in accord with adiabatic potentials. The tunneling appearance potentials observed for the fragments H2+ and H+ are lower than reported for other techniques. In fact, the appearance potential measurements for these species resulting from silane are lower than their ionization potentials. The fragmentation rate of silane is determined to be nearly 20 times larger than the ionization rate. The main precursor for producing amorphous silicon (a-Si:H) thin films, SiH3+ is the dominant fragmentation product making up roughly a third of the total ion yield, a substantial increase from other techniques.

  9. Plasmonic black gold by adiabatic nanofocusing and absorption of light in ultra-sharp convex grooves

    Søndergaard, Thomas; Novikov, Sergey M.; Stær, Tobias Holmgaard; Eriksen, René L.; Beermann, Jonas; Han, Zhanghua; Pedersen, Kjeld; Bozhevolnyi, Sergey I.

    2012-01-01

    -defined geometry by using ultra-sharp convex metal grooves via adiabatic nanofocusing of gap surface plasmon modes excited by scattering off subwavelength-sized wedges. We demonstrate experimentally that two-dimensional arrays of sharp convex grooves in gold ensure efficient (>87%) broadband (450-850 nm...

  10. Bending light via adiabatic optical transition in longitudinally modulated photonic lattices

    Han, Bin; Xu, Lei; Dou, Yiling; Xu, Jingjun; Zhang, Guoquan

    2015-10-01

    Bending light in a controllable way is desired in various applications such as beam steering, navigating and cloaking. Different from the conventional way to bend light by refractive index gradient, transformation optics or special beams through wavefront design such as Airy beams and surface plasmons, we proposed a mechanism to bend light via resonant adiabatic optical transition between Floquet-Bloch (FB) modes from different FB bands in longitudinally modulated photonic lattices. The band structure of longitudinally modulated photonic lattices was calculated by employing the concept of quasi-energy based on the Floquet-Bloch theory, showing the existence of band discontinuities at specific resonant points which cannot be revealed by the coupled-mode theory. Interestingly, different FB bands can be seamlessly connected at these resonant points in longitudinally modulated photonic lattices driven by adiabatically varying the longitudinal modulation period along the propagation direction, which stimulates the adiabatic FB mode transition between different FB bands.

  11. Wave front adaptation using a deformable mirror for adiabatic nanofocusing along an ultrasharp gold taper

    Schmidt, Slawa; Piglosiewicz, Bjoern; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Gross, Petra

    2013-01-01

    We describe and demonstrate the use of an adaptive wave front optimization scheme for enhancing the efficiency of adiabatic nanofocusing of surface plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic nanofocusing is an emerging and promising scheme for controlled focusing of far field light into nanometric volumes. It comprises three essential steps: SPP excitation by coupling far field light to an SPP waveguide, SPP propagation along the waveguide and adiabatic SPP nanofocusing towards a geometric singularity. For commonly used complex waveguide geometries, such as, e.g., conical metal tapers, a realistic modeling and efficiency optimization is challenging. Here, we use a deformable mirror to adaptively control the wave front of the incident far field light. We demonstrate an eight-fold enhancement in nanofocusing efficiency and analyze the shape of the resulting optimized wave front. The introduced wave front optimization scheme is of general interest for guiding and controlling ...

  12. "Magic" Ionization Mass Spectrometry

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  13. Alkali metal ionization detector

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  14. "Magic" Ionization Mass Spectrometry.

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers. PMID:26486514

  15. On the power of coherently controlled quantum adiabatic evolutions

    We provide a new approach to adiabatic state preparation that uses coherent control and measurement to average different adiabatic evolutions in ways that cause their diabatic errors to cancel, allowing highly accurate state preparations using less time than conventional approaches. We show that this new model for adiabatic state preparation is polynomially equivalent to conventional adiabatic quantum computation by providing upper bounds on the cost of simulating such evolutions on a circuit-based quantum computer. Finally, we show that this approach is robust to small errors in the quantum control register and that the system remains protected against noise on the adiabatic register by the spectral gap. (paper)

  16. Ambient ionization mass spectrometry: A tutorial

    Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

    2011-09-19

    Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

  17. Adiabatic Quantum Optimization for Associative Memory Recall

    Hadayat eSeddiqi

    2014-12-01

    Full Text Available Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO. Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.

  18. Weinberg Soft Theorems from Weinberg Adiabatic Modes

    Mirbabayi, Mehrdad

    2016-01-01

    Soft theorems for the scattering of low energy photons and gravitons and cosmological consistency conditions on the squeezed-limit correlation functions are both understood to be consequences of invariance under large gauge transformations. We apply the same method used in cosmology -- based on the identification of an infinite set of "adiabatic modes" and the corresponding conserved currents -- to derive flat space soft theorems for electrodynamics and gravity. We discuss how the recent derivations based on the asymptotic symmetry groups (BMS) can be continued to a finite size sphere surrounding the scattering event, when the soft photon or graviton has a finite momentum. We give a finite distance derivation of the antipodal matching condition previously imposed between future and past null infinities, and explain why all but one radiative degrees of freedom decouple in the soft limit. In contrast to earlier works on BMS, we work with adiabatic modes which correspond to large gauge transformations that are $...

