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.
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
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...
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.
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
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.
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...
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
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
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...
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
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.
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.
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.
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
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.
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.
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.
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
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,KMã€‰ = |1, − 1ã€‰ 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)
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
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.
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.
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.)
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.
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...
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.
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
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)
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.).
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
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.
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)
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.
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.
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
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
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...
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
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
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.
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
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.
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.
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.
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
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.
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...
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...
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
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
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
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)
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
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...
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...
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
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.
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.
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.
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...
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
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.
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)
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
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.
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.
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)
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
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.
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.)
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.)
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.
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
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.
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
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
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.
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 ...
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.
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)
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.
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*.
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
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.
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
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)
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
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.
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.
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.
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
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.
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.…
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
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.
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
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.
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.
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.
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
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
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.
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)
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.
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.)
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.
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.
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.
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.
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…
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
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
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 ...
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
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.
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.
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.
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
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 H_{3} were performed at 1397 symmetry-unique configurations using the Born-Handy 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 (~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.
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.
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
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.
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.
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.
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...
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.
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)
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.
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%.
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...
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)
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))
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.
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.
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)
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.)
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
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
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.
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...
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.
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
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.
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.
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.
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.
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
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
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.
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'
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
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
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
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
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
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.)
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.
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.
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.
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.
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)
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.
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
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.
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)
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.
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.
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 ...
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
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
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.
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.
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.
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...
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.
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...
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
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.
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...
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 ...
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...
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...
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...
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.)
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.
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.)
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
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...
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.
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
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)
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.
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.
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.
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)
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
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.
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)
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
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.
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.
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...
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
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.
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.
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.
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
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.
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)
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
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)
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.
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)
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
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.)
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.)
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.
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.
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.
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.
"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
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 ...
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.
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
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...
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.
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.
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...
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.
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 ...
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)
"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.
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.
"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
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.
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 $...
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.
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.
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.
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...
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)
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.
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)
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.
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.
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
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
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.
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
Non-adiabatic molecular dynamics with complex quantum trajectories. I. The diabatic representation.
Zamstein, Noa; Tannor, David J
2012-12-14
We extend a recently developed quantum trajectory method [Y. Goldfarb, I. Degani, and D. J. Tannor, J. Chem. Phys. 125, 231103 (2006)] to treat non-adiabatic transitions. Each trajectory evolves on a single surface according to Newton's laws with complex positions and momenta. The transfer of amplitude between surfaces stems naturally from the equations of motion, without the need for surface hopping. In this paper we derive the equations of motion and show results in the diabatic representation, which is rarely used in trajectory methods for calculating non-adiabatic dynamics. We apply our method to the first two benchmark models introduced by Tully [J. Chem. Phys. 93, 1061 (1990)]. Besides giving the probability branching ratios between the surfaces, the method also allows the reconstruction of the time-dependent wavepacket. Our results are in quantitative agreement with converged quantum mechanical calculations. PMID:23249054
The purpose of this article is to simplify some of the relevant points of legislation, biological effects and protection for the benefit of the occupational health nurse not familiar with the nuclear industries. The subject is dealt with under the following headings; Understanding atoms. What is meant by ionizing radiation. Types of ionizing radiation. Effects of radiation: long and short term somatic effects, genetic effects. Control of radiation: occupational exposure, women of reproductive age, medical aspects, principles of control. The occupational health nurse's role. Emergency arrangements: national arrangements for incidents involving radiation, action to be taken by the nurse. Decontamination procedures: external and internal contamination. (U.K.)
III. Penning ionization, associative ionization and chemi-ionization processes
Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Maitra, Neepa T.; Gross, E. K. U.
2015-03-01
The Born-Oppenheimer (BO) approximation allows to visualize the coupled electron-nuclear dynamics in molecular systems as a set of nuclei moving on a single potential energy surface representing the effect of the electrons in a given eigenstate. Many interesting phenomena, however, such as vision or charge separation in organic photovoltaic materials, take place in conditions beyond its range of validity. Nevertheless, the basic construct of the adiabatic treatment, the BO potential energy surfaces, is employed to describe non-adiabatic processes and the full problem is represented in terms of adiabatic states and transitions among them in regions of strong non-adiabatic coupling. But the concept of single potential energy is lost. The alternative point of view arising in the framework of the exact factorization of the electron-nuclear wave function will be presented. A single, time-dependent, potential energy provides the force driving the nuclear motion and is adopted as starting point for the development of quantum-classical approximations to the full quantum mechanical problem.
Rotation-vibrational states of H3+ and the adiabatic approximation.
Alijah, Alexander; Hinze, Juergen
2006-11-15
We discuss recent progress in the calculation and identification of rotation-vibrational states of H3+ at intermediate energies up to 13,000 cm(-1). Our calculations are based on the potential energy surface of Cencek et al. which is of sub-microhartree accuracy. As this surface includes diagonal adiabatic and relativistic corrections to the fixed nuclei electronic energies, the remaining discrepancies between our calculated and experimental data should be due to the neglect of non-adiabatic coupling to excited electronic states in the calculations. To account for this, our calculated energy values were adjusted empirically by a simple correction formula. Based on our understanding of the adiabatic approximation, we suggest two new approaches to account for the off-diagonal adiabatic correction, which should work; however, they have not been tested yet for H3+. Theoretical predictions made for the above-barrier energy region of recent experimental interest are accurate to 0.35 cm(-1) or better. PMID:17015396
Ionization of atoms by slow heavy particles
Roberts, B M; Gribakin, G F
2016-01-01
Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 sigma annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusp-like behaviour of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, meaning that nonrelativistic calculations m...
Accuracy vs run time in adiabatic quantum search
Rezakhani, A T; Lidar, D A
2010-01-01
Adiabatic quantum algorithms are characterized by their run time and accuracy. The relation between the two is essential for quantifying adiabatic algorithmic performance, yet is often poorly understood. We study the dynamics of a continuous time, adiabatic quantum search algorithm, and find rigorous results relating the accuracy and the run time. Proceeding with estimates, we show that under fairly general circumstances the adiabatic algorithmic error exhibits a behavior with two discernible regimes: the error decreases exponentially for short times, then decreases polynomially for longer times. We show that the well known quadratic speedup over classical search is associated only with the exponential error regime. We illustrate the results through examples of evolution paths derived by minimization of the adiabatic error. We also discuss specific strategies for controlling the adiabatic error and run time.
Hypergraph Ramsey Numbers and Adiabatic Quantum Algorithm
Qu, Ri; Bao, Yan-ru
2012-01-01
Gaitan and Clark [Phys. Rev. Lett. 108, 010501 (2012)] have recently presented a quantum algorithm for the computation of the Ramsey numbers R(m, n) using adiabatic quantum evolution. We consider that the two-color Ramsey numbers R(m, n; r) for r-uniform hypergraphs can be computed by using the similar ways in [Phys. Rev. Lett. 108, 010501 (2012)]. In this comment, we show how the computation of R(m, n; r) can be mapped to a combinatorial optimization problem whose solution be found using adi...
Adiabatic quantum algorithm for search engine ranking
Garnerone, Silvano; Lidar, Daniel A
2011-01-01
We propose an adiabatic quantum algorithm to evaluate the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this quantum algorithm outputs any component of the PageRank vector-and thus the ranking of the corresponding webpage-in a time which scales polylogarithmically in the number of webpages. This would constitute an exponential speed-up with respect to all known classical algorithms designed to evaluate the PageRank.
Adiabatic chaos in the spin orbit problem
Benettin, Giancarlo; Guzzo, Massimiliano; Marini, Valerio
2008-05-01
We provide evidences that the angular momentum of a symmetric rigid body in a spin orbit resonance can perform large scale chaotic motions on time scales which increase polynomially with the inverse of the oblateness of the body. This kind of irregular precession appears as soon as the orbit of the center of mass is non-circular and the angular momentum of the body is far from the principal directions with minimum (maximum) moment of inertia. We also provide a quantitative explanation of these facts by using the theory of adiabatic invariants, and we provide numerical applications to the cases of the 1:1 and 1:2 spin orbit resonances.
Brane World Dynamics and Adiabatic Matter creation
Gopakumar, P
2006-01-01
We have treated the adiabatic matter creation process in various three-brane models by applying thermodynamics of open systems. The matter creation rate is found to affect the evolution of scale factor and energy density of the universe. We find modification at early stages of cosmic dynamics. In GB and RS brane worlds, by chosing appropriate parameters we obtain standard scenario, while the warped DGP model has different Friedmann equations. During later stages, since the matter creation is negligible the evolution reduces to FRW expansion, in RS and GB models.
The subject is discussed under the headings: characteristics of ionizing radiations; biological effects; comparison of radiation and other industrial risks; principles of protection; cost-benefit analysis; dose limits; the control and monitoring of radiation; reference levels; emergency reference levels. (U.K.)
Dark Energy and Dark Matter from an additional adiabatic fluid
Dunsby, Peter K. S.; Luongo, Orlando; Reverberi, Lorenzo
2016-01-01
The Dark Sector is described by an additional barotropic fluid which evolves adiabatically during the universe's history and whose adiabatic exponent $\\gamma$ is derived from the standard definitions of specific heats. Although in general $\\gamma$ is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with $\\gamma = $ constant in a FLRW universe. The adiabatic fluid acts effectively as the sum of two distinct compone...
Adiabatic Flame Temperature and Specific Heat of Combustion Gases
Torii, Shuichi; Yano, Toshiaki; Tsunoda, Yukio; トリイ, シュウイチ; ヤノ, トシアキ; ツノダ, ユキオ; 鳥居, 修一; 矢野, 利明; 角田, 幸男
1992-01-01
The aim of the present work is to examine adiabatic flame temperature and the specific heat of combustion gases for both hydrocarbon-air and alcohol-air mixtures by means of a method of chemical equilibrium calculation. Emphasis is placed on the elucidation of simplified correlation equations capable of predicting (i) adiabatic flame temperature at any equivalence ratio and (ii) the specific heat of combustion gases when the adiabatic flame temperature, the gas temperature and the equivalence...
Adiabatic renormalization in theories with modified dispersion relations
Nacir, D. Lopez; Mazzitelli, F. D.; Simeone, C.
2007-01-01
We generalize the adiabatic renormalization to theories with dispersion relations modified at energies higher than a new scale $M_C$. We obtain explicit expressions for the mean value of the stress tensor in the adiabatic vacuum, up to the second adiabatic order. We show that for any dispersion relation the divergences can be absorbed into the bare gravitational constants of the theory. We also point out that, depending on the renormalization prescription, the renormalized stress tensor may c...
Harmsen, M.M.; Jansen, J.; Westra, D.F.; Coco-Martin, J.M.
2010-01-01
We have used a novel method, surface-enhanced laser desorption ionization-time of flight-mass spectrometry (SELDI-TOF-MS), to characterize foot-and-mouth disease virus (FMDV) vaccine antigens. Using specific capture with FMDV binding recombinant antibody fragments and tryptic digestion of FMDV antig
CASPERSEN, M. B.; Sørensen, N. M.; Iversen, P;
2007-01-01
in plasma, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF MS) was used. TIMP-1 measurements of plasma from 16 healthy donors and 14 CRC patients were performed using TIMP-1 monoclonal antibody in SELDI TOF MS and ELISA. SELDI TOF MS applying an antibody to TIMP-1...
Symmetry of the adiabatic condition in the piston problem
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be compatible with the invariance of total entropy under a system-surroundings interchange. This paper also strengthens some recently published ideas concerning the concepts of heat and dissipative work, and is primarily intended for teachers and graduate students, as well as for all who are interested in this fascinating problem.
Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project
National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators (ADRs) in space applications, it is desirable to have very light weight, small diameter, high current density...
A quantum search algorithm based on partial adiabatic evolution
Zhang Ying-Yu; Hu He-Ping; Lu Song-Feng
2011-01-01
This paper presents and implements a specified partial adiabatic search algorithm on a quantum circuit. It studies the minimum energy gap between the first excited state and the ground state of the system Hamiltonian and it finds that, in the case of M=1, the algorithm has the same performance as the local adiabatic algorithm. However, the algorithm evolves globally only within a small interval, which implies that it keeps the advantages of global adiabatic algorithms without losing the speedup of the local adiabatic search algorithm.
A quantum search algorithm based on partial adiabatic evolution
This paper presents and implements a specified partial adiabatic search algorithm on a quantum circuit. It studies the minimum energy gap between the first excited state and the ground state of the system Hamiltonian and it finds that, in the case of M = 1, the algorithm has the same performance as the local adiabatic algorithm. However, the algorithm evolves globally only within a small interval, which implies that it keeps the advantages of global adiabatic algorithms without losing the speedup of the local adiabatic search algorithm. (general)
Adiabatic collapse of rotating gas clouds
The gravitational, axisymmetric and adiabatic collapse of rotating gas clouds with various initial conditions has been calculated numerically by means of Fluid-In-Cell method. We have assumed that the gas is ideal and its change is adiabatic except for heat production by shock waves and that, initially, a cloud has no motion in a meridional plane and has spherical and polytropic distributions of mass and temperature. The results of calculations show that a cloud which has initially larger rotational energy bounced more easily, i.e., bounces at lower central density. The bounce occurs first in the direction of the rotation axis and next in direction perpendicular to it. A shock wave generated by the bounce is strong especially in the vicinity of the rotation axis. At first the shock front is nearly parallel to the equatorial plane but it becomes gradually spherical as it propagates outwards. Calculations have been performed until the mass enclosed inside the shock front becomes as large as 95 percent of the total mass. At this final stage either a rotating spheroidal core or a rotating ring is left in the central region; a ring is formed if initially a cloud is rotating more rapidly, less centrally condensed and at lower temperature. (auth.)
Adiabatic cooling of solar wind electrons
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Graphical abstract: The time-dependent electron density is mapped via inversion of the ground-state Kohn–Sham formalism on two spin-densities, and thus an accurate adiabatic correlation potential is obtained. Research highlights: ► An adiabatic approximation for time-dependent density functional theory is proposed. ► Inverting static spin-density functional theory yields accurate correlation potentials. ► The derivative discontinuity is reproduced. ► Tested for strong-field ionization and molecules at large internuclear distance. - Abstract: It has recently been shown by Thiele et al. [M. Thiele, E. K. U. Gross, S. Kümmel, Phys. Rev. Lett. 100 (2008) 153004] that the exact adiabatic approximation in time-dependent density functional theory gives a good description of non-sequential double ionization in the one-dimensional helium atom. In this paper, we propose an adiabatic approximation based on the inversion of ground-state spin-density functional theory and apply it to several model systems. We demonstrate that our approach reproduces the derivative discontinuity and yields correlation potentials close to the exact correlation potentials for a strong-field ionization process as well as for the 1D H2 and LiH molecules at large internuclear distance.
Rocha, C. M. R.; Varandas, A. J. C.
2015-08-01
A fully ab initio-based potential energy surface is first reported for the ground electronic state of the C3 radical using the double many-body expansion (DMBE) method. The DMBE form so obtained mimics the full set of energies calculated at the multireference configuration interaction level of theory with chemical accuracy. To account for the incompleteness of the one- and N -electron bases, the calculated external correlation energies have been scaled prior to the fitting procedure via DMBE-scaled external correlation method. Furthermore, the novel potential energy surface reproduces accurately dissociation energies, diatomic potentials, long-range interactions at all asymptotic channels, and the correct topological behavior at the region of 4 conical intersections with the partner state of the same symmetry near equilateral triangular geometries due to combined Jahn-Teller (E' ⊗ e') plus pseudo-Jahn-Teller [ ( E ' + A1 ' ) ⊗ e ' ] interactions. Rovibrational calculations have also been performed, unveiling a good match of the vibrational spectrum of C3 for 53 calculated levels. The present DMBE form is, therefore, commended for both spectroscopic and reaction dynamics studies, some also performed in the present work.
Positronium formation and ionization in slow positron-hydrogen atom collisions
The electron capture and ionization processes in slow collisions of positrons with hydrogen atoms are considered within the advanced adiabatic approach to atomic collisions. The mass asymmetry of the (p,e-,e+) collision system is properly taken into account. The calculated positronium formation and ionization cross sections compare favourably with the available experimental data in the adiabatic energy region. It is shown that the potential energy curve of the 2p σ molecular state supports a quasi-bound level of the three-particle (p,e+,e-) system with an energy of -0.3 eV and decay width of 0.15 eV, approximately. (author)
Wang, Chia-Wei; Chen, Wen-Tsen; Chang, Huan-Tsung
2014-07-01
Quantification of monosaccharides and disaccharides in five honey samples through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using HgTe nanostructures as the matrix and sucralose as an internal standard has been demonstrated. Under optimal conditions (1× HgTe nanostructure, 0.2 mM ammonium citrate at pH 9.0), the SALDI-MS approach allows detection of fructose and maltose at the concentrations down to 15 and 10 μM, respectively. Without conducting tedious sample pretreatment and separation, the SALDI-MS approach allows determination of the contents of monosaccharides and disaccharides in honey samples within 30 min, with reproducibility (relative standard deviation <15%). Unlike only sodium adducts of standard saccharides detected, sodium adducts and potassium adducts with differential amounts have been found among various samples, showing different amounts of sodium and potassium ions in the honey samples. The SALDI-MS data reveal that the contents of monosaccharides and disaccharides in various honey samples are dependent on their nectar sources. In addition to the abundant amounts of monosaccharides and disaccharides, oligosaccharides in m/z range of 650 - 2700 are only detected in pomelo honey. Having advantages of simplicity, rapidity, and reproducibility, this SALDI-MS holds great potential for the analysis of honey samples.
Plasmas in particle accelerators: adiabatic theories for bunched beams
Three different formalisms for discussing Vlasov's equation for bunched beam problems with anharmonic space charge forces are outlined. These correspond to the use of a drift kinetic equation averaged over random betatron motions; a fluidkinetic adiabatic regime analogous to the theory of Chew, Goldberger, and Low; and an adiabatic hydrodynamic theory
Teleportation of an Unknown Atomic State via Adiabatic Passage
无
2007-01-01
We propose a scheme for teleporting an unknown atomic state via adiabatic passage. Taking advantage of adiabatic passage, the atom has no probability of being excited and thus the atomic spontaneous emission is suppressed.We also show that the fidelity can reach 1 under certain condition.
Examination of the adiabatic approximation in open systems
We examine the notion of the adiabatic approximation in open systems by applying it to closed systems. Our results shows that the notion is equivalent to the standard adiabatic approximation if the systems are initially in eigenstates, and it leads to a more general expression if the systems are in mixed states
Adiabat-shaping in indirect drive inertial confinement fusion
Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures
High Fidelity Adiabatic Quantum Computation via Dynamical Decoupling
Quiroz, Gregory
2012-01-01
We introduce high-order dynamical decoupling strategies for open system adiabatic quantum computation. Our numerical results demonstrate that a judicious choice of high-order dynamical decoupling method, in conjunction with an encoding which allows computation to proceed alongside decoupling, can dramatically enhance the fidelity of adiabatic quantum computation in spite of decoherence.
Quantum adiabatic algorithm for factorization and its experimental implementation.
Peng, Xinhua; Liao, Zeyang; Xu, Nanyang; Qin, Gan; Zhou, Xianyi; Suter, Dieter; Du, Jiangfeng
2008-11-28
We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in a NMR quantum information processor and experimentally factorize the number 21. In the range that our classical computer could simulate, the quantum adiabatic algorithm works well, providing evidence that the running time of this algorithm scales polynomially with the problem size. PMID:19113467
Robust Classification with Adiabatic Quantum Optimization
Denchev, Vasil S; 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 validate this approach by using a heuristic classical solver as a stand-in for quantum hardware. Testing on several popular data sets and comparing with a number of existing losses we find substantial advantages in robustness as measured by test error under increasing label noise. Robustness is enabled by the non-convexity of our hardware-compatible loss function, which we name q-loss.
Number Partitioning via Quantum Adiabatic Computation
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.
Entropy in adiabatic regions of convection simulations
Tanner, Joel D; Demarque, Pierre
2016-01-01
One of the largest sources of uncertainty in stellar models is caused by the treatment of convection in stellar envelopes. One dimensional stellar models often make use of the mixing length or equivalent approximations to describe convection, all of which depend on various free parameters. There have been attempts to rectify this by using 3D radiative-hydrodynamic simulations of stellar convection, and in trying to extract an equivalent mixing length from the simulations. In this paper we show that the entropy of the deeper, adiabatic layers in these simulations can be expressed as a simple function of og g and log T_{eff} which holds potential for calibrating stellar models in a simple and more general manner.
Adiabatic Liquid Piston Compressed Air Energy Storage
Petersen, Tage; Elmegaard, Brian; Pedersen, Allan Schrøder
This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting the...... compensates the added investment. •When comparing ALP-CAES to an adiabatic CAES system, where compression heat is stored in thermal oil, the ALP-CAES system is found only to be competitive under a very specific set of operating/design conditions, including very high operation pressure and the use of very...... primarily due to the investment in turbine/generator, heat exchangers, and a large quantity of thermal oil. To improve the economy, it would be relevant to investigate the possibility of replacing the thermal oil by water, for example by injecting the water directly into the air flow between the different...