  19. Quantum adiabatic evolution with energy degeneracy levels

    Zhang, Qi

    2016-01-01

    A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.

  20. Adiabatic Quantum Simulation of Quantum Chemistry

    Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán

    2014-10-01

    We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.

  1. Robust Classification with Adiabatic Quantum Optimization

    Denchev, Vasil S.; Ding, Nan; Vishwanathan, S. V. N.; Neven, Hartmut

    2012-01-01

    We propose a non-convex training objective for robust binary classification of data sets in which label noise is present. The design is guided by the intention of solving the resulting problem by adiabatic quantum optimization. Two requirements are imposed by the engineering constraints of existing quantum hardware: training problems are formulated as quadratic unconstrained binary optimization; and model parameters are represented as binary expansions of low bit-depth. In the present work we...

  2. Dark matter search within the Edelweiss experiment with double component Ionisation/Heat bolometer, surface event rejection with the ionization channel

    Understanding the nature of non-baryonic dark matter is one of the most fascinating and challenging goals of modern physics. WIMP (Weak Interactive Massive Particle) direct detection experiments such as EDELWEISS test the hypothesis that dark matter is made up of particles (neutralino) predicted by the supersymmetry and having an interaction cross-section with the nucleon of about 10-8 pico-barn. For that purpose, EDELWEISS uses ultrapure cryogenic germanium detectors combining ionisation and heat measurements. This allows the discrimination between nuclear recoils as expected for WIMPs and the electronic recoils induced by the particles of the radioactive background. The main limitation of this technique comes from events close to the detector surface that mimic nuclear recoils. The solution presented here is based on a coplanar grid technique for surface event identification with ionization signals. We present the principle of this type of detector, the fabrication of a prototype and its study: tests with different radioactive sources in a surface laboratory and in the site of the experiment in the Modane underground laboratory (LSM). The experimental results are analysed in details and compared to a simulation of the signals expected for the different event populations. The obtained gamma and surface event (beta) rejection demonstrates the possibility to reach at least 10-8 pico-barn in the frame of the EDELWEISS II experiment. (author)

  3. Surface and Buildup Region Dose Measurements with Markus Parallel-Plate Ionization Chamber, GafChromic EBT3 Film, and MOSFET Detector for High-Energy Photon Beams

    Ugur Akbas

    2016-01-01

    Full Text Available The aim of the study was to investigate surface and buildup region doses for 6 MV and 15 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film, and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV and 15 MV photon beams at 100 cm source-detector distance for 5 × 5, 10 × 10, and 20 × 20 cm2 field sizes and 0°, 30°, 60°, and 80° beam angles. The surface doses using 6 MV photon beams for 10 × 10 cm2 field size were found to be 20.3%, 18.8%, and 25.5% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface doses using 15 MV photon beams for 10 × 10 cm2 field size were found to be 14.9%, 13.4%, and 16.4% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary; thus, the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry and must be taken into account.

  4. Adiabatic graph-state quantum computation

    Measurement-based quantum computation (MBQC) and holonomic quantum computation (HQC) are two very different computational methods. The computation in MBQC is driven by adaptive measurements executed in a particular order on a large entangled state. In contrast in HQC the system starts in the ground subspace of a Hamiltonian which is slowly changed such that a transformation occurs within the subspace. Following the approach of Bacon and Flammia, we show that any MBQC on a graph state with generalized flow (gflow) can be converted into an adiabatically driven holonomic computation, which we call adiabatic graph-state quantum computation (AGQC). We then investigate how properties of AGQC relate to the properties of MBQC, such as computational depth. We identify a trade-off that can be made between the number of adiabatic steps in AGQC and the norm of H-dot as well as the degree of H, in analogy to the trade-off between the number of measurements and classical post-processing seen in MBQC. Finally the effects of performing AGQC with orderings that differ from standard MBQC are investigated. (paper)

  5. Collisional and Radiative Processes in Adiabatic Deceleration, Deflection, and Off-Axis Trapping of a Rydberg Atom Beam

    A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90 deg., decelerated to zero velocity in less than 25 μs, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.