Adiabatic approximation, semiclassical scattering, and unidirectional invisibility
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(τ). We show that the application of the adiabatic approximation to H(τ) corresponds to the semiclassical description of the original scattering problem. In particular, the geometric part of the phase of the evolving eigenvectors of H(τ) gives the pre-exponential factor of the WKB wave functions. We use these observations to give an explicit semiclassical expression for the transfer matrix. This allows for a detailed study of the semiclassical unidirectional reflectionlessness and invisibility. We examine concrete realizations of the latter in the realm of optics. (paper)
Index Theory and Adiabatic Limit in QFT
Wawrzycki, Jaroslaw
2011-01-01
The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: 1) local algebraic formulation of Haag, 2) Wightman formulation and 3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between 1) and 3) and utilize the known relationships between 1) and 2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit (confinement problem in the phenomenological standard model approach). We extend the method of deformation of D\\"utsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index -- an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.
Index Theory and Adiabatic Limit in QFT
Wawrzycki, Jarosław
2013-08-01
The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: (1) local algebraic formulation of Haag, (2) Wightman formulation and (3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between (1) and (3) and utilize the known relationships between (1) and (2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit ( confinement problem in the phenomenological standard model approach). We extend the method of deformation of Dütsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index—an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.
The adiabatic approximation in multichannel scattering
Using two-dimensional models, an attempt has been made to get an impression of the conditions of validity of the adiabatic approximation. For a nucleon bound to a rotating nucleus the Coriolis coupling is neglected and the relation between this nuclear Coriolis coupling and the classical Coriolis force has been examined. The approximation for particle scattering from an axially symmetric rotating nucleus based on a short duration of the collision, has been combined with an approximation based on the limitation of angular momentum transfer between particle and nucleus. Numerical calculations demonstrate the validity of the new combined method. The concept of time duration for quantum mechanical collisions has also been studied, as has the collective description of permanently deformed nuclei. (C.F.)
Entropy in Adiabatic Regions of Convection Simulations
Tanner, Joel D.; Basu, Sarbani; Demarque, Pierre
2016-05-01
One of the largest sources of uncertainty in stellar models is caused by the treatment of convection in stellar envelopes. One-dimensional stellar models often make use of the mixing length or equivalent approximations to describe convection, all of which depend on various free parameters. There have been attempts to rectify this by using 3D radiative-hydrodynamic simulations of stellar convection, and in trying to extract an equivalent mixing length from the simulations. In this Letter, we show that the entropy of the deeper, adiabatic layers in these simulations can be expressed as a simple function of {log}g and {log}{T}{{eff}}, which holds potential for calibrating stellar models in a simple and more general manner.
The exact forces on classical nuclei in non-adiabatic charge transfer
Agostini, Federica; Suzuki, Yasumitsu; Min, Seung Kyu; Maitra, Neepa T; Gross, E K U
2014-01-01
The decomposition of electronic and nuclear motion presented in [A. Abedi, N. T. Maitra, and E. K. U. Gross, Phys. Rev. Lett. 105, 123002 (2010)] yields a time dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. Further, we investigate the properties of the exact potential that enable the correct splitting of the quasiclassical nuclear wave packet in space: after the nuclear wave packet passes through an avoided crossing between two Born-Oppenheimer surfaces, the potential becomes piecewise parallel to one or the other adiabatic surface and, in the intermediate region, it develops steps or bumps. A detailed analysis of the shape of the potential and its connection to standard mixed quantum-classica...
Natural convection around a horizontal cylinder near an adiabatic cover wall
The main objective of this work was to determine numerically the influence of the proximity of an adiabatic top surface over the natural convective coefficient, around an isothermal horizontal cylinder in atmospheric air. The local and mean Nusselt numbers around the cylinder were obtained through a numerical solution of the dimensionless equations for two-dimensional laminar natural convection flow at steady state in Cartesian coordinates, using the ω, ψ, Τ, formulation. The software was run for different Rayleigh values (102 5) and distances cylinder-cover wall (0.55 < L/D < 2.5). The results allow concluding that the top adiabatic surface diminishes the convective coefficient in comparison with the value obtained using an infinite medium as boundary condition, it occurs when L/D<2, at any Rayleigh number value. (authors)
Strong Ionization in carbon Nanowires
Kaymak, Vural; Shlyaptsev, Vyacheslav N; Rocca, Jorge J
2015-01-01
Surfaces covered with nanostructures, such as nanowire arrays, have shown to facilitate a significantly higher absorption of laser energy as compared to flat surfaces. Due to the efficient coupling of the laser energy, highly energetic electrons are produced, which in turn can emit intense ultrafast X-ray pulses. In the present work we use full three dimensional PIC simulations to analyze the behavior of arrays of carbon nanowires $400 nm$ in diameter, irradiated by a $\\lambda_0 = 400 nm$ laser pulse of $60 fs$ duration at FWHM and a vector potential of $a_0 = 18$. We analyze the ionization dynamics of the nanowires. We investigate the difference of the ionization strength and structure between linearly and circularly polarized laser beam. The nanowires are found to be fully ionized after about 30 laser cycles. Circularly polarized light reveals a slightly stronger ionization effect.
Adiabatic and Isocurvature Perturbation Projections in Multi-Field Inflation
Gordon, Chris
2013-01-01
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the adiabatic perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic pe...
Adiabatic logic future trend and system level perspective
Teichmann, Philip
2012-01-01
Adiabatic logic is a potential successor for static CMOS circuit design when it comes to ultra-low-power energy consumption. Future development like the evolutionary shrinking of the minimum feature size as well as revolutionary novel transistor concepts will change the gate level savings gained by adiabatic logic. In addition, the impact of worsening degradation effects has to be considered in the design of adiabatic circuits. The impact of the technology trends on the figures of merit of adiabatic logic, energy saving potential and optimum operating frequency, are investigated, as well as degradation related issues. Adiabatic logic benefits from future devices, is not susceptible to Hot Carrier Injection, and shows less impact of Bias Temperature Instability than static CMOS circuits. Major interest also lies on the efficient generation of the applied power-clock signal. This oscillating power supply can be used to save energy in short idle times by disconnecting circuits. An efficient way to generate the p...
How detrimental is decoherence in adiabatic quantum computation?
Albash, Tameem
2015-01-01
Recent experiments with increasingly larger numbers of qubits have sparked renewed interest in adiabatic quantum computation, and in particular quantum annealing. A central question that is repeatedly asked is whether quantum features of the evolution can survive over the long time-scales used for quantum annealing relative to standard measures of the decoherence time. We reconsider the role of decoherence in adiabatic quantum computation and quantum annealing using the adiabatic quantum master equation formalism. We restrict ourselves to the weak-coupling and singular-coupling limits, which correspond to decoherence in the energy eigenbasis and in the computational basis, respectively. We demonstrate that decoherence in the instantaneous energy eigenbasis does not necessarily detrimentally affect adiabatic quantum computation, and in particular that a short single-qubit $T_2$ time need not imply adverse consequences for the success of the quantum adiabatic algorithm. We further demonstrate that boundary canc...
Power spectra in the eikonal approximation with adiabatic and non-adiabatic modes
Bernardeau, Francis; Vernizzi, Filippo
2012-01-01
We use the so-called eikonal approximation, recently introduced in the context of cosmological perturbation theory, to compute power spectra for multi-component fluids. We demonstrate that, at any given order in standard perturbation theory, multi-point power spectra do not depend on the large-scale adiabatic modes. Moreover, we employ perturbation theories to decipher how non-adiabatic modes, such as a relative velocity between two different components, damp the small-scale matter power spectrum, a mechanism recently described in the literature. In particular, we do an explicit calculation at 1-loop order of this effect. While the 1-loop result eventually breaks down, we show how the damping effect can be fully captured by the help of the eikonal approximation. A relative velocity not only induces mode damping but also creates large-scale anisotropic modulations of the matter power spectrum amplitude. We illustrate this for the Local Group environment.
Irineu, Rosa Maria da Silva
2010-07-01
This study aims to compare the surface properties of polyamide 6.6 plasma treatment and ionizing radiation, as well as determine the best technique and condition of the surface activation, adhesion of the same order and polyacrylic rubber used in manufacturing of automotive retainers. Treatment of polyamide 6.6 plasma was performed using an equipment 'Electronic Diener - Plasma - Surface-Technology LFG40' with nitrogen gas at a pressure of 1.40 kg/cm{sup 2}. Samples of polyamide 6.6 were also treated with ionizing radiation, atmospheric pressure and in vacuum, using an industrial electron accelerator, Dynamitron JOB 188 with radiation dose of 5, 10, 20, 40, 50, 100, 200, 300, 400 and 500kGy with a dose rate of 11.22 kGy/s for all doses and rate of 11.22 kGy/s and 22.38 kGy/s for a dose of 20kGy. After the processes of surface modification of polyamide 6.6, part of the untreated samples, treated by plasma and by ionizing radiation were incorporated into the polyacrylic rubber, and another part was designed to characterize the surface using the techniques of SEM / EDS, FT- IR, PIXE / RBS, AFM and contact angle. Untreated samples and the irradiated samples did not join the polyacrylic rubber. The samples treated by plasma joined the polyacrylic rubber efficiently and showed differences in roughness in SEM and AFM, and an increase in contact angle when compared with untreated samples. The irradiated samples showed no significant differences in the analysis of properties used in this study when compared with untreated samples. Ionizing radiation was not effective in surface modification of polyamide 6.6 for adherence with polyacrylic rubber. (author)
Effects of finite-β on the adiabatic invariant J in axisymmetric magnetic confinement configurations
An expression for the second adiabatic invariant J is derived including the effects of plasma diamagnetism and displaced magnetic surfaces. It is shown that for values of β approximately little than epsilon, where β is the ratio of kinetic to magnetic pressure and epsilon is the inverse aspect ratio of the torus, J becomes a decreasing function of PSI, the flux function, in the outer region of the plasma column. (author)
Extended adiabatic blast waves and a model of the soft x-ray background
An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. At early times when the external pressure is negligible, the structure is that of the usual self-similar solution. At later times, the structure evolves smoothly as the shock weakens, the postshock compression declines, and the gradients in pressure and density become less severe within the shocked region. The complete structure should be reliable down to a postshock compression of about 2, with conditions close inside the shock remaining well described somewhat longer. An analytical approximation is also presented for the electron-temperature distribution resulting from Coulomb collisional heating. It is shown that thermal conduction, limited by saturation at early times, fades in importance just as Coulomb collisional heating becomes significant. An estimate is made of the nonequilibrium cooling coefficient and the degree of ionization equilibrium expected by the time significant cooling sets in. From the estimates of the end point of the adiabatic era, based on the collisional equilibrium emissivity, are shown to be reasonably accurate. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E0 = 5 x 1050 ergs in a hot, low-density interstellar environment. A formulais presented for estimating the luminosity evolution of such explosions, including the effects of nonequilibrium ionization. It is shown that the B and C bands of the soft x-ray background are reproduced by such a model explosion if the ambient density is about 0.004 cm(sup -3), the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. The age of such an explosion is roughly 10(sup 5) years. This result is almost independent of whether there is apprecialy non-Coulomb heating of the electrons
Multiphoton atom ionization on the field of an ultrashort laser pulse
One derived closed analytical expressions for probability of multiphoton ionization of atoms and ions under the effect of alternating electrical field applicable for arbitrary values of Keldysh parameter. One studies dependences of ionization probability and pulsed spectrum of photoelectrons on the shape of ultrashort laser pulse. One studied in detail examples of various type pulsed fields. One studied interference effect in energy spectrum of photoelectrons at atom ionization by general periodical field. One discusses field of application for adiabatic approximation in theory of multiphoton ionization
Mass Modeling of Disk Galaxies: Constraints and Adiabatic Contraction
Dutton, A A; Carignan, C; De Jong, R; Dutton, Aaron A.; Courteau, Stephane; Carignan, Claude; Jong, Roelof de
2003-01-01
We present a comprehensive mass modeling technique for disk galaxies with resolved rotation curves. Our models allow for a stellar disk of variable thickness and mass-to-light ratio, a gaseous disk, halo profiles with a range of inner density profile slopes (-ALPHA), oblate halos, adiabatic contraction of the halo, and fixed minimum rotation curve error values. We test our technique with data from the literature consisting of high quality HI and Halpha rotation curves for galaxies with available photometry. These galaxies consist of dwarf, low surface brightness (LSB), and high surface brightness (HSB) galaxies. We apply constraints on the disk, and halo parameters in an attempt to break the degeneracies that exist between the disk and halo and between the halo parameters themselves. With our full set of constraints we find that ALPHA=0 halos provide the best fits for 6 out of 7 galaxies; in agreement with the literature; the exception, NGC 2403 an HSB galaxy, is best fit with ALPHA~1, though ALPHA=0 still pr...
Smirnov, Boris M
2001-01-01
A comprehensive textbook and reference for the study of the physics of ionized gasesThe intent of this book is to provide deep physical insight into the behavior of gases containing atoms and molecules from which one or more electrons have been ionized. The study of these so-called plasmas begins with an overview of plasmas as they are found in nature and created in the laboratory. This serves as a prelude to a comprehensive study of plasmas, beginning with low temperature and "ideal" plasmas and extending to radiation and particle transport phenomena, the response of plasmas to external fields, and an insightful treatment of plasma waves, plasma instabilities, nonlinear phenomena in plasmas, and the study of plasma interactions with surfaces
Unified treatment of dissociation and ionization processes in molecular hydrogen
A theoretical procedure is introduced which yields eigenvalues and eigenvectors of the reactance matrix pertaining to competing dissociation and ionization processes in molecular Rydberg states. A calculation is set up in terms of adiabatic (nuclear-coordinate dependent) quantum defects μ(R) which contain the essence of the physics of the excited molecular complex at short range. The application to preionized and predissociated resonances in the H2 spectrum yields good agreement with experiment
An ionization manometer is proposed which contains a transducer consisting of an anode, a directly heated cathode and a collector, a power source, a cathode emission current stabilizer, an ionic current amplifier connected to a recorder, and a cathode emission current modulator. To increase the accuracy of measurements under conditions of vacuum evaporation of materials, the modulator has been designed to comprise a source of controlling electric unipolar pulses of a specified duration and frequency and a blocking device connected to the collector. The output of the source of controlling electric unipolar pulses is connected to the emission current stabilizer and to the second input of the blocking device whose output is connected to the ionic current amplifier. The amount of pressure exerted in the vacuum chamber is estimated from the magnitude of the variable constituent of the collector signal
Are the reactions of quinones on graphite adiabatic?
Outer sphere electron transfer reactions on pure metal electrodes are often adiabatic and hence independent of the electrode material. Since it is not clear, whether adiabatic electron transfer can also occur on a semi-metal like graphite, we have re-investigated experimental data presented in a recent communication by Nissim et al. [Chemical Communications 48 (2012) 3294] on the reactions of quinones on graphite. We have supplemented their work by DFT calculations and conclude, that these reactions are indeed adiabatic. This contradicts the assertion of Nissim et al. that the rates are proportional to the density of states at the Fermi level
Approximability of optimization problems through adiabatic quantum computation
Cruz-Santos, William
2014-01-01
The adiabatic quantum computation (AQC) is based on the adiabatic theorem to approximate solutions of the Schrödinger equation. The design of an AQC algorithm involves the construction of a Hamiltonian that describes the behavior of the quantum system. This Hamiltonian is expressed as a linear interpolation of an initial Hamiltonian whose ground state is easy to compute, and a final Hamiltonian whose ground state corresponds to the solution of a given combinatorial optimization problem. The adiabatic theorem asserts that if the time evolution of a quantum system described by a Hamiltonian is l
A note on the geometric phase in adiabatic approximation
Tong, D M; Kwek, L C; Oh, C H
2004-01-01
It is widely held that the Berry phase of a quantum system is the geometric phase in adiabatic approximation. However, Pati and Rajagopal recently claimed that the Berry phase vanishes under strict adiabatic evolution. In this note, we reexamine and address this issue. In particular, we show that the use of the adiabatic theorem does not lead to this inconsistency. We also examine the difference between the Berry phase and the exact geometric phase. Here we find that the Berry phase may differ appreciably from the exact geometric phase if the evolution time is large enough.
Beneficial Role of the Industrial Wastes to Combat Adiabatic Temperature Rise in Massive Concrete
Ashraf, M.; Goyal, A.; Anwar, A. M.; Hattori, K.; Ogata, H.; Guo, S.
An evaluation was made on the mutual beneficial role of fly ash and ground granulated blast furnace slag in combating adiabatic temperature rise. The experimental program was designed in two stages; the main experiment consisted of two massive concrete specimens with dimensions (50x50x50) cm. In first stage of experiment, an adiabatic rise in temperature of specimens was measured. In second stage, the mechanical properties of massive concrete specimens were measured at the ages of 8, 14, 28, 56 and 91 days. At the age of 91 days, surface core and central cores were extracted from the surface and the central part of massive concrete specimens to determine compressive strength and dynamic modulus of elasticity. In the massive concrete specimen without any additive, the peak temperature noted was 64.5°C at 7th h after casting. While in mineral substituted concrete the maximum adiabatic temperature was 49.6°C at 19th h after casting. Lower rate of temperature rise in mineral substituted concrete has resulted in higher value of ultrasonic pulse velocity and ultimate compressive strength of concrete.
Adiabatic nanofocusing: spectroscopy, transport and imaging investigation of the nano world
Giugni, A.; Allione, M.; Torre, B.; Das, G.; Francardi, M.; Moretti, M.; Malerba, M.; Perozziello, G.; Candeloro, P.; Di Fabrizio, E.
2014-11-01
Adiabatic compression plays a fundamental role in the realization of localized enhanced electromagnetic field hot spots, it provides the possibility to focus at nanoscale optical excitation. It differs from the well-known lightning rod effect since it is based on the lossless propagation of surface plasmon polaritons (SPPs) up to a nano-sized metal tip where the energy density is largely enhanced. Here we discuss two important applications of adiabatic compression: Raman and hot electron spectroscopy at nanometric resolution. The underlying phenomena are the conversion of SPPs into photons or hot electrons. New scanning probe spectroscopy techniques along with experimental results are discussed. We foresee that these techniques will play a key role in relating the functional and structural properties of matter at the nanoscale.
Fully quantum non-adiabatic dynamics in electronic-nuclear coherent state basis
Humeniuk, Alexander
2016-01-01
Direct dynamics methods using Gaussian wavepackets have to rely only on local properties, such as gradients and hessians at the center of the wavepacket, so as to be compatible with the usual quantum chemistry methods. Matrix elements of the potential energy surfaces between wavepackets therefore usually have to be approximated. It is shown, that if a modified form of valence bond theory is used instead of the usual MO-based theories, the matrix elements can be obtained exactly. This is so because the molecular Hamiltonian only contains the Coulomb potential, for which matrix elements between different basis functions (consisting of Gaussian nuclear and electronic orbitals) are all well-known. In valence bond theory the self-consistent field calculation can be avoided so that the matrix elements are analytical functions of the nuclear coordinates. A method for simulating non-adiabatic quantum dynamics is sketched, where coherent state trajectories are propagated "on the fly" on adiabatic potential energy surf...
Adiabatic electronic flux density: a Born-Oppenheimer Broken Symmetry ansatz
Pohl, Vincent
2016-01-01
The Born-Oppenheimer approximation leads to the counterintuitive result of a vanishing electronic flux density upon vibrational dynamics in the electronic ground state. To circumvent this long known issue, we propose using pairwise anti-symmetrically translated vibronic densities to generate a symmetric electronic density that can be forced to satisfy the continuity equation approximately. The so-called Born-Oppenheimer broken symmetry ansatz yields all components of the flux density simultaneously while requiring only knowledge about the nuclear quantum dynamics on the electronic adiabatic ground state potential energy surface. The underlying minimization procedure is transparent and computationally inexpensive, and the solution can be computed from the standard output of any quantum chemistry program. Taylor series expansion reveals that the implicit electron dynamics originates from non-adiabatic coupling to the explicit Born-Oppenheimer nuclear dynamics. The new approach is applied to the ${\\rm H}_2^+$ mo...
Adiabatic nanofocusing: spectroscopy, transport and imaging investigation of the nano world
Adiabatic compression plays a fundamental role in the realization of localized enhanced electromagnetic field hot spots, it provides the possibility to focus at nanoscale optical excitation. It differs from the well-known lightning rod effect since it is based on the lossless propagation of surface plasmon polaritons (SPPs) up to a nano-sized metal tip where the energy density is largely enhanced. Here we discuss two important applications of adiabatic compression: Raman and hot electron spectroscopy at nanometric resolution. The underlying phenomena are the conversion of SPPs into photons or hot electrons. New scanning probe spectroscopy techniques along with experimental results are discussed. We foresee that these techniques will play a key role in relating the functional and structural properties of matter at the nanoscale. (review)
Adiabatic nanofocusing: Spectroscopy, transport and imaging investigation of the nano world
Giugni, Andrea
2014-11-01
Adiabatic compression plays a fundamental role in the realization of localized enhanced electromagnetic field hot spots, it provides the possibility to focus at nanoscale optical excitation. It differs from the well-known lightning rod effect since it is based on the lossless propagation of surface plasmon polaritons (SPPs) up to a nano-sized metal tip where the energy density is largely enhanced. Here we discuss two important applications of adiabatic compression: Raman and hot electron spectroscopy at nanometric resolution. The underlying phenomena are the conversion of SPPs into photons or hot electrons. New scanning probe spectroscopy techniques along with experimental results are discussed. We foresee that these techniques will play a key role in relating the functional and structural properties of matter at the nanoscale.
Penetration of a resonant magnetic perturbation in an adiabatically rippled plasma slab
Dewar, Robert L; Bhattacharjee, Amitava; Yoshida, Zensho
2016-01-01
The adiabatic limit of a recently proposed dynamical extension of Taylor relaxation, \\emph{multi-region relaxed magnetohydrodynamics} (MRxMHD) is summarized, with special attention to the appropriate definition of relative magnetic helicity. The formalism is illustrated using a simple two-region, sheared-magnetic-field model similar to the Hahm--Kulsrud--Taylor (HKT) rippled-boundary slab model. In MRxMHD a linear Grad--Shafranov equation applies, even at finite ripple amplitude. The adiabatic switching on of boundary ripple excites a shielding current sheet opposing reconnection at a resonant surface. The perturbed magnetic field as a function of ripple amplitude is calculated by invoking conservation of magnetic helicity in the two regions separated by the current sheet. At low ripple amplitude "half islands" appear on each side of the current sheet, locking the rotational transform at the resonant value. Beyond a critical amplitude these islands disappear and the rotational transform develops a discontinui...
On the persistence of adiabatic shear bands
Bassim M.N.
2012-08-01
Full Text Available It is generally agreed that the initiation and development of adiabatic shear bands (ASBs are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the “scars” due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.
Graph isomorphism and adiabatic quantum computing
Gaitan, Frank; Clark, Lane
2014-03-01
In the Graph Isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and maps G --> G'. If yes (no), then G and G' are said to be isomorphic (non-isomorphic). The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. We present a quantum algorithm that solves arbitrary instances of GI, and which provides a novel approach to determining all automorphisms of a graph. The algorithm converts a GI instance to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. Numerical simulation of the algorithm's quantum dynamics shows that it correctly distinguishes non-isomorphic graphs; recognizes isomorphic graphs; and finds the automorphism group of a graph. We also discuss the algorithm's experimental implementation and show how it can be leveraged to solve arbitrary instances of the NP-Complete Sub-Graph Isomorphism problem.
General dynamical description of quasi-adiabatically encircling exceptional points
Milburn, Thomas J; Holmes, Catherine A; Portolan, Stefano; Rotter, Stefan; Rabl, Peter
2014-01-01
The appearance of so-called exceptional points in the complex spectra of non-Hermitian systems is often associated with phenomena that contradict our physical intuition. One example of particular interest is the state-exchange process predicted for an adiabatic encircling of an exceptional point. In this work we analyze this process for the generic system of two coupled oscillator modes with loss or gain. We identify a characteristic system evolution consisting of periods of quasi-stationarity interrupted by abrupt non-adiabatic transitions. Our findings explain the breakdown of the adiabatic theorem as well as the chiral behavior noticed previously in this context, and we provide a unified framework to describe quasi-adiabatic dynamical effects in non-Hermitian systems in a qualitative and quantitative way.
Adiabatic and isocurvature perturbation projections in multi-field inflation
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit
AN ADIABATIC APPROACH FOR LOW POWER FULL ADDER DESIGN
Prof. Dinesh Chandra
2011-09-01
Full Text Available Over the past decade, several adiabatic logic styles have been reported. This paper deals with the design of a 1-bit full adder using several adiabatic logic styles, which are derived from static CMOS logic, without a large change. The full adders are designed using 180nm technology parameters provided by predictive technology and simulated using HSPICE. The full adders designed are compared in terms of average power consumption with different values of load capacitance, temperature and input frequency. The different designs of full adder are also compared on the basis of propagation delay exhibit by them. It is found that, full adders designed with adiabatic logic styles tends to consume very low power in comparison to full adder designed with static CMOS logic. Under certain operating conditions, one of adiabatic designs of full adder achieves upto 74% power saving in comparison to the full adder designedwith static CMOS logic.
Magnesium Diboride Superconducting Coils for Adiabatic Demagnetization Refrigerators (ADR's) Project
National Aeronautics and Space Administration — For Adiabatic Demagnetization Refrigerators(ADR's) for space it is desirable to have very light weight, small diameter, high current density superconducting wires...
Application of adiabatic calorimetry to metal systems. Final report
Research on the application of adiabatic calorimetry to metal systems is described. Investigations into formation of pearlite in steels, ferromagnetic effects, cold working and annealing, solid solution alloys, pure solid metals, and pure liquid metals, are briefly described
Case Study of Indirect Adiabatic Cooling System in Historical Building
Brahmanis, A; Lešinskis, A; Krūmiņš, A
2013-01-01
The objective of the present study is to investigate the efficiency of indirect adiabatic chiller-based cooling system efficiency dependence of outdoor air humidity. The system is located in historical building, in temperate climate of Latvia.
Vaidya, B; Bodo, G; Massaglia, S
2015-01-01
An Equation of State (\\textit{EoS}) closes the set of fluid equations. Although an ideal EoS with a constant \\textit{adiabatic index} $\\Gamma$ is the preferred choice due to its simplistic implementation, many astrophysical fluid simulations may benefit from a more sophisticated treatment that can account for diverse chemical processes. Here, we first review the basic thermodynamic principles of a gas mixture in terms of its thermal and caloric EoS by including effects like ionization, dissociation as well as temperature dependent degrees of freedom such as molecular vibrations and rotations. The formulation is revisited in the context of plasmas that are either in equilibrium conditions (local thermodynamic- or collisional excitation- equilibria) or described by non-equilibrium chemistry coupled to optically thin radiative cooling. We then present a numerical implementation of thermally ideal gases obeying a more general caloric EoS with non-constant adiabatic index in Godunov-type numerical schemes.We discu...
Adiabatic instability in coupled dark energy-dark matter models
Bean, Rachel; Flanagan, Eanna E.; Trodden, Mark
2007-01-01
We consider theories in which there exists a nontrivial coupling between the dark matter sector and the sector responsible for the acceleration of the universe. Such theories can possess an adiabatic regime in which the quintessence field always sits at the minimum of its effective potential, which is set by the local dark matter density. We show that if the coupling strength is much larger than gravitational, then the adiabatic regime is always subject to an instability. The instability, whi...
Hybrid adiabatic potentials in the QCD string model
Kalashnikova, Yu S; Kalashnikova, Yu.S.
2003-01-01
The short- and intermediate-distance behaviour of the hybrid adiabatic potentials is calculated in the framework of the QCD string model. The calculations are performed with the inclusion of Coulomb force. Spin-dependent force and the so-called string correction term are treated as perturbation at the leading potential-type regime. Reasonably good agreement with lattice measurements takes place for adiabatic curves excited with magnetic components of field strength correlators.
Adiabatic frequency conversion of quantum optical information in atomic vapor
Vewinger, Frank; Appel, Juergen; Figueroa, Eden; Lvovsky, A. I.
2006-01-01
We experimentally demonstrate a quantum communication protocol that enables frequency conversion and routing of quantum optical information in an adiabatic and thus robust way. The protocol is based on electromagnetically-induced transparency in systems with multiple excited levels: transfer and/or distribution of optical states between different signal modes is implemented by adiabatically changing the control fields. The proof-of-principle experiment is performed using the hyperfine levels ...
Adiabatic CMB perturbations in pre-big bang string cosmology
Enqvist, Kari; Enqvist, Kari; Sloth, Martin S.
2002-01-01
We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in the axion field can give rise to a nearly flat spectrum of adiabatic perturbations with a spectral tilt $\\Delta n$ in the range $-0.1 \\lesssim \\Delta n \\lesssim 0.3$.
Realization of adiabatic Aharonov-Bohm scattering with neutrons
Sjöqvist, Erik; Almquist, Martin; Mattsson, Ken; Gürkan, Zeynep Nilhan; Hessmo, Björn
2015-11-01
The adiabatic Aharonov-Bohm (AB) effect is a manifestation of the Berry phase acquired when some slow variables take a planar spin around a loop. While the effect has been observed in molecular spectroscopy, direct measurement of the topological phase shift in a scattering experiment has been elusive in the past. Here, we demonstrate an adiabatic AB effect by explicit simulation of the dynamics of unpolarized very slow neutrons that scatter on a long straight current-carrying wire.
Dependence of adiabatic population transfer on pulse profile
S Dasgupta; T kushwaha; D Goswami
2006-06-01
Control of population transfer by rapid adiabatic passage has been an established technique wherein the exact amplitude profile of the shaped pulse is considered to be insignificant. We study the effect of ultrafast shaped pulses for two-level systems, by density-matrix approach. However, we find that adiabaticity depends simultaneously on pulse profile as well as the frequency modulation under non-resonant conditions.
Adiabatic Invariant Treatment of a Collapsing Sphere of Quantized Dust
Roberto CasadioDipartimento di Fisica, Universita' di Bologna and INFN, Bologna; Fabio Finelli(Dipartimento di Fisica, Universita' di Bologna and INFN, Bologna); Giovanni Venturi(Department of Physics, University of Bologna, and Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Italy)
2015-01-01
The semiclassical collapse of a sphere of quantized dust is studied. A Born-Oppenheimer decomposition is performed for the wave function of the system and the semiclassical limit is considered for the gravitational part. The method of adiabatic invariants for time dependent Hamiltonians is then employed to find (approximate) solutions to the quantum dust equations of motions. This allows us to obtain corrections to the adiabatic approximation of the dust states associated with the time evolut...
Time Development of Exponentially Small Non-Adiabatic Transitions
Hagedorn, George A.; Joye, Alain
2003-01-01
Optimal truncations of asymptotic expansions are known to yield approximations to adiabatic quantum evolutions that are accurate up to exponentially small errors. In this paper, we rigorously determine the leading order non--adiabatic corrections to these approximations for a particular family of two--level analytic Hamiltonian functions. Our results capture the time development of the exponentially small transition that takes place between optimal states by means of a particular switching fu...
Adiabatic Quantum Programming: Minor Embedding With Hard Faults
Klymko, Christine; Sullivan, Blair D.; Humble, Travis S.
2012-01-01
Adiabatic quantum programming defines the time-dependent mapping of a quantum algorithm into an underlying hardware or logical fabric. An essential step is embedding problem-specific information into the quantum logical fabric. We present algorithms for embedding arbitrary instances of the adiabatic quantum optimization algorithm into a square lattice of specialized unit cells. These methods extend with fabric growth while scaling linearly in time and quadratically in footprint. We also provi...
Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments
DeLucia, J.; Bell, M.; Wong, K.L.
1985-07-01
A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is of generation applicability.
Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments
A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is of generation applicability
Non Adiabatic Centrifugal Compressor Gas Dynamic Performance Definition
Soldatova, Kristina
2014-01-01
Most centrifugal compressors operate in conditions with negligible heat transfer (adiabatic compression). Their plant tests conditions are similar or close to adiabatic conditions. Test regulations establish measures to diminish influence of a heat transfer “compressor body – atmospheric air” to an exit temperature. Therefore a temperature rise in a compressor is used to calculate a work input coefficient and efficiency. Unlike it high pressure centrifugal compressors of gas turbines and supe...
Adiabatic boiling of two-phase coolant in upward flow
A mathematical model of the process of adiabatic boiling (self-condensation) of a two-phase coolant in upward (downward) flow is developed. The model takes account of changes in phase properties with static pressure decrease. The process is investigated numerically. Approximate analytical formulas for design calculations are obtained. It is shown that effects of adiabatic boiling (self-condensation) should be taken into account when calculating two-phase coolant flow in stretched vertical channels
Frozen natural orbitals for ionized states within equation-of-motion coupled-cluster formalism
Landau, Arie; Khistyaev, Kirill; Dolgikh, Stanislav; Krylov, Anna I.
2010-01-01
The frozen natural orbital (FNO) approach, which has been successfully used in ground-state coupled-cluster calculations, is extended to open-shell ionized electronic states within equation-of-motion coupled-cluster (EOM-IP-CC) formalism. FNOs enable truncation of the virtual orbital space significantly reducing the computational cost with a negligible decline in accuracy. Implementation of the MP2-based FNO truncation scheme within EOM-IP-CC is presented and benchmarked using ionized states of beryllium, dihydrogen dimer, water, water dimer, nitrogen, and uracil dimer. The results show that the natural occupation threshold, i.e., percentage of the total natural occupation recovered in the truncated virtual orbital space, provides a more robust truncation criterion as compared to the fixed percentage of virtual orbitals retained. Employing 99%-99.5% natural occupation threshold, which results in the virtual space reduction by 70%-30%, yields errors below 1 kcal/mol. Moreover, the total energies exhibit linear dependence as a function of the percentage of the natural occupation retained allowing for extrapolation to the full virtual space values. The capabilities of the new method are demonstrated by the calculation of the 12 lowest vertical ionization energies (IEs) and the lowest adiabatic IE of guanine. In addition to IE calculations, we present the scans of potential energy surfaces (PESs) for ionized (H2O)2 and (H2)2. The scans demonstrate that the FNO truncation does not introduce significant nonparallelity errors and accurately describes the PESs shapes and the corresponding energy differences, e.g., dissociation energies.
Adiabatic self-trapped states in zigzag nanotubes
Brizhik, L S [Bogolyubov Institute for Theoretical Physics, 03680 Kyiv (Ukraine); Eremko, A A [Bogolyubov Institute for Theoretical Physics, 03680 Kyiv (Ukraine); Piette, B M A G [Department of Mathematical Sciences, University of Durham, Durham DH1 3LE (United Kingdom); Zakrzewski, W J [Department of Mathematical Sciences, University of Durham, Durham DH1 3LE (United Kingdom)
2007-08-01
We study the polaron (soliton) states of a quasiparticle (electron, hole, exciton) in a quasi-one-dimensional (quasi-1D) model which describes a carbon-type zigzag nanotube structure. In the Hamiltonian of the system we include the electron-phonon interaction that arises from the dependence of both the on-site and the hopping interaction energies on the lattice deformation. We derive, in the adiabatic approximation, the equations for the self-trapped states of a quasiparticle in a zigzag nanotube. We show that the ground state of such a system depends on the strength of the electron-phonon coupling and we find polaron-type solutions with different symmetries. Namely, at a relatively weak coupling a quasiparticle is self-trapped in a quasi-1D polaron state which has an azimuthal symmetry. When the coupling constant exceeds some critical value, the azimuthal symmetry breaks down and the quasiparticle state can be described as a two-dimensional small polaron on the nanotube surface. In the crossover region between the two solutions there is a range of intermediate couplings, in which the two structures, the quasi-1D polaron and the strongly localized 2D polaron, coexist as their energies are very close together. We note that the results of this analytical study are in quantitative agreement with what has recently been observed numerically.
Seiler, Ch; Hogan, S D; Schmutz, H; Agner, J A; Merkt, F
2011-02-18
A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90°, 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. PMID:21405512
Tscherbul, Timur V
2014-01-01
We use quantum and classical adiabatic capture theories to study the chemical reaction Li + CaH -> LiH + Ca. Using a recently developed ab initio potential energy surface, which provides an accurate representation of long-range interactions in the entrance reaction channel, we calculate the adiabatic channel potentials by diagonalizing the atom-molecule Hamiltonian as a function of the atom-molecule separation. The resulting adiabatic channel potentials are used to calculate both the classical and quantum capture probabilities as a function of collision energy, as well as the temperature dependencies of the partial and total reaction rates. The calculated reaction rate agrees well with the measured value at 1 K [V. Singh et al., Phys. Rev. Lett. 108, 203201 (2012)], suggesting that the title reaction proceeds without an activation barrier. The calculated classical adiabatic capture rate agrees well with the quantum result in the multiple partial wave regime of relevance to the experiment. Significant differen...
Stimulated Raman adiabatic passage for improved performance of a cold-atom electron and ion source
Sparkes, B. M.; Murphy, D.; Taylor, R. J.; Speirs, R. W.; McCulloch, A. J.; Scholten, R. E.
2016-08-01
We implement high-efficiency coherent excitation to a Rydberg state using stimulated Raman adiabatic passage in a cold-atom electron and ion source. We achieve an efficiency of 60% averaged over the laser excitation volume with a peak efficiency of 82%, a 1.6 times improvement relative to incoherent pulsed-laser excitation. Using pulsed electric field ionization of the Rydberg atoms we create electron bunches with durations of 250 ps. High-efficiency excitation will increase source brightness, crucial for ultrafast electron diffraction experiments, and 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.
Extended adiabatic blast waves and a model of the soft X-ray background. [interstellar matter
Cox, D. P.; Anderson, P. R.
1981-01-01
An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. An analytical approximation is also presented for the electron temperature distribution resulting from coulomb collisional heating. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E sub 0 = 5 x 10 to the 50th power ergs in a hot low-density interstellar environment. A formula is presented for estimating the luminosity evolution of such explosions. The B and C bands of the soft X-ray background, it is shown, are reproduced by such a model explosion if the ambient density is about .000004 cm, the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. Evolution in a pre-existing cavity with a strong density gradient may, it is suggested, remove both the M band and OVI discrepancies.
Adiabatic and non-adiabatic charge pumping in a single-level molecular motor
We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green’s function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups. (paper)
Kinetically constrained ring-polymer molecular dynamics for non-adiabatic chemical reactions
We extend ring-polymer molecular dynamics (RPMD) to allow for the direct simulation of general, electronically non-adiabatic chemical processes. The kinetically constrained (KC) RPMD method uses the imaginary-time path-integral representation in the set of nuclear coordinates and electronic states to provide continuous equations of motion that describe the quantized, electronically non-adiabatic dynamics of the system. KC-RPMD preserves the favorable properties of the usual RPMD formulation in the position representation, including rigorous detailed balance, time-reversal symmetry, and invariance of reaction rate calculations to the choice of dividing surface. However, the new method overcomes significant shortcomings of position-representation RPMD by enabling the description of non-adiabatic transitions between states associated with general, many-electron wavefunctions and by accurately describing deep-tunneling processes across asymmetric barriers. We demonstrate that KC-RPMD yields excellent numerical results for a range of model systems, including a simple avoided-crossing reaction and condensed-phase electron-transfer reactions across multiple regimes for the electronic coupling and thermodynamic driving force
Kinetically constrained ring-polymer molecular dynamics for non-adiabatic chemical reactions
Menzeleev, Artur R.; Bell, Franziska; Miller, Thomas F., E-mail: tfm@caltech.edu [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States)
2014-02-14
We extend ring-polymer molecular dynamics (RPMD) to allow for the direct simulation of general, electronically non-adiabatic chemical processes. The kinetically constrained (KC) RPMD method uses the imaginary-time path-integral representation in the set of nuclear coordinates and electronic states to provide continuous equations of motion that describe the quantized, electronically non-adiabatic dynamics of the system. KC-RPMD preserves the favorable properties of the usual RPMD formulation in the position representation, including rigorous detailed balance, time-reversal symmetry, and invariance of reaction rate calculations to the choice of dividing surface. However, the new method overcomes significant shortcomings of position-representation RPMD by enabling the description of non-adiabatic transitions between states associated with general, many-electron wavefunctions and by accurately describing deep-tunneling processes across asymmetric barriers. We demonstrate that KC-RPMD yields excellent numerical results for a range of model systems, including a simple avoided-crossing reaction and condensed-phase electron-transfer reactions across multiple regimes for the electronic coupling and thermodynamic driving force.
New simple expressions for average number of electrons in the valence orbital of a reacting ion and the charge susceptibility are obtained that allow one to calculate adiabatic free energy surfaces (AFES) and corresponding kinetic regime diagrams (KRD) for adiabatic processes of electron transfer from the ion, located in a polar liquid, to a metal within the framework of the exactly solvable (in the limit T→0) model of the metal with the infinitely wide conduction band. This model represents one of limiting cases of the Anderson model that may be applied to s-p metals. Unlike previous studies of the adiabatic reactions in the model of the metal with the infinitely wide conduction band, the present work takes into account the electron-electron correlation effects in an exact manner. General results are illustrated with KRD which determine the regions of the physical parameters of the system corresponding to various types of electron transfer processes. AFES are calculated for some typical parameters sets. The exact AFES are compared with those calculated within the Hartree-Fock approximation. It is shown that the correlation effects are of importance and results not only in a considerable decrease of the activation free energy but also to qualitatively different shapes of AFES in some regions of the system parameters
Dynamical fluctuations in classical adiabatic processes: General description and their implications
Zhang, Qi; Gong, Jiangbin; Oh, C. H.
2010-01-01
Dynamical fluctuations in classical adiabatic processes are not considered by the conventional classical adiabatic theorem. In this work a general result is derived to describe the intrinsic dynamical fluctuations in classical adiabatic processes. Interesting implications of our general result are discussed via two subtopics, namely, an intriguing adiabatic geometric phase in a dynamical model with an adiabatically moving fixed-point solution, and the possible "pollution" to Hannay's angle or...
WANG Xue-bin
2008-01-01
The coexistent phenomenon of deformed and transformed adiabatic shear bands(ASBs) of ductile metal was analyzed using the JOHNSON-COOK model and gradient-dependent plasticity(GDP). The effects of melting point, density, heat capacity and work to heat conversion factor were investigated. Higher work to heat conversion factor, lower density, lower heat capacity and higher melting point lead to wider transformed ASB and higher local plastic shear deformation between deformed and transformed ASBs. Higher work to heat conversion factor, lower density, lower heat capacity and lower melting point cause higher local plastic shear deformation in the deformed ASB. Three reasons for the scatter in experimental data on the ASB width were pointed out and the advantages of the work were discussed. If the transformed ASB width is used to back-calculate the internal length parameter in the GDP, undoubtedly, the parameter will be extremely underestimated.