  6. Stimulated Raman Adiabatic Passage for Improved Performance of a Cold Atom Electron and Ion Source

    Sparkes, B M; Taylor, R J; Spiers, R W; McCulloch, A J; Scholten, R E

    2016-01-01

    We experimentally implement high-efficiency coherent excitation to a Rydberg state using stimulated Raman adiabatic passage in a cold atom electron and ion source, leading to a peak efficiency of 85%, a 1.7 times improvement in excitation probability relative to incoherent pulsed-laser excitation. Using streak measurements and pulsed electric field ionization of the Rydberg atoms we demonstrate electron bunches with duration of 250 ps. High-efficiency excitation will increase source brightness, crucial for ultrafast electron diffraction experiments, while using coherent excitation to high-lying Rydberg states could allow for the reduction of internal bunch heating and the creation of a high-speed single ion source.

  7. Determination of pharmaceutical compounds in surface- and ground-water samples by solid-phase extraction and high-performance liquid chromatography-electrospray ionization mass spectrometry

    Cahill, J.D.; Furlong, E.T.; Burkhardt, M.R.; Kolpin, D.; Anderson, L.G.

    2004-01-01

    Commonly used prescription and over-the-counter pharmaceuticals are possibly present in surface- and ground-water samples at ambient concentrations less than 1 μg/L. In this report, the performance characteristics of a combined solid-phase extraction isolation and high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC–ESI-MS) analytical procedure for routine determination of the presence and concentration of human-health pharmaceuticals are described. This method was developed and used in a recent national reconnaissance of pharmaceuticals in USA surface waters. The selection of pharmaceuticals evaluated for this method was based on usage estimates, resulting in a method that contains compounds from diverse chemical classes, which presents challenges and compromises when applied as a single routine analysis. The method performed well for the majority of the 22 pharmaceuticals evaluated, with recoveries greater than 60% for 12 pharmaceuticals. The recoveries of angiotensin-converting enzyme inhibitors, a histamine (H2) receptor antagonist, and antihypoglycemic compound classes were less than 50%, but were retained in the method to provide information describing the potential presence of these compounds in environmental samples and to indicate evidence of possible matrix enhancing effects. Long-term recoveries, evaluated from reagent-water fortifications processed over 2 years, were similar to initial method performance. Method detection limits averaged 0.022 μg/L, sufficient for expected ambient concentrations. Compound-dependent matrix effects on HPLC/ESI-MS analysis, including enhancement and suppression of ionization, were observed as a 20–30% increase in measured concentrations for three compounds and greater than 50% increase for two compounds. Changing internal standard and more frequent ESI source maintenance minimized matrix effects. Application of the method in the national survey demonstrates that several

  8. Ionizing radiation detecting unit

    A design of a unit for ionizing radiation detection under high mechanical loads is described. The unit consists of a detector (scintillation or ionization), switching unit, an electronic unit, a compensation unit and absorption unit, and a jacket. To increase reliability of the unit under operation conditions at any space position in the wide range of mechanical loads and to simplify the construction, the absorption assembly has been made in the form of an elastic reference barrel-shaped element with slots along the element surface and connected to the switching unit and electronic unit by the compensation unit, which ridigity is higher than the element ridigity

  9. Optimization and evaluation of surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry for protein profiling of cerebrospinal fluid

    Gomez-Mancilla Baltazar

    2006-04-01

    Full Text Available Abstract Cerebrospinal fluid (CSF potentially carries an archive of peptides and small proteins relevant to pathological processes in the central nervous system (CNS and surrounding brain tissue. Proteomics is especially well suited for the discovery of biomarkers of diagnostic potential in CSF for early diagnosis and discrimination of several neurodegenerative diseases. ProteinChip surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS is one such approach which offers a unique platform for high throughput profiling of peptides and small proteins in CSF. In this study, we evaluated methodologies for the retention of CSF proteins m/z we found a high degree of overlap between the tested array surfaces. The combination of CM10 and IMAC30 arrays was sufficient to represent between 80–90% of all assigned peaks when using either sinapinic acid or α-Cyano-4-hydroxycinnamic acid as the energy absorbing matrices. Moreover, arrays processed with SPA consistently showed better peak resolution and higher peak number across all surfaces within the measured mass range. We intend to use CM10 and IMAC30 arrays prepared in sinapinic acid as a fast and cost-effective approach to drive decisions on sample selection prior to more in-depth discovery of diagnostic biomarkers in CSF using alternative but complementary proteomic strategies.

  10. Ionization detector

    An ionization detecting fire alarm device that comprises a double chamber structure, a source disposed in at least one of the chambers and a vernier adjusting screw electrode protruding into one chamber is described. The chamber containing the adjustable electrode is more open to the atmosphere than the other chamber, porting is provided between chambers and detection occurs by sensing the rate of change of ionization current in the chamber structure. The source or sources, one being in each chamber, is a beta source such as a nickel 63 source. A change in ionization current is detected by a unique circuit of this invention which comprises a programmable unijunction transistor oscillator circuit. 19 claims, 4 figures