FIELD IONIZATION OF MOLECULES IN AN INTENSE LASER FIELD
吴成印; 龚旗煌
2001-01-01
In order to predict the field ionization probabilities, the accurate ab initio electrostatic potential of molecules has to be calculated. However, the calculation of the full ab initio electrostatic potential of molecules is complicated,even impossible for some larger molecules with low symmetry. Here, we present a semi-empirical model to treat the field ionization of molecules in an intense laser field. In this model, a modified Coulomb potential is used to take the place of the complicated ab initio electrostatic potential of molecules. The analytic equations of the Keldysh adiabatic parameter using the Coulomb potential and the modified Coulomb potential have first been given. Using our semiempirical model, we have calculated the field ionization probabilities and the Keldysh adiabatic parameters of O2,N2, SO2, C2H4, CH3CN and C6H6 in an intense laser field. The results agree excellently with the calculations using the ab initio electrostatic potential of molecules. As the modified parameter for the Coulomb potential can be found from experimental measurements, the field ionization mechanism of molecules can be immediately predicted with our semi-empirical model.
Physics on the adiabatically changed Finslerian manifold and cosmology
Lipovka, Anton A
2016-01-01
In present paper we confirm our previous result [4] that Planck constant is adiabatic invariant of electromagnetic field propagating on the adiabatically changed Finslerian manifold. Direct calculation from cosmological parameters gives value h=6x10(-27) (erg s). We also confirm that Planck constant (and hence other fundamental constants which depend on h) is varied on time due to changing of geometry. As an example the variation of the fine structure constant is calculated. Its relative variation ((da/dt)/a) consist 1.0x10(-18) (1/s). We show that on the Finsler manifold characterized by adiabatically changed geometry, classical free electromagnetic field is quantized geometrically, from the properties of the manifold in such manner that adiabatic invariant of field is ET=6x10(-27)=h. Electrodynamic equations on the Finslerian manifold are suggested. It is stressed that quantization naturally appears from these equations and is provoked by adiabatically changed geometry of manifold. We consider in details tw...
Adiabatic condition and the quantum hitting time of Markov chains
We present an adiabatic quantum algorithm for the abstract problem of searching marked vertices in a graph, or spatial search. Given a random walk (or Markov chain) P on a graph with a set of unknown marked vertices, one can define a related absorbing walk P' where outgoing transitions from marked vertices are replaced by self-loops. We build a Hamiltonian H(s) from the interpolated Markov chain P(s)=(1-s)P+sP' and use it in an adiabatic quantum algorithm to drive an initial superposition over all vertices to a superposition over marked vertices. The adiabatic condition implies that, for any reversible Markov chain and any set of marked vertices, the running time of the adiabatic algorithm is given by the square root of the classical hitting time. This algorithm therefore demonstrates a novel connection between the adiabatic condition and the classical notion of hitting time of a random walk. It also significantly extends the scope of previous quantum algorithms for this problem, which could only obtain a full quadratic speedup for state-transitive reversible Markov chains with a unique marked vertex.
Global adiabaticity and non-Gaussianity consistency condition
Romano, Antonio Enea; Sasaki, Misao
2016-01-01
In the context of single-field inflation, the conservation of the curvature perturbation on comoving slices, $R_c$, on super-horizon scales is one of the assumptions necessary to derive the consistency condition between the squeezed limit of the bispectrum and the spectrum of the primordial curvature perturbation. However, the conservation of $R_c$ holds only after the perturbation has reached the adiabatic limit where the constant mode of $R_c$ dominates over the other (usually decaying) mode. In this case, the non-adiabatic pressure perturbation defined in the thermodynamic sense, $\\delta P_{nad}\\equiv\\delta P-c_w^2\\delta\\rho$ where $c_w^2=\\dot P/\\dot\\rho$, usually becomes also negligible on superhorizon scales. Therefore one might think that the adiabatic limit is the same as thermodynamic adiabaticity. This is in fact not true. In other words, thermodynamic adiabaticity is not a sufficient condition for the conservation of $R_c$ on super-horizon scales. In this paper, we consider models that satisfies $\\d...
Interplay between electric and magnetic effect in adiabatic polaritonic systems
Alabastri, Alessandro
2013-01-01
We report on the possibility of realizing adiabatic compression of polaritonic wave on a metallic conical nano-structure through an oscillating electric potential (quasi dynamic regime). By comparing this result with an electromagnetic wave excitation, we were able to relate the classical lighting-rod effect to adiabatic compression. Furthermore, we show that while the magnetic contribution plays a marginal role in the formation of adiabatic compression, it provides a blue shift in the spectral region. In particular, magnetic permeability can be used as a free parameter for tuning the polaritonic resonances. The peculiar form of adiabatic compression is instead dictated by both the source and the metal permittivity. The analysis is performed by starting from a simple electrostatic system to end with the complete electromagnetic one through intermediate situations such as the quasi-electrostatic and quasi-dynamic regimes. Each configuration is defined by a particular set of equations which allows to clearly determine the individual role played by the electric and magnetic contribution in the generation of adiabatic compression. We notice that these findings can be applied for the realization of a THz nano-metric generator. © 2013 Optical Society of America.
Karras, Gabriel; Lockyer, Nicholas P
2014-05-01
A systematic mass spectrometric study of two of the most common analgesic drugs, paracetamol and ibuprofen, is reported. The drugs were studied by means of secondary ion mass spectrometry (SIMS) and secondary neutral mass spectrometry (SNMS) using laser post-ionization (LPI) both in pure samples and in a two-component mixture. Ion suppression within the two-component system observed in SIMS mode is ameliorated using LPI under room temperature analysis. However, suppression effects are apparent in LPI mode on performing the analysis at cryogenic temperatures, which we attribute to changes in the desorption characteristics of sputtered molecules, which influences the subsequent post-ionization efficiency. This suggests different mechanisms of ion suppression in SIMS and LPI modes. PMID:24658806
Karras, Gabriel; Lockyer, Nicholas P.
2014-05-01
A systematic mass spectrometric study of two of the most common analgesic drugs, paracetamol and ibuprofen, is reported. The drugs were studied by means of secondary ion mass spectrometry (SIMS) and secondary neutral mass spectrometry (SNMS) using laser post-ionization (LPI) both in pure samples and in a two-component mixture. Ion suppression within the two-component system observed in SIMS mode is ameliorated using LPI under room temperature analysis. However, suppression effects are apparent in LPI mode on performing the analysis at cryogenic temperatures, which we attribute to changes in the desorption characteristics of sputtered molecules, which influences the subsequent post-ionization efficiency. This suggests different mechanisms of ion suppression in SIMS and LPI modes.
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
Romano, Antonio Enea; Sasaki, Misao
2015-01-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid $\\delta P_{nad}$, another is for a general matter field $\\delta P_{c,nad}$, and the last one is valid only on superhorizon scales. The first two definitions coincide if $c_s^2=c_w^2$ where $c_s$ is the propagation speed of the perturbation, while $c_w^2=\\dot P/\\dot\\rho$. Assuming the adiabaticity in the general sense, $\\delta P_{c,nad}=0$, we derive a relation between the lapse function in the comoving slicing $A_c$ and $\\delta P_{nad}$ valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as $c_s\
Integrated polarization rotator/converter by stimulated Raman adiabatic passage.
Xiong, Xiao; Zou, Chang-Ling; Ren, Xi-Feng; Guo, Guang-Can
2013-07-15
We proposed a polarization rotator inspired by stimulated Raman adiabatic passage model from quantum optics, which is composed of a signal waveguide and an ancillary waveguide. The two orthogonal modes in signal waveguide and the oblique mode in ancillary waveguide form a Λ-type three-level system. By controlling the width of signal waveguide and the gap between two waveguides, adiabatic conversion between two orthogonal modes can be realized in the signal waveguide. With such adiabatic passage, polarization conversion is completed within 150 μm length, with the efficiencies over 99% for both conversions between horizontal polarization and vertical polarization. In addition, such a polarization rotator is quite robust against fabrication error, allowing a wide range of tolerances for the rotator geometric parameters. Our work is not only significative to photonic simulations of coherent quantum phenomena with engineered photonic waveguides, but also enlightens the practical applications of these phenomena in optical device designs. PMID:23938558
Ionization of Atoms by Slow Heavy Particles, Including Dark Matter
Roberts, B. M.; Flambaum, V. V.; Gribakin, G. F.
2016-01-01
Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times.
Ionization of Atoms by Slow Heavy Particles, Including Dark Matter.
Roberts, B M; Flambaum, V V; Gribakin, G F
2016-01-15
Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times. PMID:26824537
Adiabatic fluctuations from cosmic strings in a contracting universe
We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as cosmic strings on super-Hubble scales lead to a source term which seeds the growth of curvature fluctuations on these scales. Once the symmetry has been restored at high temperatures, the isocurvature seeds disappear, and the fluctuations evolve as adiabatic ones in the expanding phase. Thus, cosmic strings may be resurrected as a mechanism for generating the primordial density fluctuations observed today
Non-adiabatic pumping through interacting quantum dots
Cavaliere, Fabio; Governale, Michele; König, Jürgen
2009-01-01
We study non-adiabatic two-parameter charge and spin pumping through a single-level quantum dot with Coulomb interaction. For the limit of weak tunnel coupling and in the regime of pumping frequencies up to the tunneling rates, $\\Omega \\lesssim \\Gamma/\\hbar$, we perform an exact resummation of contributions of all orders in the pumping frequency. As striking non-adiabatic signatures, we find frequency-dependent phase shifts in the charge and spin currents, which allow for an effective single-...
Quantum Adiabatic Pumping by Modulating Tunnel Phase in Quantum Dots
Taguchi, Masahiko; Nakajima, Satoshi; Kubo, Toshihiro; Tokura, Yasuhiro
2016-08-01
In a mesoscopic system, under zero bias voltage, a finite charge is transferred by quantum adiabatic pumping by adiabatically and periodically changing two or more control parameters. We obtained expressions for the pumped charge for a ring of three quantum dots (QDs) by choosing the magnetic flux penetrating the ring as one of the control parameters. We found that the pumped charge shows a steplike behavior with respect to the variance of the flux. The value of the step heights is not universal but depends on the trajectory of the control parameters. We discuss the physical origin of this behavior on the basis of the Fano resonant condition of the ring.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Gross, E K U
2014-01-01
We present a detailed derivation and numerical tests of a new mixed quantum-classical scheme to deal with non-adiabatic processes. The method is presented as the zero-th order approximation to the exact coupled dynamics of electrons and nuclei offered by the factorization of the electron-nuclear wave function [A. Abedi, N. T. Maitra and E. K. U. Gross, Phys. Rev. Lett., 105 (2010)]. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Abedi, Ali; Gross, E. K. U.
2014-12-01
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Abedi, Ali; Gross, E. K. U. [Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)
2014-12-07
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations
Resonances and adiabatic invariance in classical and quantum scattering theory
Jain, S R
2004-01-01
We discover that the energy-integral of time-delay is an adiabatic invariant in quantum scattering theory and corresponds classically to the phase space volume. The integral thus found provides a quantization condition for resonances, explaining a series of results recently found in non-relativistic and relativistic regimes. Further, a connection between statistical quantities like quantal resonance-width and classical friction has been established with a classically deterministic quantity, the stability exponent of an adiabatically perturbed periodic orbit. This relation can be employed to estimate the rate of energy dissipation in finite quantum systems.
Nanoscale resolution for fluorescence microscopy via adiabatic passage
Rubio, Juan Luis; Ahufinger, Verònica; Mompart, Jordi
2015-01-01
We propose the use of the subwavelength localization via adiabatic passage technique for fluorescence microscopy with nanoscale resolution in the far field. This technique uses a {\\Lambda}-type medium coherently coupled to two laser pulses: the pump, with a node in its spatial profile, and the Stokes. The population of the {\\Lambda} system is adiabatically transferred from one ground state to the other except at the node position, yielding a narrow population peak. This coherent localization allows fluorescence imaging with nanometer lateral resolution. We derive an analytical expression to asses the resolution and perform a comparison with the coherent population trapping and the stimulated-emission-depletion techniques.
Adiabatic and isothermal compressibility in the liquid state
The paper reviews the work carried out on the adiabatic and isothermal compressibility of liquid alkali metals. Saturated liquid states are discussed, including thermodynamic relations, adiabatic compressibility and isothermal compressibility. Results for the compressibility, and other related quantities, for the saturated liquids: lithium, potassium, rubidium, caesium and sodium, over the temperature range approx.= 300 - 18000 K, are presented. Subcooled liquid states are also examined with respect to its thermodynamic relations, and compressibility results (and other related quantities) for the same elements are given. An assessment of errors and data reliability is briefly discussed. (U.K.)
High beta lasing in micropillar cavities with adiabatic layer design
Lermer, M.; Gregersen, Niels; Lorke, M.;
2013-01-01
We report on lasing in optically pumped adiabatic micropillar cavities, based on the AlAs/GaAs material system. A detailed study of the threshold pump power and the spontaneous emission β factor in the lasing regime for different diameters dc is presented. We demonstrate a reduction of the thresh...... threshold pump power by over 2 orders of magnitude from dc = 2.25 μm down to 0.95 μm. Lasing with β factors exceeding 0.5 shows that adiabatic micropillars are operating deeply in the cavity quantum electrodynamics regime....
Nonadiabatic dynamics of floppy hydrogen bonded complexes: the case of the ionized ammonia dimer.
Chalabala, Jan; Slavíček, Petr
2016-07-27
In the case of the ammonia dimer, we address the following questions: how ultrafast ionization dynamics is controlled by hydrogen bonding and whether we can control the products via selective ionization of a specific electron. We use quantum chemical calculations and ab initio non-adiabatic molecular dynamics simulations to model the femtosecond dynamics of the ammonia dimer upon ionization. The role of nuclear quantum effects and thermal fluctuations in predicting the structure of the dimer is emphasized; it is shown that the minimum energy and vibrationally averaged structures are rather different. The ground state structure subsequently controls the ionization dynamics. We describe reaction pathways, electronic population transfers and reaction yields with respect to ionization from different molecular orbitals. The simulations showed that the ionized ammonia dimer is highly unstable and its decay rate is primarily driven by the position of the electron hole. In the case of ground state ionization (i.e. the HOMO electron is ionized), the decay is likely to be preceded by a proton transfer (PT) channel yielding NH4(+) and NH2˙ fragments. The PT is less intense and slower compared with the ionized water dimer. After ionizing deeper lying electrons, mainly NH3(+)˙ and NH3 fragments are formed. Overall, our results show that the ionization dynamics of the ammonia and water dimers differ due to the nature of the hydrogen bond in these systems. PMID:27402376
Calculational schemes enabling to go beyond crude Condon approximation in non-adiabatic electron transfer reactions are discussed with the use of continuum approximation for the solvent polarization. An algorithm for the self-consistent introduction of an effective reaction coordinate in the adiabatic transition is suggested. Effects due to deviations from the Born-Oppenheimer approximation in bridge-assisted electron transfer reactions are discussed. Interpolation formulae covering limits of coherent and sequential electron transfer in bridge-assisted processes are presented. Simple equations determining a parametric dependence of the transition probability on the reaction free energy in crude Condon approximation are included. (author)
Bravaya, Ksenia B.; Kostko, Oleg; Dolgikh, Stanislav; Landau, Arie; Ahmed, Musahid; Krylov, Anna I.
2010-08-02
We report high-level ab initio calculations and single-photon ionization mass spectrometry study of ionization of adenine (A), thymine (T), cytosine (C) and guanine (G). For thymine and adenine, only the lowest-energy tautomers were considered, whereas for cytosine and guanine we characterized five lowest-energy tautomeric forms. The first adiabatic and several vertical ionization energies were computed using equation-of-motion coupled-cluster method for ionization potentials with single and double substitutions. Equilibrium structures of the cationic ground states were characterized by DFT with the {omega}B97X-D functional. The ionization-induced geometry changes of the bases are consistent with the shapes of the corresponding molecular orbitals. For the lowest-energy tautomers, the magnitude of the structural relaxation decreases in the following series G > C > A > T, the respective relaxation energies being 0.41, 0.32, 0.25 and 0.20 eV. The computed adiabatic ionization energies (8.13, 8.89, 8.51-8.67 and 7.75-7.87 eV for A,T,C and G, respectively) agree well with the onsets of the photoionization efficiency (PIE) curves (8.20 {+-} 0.05, 8.95 {+-} 0.05, 8.60 {+-} 0.05 and 7.75 {+-} 0.05 eV). Vibrational progressions for the S{sub 0}-D{sub 0} vibronic bands computed within double-harmonic approximation with Duschinsky rotations are compared with previously reported experimental photoelectron spectra.
Highlights: • TiO2 nanowires were synthesized as a solid matrix for SALDI-TOF MS by hydrothermal process. • The optimal crystal structure of TiO2 nanowires for SALDI-TOF MS were analyzed. • The feasibility TiO2 nanowires for SALDI-TOF MS was demonstrated for the analysis of amino acids and peptides. - Abstract: Top-down synthesized TiO2 nanowires are presented as an ideal solid matrix to analyze small biomolecules at a m/z of less than 500. The TiO2 nanowires were synthesized as arrays using a modified hydrothermal process directly on the surface of a Ti plate. Finally, the feasibility of the TiO2 nanowires in the anatase phase as a solid matrix. The crystal and electronic structures of the top-down TiO2 nanowires were analyzed at each step of the hydrothermal process, and the optimal TiO2 nanowires were identified by checking their performance toward the ionization of analytes in surface-assisted laser desorption/ionization time-of-flight (SALDI-TOF) mass spectrometry. Finally, the feasibility of the TiO2 nanowires in the anatase phase as a solid matrix for SALDI-TOF mass spectrometry was demonstrated using eight types of amino acids and peptides as model analytes
This study compares two ethylene-tetrafluoroethylene (ETFE) surface activation treatments, namely chemical attack with a solution of sodium naphthenate and plasma erosion via air-ionization corona discharge in order to improve the adhesive properties of the ETFE. An experimental design was prepared for both treatments in order to assess the effect of the treatment characteristics on the tensile load needed to break the bond between the ETFE and the acrylonitrile-butadiene-styrene polymer (ABS) formed with a cyanoacrylate adhesive (CAA) applied between them. The reason for the selection of this problem is that both polymers are frequently used in the biomedical industry for their properties, and they need to be joined firmly in biomedical devices, and the cyanoacrylate adhesive is the adhesive traditionally used for fluoropolymers, in this case the ETFE, and the same CAA has also shown good adhesion with ABS. However, the strength of the bond for the triplet ETFE-CAA-ABS has not been reported and the improvement of the strength of the bond with surface treatments is not found in scholarly journals for modern medical devices such as stents and snares. Both treatments were compared based on the aforementioned design of experiments. The case where ETFE receives no surface treatment serves as the reference. The results indicated that the three factors evaluated (initial drying of the material, temperature of the chemical bath, and immersion time), and their interactions have no significant effect over the tensile load at failure (tensile strength) of the adhesive bond being evaluated. For the air-ionization corona discharge treatment, two factors were evaluated: discharge exposition time and air pressure. The results obtained from this experimental design indicate that there is no significant difference between the levels of the factors evaluated. These results were unexpected as the ranges used were representative of the maximum ranges permissible in manufacturing
Lucía Johanning-Solís, Ana; Stradi-Granados, Benito A.
2014-09-01
This study compares two ethylene-tetrafluoroethylene (ETFE) surface activation treatments, namely chemical attack with a solution of sodium naphthenate and plasma erosion via air-ionization corona discharge in order to improve the adhesive properties of the ETFE. An experimental design was prepared for both treatments in order to assess the effect of the treatment characteristics on the tensile load needed to break the bond between the ETFE and the acrylonitrile-butadiene-styrene polymer (ABS) formed with a cyanoacrylate adhesive (CAA) applied between them. The reason for the selection of this problem is that both polymers are frequently used in the biomedical industry for their properties, and they need to be joined firmly in biomedical devices, and the cyanoacrylate adhesive is the adhesive traditionally used for fluoropolymers, in this case the ETFE, and the same CAA has also shown good adhesion with ABS. However, the strength of the bond for the triplet ETFE-CAA-ABS has not been reported and the improvement of the strength of the bond with surface treatments is not found in scholarly journals for modern medical devices such as stents and snares. Both treatments were compared based on the aforementioned design of experiments. The case where ETFE receives no surface treatment serves as the reference. The results indicated that the three factors evaluated (initial drying of the material, temperature of the chemical bath, and immersion time), and their interactions have no significant effect over the tensile load at failure (tensile strength) of the adhesive bond being evaluated. For the air-ionization corona discharge treatment, two factors were evaluated: discharge exposition time and air pressure. The results obtained from this experimental design indicate that there is no significant difference between the levels of the factors evaluated. These results were unexpected as the ranges used were representative of the maximum ranges permissible in manufacturing
Ionization Energies of Lanthanides
Lang, Peter F.; Smith, Barry C.
2010-01-01
This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…
Foodstuffs preservation by ionization
This document contains all the papers presented at the meeting on foodstuffs preservation by ionization. These papers deal especially with the food ionization process, its development and the view of the food industry on ionization. Refs and figs (F.M.)
On Models of Nonlinear Evolution Paths in Adiabatic Quantum Algorithms
In this paper, we study two different nonlinear interpolating paths in adiabatic evolution algorithms for solving a particular class of quantum search problems where both the initial and final Hamiltonian are one-dimensional projector Hamiltonians on the corresponding ground state. If the overlap between the initial state and final state of the quantum system is not equal to zero, both of these models can provide a constant time speedup over the usual adiabatic algorithms by increasing some another corresponding “complexity. But when the initial state has a zero overlap with the solution state in the problem, the second model leads to an infinite time complexity of the algorithm for whatever interpolating functions being applied while the first one can still provide a constant running time. However, inspired by a related reference, a variant of the first model can be constructed which also fails for the problem when the overlap is exactly equal to zero if we want to make up the 'intrinsic' fault of the second model — an increase in energy. Two concrete theorems are given to serve as explanations why neither of these two models can improve the usual adiabatic evolution algorithms for the phenomenon above. These just tell us what should be noted when using certain nonlinear evolution paths in adiabatic quantum algorithms for some special kind of problems. (general)
Scalings for a traveling mirror adiabatic magnetic compressor
Bellan, P. M.
1982-01-01
Detailed practical scaling relations for a traveling mirror adiabatic magnetic compressor are derived, and an example is given of how this technique could be used to translate, compress, and heat the Los Alamos FRX-C reversed field theta pinch plasma.
Adiabatic waves along interfacial layers near the critical point
Gouin, Henri
2008-01-01
Near the critical point, isothermal interfacial zones are investigated starting from a non-local density of energy. From the equations of motion of thermocapillary fluids, we point out a new kind of adiabatic waves propagating along the interfacial layers. The waves are associated with the second derivatives of densities and propagate with a celerity depending on the proximity of the critical point.
When an Adiabatic Irreversible Expansion or Compression Becomes Reversible
Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.
2009-01-01
This paper aims to contribute to a better understanding of the concepts of a "reversible process" and "entropy". For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P[subscript i] to a final pressure P[subscript f], by being placed in…
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable. PMID:27279216
Evolutions of Yang Phase Under Cyclic Condition and Adiabatic Condition
QIAN Shang-Wu; GU Zhi-Yu
2005-01-01
There are three non-integrable phases in literatures: Berry phase, Aharonov-Anandan phase, and Yang phase. This article discusses the evolutions of Yang phase under the cyclic condition and the adiabatic condition for the generaltime-dependent harmonic oscillator, thus reveals the intimate relations between these three non-integrable phases.
Adiabatic CMB perturbations in pre-big bang string cosmology
Enqvist, Kari; Sloth, Martin Snoager
2001-01-01
We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in...
Digitized adiabatic quantum computing with a superconducting circuit
Barends, R.; Shabani, A.; Lamata, L.; Kelly, J.; Mezzacapo, A.; Heras, U. Las; Babbush, R.; Fowler, A. G.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Lucero, E.; Megrant, A.; Mutus, J. Y.; Neeley, M.; Neill, C.; O’Malley, P. J. J.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Solano, E.; Neven, H.; Martinis, John M.
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Evolutions of Yang Phase Under Cyclic Condition and Adiabatic Condition
There are three non-integrable phases in literatures: Berry phase, Aharonov-Anandan phase, and Yang phase. This article discusses the evolutions of Yang phase under the cyclic condition and the adiabatic condition for the general time-dependent harmonic oscillator, thus reveals the intimate relations between these three non-integrable phases.
Adiabatic single scan two-dimensional NMR spectrocopy.
Pelupessy, Philippe
2003-10-01
New excitation schemes, based on the use adiabatic pulses, for single scan two-dimensional NMR experiments (Frydman et al., Proc. Nat. Acad. Sci. 2002, 99, 15 858-15 862) are introduced. The advantages are discussed. Applications in homo- and heteronuclear experiments are presented. PMID:14519020
A Quantum Adiabatic Algorithm for Factorization and Its Experimental Implementation
Peng, Xinhua; Liao, Zeyang; Xu, Nanyang; Qin, Gan; Zhou, Xianyi; Suter, Dieter; Du, Jiangfeng
2008-01-01
We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in an NMR quantum information processor and experimentally factorize the number 21. Numerical simulations indicate that the running time grows only quadratically with the number of qubits.
Dark Energy and Dark Matter from an additional adiabatic fluid
Dunsby, Peter K S; Reverberi, Lorenzo
2016-01-01
The Dark Sector is described by an additional barotropic fluid which evolves adiabatically during the universe's history and whose adiabatic exponent $\\gamma$ is derived from the standard definitions of specific heats. Although in general $\\gamma$ is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with $\\gamma = $ constant in a FLRW universe. The adiabatic fluid acts effectively as the sum of two distinct components, one evolving like non-relativistic matter and the other depending on the value of the adiabatic index. This makes the model particularly interesting as a way of simultaneously explaining the nature of both Dark Energy and Dark Matter, at least at the level of the background cosmology. The $\\Lambda$CDM model is included in this family of theories when $\\gamma = 0$. We fit our model to SNIa, $H(z)$ and BAO data, discussing the model selection criteria. The implications for the early-universe and the growth of small per...
On the hydrogen-air adiabatic isochoric complete combustion pressure
A simple and fast method for calculating the AICC state (adiabatic Isochoric Complete Combustion) for the hydrogen-air reaction is presented. By comparison with more detailed algorithms it is shown that the proposed method produces satisfactory results, and is thus a viable alternative in situations where the use of detailed algorithms or of tables is too time-consuming. (orig.)
Reiser, Georg; Habenicht, Wieland; Mueller-Dethlefs, Klaus
1993-06-01
Results are presented of nonresonant two-photon zero kinetic energy spectroscopy of ammonia, with resolution down to 0.4/cm. The spectra provide new rotational and vibrational data on the nu(2) vibrational progression of NH3(+). The adiabatic (field corrected) ionization energy is confirmed at 82,159 +/- 1 per cm.
Zero-point energy, tunneling, and vibrational adiabaticity in the Mu + H2 reaction
Mielke, Steven L.; Garrett, Bruce C.; Fleming, Donald G.; Truhlar, Donald G.
2015-01-09
Abstract: Isotopic substitution of muonium for hydrogen provides an unparalleled opportunity to deepen our understanding of quantum mass effects on chemical reactions. A recent topical review [Aldegunde et al., Mol. Phys. 111, 3169 (2013)] of the thermal and vibrationally-stateselected reaction of Mu with H2 raises a number of issues that are addressed here. We show that some earlier quantum mechanical calculations of the Mu + H2 reaction, which are highlighted in this review and which have been used to benchmark approximate methods, are in error by as much as 19% in the low-temperature limit. We demonstrate that an approximate treatment of the Born–Oppenheimer diagonal correction that was used in some recent studies is not valid for treating the vibrationally-state-selected reaction. We also discuss why vibrationally adiabatic potentials that neglect bend zero-point energy are not a useful analytical tool for understanding reaction rates and why vibrationally nonadiabatic transitions cannot be understood by considering tunneling through vibrationally adiabatic potentials. Finally, we present calculations on a hierarchical family of potential energy surfaces to assess the sensitivity of rate constants to the quality of the potential surface.
Physics of Partially Ionized Plasmas
Krishan, Vinod
2016-05-01
Figures; Preface; 1. Partially ionized plasmas here and everywhere; 2. Multifluid description of partially ionized plasmas; 3. Equilibrium of partially ionized plasmas; 4. Waves in partially ionized plasmas; 5. Advanced topics in partially ionized plasmas; 6. Research problems in partially ionized plasmas; Supplementary matter; Index.
Magnetite Nucleation in Mantle Xenoliths During Quasi-Adiabatic Ascent
Walsh, K. B., Jr.; Filiberto, J.; Friedman, S. A.; Knafelc, J.; Conder, J. A.; Ferre, E. C.; Khakhalova, E.; Feinberg, J. M.; Neal, C. R.; Ionov, D. A.; Hernandez, F. M.
2014-12-01
Can magnetite be a stable phase in the lithospheric mantle? Equilibrium-based thermodynamic calculations and petrologic models predict that it should not be stable. Studies of mantle xenoliths during the 1980s concluded that even though there were rare exceptions, mantle rocks do not host sufficient concentrations of ferromagnetic minerals and are too hot to allow any magnetic remanence. Thus, conventional wisdom dictates that the Moho constitutes a fundamental magnetic boundary. Yet, growing evidence from a more complete global mantle xenolith survey indicates the presence of ferromagnetic minerals in mantle materials. Examination of mantle xenoliths devoid of serpentinization and meteoric alteration show the presence of ferromagnetic minerals within primary silicate mineral phases, including olivine, pyroxene, and spinel. Nucleation of these magnetic minerals could occur at three different stages: in-situ in the mantle, upon ascent, and at the surface. This study reports the results of laboratory-based quasi-adiabatic decompression experiments that aim to simulate the ascent of mantle xenoliths through the lithosphere and test if magnetite growth is promoted during the process. The starting material for these experiments is San Carlos olivine, which holds a magnetic remanence of less than ~10-10 A/m2-1kg2 (the detection limit of the vibrating sample magnetometer). This low starting remanence will allow us to identify whether new magnetic minerals are formed during the decompression experiments using either vibrating sample magnetometry or SQUID-based rock magnetometers. All olivine grains in these experiments were hand-picked under a light microscope in an effort to avoid the inclusion of grains with spurious magnetic minerals. Olivine powders from these carefully selected grains will be used to represent average mantle olivine compositions (Fo90-Fo92). Experiments will start at 1 GPa and be decompressed to 0.3 GPa over 60 hrs at constant temperature (1200° C
Graphical abstract: Two trajectories for the collision of a proton with the Lithium tetramer. On the left, the proton is scattered away, and a Li2 molecule plus two isolated Lithium atoms result. On the right, the proton is captured and a LiH molecule is created. Highlights: ► Scattering of a proton with Lithium clusters described from first principles. ► Description based on non-adiabatic molecular dynamics. ► The electronic structure is described with time-dependent density-functional theory. ► The method allows to discern reaction channels depending on initial parameters. - Abstract: We have employed non-adiabatic molecular dynamics based on time-dependent density-functional theory to characterize the scattering behavior of a proton with the Li4 cluster. This technique assumes a classical approximation for the nuclei, effectively coupled to the quantum electronic system. This time-dependent theoretical framework accounts, by construction, for possible charge transfer and ionization processes, as well as electronic excitations, which may play a role in the non-adiabatic regime. We have varied the incidence angles in order to analyze the possible reaction patterns. The initial proton kinetic energy of 10 eV is sufficiently high to induce non-adiabatic effects. For all the incidence angles considered the proton is scattered away, except in one interesting case in which one of the Lithium atoms captures it, forming a LiH molecule. This theoretical formalism proves to be a powerful, effective and predictive tool for the analysis of non-adiabatic processes at the nanoscale.
Hole dynamics and spin currents after ionization in strong circularly polarized laser fields
We apply the time-dependent analytical R-matrix theory to develop a movie of hole motion in a Kr atom upon ionization by strong circularly polarized field. We find rich hole dynamics, ranging from rotation to swinging motion. The motion of the hole depends on the final energy and the spin of the photoelectron and can be controlled by the laser frequency and intensity. Crucially, hole rotation is a purely non-adiabatic effect, completely missing in the framework of quasistatic (adiabatic) tunneling theories. We explore the possibility to use hole rotation as a clock for measuring ionization time. Analyzing the relationship between the relative phases in different ionization channels we show that in the case of short-range electron-core interaction the hole is always initially aligned along the instantaneous direction of the laser field, signifying zero delays in ionization. Finally, we show that strong-field ionization in circular fields creates spin currents (i.e. different flow of spin-up and spin-down density in space) in the ions. This phenomenon is intimately related to the production of spin-polarized electrons in strong laser fields Barth and Smirnova (2013 Phys. Rev. A 88 013401). We demonstrate that rich spin dynamics of electrons and holes produced during strong field ionization can occur in typical experimental conditions and does not require relativistic intensities or strong magnetic fields. (paper)
Reimers, Jeffrey R; McKemmish, Laura K; McKenzie, Ross H; Hush, Noel S
2015-10-14
Using a simple model Hamiltonian, the three correction terms for Born-Oppenheimer (BO) breakdown, the adiabatic diagonal correction (DC), the first-derivative momentum non-adiabatic correction (FD), and the second-derivative kinetic-energy non-adiabatic correction (SD), are shown to all contribute to thermodynamic and spectroscopic properties as well as to thermal non-diabatic chemical reaction rates. While DC often accounts for >80% of thermodynamic and spectroscopic property changes, the commonly used practice of including only the FD correction in kinetics calculations is rarely found to be adequate. For electron-transfer reactions not in the inverted region, the common physical picture that diabatic processes occur because of surface hopping at the transition state is proven inadequate as the DC acts first to block access, increasing the transition state energy by (ℏω)(2)λ/16J(2) (where λ is the reorganization energy, J the electronic coupling and ω the vibration frequency). However, the rate constant in the weakly-coupled Golden-Rule limit is identified as being only inversely proportional to this change rather than exponentially damped, owing to the effects of tunneling and surface hopping. Such weakly-coupled long-range electron-transfer processes should therefore not be described as "non-adiabatic" processes as they are easily described by Born-Huang ground-state adiabatic surfaces made by adding the DC to the BO surfaces; instead, they should be called just "non-Born-Oppenheimer" processes. The model system studied consists of two diabatic harmonic potential-energy surfaces coupled linearly through a single vibration, the "two-site Holstein model". Analytical expressions are derived for the BO breakdown terms, and the model is solved over a large parameter space focusing on both the lowest-energy spectroscopic transitions and the quantum dynamics of coherent-state wavepackets. BO breakdown is investigated pertinent to: ammonia inversion, aromaticity
Adiabatic models of the cosmological radiative era
Sussman, R A; Sussman, Roberto A.; Ishak, Mustapha
2001-01-01
We consider a generalization of the Lemaitre-Tolman-Bondi (LTB) solutions by keeping the LTB metric but replacing its dust matter source by an imperfect fluid with anisotropic pressure $\\Pi_{ab} $. Assuming that total matter-energy density $\\rho$ is the sum of a rest mass term, $\\rhom$, plus a radiation $\\rhor=3p$ density where $p$ is the isotropic pressure, Einstein's equations are fully integrated without having to place any previous assumption on the form of $\\Pi_{ab} $. Three particular cases of interest are contained: the usual LTB dust solutions (the dust limit), a class of FLRW cosmologies (the homogeneous limit) and of the Vaydia solution (the vacuum limit). Initial conditions are provided in terms of suitable averages and contrast functions of the initial densities of $\\rhom, \\rhor$ and the 3-dimensional Ricci scalar along an arbitrary initial surface $t=t_i$. We consider the source of the models as an interactive radiation-matter mixture in local thermal equilibrium that must be consistent with caus...
Zakrzewski, J.; Saini, S.; Taylor, H.S.
1988-10-15
A general theoretical base and a general strategy for implementing semiclassical quantization using the adiabatic-switching method are presented for two-dimensional systems. The method proposed does not depend on specialized coordinates, trajectory, or surfaces-of-section studies and is generalizable to multidimensional systems. The choice of the initial tori for the switching procedure is accomplished by simple diagonalizations of small-dimensional matrix representations of invariant operators obtained from perturbation theory. The method gives quantum energies at a useful level of accuracy for the vast majority of states in many of the well-known nonresonant and resonant Hamiltonian cases. Many eigenvalues previously thought unobtainable when the adiabatic-switching method is used are obtained in a quite simple manner.
Heaps, Charles W
2016-01-01
Quantum molecular dynamics requires an accurate representation of the molecular potential energy surface from a minimal number of electronic structure calculations, particularly for nonadiabatic dynamics where excited states are required. In this paper, we employ pseudospectral sampling of time-dependent Gaussian basis functions for the simulation of non-adiabatic dynamics. Unlike other methods, the pseudospectral Gaussian molecular dynamics tests the Schr\\"{o}dinger equation with $N$ Dirac delta functions located at the centers of the Gaussian functions reducing the scaling of potential energy evaluations from $\\mathcal{O}(N^2)$ to $\\mathcal{O}(N)$. By projecting the Gaussian basis onto discrete points in space, the method is capable of efficiently and quantitatively describing nonadiabatic population transfer and intra-surface quantum coherence. We investigate three model systems; the photodissociation of three coupled Morse oscillators, the bound state dynamics of two coupled Morse oscillators, and a two-d...
The exact forces on classical nuclei in non-adiabatic charge transfer
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Gross, E. K. U. [Max-Planck-Institut of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); Maitra, Neepa T. [Department of Physics and Astronomy, Hunter College and the Graduate Center of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States)
2015-02-28
The decomposition of electronic and nuclear motion presented in Abedi et al. [Phys. Rev. Lett. 105, 123002 (2010)] yields a time-dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here, we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. We point out the importance of step and bump features in the exact potential that are critical in obtaining the correct splitting of the quasiclassical nuclear wave packet in space after it passes through an avoided crossing between two Born-Oppenheimer surfaces and analyze their structure. Finally, an analysis of the exact potentials in the context of trajectory surface hopping is presented, including preliminary investigations of velocity-adjustment and the force-induced decoherence effect.
The exact forces on classical nuclei in non-adiabatic charge transfer
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Maitra, Neepa T.; Gross, E. K. U.
2015-02-01
The decomposition of electronic and nuclear motion presented in Abedi et al. [Phys. Rev. Lett. 105, 123002 (2010)] yields a time-dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here, we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. We point out the importance of step and bump features in the exact potential that are critical in obtaining the correct splitting of the quasiclassical nuclear wave packet in space after it passes through an avoided crossing between two Born-Oppenheimer surfaces and analyze their structure. Finally, an analysis of the exact potentials in the context of trajectory surface hopping is presented, including preliminary investigations of velocity-adjustment and the force-induced decoherence effect.
On some issues of gravitationally induced adiabatic particle productions
Pan, Supriya; Pramanik, Souvik
2016-01-01
In this work, we investigate the current accelerating universe driven by the gravitationally induced adiabatic matter creation process. To elaborate the underlying cognitive content, here we consider three models of adiabatic particle creation and constrain the model parameters by fitting the models with the Union 2.1 data set using $\\chi^2$ minimization technique. The models are analyzed by two geometrical and model independent tests, viz., cosmography and $Om$-diagnostic, which are widely used to distinguish the cosmological models from $\\Lambda$CDM. We also compared present values of those model independent parameters with that of the flat $\\Lambda$CDM model. Finally, the validity of the generalized second law of thermodynamics and the condition of thermodynamic equilibrium for the particle production models have been tested.
Improved Refrigerant Characteristics Flow Predictions in Adiabatic Capillary Tube
Shodiya Sulaimon
2012-07-01
Full Text Available This study presents improved refrigerant characteristics flow predictions using homogenous flow model in adiabatic capillary tube, used in small vapor compression refrigeration system. The model is based on fundamental equations of mass, momentum and energy. In order to improve the flow predictions, the inception of vaporization in the capillary tube is determined by evaluating initial vapor quality using enthalpy equation of refrigerant at saturation point and the inlet entrance effect of the capillary tube is also accounted for. Comparing this model with experimental data from open literature showed a reasonable agreement. Further comparison of this new model with earlier model of Bansal showed that the present model could be use to improve the performance predictions of refrigerant flow in adiabatic capillary tube.
Non-adiabatic theoretical observables in Delta Scuti stars
Moya, A; Dupret, M A
2004-01-01
Phase differences and amplitude ratios at different colour photometric bands are currently being used to discriminate pulsation modes in order to facilitate mode identification of kappa-driven non-radial pulsating stars. In addition to physical inputs (e.g., mass, T_eff, etc.), these quantities depend on the non-adiabatic treatment of the atmosphere. This paper presents theoretical results concerning Delta Scuti pulsating stars. The envelope of each of these stellar structures possesses a convection zone whose development is determined by various factors. An interacting pulsation-atmosphere physical treatment is introduced which supplies two basic non-adiabatic physical quantities: the relative effective temperature variation and the phase lag phi^T, defined as the angle between effective temperature variations and radial displacement. These quantities can be used to derive the phase differences and amplitude ratios. Numerical values for these quantities depend critically on the alpha MLT parameter used to ca...
The adiabatic motion of charged dust grains in rotating magnetospheres
Northrop, T. G.; Hill, J. R.
1983-01-01
Adiabatic equations of motion are derived for the micrometer-sized dust grains detected in the Jovian and Saturn magnetospheres by the Pioneer 10 and 11 spacecraft. The adiabatic theory of charged particle motion is extended to the case of variable grain charge. Attention is focused on the innermost and outermost limits to the grain orbit evolution, with all orbits tending to become circular with time. The parameters such as the center equation of motion, the drift velocity, and the parallel equation of motion are obtained for grains in a rotating magnetosphere. Consideration is given to the effects of periodic grain charge-discharge, which are affected by the ambient plasma properties and the grain plasma velocity. The charge-discharge process at the gyrofrequency is determined to eliminate the invariance of the magnetic moment and cause the grain to exhibit radial movement. The magnetic moment increases or decreases as a function of the gyrophase of the charge variation.
Crack propagation of Ti alloy via adiabatic shear bands
This study was focused on the characterization of the origin and mechanism of crack propagation as a result of hot induction bending of Ti alloy. Plates of Ti–6Al–4V alloy with 12.5 mm of thickness were submitted to hot induction bending below the beta transus temperature. Optical and scanning electron microscopy analysis showed crack formation in the tensile zone. Microstructural evidence showed that cracks propagate through the adiabatic shear bands by Dimple-Void mechanism. However, voids formation before shear banding also occurred. In both mechanisms adiabatic shear bands are formed via dynamic recrystallization where the alpha–beta interphase works as stress concentrator promoting the formation of dimples and voids
Stellar oscillations. II The non-adiabatic case
Samadi, R; Sonoi, T
2015-01-01
A leap forward has been performed due to the space-borne missions, MOST, CoRoT and Kepler. They provided a wealth of observational data, and more precisely oscillation spectra, which have been (and are still) exploited to infer the internal structure of stars. While an adiabatic approach is often sufficient to get information on the stellar equilibrium structures it is not sufficient to get a full understanding of the physics of the oscillation. Indeed, it does not permit one to answer some fundamental questions about the oscillations, such as: What are the physical mechanisms responsible for the pulsations inside stars? What determines the amplitudes? To what extent the adiabatic approximation is valid? All these questions can only be addressed by considering the energy exchanges between the oscillations and the surrounding medium. This lecture therefore aims at considering the energetical aspects of stellar pulsations with particular emphasis on the driving and damping mechanisms. To this end, the full non-...
Excitation energies along a range-separated adiabatic connection
Rebolini, Elisa; Teale, Andrew M; Helgaker, Trygve; Savin, Andreas
2014-01-01
We present a study of the variation of total energies and excitationenergies along a range-separated adiabatic connection. This connectionlinks the non-interacting Kohn-Sham electronic system to the physicalinteracting system by progressively switching on theelectron-electron interactions whilst simultaneously adjusting aone-electron effective potential so as to keep the ground-statedensity constant. The interactions are introduced in arange-dependent manner, first introducing predominantly long-range,and then all-range, interactions as the physical system is approached,as opposed to the conventional adiabatic connection where theinteractions are introduced by globally scaling the standard Coulomb interaction.Reference data are reported for the He and Be atoms and the H2molecule, obtained by calculating the short-range effective potentialat the full configuration-interaction level using Lieb'sLegendre-transform approach. As the strength of the electron-electroninteractions increases, the excitation energies, ...
Crack propagation of Ti alloy via adiabatic shear bands
Mendoza, I., E-mail: ivanmendozabravo@gmail.com [Instituto Tecnológico de Veracruz (Mexico); Villalobos, D. [Instituto Tecnológico de Veracruz (Mexico); Alexandrov, B.T. [The Ohio State University (United States)
2015-10-01
This study was focused on the characterization of the origin and mechanism of crack propagation as a result of hot induction bending of Ti alloy. Plates of Ti–6Al–4V alloy with 12.5 mm of thickness were submitted to hot induction bending below the beta transus temperature. Optical and scanning electron microscopy analysis showed crack formation in the tensile zone. Microstructural evidence showed that cracks propagate through the adiabatic shear bands by Dimple-Void mechanism. However, voids formation before shear banding also occurred. In both mechanisms adiabatic shear bands are formed via dynamic recrystallization where the alpha–beta interphase works as stress concentrator promoting the formation of dimples and voids.
Adiabatic compression of elongated field-reversed configurations
The simplest model of plasma dynamics is the adiabatic model. In this model the plasma is assumed to be in MHD equilibrium at each instant of time. The equilibria are connected by the requirement that they all have the same entropy per unit flux, i.e., the equilibria form a sequence generated by adiabatic changes. The standard way of computing such a sequence of equilibria was developed by Grad, but its practical use requires a fairly complicated code. It would be helpful if approximately the same results could be gotten either with a much simpler code or by analytical techniques. A one-dimensional equilibrium code is described and its results are checked against a two-dimensional equilibrium. An even simpler analytic calculation is then presented
Adiabatic theorem for the time-dependent wave operator
The application of time-dependent wave operator theory to the development of a quantum adiabatic perturbation theory is treated both theoretically and numerically, with emphasis on the description of field-matter interactions which involve short laser pulses. It is first shown that the adiabatic limit of the time-dependent wave operator corresponds to a succession of instantaneous static Bloch wave operators. Wave operator theory is then shown to be compatible with the two-time Floquet theory of light-matter interaction, thus allowing the application of Floquet theory to cases which require the use of a degenerate active space. A numerical study of some problems shows that the perturbation strength associated with nonadiabatic processes can be reduced by using multidimensional active spaces and illustrates the capacity of the wave operator approach to produce a quasiadiabatic treatment of a nominally nonadiabatic Floquet dynamical system
Microscopic expression for heat in the adiabatic basis.
Polkovnikov, Anatoli
2008-11-28
We derive a microscopic expression for the instantaneous diagonal elements of the density matrix rho(nn)(t) in the adiabatic basis for an arbitrary time-dependent process in a closed Hamiltonian system. If the initial density matrix is stationary (diagonal) then this expression contains only squares of absolute values of matrix elements of the evolution operator, which can be interpreted as transition probabilities. We then derive the microscopic expression for the heat defined as the energy generated due to transitions between instantaneous energy levels. If the initial density matrix is passive [diagonal with rho(nn)(0) monotonically decreasing with energy] then the heat is non-negative in agreement with basic expectations of thermodynamics. Our findings also can be used for systematic expansion of various observables around the adiabatic limit. PMID:19113464
Influence of viscosity and the adiabatic index on planetary migration
Bitsch, B; Kley, W
2013-01-01
The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state, where the internal dissipation is balanced by radiative transport, and the migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. In this paper we investigate the influence of different viscosity prescriptions (alpha-type and constant) and adiabatic indices on disk structures and how this affects the migration rate of planets embedded in such disks. We perform 3D numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20Earthmass planets is studied. Low-viscosity disks...
DESIGN OF TERNARY COUNTER BASED ON ADIABATIC DOMINO CIRCUIT
Yang Qiankun; Wang Pengjun; Zheng Xuesong
2013-01-01
By researching the ternary counter and low power circuit design method,a novel design of low power ternary Domino counter on switch-level is proposed.Firstly,the switch-level structure expression of ternary loop operation circuit with enable pin is derived according to the switch-signal theory,and the one bit ternary counter is obtained combining the ternary adiabatic Domino literal operation circuit and buffer.Then the switch-level structure expression of enable signal circuit is derived,and the four bits ternary counter is obtained by cascade connection.Finally,the circuit is simulated by Spice tool and the output waveforms transform in proper order indicating that the logic function is correct.The energy consumption of the four bits ternary adiabatic Domino counter is 63％ less than the conventional Domino counterpart.
Fujisawa, Jun-ichi; Hanaya, Minoru
2016-06-01
Interfacial charge-transfer (ICT) transitions between inorganic semiconductors and π-conjugated molecules allow direct charge separation without loss of energy. This feature is potentially useful for efficient photovoltaic conversions. Charge-transferred complexes of TiO2 nanoparticles with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its analogues (TCNX) show strong ICT absorption in the visible region. The ICT band was reported to be significantly red-shifted with extension of the π-conjugated system of TCNX. In order to clarify the mechanism of the red-shift, in this work, we systematically study electronic structures of the TiO2-TCNX surface complexes (TCNX; TCNE, TCNQ, 2,6-TCNAQ) by ionization potential measurements and density functional theory (DFT) calculations.
A custom-built graphite-coated transmission ionization chamber is compared to the VacuDAP 2001 (VacuTec, Dresden, Germany), which has transparent conductive electrodes. A study was made of the dependence of response on x-ray tube potential for both types of chamber under identical conditions of exposure using over-table and under-table x-ray tubes. Since the calibration factor is the dose-area product of the radiation incident on the patient per chamber reading, it depends on the intrinsic response of the chamber as well as the effect of material in the beam between the x-ray tube and patient. Differences of about 20% were measured between the intrinsic and the over-table calibration factors and between the over-table and the under-table calibration factors for both chambers. The VacuDAP display is specifically calibrated for the over-table condition and would overstate the actual DAP in the under-table case. The intrinsic response of the graphite chamber is nearly independent of tube potential. Although the variation of response with tube potential of the graphite chamber is increased when it is used as an over-table and an under-table patient monitor, it shows less overall variation of response than the VacuDAP. The average deviation of each range of 40 to 140 kVp for both chambers
Abnormal ionization in sonoluminescence
张文娟; 安宇
2015-01-01
Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%–70%as the bubble flashes, which is difficult to explain by using previous models.
Dartnell, L. R.
2011-01-01
Ionizing radiation is a ubiquitous feature of the Cosmos, from exogenous cosmic rays (CR) to the intrinsic mineral radioactivity of a habitable world, and its influences on the emergence and persistence of life are wide-ranging and profound. Much attention has already been focused on the deleterious effects of ionizing radiation on organisms and the complex molecules of life, but ionizing radiation also performs many crucial functions in the generation of habitable planetary environments and ...
The Adiabatic Piston and the Second Law of Thermodynamics
Crosignani, B; Conti, C
2002-01-01
A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law when dealing with systems of mesoscopic dimensions.
Single-parameter adiabatic charge pumping in carbon nanotube resonators
Perroni, C. A.; Nocera, A.; Cataudella, V.
2013-01-01
Single-parameter adiabatic charge pumping, induced by a nearby radio-frequency antenna, is achieved in suspended carbon nanotubes close to the mechanical resonance. The charge pumping is due to an important dynamic adjustment of the oscillating motion to the antenna signal and it is different from the mechanism active in the two-parameter pumping. Finally, the second harmonic oscillator response shows an interesting relationship with the first harmonic that should be experimentally observed.
Quantum pumping with adiabatically modulated barriers in graphene
Zhu, Rui; Chen, Huiming
2009-01-01
We study the adiabatic quantum pumping characteristics in the graphene modulated by two oscillating gate potentials out of phase. The angular and energy dependence of the pumped current is presented. The direction of the pumped current can be reversed when a high barrier demonstrates stronger transparency than a low one, which results from the Klein paradox. The underlying physics of the pumping process is illuminated.
Geometry of adiabatic Hamiltonians for two-level quantum systems
We present the formulation of the problem of the coherent dynamics of quantum mechanical two-level systems in the adiabatic region in terms of the differential geometry of plane curves. We show that there is a natural plane curve corresponding to the Hamiltonian of the system for which the geometrical quantities have a simple physical interpretation. In particular, the curvature of the curve has the role of the nonadiabatic coupling. (paper)
High-Fidelity Entangled Bell States via Shortcuts to Adiabaticity
Paul, Koushik
2016-01-01
We present a couple of protocols based on shortcut to adiabaticity techniques for rapid generation of robust entangled Bell states in a system of two two-state systems. Our protocols rely on the so-called transitionless quantum driving (TQD) algorithm and Lewis-Riesenfeld invariant (LRI) method. Both TQD and LRI methods result in high fidelity in population transfer.Our study shows that it is possible to prepare an entangled state in infinitely short time without losing robustness and efficiency.
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-04-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid δPnad, another is for a general matter field δPc,nad, and the last one is valid only on superhorizon scales. The first two definitions coincide if cs2 = cw2 where cs is the propagation speed of the perturbation, while cw2 = P ˙ / ρ ˙ . Assuming the adiabaticity in the general sense, δPc,nad = 0, we derive a relation between the lapse function in the comoving slicing Ac and δPnad valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as cs ≠cw, the uniform density, comoving and the proper-time slicings coincide approximately for any gravity theory and for any matter field if δPnad = 0 approximately. In the case of general relativity this gives the equivalence between the comoving curvature perturbation Rc and the uniform density curvature perturbation ζ on superhorizon scales, and their conservation. This is realized on superhorizon scales in standard slow-roll inflation. We then consider an example in which cw =cs, where δPnad = δPc,nad = 0 exactly, but the equivalence between Rc and ζ no longer holds. Namely we consider the so-called ultra slow-roll inflation. In this case both Rc and ζ are not conserved. In particular, as for ζ, we find that it is crucial to take into account the next-to-leading order term in ζ's spatial gradient expansion to show its non-conservation, even on superhorizon scales. This is an example of the fact that adiabaticity (in the thermodynamic sense) is not always enough to ensure the conservation of Rc or ζ.
Adiabatic Hyperspherical Approach to the Problems of Muon Catalyzed Fusion
The adiabatic hyperspherical approach (AHSA) is applied for the numerical investigation of the scattering processes and resonances in Coulomb three-body mesic atomic systems. The results of the calculations of elastic and inelastic cross sections in low-energy collisions aμ + b (a, b = p, d, t), energies, lifetimes and local characteristics of resonant states of mesic molecular ions nHeaμ+ (n = 3, 4) are presented.
Linear response of galactic halos to adiabatic gravitational perturbations
Murali, Chigurupati; Tremaine, Scott
1997-01-01
We determine the response of a self-similar isothermal stellar system to small adiabatic gravitational perturbations. For odd spherical harmonics, the response is identical to the response of the analogous isothermal fluid system. For even spherical harmonics, the response can be regarded as an infinite series of wavetrains in $\\log r$, implying alternating compression and rarefaction in equal logarithmic radius intervals. Partly because of the oscillatory nature of the solutions, tidal field...
Highly stripped ions on hydrogen atoms: the adiabatic approach
The simple Lorentzian form for the adiabatic radial matrix elements which dominate low-energy charge transfer in highly stripped systems is exploited to derive the S matrix for the Asub(Z)sup(Z+) + H(1s) → Asub(Z)sup(Z-1)+ + H+ scattering process. The approximations used are discussed and the results of the theory are compared with measured He2+ + H(1s) → He+ + H+ cross sections. Agreement is satisfactory for low velocities. (author)
The Adiabatic Piston and the Second Law of Thermodynamics
Crosignani, B.; Di Porto, P.; de Conti, C.
2002-01-01
A detailed analysis of the adiabatic-piston problem reveals peculiar dynamical features that challenge the general belief that isolated systems necessarily reach a static equilibrium state. In particular, the fact that the piston behaves like a perpetuum mobile, i.e., it never stops but keeps wandering, undergoing sizable oscillations, around the position corresponding to maximum entropy, has remarkable implications on the entropy variations of the system and on the validity of the second law...
New empirical correlations for sizing adiabatic capillary tubes in refrigeration systems
Shodiya, S.; Aahar, A. A.; Henry, N.; Darus, A. N.
2012-06-01
This paper presents new empirical correlations that have been developed for sizing adiabatic capillary tubes used in small vapor compression refrigeration and air-conditioning systems. A numerical model which is based on the basic equations of conservation of mass, momentum and energy was developed. Colebrook's formulation was used to determine the single phase friction factor. The two-phase viscosity models - Cicchitti et al., Dukler et al. and McAdam et al. were used based on the recommendation from literature to determine the two-phase viscosity factor. The developed numerical model was validated using the experimental data from literature. The numerical model was used to study the effects of relevant parameters on capillary tube length and the results showed that the length of capillary tube increase with increase in condensing temperature, subcooling, and inner diameter of tube but decrease with increase in surface roughness and mass flow rate. Thereafter, empirical correlation of the capillary tube length with the five dependent variables was presented. The empirical models are validated using experimental data from literature. Different from the previous studies, the empirical models have a large set of refrigerants and wide operating conditions. The developed correlation can be used as an effective tool for sizing adiabatic capillary tube with system models working with alternative refrigerants.
Analytical instruments, ionization sources, and ionization methods
Atkinson, David A.; Mottishaw, Paul
2006-04-11
Methods and apparatus for simultaneous vaporization and ionization of a sample in a spectrometer prior to introducing the sample into the drift tube of the analyzer are disclosed. The apparatus includes a vaporization/ionization source having an electrically conductive conduit configured to receive sample particulate which is conveyed to a discharge end of the conduit. Positioned proximate to the discharge end of the conduit is an electrically conductive reference device. The conduit and the reference device act as electrodes and have an electrical potential maintained between them sufficient to cause a corona effect, which will cause at least partial simultaneous ionization and vaporization of the sample particulate. The electrical potential can be maintained to establish a continuous corona, or can be held slightly below the breakdown potential such that arrival of particulate at the point of proximity of the electrodes disrupts the potential, causing arcing and the corona effect. The electrical potential can also be varied to cause periodic arcing between the electrodes such that particulate passing through the arc is simultaneously vaporized and ionized. The invention further includes a spectrometer containing the source. The invention is particularly useful for ion mobility spectrometers and atmospheric pressure ionization mass spectrometers.
The Si Mini-Pad sensor is an essential component of the MPC-EX preshower detector. This detector will be integrated into the PHENIX experiment at Brookhaven National Laboratory's Relativistic Heavy Ion Collider. We describe the development of the surface pattern and the fabrication process of the Si Mini-Pad sensor and present a test by the low energy γ irradiation that is sensitive to the surface design.
NMR implementation of adiabatic SAT algorithm using strongly modulated pulses.
Mitra, Avik; Mahesh, T S; Kumar, Anil
2008-03-28
NMR implementation of adiabatic algorithms face severe problems in homonuclear spin systems since the qubit selective pulses are long and during this period, evolution under the Hamiltonian and decoherence cause errors. The decoherence destroys the answer as it causes the final state to evolve to mixed state and in homonuclear systems, evolution under the internal Hamiltonian causes phase errors preventing the initial state to converge to the solution state. The resolution of these issues is necessary before one can proceed to implement an adiabatic algorithm in a large system where homonuclear coupled spins will become a necessity. In the present work, we demonstrate that by using "strongly modulated pulses" (SMPs) for the creation of interpolating Hamiltonian, one can circumvent both the problems and successfully implement the adiabatic SAT algorithm in a homonuclear three qubit system. This work also demonstrates that the SMPs tremendously reduce the time taken for the implementation of the algorithm, can overcome problems associated with decoherence, and will be the modality in future implementation of quantum information processing by NMR. PMID:18376911
Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning
Smelyanskiy, Vadius; vonToussaint, Udo V.; Timucin, Dogan A.; Clancy, Daniel (Technical Monitor)
2002-01-01
We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum exitation gap, gmin = O(n2(sup -n/2)), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.
Non-adiabatic energy dissipation in metal homoepitaxy
Hagemann, Ulrich; Huba, Kornelia; Krix, David; Nienhaus, Hermann [Experimental Physics, University of Duisburg-Essen (Germany)
2009-07-01
The growth of metal films releases energies of typically a few eV per metal atom. By now, the energy is believed to be dissipated adiabatically by direct excitation of phonons. We present data which give strong evidence for the creation of electron-hole pairs during Mg homoepitaxy, i.e., for a non-adiabatic dissipation channel. To detect the generated hot charge carriers, large-area ultrathin metal film Mg/p-Si(001) Schottky diodes were fabricated. The homogeneous Schottky barrier height was determined as 0.52 eV and the reverse current could be reduced to below 1 nA at low temperatures. During exposure of the diodes to a thermal Mg atom beam internal currents in the 100 pA range are observed. The currents can be attributed to two mechanisms: first the internal exoemission process (chemicurrent effect) due to non-adiabatic energy dissipation and second the photocurrent due to the infrared radiation of the evaporator. By varying the evaporator temperature and the Mg film thickness the two current contributions can be distinguished. The chemicurrent during Mg homoepitaxy depends exponentially on the evaporation temperature yielding the Mg evaporation enthalpy of 1.3 eV. The strong exponential attenuation of the chemicurrent with increasing Mg film thickness further supports the concept of generation of ballistic charge carriers by the metal formation process.
Analysis of adiabatic transfer in cavity quantum electrodynamics
Joyee Ghosh; R Ghosh; Deepak Kumar
2011-10-01
A three-level atom in a conﬁguration trapped in an optical cavity forms a basic unit in a number of proposed protocols for quantum information processing. This system allows for efﬁcient storage of cavity photons into long-lived atomic excitations, and their retrieval with high ﬁdelity, in an adiabatic transfer process through the ‘dark state’ by a slow variation of the control laser intensity. We study the full quantum mechanics of this transfer process with a view to examine the non-adiabatic effects arising from inevitable excitations of the system to states involving the upper level of , which is radiative. We ﬁnd that the ﬁdelity of storage is better, the stronger the control ﬁeld and the slower the rate of its switching off. On the contrary, unlike the adiabatic notion, retrieval is better with faster rates of switching on of an optimal control ﬁeld. Also, for retrieval, the behaviour with dissipation is non-monotonic. These results lend themselves to experimental tests. Our exact computations, when applied to slow variations of the control intensity for strong atom–photon couplings, are in very good agreement with Berry’s superadiabatic transfer results without dissipation.
Adiabatic Shear Mechanisms for the Hard Cutting Process
YUE Caixu; WANG Bo; LIU Xianli; FENG Huize; CAI Chunbin
2015-01-01
The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remalns some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high straln domaln caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.
Irreconcilable difference between quantum walks and adiabatic quantum computing
Wong, Thomas G.; Meyer, David A.
2016-06-01
Continuous-time quantum walks and adiabatic quantum evolution are two general techniques for quantum computing, both of which are described by Hamiltonians that govern their evolutions by Schrödinger's equation. In the former, the Hamiltonian is fixed, while in the latter, the Hamiltonian varies with time. As a result, their formulations of Grover's algorithm evolve differently through Hilbert space. We show that this difference is fundamental; they cannot be made to evolve along each other's path without introducing structure more powerful than the standard oracle for unstructured search. For an adiabatic quantum evolution to evolve like the quantum walk search algorithm, it must interpolate between three fixed Hamiltonians, one of which is complex and introduces structure that is stronger than the oracle for unstructured search. Conversely, for a quantum walk to evolve along the path of the adiabatic search algorithm, it must be a chiral quantum walk on a weighted, directed star graph with structure that is also stronger than the oracle for unstructured search. Thus, the two techniques, although similar in being described by Hamiltonians that govern their evolution, compute by fundamentally irreconcilable means.
Adiabatic shear mechanisms for the hard cutting process
Yue, Caixu; Wang, Bo; Liu, Xianli; Feng, Huize; Cai, Chunbin
2015-05-01
The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remains some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high strain domain caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.
Dosimetry of ionizing radiation
The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs
Positronium formation and ionization in slow positron-hydrogen atom collisions
Janev, R.K. [International Atomic Energy Agency, PO Box 100, A-1400 Vienna (Austria); Solov' ev, E.A. [Research Centre for Energy and Informatics, Macedonian Academy of Sciences and Arts, PO Box 428, 9100 Skopje (Macedonia, The Former Yugoslav Republic of)
1999-07-14
The electron capture and ionization processes in slow collisions of positrons with hydrogen atoms are considered within the advanced adiabatic approach to atomic collisions. The mass asymmetry of the (p,e{sup -},e{sup +}) collision system is properly taken into account. The calculated positronium formation and ionization cross sections compare favourably with the available experimental data in the adiabatic energy region. It is shown that the potential energy curve of the 2p {sigma} molecular state supports a quasi-bound level of the three-particle (p,e{sup +},e{sup -}) system with an energy of -0.3 eV and decay width of 0.15 eV, approximately. (author)
A theoretical approach based on molecular orbital theory has been provided. By applying this theory to a bond-breaking process, the ionization probability of Cu adsobates sputtered from a ''5x5''-Cu/Si(1 1 1) surface has been studied. Three important aspects have been confirmed: (1) importance of a long range electrostatic potential such as the image potential, (2) importance of the coulomb repulsive potential between the Cu 4s spin-up and spin-down electron, and finally (3) acceleration and deceleration effects depending on charge state, which is a result of the interplay of the molecular bonding interaction and the long range electrostatic interaction. The measurements of ionization probability will provide us more information of the adiabatic potential curves of the reactants from the surfaces
Ionization photophysics and Rydberg spectroscopy of diacetylene
Schwell, Martin
2012-11-01
Photoionization of diacetylene was studied using synchrotron radiation over the range 8-24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron-photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IE ad=(10.17±0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE=(16.15±0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions C+ 4, C3H+, C+3 and C 4H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene in the 11-13 eV region were assigned to vibrational components of three new Rydberg series, R1(nsσg, n=4-11), R2(ndσg, n=4-7) and R3(ndδg, n=4-6) converging to the A2Πu state of the cation, and to a new series R01(nsσg, n=3) converging to the B\\' 2Σ+u state of the cation. The autoionization mechanisms and their consistence with specific selection rules are discussed. © 2012 Taylor and Francis.
Piezoelectric control of the mobility of a domain wall driven by adiabatic and non-adiabatic torques
de Ranieri, E.; Roy, P. E.; Fang, D.; Vehsthedt, E. K.; Irvine, A. C.; Heiss, D.; Casiraghi, A.; Campion, R. P.; Gallagher, B. L.; Jungwirth, T.; Wunderlich, J.
2013-09-01
The rich internal degrees of freedom of magnetic domain walls make them an attractive complement to electron charge for exploring new concepts of storage, transport and processing of information. Here we use the tunable internal structure of a domain wall in a perpendicularly magnetized GaMnAsP/GaAs ferromagnetic semiconductor and demonstrate devices in which piezoelectrically controlled magnetic anisotropy yields up to 500% mobility variations for an electrical-current-driven domain wall. We observe current-induced domain wall motion over a wide range of current-pulse amplitudes and report a direct observation and the piezoelectric control of the Walker breakdown separating two regimes with different mobilities. Our work demonstrates that in spin-orbit-coupled ferromagnets with weak extrinsic domain wall pinning, the piezoelectric control allows one to experimentally assess the upper and lower boundaries of the characteristic ratio of adiabatic and non-adiabatic spin-transfer torques in the current-driven domain wall motion.
Rajinder Pal
2016-01-01
Entropy generation, and hence exergy destruction, in adiabatic flow of unstable and surfactant-stabilized emulsions was investigated experimentally in different diameter pipes. Four types of emulsion systems are investigated covering a broad range of the dispersed-phase concentration: (a) unstable oil-in-water (O/W) emulsions without surfactant; (b) surfactant-stabilized O/W emulsions; (c) unstable water-in-oil (W/O) emulsions without surfactant; and (d) surfactant-stabilized W/O emulsions. T...
Can strong-field ionization prepare attosecond dynamics?
Pabst, Stefan
2015-01-01
Strong-field ionization (SFI) has been shown to prepare wave packets with few-femtosecond periods. Here, we explore whether this technique can be extended to the attosecond time scale. We introduce an intuitive model for predicting the bandwidth of ionic states that can be coherently prepared by SFI. This bandwidth is given by the Fourier-transformed sub-cycle SFI rate and decreases considerably with increasing central wavelength of the ionizing pulse. Many-body calculations based on time-dependent configuration-interaction singles (TDCIS) quantitatively support this result and reveal an additional decrease of the bandwidth as a consequence of channel interactions and non-adiabatic dynamics. Our results further predict that multi-cycle femtosecond pulses can coherently prepare attosecond wave packets with higher selectivity and versatility compared to single-cycle pulses.
The results on investigation of the absorbed energy detectors used at IHEP, i. e., polyethylene detector (PD)-based on hydrogen release from polymer under effect of ionizing radiation and adiabatic calorimeter (AC) are presented. The sensitivity function for these detectors for 6 MeV-3000 GeV hadrons have been calculated. The PD and AC readings have been measured and calculated for the radiation fields near the IHEP proton synchrotron vacuum chamber. The dependence of the calorimeter readings on the working medium has been studied. The PD has been calibrated with the AC. It is ahown that in the hadron spectra the calorimeter readings do not depend on the working medium in the limit of 8%. The PD calibration enchanced the accuracy of radiation dose measuring in the accelerator radiation mixed field. The sensitivity function calculations showed that detectors studied applied for measuring absorved dose have the energy threshold, so for PD it is equal 18 MEV for protons, 6 MeV for charged poins. Results of investigations showed the possibility of PD utilization for measuring absorbed dose in different structural materials operating in mixed radiation fields of accelerators
Multiphoton ionization of atoms
The paper is devoted to the analysis of high intensity effects which result from multiphoton ionization of atoms in a high laser intensity, ranging from 1010 to 1015 W cm-2. Resonant multiphoton ionization of atoms, the production of multiply charged ions, and electron energy spectra, are all discussed. (U.K.)
Application of ionizing radiation
Fundamental studies by the Nuclear Research Institute concerning the use of ionizing radiations are reported. The ROZA irradiation plant is used for sterilization in medicine and for historic objects preservation. Ionizing radiation is used in the radiation treatment of cables and drinking water. Radiopharmaceuticals are developed. The Institute is an all-state centre for research and development of semiconductor detectors. (M.S.)
Microscopic theory of warm ionized gases: equation of state and kinetic Schottky anomaly
Based on accurate Lennard-Jones type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analogue in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed.
Theory of warm ionized gases: equation of state and kinetic Schottky anomaly
Capolupo, Antonio; Illuminati, Fabrizio
2013-01-01
Based on accurate Lennard-Jones type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analogue in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed.
Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.
Capolupo, A; Giampaolo, S M; Illuminati, F
2013-10-01
Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments. PMID:24229140
Multiphoton ionization of atoms
This article provides an overview of the current understanding of multiphoton ionization of atoms. It begins with an introductory section to explain the background of the subject. Then the article develops the three topics which have been central themes of discussion in multiphoton ionization of atoms these past few years: multiply charged ion production, very high order harmonic generation, and above-threshold ionization, a name given to the absorption of a very large number of photons by an already ionized electron. A large part of the review is devoted to some theoretical aspects of multiphoton ionization of atoms and especially non-perturbative theories. Finally the article considers the very near future prospects of laser-electron interactions and more generally laser-matter interactions at 1018 -1019 W cm-2, an intensity range now within reach due to new short pulse laser technology. (author)
High-Temperature Ionization in Protoplanetary Disks
Desch, Steven J
2015-01-01
We calculate the abundances of electrons and ions in the hot (> 500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains' work functions. The charged species' abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks' dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge locat...
李伟伟; 丁坤; 王华; 陈士恒; 沈铮; 关亚风
2011-01-01
Nitrogen compounds in gasoline were extracted by liquid-liquid extraction and analyzed by gas chromatography-surface ionization detector ( GC-SID ). Compared with the chromatograms obtained from GC-flame ionization detector ( FID ) , GC-thermal ionization detector ( NPD ) and GC-mass spectrometry ( MS ), the peaks in the chromatogram obtained by GC-SID were assigned to the nitrogen compounds in gasoline. Most of these nitrogen compounds could not be detected by FID or NPD . which demonstrated the high selectivity and sensitivity of the SID. The types of nitrogen compounds in three gasoline samples ( 90#、93#、97# ) were similar,but their contents varied with different gasoline brands. The extracted nitrogen compounds were mainly anilines. the amounts of which in the three gasoline samples were different. Trace amounts of several high boiling point nitrogen compounds were successfully detected because of the high sensitivity of SID. The SID is superior to the commercial NPD in detecting the nitrogen compounds in gasoline samples. In view of its high sensitivity and selectivity , the SID is a promising GC detector.%采用液液萃取的方法分别从90#、93#、97#汽油中提取了含氮化合物,并将气相色谱(GC)和作者所在研究组研制的表面电离检测器(SID)联用对含氮化合物进行了分析.结合GC-氢火焰离子化检测器(FID)、GC-氮磷检测器(NPD)和GC-质谱(MS)的分析结果,可鉴定出GC-SID谱图中的峰基本为含氮化合物,且大部分为NPD和FID 未检出的峰,说明SID的选择性和灵敏度更好.分析结果表明,这3种汽油含氮化合物种类相似,含量有所差异;所提取的含氮化合物主要是苯胺类化合物;SID能从汽油样品中检出多种痕量的高沸点含氮组分,对于检测含氮组分而言,SID具有优于商品NPD的灵敏度和选择性.SID为GC分析提供了一种性能优异的选择性检测器.
Michele L. Etter
2010-02-01
Full Text Available A new liquid chromatography (LC-negative ion electrospray ionization (ESI–tandem mass spectrometry (MS/MS method with post-column addition of ammonia in methanol has been developed for the analysis of acid herbicides: 2,4-dichlorophenoxy ace- tic acid, 4-chloro-o-tolyloxyacetic acid, 2-(2-methyl-4-chlorophenoxybutyric acid, mecoprop, dichlorprop, 4-(2,4-dichlorophenoxy butyric acid, 2,4,5-trichlorophenoxy propionic acid, dicamba and bromoxynil, along with their degradation products: 4-chloro-2- methylphenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and 3,5-dibromo-4-hydroxybenzoic acid. The samples were extracted from the surface water matrix using solid-phase extraction (SPE with a polymeric sorbent and analyzed with LC ESI- with selected reaction monitoring (SRM using a three-point confirmation approach. Chromatography was performed on a Zorbax Eclipse XDB-C18 (50 × 4.6 mm i.d., 1.8 µm with a gradient elution using water-methanol with 2 mM ammonium acetate mobile phase at a flow rate of 0.15 mL/min. Ammonia in methanol (0.8 M was added post-column at a flow rate of 0.05 mL/min to enhance ionization of the deg- radation products in the MS source. One SRM transition was used for quantitative analysis while the second SRM along with the ratio of SRM1/SRM2 within the relative standard deviation determined by standards for each individual pesticide and retention time match were used for confirmation. The standard deviation of ratio of SRM1/SRM2 obtained from standards run on the day of analysis for different phenoxyacid herbicides ranged from 3.9 to 18.5%. Limits of detection (LOD were between 1 and 15 ng L-1 and method detection limits (MDL with strict criteria requiring
Biological Effects of Ionizing Radiation
Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.
1952-04-07
This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.
Fernandez-Alberti, Sebastian; Makhov, Dmitry V; Tretiak, Sergei; Shalashilin, Dmitrii V
2016-04-21
Photoinduced dynamics of electronic and vibrational unidirectional energy transfer between meta-linked building blocks in a phenylene ethynylene dendrimer is simulated using a multiconfigurational Ehrenfest in time-dependent diabatic basis (MCE-TDDB) method, a new variant of the MCE approach developed by us for dynamics involving multiple electronic states with numerous abrupt crossings. Excited-state energies, gradients and non-adiabatic coupling terms needed for dynamics simulation are calculated on-the-fly using the Collective Electron Oscillator (CEO) approach. A comparative analysis of our results obtained using MCE-TDDB, the conventional Ehrenfest method and the surface-hopping approach with and without decoherence corrections is presented. PMID:27004611
Non-adiabatic molecular dynamic simulations of opening reaction of molecular junctions
Zobač, Vladmír; Lewis, James P.; Jelínek, Pavel
2016-07-01
We report non-adiabatic molecular dynamic simulations of the ring opening reaction of diarylethene (DAE) derivative molecules, both free standing and embedded between gold electrodes. Simulations are performed by the surface hopping method employing density functional theory. Typically, the free-standing molecules exhibit large quantum yields to open and close; however the process is quenched for the molecules embedded between electrodes. Our simulations reveal the importance of the DAE side chemical groups, which explain the efficiency of the quenching process. Namely, delocalization of the LUMO state contributes to electronic coupling between the molecule and electrodes, suppressing or enhancing the reaction process. The simulations indicate that a proper choice of the chemical side group, which provides the strong localization of the LUMO state, can substantially diminish the quenching mechanism. Additionally, we analyze a strong dependency of the quantum yield of the opening reaction coming from the mechanical strength of the molecules.
Fowler-Nordheim emission modified by laser pulses in the adiabatic regime
Rokhlenko, Alexander
2016-01-01
We investigate enhanced field emission due to a continuous or pulsed oscillating field added to a constant electric field $E$ at the emitter surface. When the frequency of oscillation, field strength, and property of the emitter material satisfy the Keldysh condition $\\gamma<1/2$ one can use the adiabatic approximation for treating the oscillating field, i.e. consider the tunneling through the instantaneous Fowler-Nordheim barrier created by both fields. Due to the great sensitivity of the emission to the field strength the average tunneling current can be much larger than the current produced by only the constant field. We carry out the computations for arbitrary strong constant electric fields, beyond the commonly used Fowler-Nordheim approximation which exhibit in particular an important property of the wave function inside the potential barrier where it is found to be monotonically decreasing without oscillations.
Influence of viscosity and the adiabatic index on planetary migration
Bitsch, B.; Boley, A.; Kley, W.
2013-02-01
Context. The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state. It has been shown that in active disks, where the internal dissipation is balanced by radiative transport, migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. Aims: In this paper we investigate the influence of different viscosity prescriptions (α-type and constant) and adiabatic indices on disk structures. We then determine how this affects the migration rate of planets embedded in such disks. Methods: We perform three-dimensional numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20 MEarth planets is studied. Results: Low-viscosity disks have cooler temperatures and the migration rates of embedded planets tend toward the isothermal limit. Hence, in these disks, planets migrate inwards even in the fully radiative case. The effect of outward migration can only be sustained if the viscosity in the disk is large. Overall, the differences between the treatments for the equation of state seem to play a more important role in disks with higher viscosity. A change in the adiabatic index and in the viscosity changes the zero-torque radius that separates inward from outward migration. Conclusions: For larger viscosities, temperatures in the disk become higher and the zero-torque radius moves to larger radii, allowing outward migration of a 20-MEarth planet to persist over an extended radial range. In combination with large disk masses, this may allow for an extended period of the outward migration of growing
Shortcuts to Adiabaticity by Counterdiabatic Driving in Trapped-ion Transport
An, Shuoming; del Campo, Adolfo; Kim, Kihwan
2016-01-01
Adiabatic dynamics plays an essential role in quantum technologies. By driving a quantum system slowly, the quantum evolution can be engineered with suppressed excitation. Yet, environmentally-induced decoherence limits the implementation of adiabatic protocols. Shortcuts to adiabaticity (STA) have the potential to revolutionize quantum technologies by speeding up the time evolution while mimicking adiabatic dynamics. These nonadiabatic protocols can be engineered by means an auxiliary control field is used to tailor excitations. Here we present the first experimental realization of counterdiabatic driving in a continuous variable system, implementing a shortcut to the adiabatic transport of a trapped ion, in which nonadiabatic transitions are suppressed during all stages of the process. The resulting dynamics is equivalent to a "fast-motion video" of the adiabatic trajectory. We experimentally demonstrate the enhanced robustness of the protocol with respect to alternative approaches based on classical local ...
Nonlinear effects generation in non-adiabatically tapered fibres
Palací, Jesús; Mas, Sara; Monzón-Hernández, David; Martí, Javier
2015-12-01
Nonlinear effects are observed in a non-adiabatically tapered optical fibre. The designed structure allows for the introduction of self-phase modulation, which is observed through pulse breaking and spectral broadening, in approximately a centimetre of propagation using a commercial telecom laser. These devices are simple to fabricate and suitable to generate and control a variety of nonlinear effects in practical applications because they do not experience short-term degradation as previously reported approaches. Experimental and theoretical results are obtained, showing a good agreement.
Landau-Zener Transitions in an Adiabatic Quantum Computer
Johansson, J; Amin, M. H. S.; Berkley, A. J.; Bunyk, P.; Choi, V.; Harris, R.; Johnson, M. W.; Lanting, T. M.; Lloyd, Seth; ROSE, G
2008-01-01
We report an experimental measurement of Landau-Zener transitions on an individual flux qubit within a multi-qubit superconducting chip designed for adiabatic quantum computation. The method used isolates a single qubit, tunes its tunneling amplitude Delta into the limit where Delta is much less than both the temperature T and the decoherence-induced energy level broadening, and forces it to undergo a Landau-Zener transition. We find that the behavior of the qubit agrees to a high degree of a...
Modeling of the Adiabatic and Isothermal Methanation Process
Porubova, Jekaterina; Bazbauers, Gatis; Markova, Darja
2011-01-01
Increased use of biomass offers one of the ways to reduce anthropogenic impact on the environment. Using various biomass conversion processes, it is possible to obtain different types of fuels: • solid, e.g. bio-carbon; • liquid, e.g. biodiesel and ethanol; • gaseous, e.g. biomethane. Biomethane can be used in the transport and energy sector, and the total methane production efficiency can reach 65%. By modeling adiabatic and isothermal methanation processes, the most effective one from the methane production point of view is defined. Influence of the process parameters on the overall efficiency of the methane production is determined.
Adiabatic transport of qubits around a black hole
Viennot, David
2016-01-01
We consider localized qubits evolving around a black hole following a quantum adiabatic dynamics. We develop a geometric structure (based on fibre bundles) permitting to describe the quantum states of a qubit and the spacetime geometry in a single framework. The quantum decoherence induced by the black hole on the qubit is analysed in this framework (the role of the dynamical and geometric phases in this decoherence is treated), especially for the quantum teleportation protocol when one qubit falls to the event horizon. A simple formula to compute the fidelity of the teleportation is derived. The case of a Schwarzschild black hole is analysed.
Numerical studies of optical forces from adiabatic rapid passage
Stack, Daniel; Elgin, John; Metcalf, Harold [Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800 (United States); Anisimov, Petr M. [Hearne Institute for Theoretical Physics and Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)
2011-07-15
We present a numerical study of the properties of optical forces on moving atoms derived from purely stimulated processes produced by multiple adiabatic rapid-passage sequences. The optical Bloch equations are solved for a carefully timed sequence of frequency-swept pulses that can produce a force much larger than the ordinary radiative force. We describe the effects of the sweep range, peak intensity, sweep direction, number of pulses, atomic velocity, and spontaneous emission. Since the momentum of thermal atoms is much larger than that transferred by a single absorption-stimulated emission cycle, multiple repetitions are needed to make a significant velocity change.
Adiabatic quantum computation and quantum annealing theory and practice
McGeoch, Catherine C
2014-01-01
Adiabatic quantum computation (AQC) is an alternative to the better-known gate model of quantum computation. The two models are polynomially equivalent, but otherwise quite dissimilar: one property that distinguishes AQC from the gate model is its analog nature. Quantum annealing (QA) describes a type of heuristic search algorithm that can be implemented to run in the ``native instruction set'''' of an AQC platform. D-Wave Systems Inc. manufactures {quantum annealing processor chips} that exploit quantum properties to realize QA computations in hardware. The chips form the centerpiece of a nov
Adiabatic regularisation of power spectra in nonminimally coupled chaotic inflation
Alinea, Allan L
2016-01-01
We investigate the effect of adiabatic regularisation on both the tensor- and scalar-perturbation power spectra in \\textit{nonminimally} coupled chaotic inflation. Similar to that of the \\textit{minimally} coupled general single-field inflation, we find that the subtraction term is suppressed by an exponentially decaying factor involving the number of $ e $-folds. By following the subtraction term long enough beyond horizon crossing, the regularised power spectrum tends to the "bare" power spectrum. This study justifies the use of the unregularised ("bare") power spectrum in standard calculations.
On the rotating wave approximation in the adiabatic limit
I revisit a longstanding question in quantum optics; when is the rotating wave approximation justified? In terms of the Jaynes–Cummings and Rabi models I demonstrate that the approximation in general breaks down in the adiabatic limit regardless of system parameters. This is explicitly shown by comparing Berry phases of the two models, where it is found that this geometrical phase is strictly zero in the Rabi model contrary to the non-trivial Berry phase of the Jaynes–Cummings model. The source of this surprising result is traced back to different topologies in the two models. (paper)
Adiabatic collapse and explosion of small mass iron nuclei
Adiabatic collapse of iron nuclei with 1.5 and 1.7 Msun masses is investigated using the equation of state and electron capture rate in the Fermi-gas approximation, derived at the Illinois University. Reduction of lepton number in the collapse process leads to the fact that under quite different presupernova nucleus parameters the calculated mass of homologie nucleus is only about 1 Msun. Therefore the mass of the above lying layers through which the shock wave should pass, becomes quite high loosing the energy for dissociation, which hampers any sufficient mass and kinetic energy losses. 17 refs.; 8 figs.; 2 tabs
Plasma heating via adiabatic magnetic compression-expansion cycle
Avinash, K.; Sengupta, M.; Ganesh, R.
2016-06-01
Heating of collisionless plasmas in closed adiabatic magnetic cycle comprising of a quasi static compression followed by a non quasi static constrained expansion against a constant external pressure is proposed. Thermodynamic constraints are derived to show that the plasma always gains heat in cycles having at least one non quasi static process. The turbulent relaxation of the plasma to the equilibrium state at the end of the non quasi static expansion is discussed and verified via 1D Particle in Cell (PIC) simulations. Applications of this scheme to heating plasmas in open configurations (mirror machines) and closed configurations (tokamak, reverse field pinche) are discussed.
Relativistic blast waves in two dimensions. I - The adiabatic case
Shapiro, P. R.
1979-01-01
Approximate solutions are presented for the dynamical evolution of strong adiabatic relativistic blast waves which result from a point explosion in an ambient gas in which the density varies both with distance from the explosion center and with polar angle in axisymmetry. Solutions are analytical or quasi-analytical for the extreme relativistic case and numerical for the arbitrarily relativistic case. Some general properties of nonplanar relativistic shocks are also discussed, including the incoherence of spherical ultrarelativistic blast-wave fronts on angular scales greater than the reciprocal of the shock Lorentz factor, as well as the conditions for producing blast-wave acceleration.
Optical Detection of Tunneling Ionization
Verhoef, Aart J.; Mitrofanov, Alexander V.; Serebryannikov, Evgenii E.; Kartashov, Daniil V.; Zheltikov, Aleksei M.; Baltuška, Andrius
2010-04-01
We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.
Optical Detection of Tunneling Ionization
We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.
Quantum pumping in closed systems, adiabatic transport, and the Kubo formula
Cohen, Doron
2003-01-01
Quantum pumping in closed systems is considered. We explain that the Kubo formula contains all the physically relevant ingredients for the calculation of the pumped charge ($Q$) within the framework of linear response theory. The relation to the common formulations of adiabatic transport and ``geometric magnetism" is clarified. We distinguish between adiabatic and dissipative contributions to $Q$. On the one hand we observe that adiabatic pumping does not have to be quantized. On the other ha...
Adiabatic heavy-ion fusion potentials for fusion at deep sub-barrier energies
S V S Sastry; S Kailas; A K Mohanty; A Saxena
2005-01-01
The recently reported unusual behaviour of fusion cross-sections at extreme sub-barrier energies has been examined. The adiabatic limit of fusion barriers has been determined from experimental data using the barrier penetration model. These adiabatic barriers are consistent with the adiabatic fusion barriers derived from the modified Wilzynska–Wilzynski prescription. The fusion barrier systematics has been obtained for a wide range of heavy-ion systems.
Wójcik, P.; Zegrodnik, M.; Rzeszotarski, B.; Adamowski, J.
2016-09-01
The tunneling conductance through the half-metal/conical magnet/superconductor (HM/CM/SC) junctions is investigated with the use of the Bogoliubov-de Gennes equations in the framework of Blonder-Tinkham-Klapwijk formalism. Due to the spin band separation in the HM, the conductance in the subgap region is mainly determined by the anomalous Andreev reflection, the probability of which strongly depends on the spin transmission in the CM layer. We show that the spins of electrons injected from the HM can be transmitted through the CM to the SC either adiabatically or non-adiabatically depending on the period of the spatial modulation of the exchange field. We find that the conductance in the subgap region oscillates as a function of the CM layer thickness wherein the oscillations transform from the irregular pattern in the non-adiabatic regime to the regular one in the adiabatic regime. For both adiabatic and non-adiabatic transport regimes the conductance is studied over a broad range of parameters determining the spiral magnetization in the CM. We find that in the non-adiabatic regime, the decrease of the exchange field amplitude in the CM leads to the emergence of the conductance peak for the particular CM thickness in agreement with recent experiments.
Adiabatic invariants of generalized Lutzky type for disturbed holonomic nonconservative systems
Based on the definition of higher-order adiabatic invariants of a mechanical system, a new type of adiabatic invariants, i.e. generalized Lutzky adiabatic invariants, of a disturbed holonomic nonconservative mechanical system are obtained by investigating the perturbation of Lie symmetries for a holonomic nonconservative mechanical system with the action of small disturbance. The adiabatic invariants and the exact invariants of the Lutzky type of some special cases, for example, the Lie point symmetrical transformations, the special Lie symmetrical transformations, and the Lagrange system, are given. And an example is given to illustrate the application of the method and results. (general)
Adiabatic regularization and particle creation for scalar and spin one-half fields
Landete, Aitor; Torrenti, Francisco
2013-01-01
The extension of the adiabatic regularization method to spin-$1/2$ fields requires a self-consistent adiabatic expansion of the field modes. We provide here the details of such expansion, which differs from the WKB ansatz that works well for scalars, to firmly establish the generalization of the adiabatic renormalization scheme to spin-$1/2$ fields. We also provide a general overview of the adiabatic method to analyze particle creation and perform renormalization of relevant expectation values. We focus on the computation of particle production in de Sitter spacetime and obtain an analytic expression of the renormalized stress-energy tensor for Dirac fermions.
Ionization Thresholds of Small Carbon Clusters: Tunable VUVExperiments and Theory
Belau, Leonid; Wheeler, Steven E.; Ticknor, Brian W.; Ahmed,Musahid; Leone, Stephen R.; Allen, Wesley D.; Schaefer III, Henry F.; Duncan, Michael A.
2007-07-31
Small carbon clusters (Cn, n = 2-15) are produced in amolecular beam by pulsed laser vaporization and studied with vacuumultraviolet (VUV) photoionization mass spectrometry. The required VUVradiation in the 8-12 eV range is provided by the Advanced Light Source(ALS) at the Lawrence Berkeley National Laboratory. Mass spectra atvarious ionization energies reveal the qualitative relative abundances ofthe neutral carbon clusters produced. By far the most abundant species isC3. Using the tunability of the ALS, ionization threshold spectra arerecorded for the clusters up to 15 atoms in size. The ionizationthresholds are compared to those measured previously with charge-transferbracketing methods. To interpret the ionization thresholds for differentcluster sizes, new ab initio calculations are carried out on the clustersfor n = 4-10. Geometric structures are optimized at the CCSD(T) levelwith cc-pVTZ (or cc-pVDZ) basis sets, and focal point extrapolations areapplied to both neutral and cation species to determine adiabatic andvertical ionization potentials. The comparison of computed and measuredionization potentials makes it possible to investigate the isomericstructures of the neutral clusters produced in this experiment. Themeasurements are inconclusive for the n = 4-6 species because ofunquenched excited electronic states. However, the data provide evidencefor the prominence of linear structures for the n = 7, 9, 11, 13 speciesand the presence of cyclic C10.
Schedule path optimization for adiabatic quantum computing and optimization
Zeng, Lishan; Zhang, Jun; Sarovar, Mohan
2016-04-01
Adiabatic quantum computing and optimization have garnered much attention recently as possible models for achieving a quantum advantage over classical approaches to optimization and other special purpose computations. Both techniques are probabilistic in nature and the minimum gap between the ground state and first excited state of the system during evolution is a major factor in determining the success probability. In this work we investigate a strategy for increasing the minimum gap and success probability by introducing intermediate Hamiltonians that modify the evolution path between initial and final Hamiltonians. We focus on an optimization problem relevant to recent hardware implementations and present numerical evidence for the existence of a purely local intermediate Hamiltonian that achieve the optimum performance in terms of pushing the minimum gap to one of the end points of the evolution. As a part of this study we develop a convex optimization formulation of the search for optimal adiabatic schedules that makes this computation more tractable, and which may be of independent interest. We further study the effectiveness of random intermediate Hamiltonians on the minimum gap and success probability, and empirically find that random Hamiltonians have a significant probability of increasing the success probability, but only by a modest amount.
Stimulated Raman Adiabatic Passage (STIRAP) Among Degenerate-Level Manifolds
Kis, Z; Shore, B W; Vitanov, N V; Kis, Zsolt; Karpati, Attila; Shore, Bruce W.; Vitanov, Nikolay V.
2004-01-01
We examine the conditions needed to accomplish stimulated Raman adiabatic passage (STIRAP) when the three levels (g, e and f) are degenerate, with arbitrary couplings contributing to the pump-pulse interaction (g - e) and to the Stokes-pulse interaction (e-f). We show that in general a sufficient condition for complete population removal from the g set of degenerate states for arbitrary, pure or mixed, initial state is that the degeneracies should not decrease along the sequence g, e and f. We show that when this condition holds it is possible to achieve the degenerate counterpart of conventional STIRAP, whereby adiabatic passage produces complete population transfer. Indeed, the system is equivalent to a set of independent three-state systems, in each of which a STIRAP procedure can be implemented. We describe a scheme of unitary transformations that produces this result. We also examine the cases when this degeneracy constraint does not hold, and show what can be accomplished in those cases. For example, fo...
Adiabatic creation of coherent superposition states via multiple intermediate states
Karpati, A
2003-01-01
We consider an adiabatic population transfer process that resembles the well established stimulated Raman adiabatic passage (STIRAP). In our system, the states have nonzero angular momentums $J$, therefore, the coupling laser fields induce transitions among the magnetic sublevels of the states. In particular, we discuss the possibility of creating coherent superposition states in a system with coupling pattern $J=0\\Leftrightarrow J=1$ and $J=1\\Leftrightarrow J=2$. Initially, the system is in the J=0 state. We show that by two delayed, overlapping laser pulses it is possible to create any final superposition state of the magnetic sublevels $|2,-2>$, $|2,0>$, $|2,+2>$. Moreover, we find that the relative phases of the applied pulses influence not only the phases of the final superposition state but the probability amplitudes as well. We show that if we fix the shape and the time-delay between the pulses, the final state space can be entirely covered by varying the polarizations and relative phases of the two pu...
Optimization using quantum mechanics: quantum annealing through adiabatic evolution
We review here some recent work in the field of quantum annealing, alias adiabatic quantum computation. The idea of quantum annealing is to perform optimization by a quantum adiabatic evolution which tracks the ground state of a suitable time-dependent Hamiltonian, where 'ℎ' is slowly switched off. We illustrate several applications of quantum annealing strategies, starting from textbook toy-models-double-well potentials and other one-dimensional examples, with and without disorder. These examples display in a clear way the crucial differences between classical and quantum annealing. We then discuss applications of quantum annealing to challenging hard optimization problems, such as the random Ising model, the travelling salesman problem and Boolean satisfiability problems. The techniques used to implement quantum annealing are either deterministic Schroedinger's evolutions, for the toy models, or path-integral Monte Carlo and Green's function Monte Carlo approaches, for the hard optimization problems. The crucial role played by disorder and the associated non-trivial Landau-Zener tunnelling phenomena is discussed and emphasized. (topical review)
Observational tests of non-adiabatic Chaplygin gas
Carneiro, S
2014-01-01
In a previous paper it was shown that any dark sector model can be mapped into a non-adiabatic fluid formed by two interacting components, one with zero pressure and the other with equation-of-state parameter $\\omega = -1$. It was also shown that the latter does not cluster and, hence, the former is identified as the observed clustering matter. This guarantees that the dark matter power spectrum does not suffer from oscillations or instabilities. It applies in particular to the generalised Chaplygin gas, which was shown to be equivalent to interacting models at both background and perturbation levels. In the present paper we test the non-adiabatic Chaplygin gas against the Hubble diagram of type Ia supernovae, the position of the first acoustic peak in the anisotropy spectrum of the cosmic microwave background and the linear power spectrum of large scale structures. We consider two different compilations of SNe Ia, namely the Constitution and SDSS samples, both calibrated with the MLCS2k2 fitter, and for the ...
The 0.1K bolometers cooled by adiabatic demagnetization
Roellig, T.; Lesyna, L.; Kittel, P.; Werner, M.
1983-01-01
The most straightforward way of reducing the noise equivalent power of bolometers is to lower their operating temperature. We have been exploring the possibility of using conventionally constructed bolometers at ultra-low temperatures to achieve NEP's suitable to the background environment of cooled space telescopes. We have chosen the technique of adiabatic demagnetization of a paramagnetic salt as a gravity independent, compact, and low power way to achieve temperatures below pumped He-3 (0.3 K). The demagnetization cryostat we used was capable of reaching temperatures below 0.08 K using Chromium Potassium Alum as a salt from a starting temperature of 1.5 K and a starting magnetic field of 30,000 gauss. Computer control of the magnetic field decay allowed a temperature of 0.2 K to be maintained to within 0.5 mK over a time period exceeding 14 hours. The refrigerator duty cycle was over 90 percent at this temperature. The success of these tests has motivated us to construct a more compact portable adiabatic demagnetization cryostat capable of bolometer optical tests and use at the 5m Hale telescope at 1mm wavelengths.
General background conditions for K-bounce and adiabaticity
Romano, Antonio Enea
2016-01-01
We study the background conditions for a bounce in a single scalar field model with a generalized kinetic term $K(X)$. At the background level we impose the existence of two turning points where the derivative of the Hubble parameter $H$ changes sign and of a bounce point where the Hubble parameter vanishes. We find the conditions for $K(X)$ and the potential which ensure the above requirements. We then give the examples of two models constructed according to these conditions. One is based on a quadratic $K$, and the other on a $K$ which is avoiding divergences of the second time derivative of the scalar field, which may otherwise occur. An appropriate choice of the initial conditions can lead to a sequence of consecutive bounces. In models where the bounce occurs when the potential is not constant, large non adiabatic perturbations are produced, which can in turn source the growth of anisotropies. In the region where these models have a constant potential they became adiabatic on any scale and because of thi...
Primeval adiabatic perturbations: constraints from the mass distribution
The autocorrelation function of the mass distribution after decoupling of matter and radiation is computed under the assumption of linear primeval adiabatic perturbations using a new numerical method, and the results are compared to what is inferred from the present galaxy distribution. The computations are based on a Friedmann-Lemaitre model with Λ = 0 containing radiation, zero-mass neutrinos, hydrogen, and helium. The primeval power spectrum of density fluctuations is taken to approximate a power law k/sup v/. If the density parameter is Ω0 = 2q0< or approx. =0.1; or, if ν< or approx. =2, then the coherence length of the residual mass distribution is too large: when the amplitude is adjusted to make the first generation of objects form at z< or approx. =2, there are unacceptably large fluctuations in the mass distribution now on scales approx.12 to 40 Mpc. If ν = 3 to 4, this problem is avoided, but to prevent diverging curvature fluctuations the power law k/sup v/ must be truncated at a rather large comoving wavelength, lambda/sub x/approx.1 Mpc. The parameters thus are tightly limited, but it appears that one still can find a consistent scenario for the development of galaxies out of linear primeval adiabatic perturbations
On the Time Dependence of Adiabatic Particle Number
Dabrowski, Robert
2016-01-01
We consider quantum field theoretic systems subject to a time-dependent perturbation, and discuss the question of defining a time dependent particle number not just at asymptotic early and late times, but also during the perturbation. Naively, this is not a well-defined notion for such a non-equilibrium process, as the particle number at intermediate times depends on a basis choice of reference states with respect to which particles and anti-particles are defined, even though the final late-time particle number is independent of this basis choice. The basis choice is associated with a particular truncation of the adiabatic expansion. The adiabatic expansion is divergent, and we show that if this divergent expansion is truncated at its optimal order, a universal time dependence is obtained, confirming a general result of Dingle and Berry. This optimally truncated particle number provides a clear picture of quantum interference effects for perturbations with non-trivial temporal sub-structure. We illustrate the...
Schedule path optimization for adiabatic quantum computing and optimization
Adiabatic quantum computing and optimization have garnered much attention recently as possible models for achieving a quantum advantage over classical approaches to optimization and other special purpose computations. Both techniques are probabilistic in nature and the minimum gap between the ground state and first excited state of the system during evolution is a major factor in determining the success probability. In this work we investigate a strategy for increasing the minimum gap and success probability by introducing intermediate Hamiltonians that modify the evolution path between initial and final Hamiltonians. We focus on an optimization problem relevant to recent hardware implementations and present numerical evidence for the existence of a purely local intermediate Hamiltonian that achieve the optimum performance in terms of pushing the minimum gap to one of the end points of the evolution. As a part of this study we develop a convex optimization formulation of the search for optimal adiabatic schedules that makes this computation more tractable, and which may be of independent interest. We further study the effectiveness of random intermediate Hamiltonians on the minimum gap and success probability, and empirically find that random Hamiltonians have a significant probability of increasing the success probability, but only by a modest amount. (paper)
FRW-type cosmologies with adiabatic matter creation
Some properties of cosmological models with matter creation are investigated in the framework of the Friedmann-Robertson-Walker line element. For adiabatic matter creation, as developed by Prigogine and co-workers, we derive a simple expression relating the particle number density n and energy density ρ which holds regardless of the matter creation rate. The conditions to generate inflation are discussed and by considering the natural phenomenological matter creation rate ψ=3βnH, where β is a pure number of the order of unity and H is the Hubble parameter, a minimally modified hot big-bang model is proposed. The dynamic properties of such models can be deduced from the standard ones simply by replacing the adiabatic index γ of the equation of state by an effective parameter γ*=γ(1-β). The thermodynamic behavior is determined and it is also shown that ages large enough to agree with observations are obtained even given the high values of H suggested by recent measurements. copyright 1996 The American Physical Society
Scintillations in ionization chambers
High purity Ar and mixtures of Ar with 1% CH4, 3% CH4, CO2 and N2, respectively, have been applied for fission fragment detection in a gridded ionization chamber. Gas scintillation has been observed simultaneously with a photomultiplier VALVO-XP 2041. Whereas all mixtures work equally well as an ionization gas, only Ar + 3% N2 shows a primary scintillation yield sufficient for fas timing. (orig.)
MULTIPHOTON IONIZATION OF ATOMS
Mainfray, G.
1985-01-01
Multiphoton ionization of one-electron atoms, such as atomic hydrogen and alkaline atoms, is well understood and correctly described by rigorous theoretical models. The present paper will be devoted to collisionless multiphoton ionization of many-electron atoms as rare gases. It induces removal of several electrons and the production of multiply charged ions. Up to Xe5+ ions are produced in Xe atoms. Doubly charged ions can be produced, either by simultaneous excitation of two electrons, or b...
Salt Tolerance of Desorption Electrospray Ionization (DESI)
Jackson, Ayanna U. [Purdue University; Talaty, Nari [Purdue University; Cooks, R G [Purdue University; Van Berkel, Gary J [ORNL
2007-01-01
Suppression of ion intensity in the presence of high salt matrices is common in most mass spectrometry ionization techniques. Desorption electrospray ionization (DESI) is an ionization method that exhibits salt tolerance, and this is investigated. DESI analysis was performed on three different drug mixtures in the presence of 0, 0.2, 2, 5, 10, and 20% NaCl:KCl weight by volume from seven different surfaces. At physiological concentrations individual drugs in each mixture were observed with each surface. Collision-induced dissociation (CID) was used to provide additional confirmation for select compounds. Multiple stage experiments, to MS5, were performed for select compounds. Even in the absence of added salt, the benzodiazepine containing mixture yielded sodium and potassium adducts of carbamazepine which masked the ions of interest. These adducts were eliminated by adding 0.1% 7M ammonium acetate to the standard methanol:water (1:1) spray solvent. Comparison of the salt tolerance of DESI with that of electrospray ionization (ESI) demonstrated much better signal/noise characteristics for DESI in this study. The salt tolerance of DESI was also studied by performing limit of detection and dynamic range experiments. Even at a salt concentration significantly above physiological concentrations, select surfaces were effective in providing spectra that allowed the ready identification of the compounds of interest. The already high salt tolerance of DESI can be optimized further by appropriate choices of surface and spray solution.
Chen, Chao-Jung; Lai, Chien-Chen; Tseng, Mei-Chun; Liu, Yu-Ching; Lin, Shih-Yi; Tsai, Fuu-Jen
2013-06-14
To enhance sample signals and improve homogeneity in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) analysis, a simple, rapid, and efficient sample preparation method was developed in this study. Polydimethylsiloxane (PDMS) was coated on a stainless steel MALDI plate, forming a transparent, hydrophobic surface that enhanced sample signals without producing observable background signals. Compared to the use of an unmodified commercial metal MALDI plate, peptide signals were enhanced by ~7.1-11.0-fold due to the reduced sample spot area of the PDMS-coated plate, and showed improved peptide mass fingerprinting (PMF) and MS/MS peptide sequencing results. In the analysis of phosphopeptides and carbohydrates with a 2,5-dihydroxybenzoic acid (DHB) matrix, the PDMS-coated plate showed improved sample homogeneity and signal enhancements of ~5.2-8.2-fold and ~2.8-3.2-fold, respectively. Improved sensitivity in the observation of more unique fragment ions by MS/MS analysis, to successfully distinguish isomeric carbohydrates, was also illustrated. In protein analysis with a sinapinic acid (SA) matrix, a ~3.4-fold signal enhancement was observed. The PDMS film coating was easily removed and refabricated to avoid sample carryover, and was applicable to diverse commercial MALDI plates. The PDMS-coated approach is a simple, practical, and attractive method for enhancing analyte signals and homogeneity. PMID:23726097