-order) above-threshold ionization (HATI) [3�5], nonsequential double (and multiple) ionization and high" (QRS) theory [3,5�9]. Related treatments of HATI without the explicit factorization but which include on the rescattering, or plateau (HATI), electrons whose behavior is calculable by QRS. The major goal of this part

We theoretically study a process in which helium is doubly ionized by absorbing two soft x-ray (91.45 eV) photons from attosecond, intense high-order harmonic sources. We directly solve the time-dependent Schroedinger equation and obtain electron energy distribution in the double continuum. Our results show that between the two peaks in electron energy spectra, expected for ...

In this paper, we extend strong-field double ionization from diatomic molecules to triatomic molecules. Strong-field double ionization of CO2 is studied here with both linear and circular polarizations. A clear nonsequential signature is seen in doubly ionized CO2. We also compare nonsequential ...

A semiclassical molecular nonsequential double ionization theory is developed based on the rescattering model. We show that, in the nonsequential double ionization of D{sub 2}, the kinetic energy of the returning electron changes from below to above the ionization threshold of the parent ion as the laser varies ...

A brief description is given of the early developments leading to the discovery of some of the basic phenomena that occur during the interaction of intense light fields with atomic systems - such as multiphoton ionization (MPI), above-threshold ionization (ATI), and high harmonic generation (HHG). Also outlined are the related theoretical concepts and the nonperturbative "KFR ...

The time-dependent multiconfiguration Hartree method is optimized for intense laser dynamics and applied to nonsequential double ionization in a two-electron diatomic model molecule with two dimensions per electron. The efficiency of our method brings these calculations from the realm of large scale computation facilities to single processor machines. The ...

We examine the nature and statistical properties of electron-electron collisions in the recollision process in a strong laser field. The separation of the double ionization yield into sequential and nonsequential components leads to a bell-shaped curve for the nonsequential probability and a monotonically rising one for the sequential ...

Double photoionization of helium has been studied using a new instrument which allows one to detect the two emitted electrons over 4 pi steradians and measure their individual momenta. The experiments have been performed at 0.2 and 0.1 eV above threshold, and both double and triple differential cross sections have ...

Electron correlation effects in strong laser fields are investigated by using a simplified two electron model to calculate the double ionization rate in helium. In our model we make a correction to the single active electron approximation by including the effect of the outer electron on the inner one through a time-dependent potential. Using this approach we are able to ...

When an atom or molecule is exposed to a short intense laser pulse, electrons that were removed at an earlier time may be driven back by the oscillating electric field of the laser to recollide with the parent ion, to incur processes like high-order harmonic generation (HHG), high-energy above-threshold ionization (HATI) and nonsequential ...

Here we report a set of converged cross-section results for double photoionization of helium atoms obtained in the hyperspherical partial wave theory for equal energy sharing kinematics at 6 eV energy above threshold. The calculated cross section results are generally in excellent agreement with the absolute measured results of Doerner ...

The influence of electron-electron Coulomb repulsion on nonsequential double ionization of rare-gas atoms is investigated. Several variants of the quantum-mechanical transition amplitude are evaluated that differ by the form of the inelastic electron-ion rescattering and whether or not Coulomb repulsion between the two electrons in the final state is ...

The nonsequential double ionization (NSDI) yield and final electron-electon correlation are examined for a laser wavelength of 800 nm over a wide range of laser intensities, using three-dimensional fully classical models. It is shown that in the transition region between NSDI and sequential ionization, turn-on stage recollisions can lead to having a ...

Nonsequential two-photon double ionization of a two-electron system (He and He-like ions) in a circularly polarized intense laser field is developed in a relativistic field theoretic way. Antisymmetry is maintained in the correlated wave functions of He in the initial state after modification to include Dirac spinor, and in the Volkov wave functions of the ...

We develop an approximate model for the process of direct (nonsequential) two-photon double ionization of atoms. Employing the model, we calculate (generalized) total cross sections as well as energy-resolved differential cross sections of helium for photon energies ranging from 39 to 54 eV. A comparison with results of ab initio calculations reveals that ...

In(1-x)Ga(x)P(1-z)As(z) double heterojunctions (77 K, yellow) are shown to exhibit either (or both) homogeneous or inhomogeneous line broadening when operated as lasers in an external grating cavity. Just above threshold, inhomogeneous line broadening is ...

Based on the full quantal recollision model and field-free electron impact ionization theory, we calculate the correlated momentum spectra of the two outgoing electrons in strong field nonsequential double ionization (NSDI) of helium to compare with recent experiments. By analyzing the relative strength of binary versus recoil collisions exhibited in the ...

We employ 3d classical ensembles to study Non-Sequential Double Ionization (NSDI) of atoms by strong laser fields at visible and infrared wavelengths. We consider in particular the wavelength dependence of final electron drift directions and the net momentum spectra parallel to the laser polarization. We find that as the wavelength is increased the ...

The degree of elliptical polarization of intense short laser pulses is shown to be related to the timing of strong-field nonsequential double ionization. Higher ellipticity is predicted to force the initiation of double ionization into a narrower time window, and this 'pins' the ionizing field strength in an ...

Quantum calculations of a (1+1)-dimensional model for double ionization in strong laser fields are used to trace the time evolution from the ground state through ionization and rescattering to the two-electron escape. The subspace of symmetric escape, a prime characteristic of nonsequential double ionization, remains accessible by a ...

We investigate the double ionization process of a three-dimensional model atom interacting with a synthesized laser pulse and explore the mechanism of non-sequential double ionization varying with the value of relative phase. The result shows that the recollision probability decreases when the value of the relative phase increases. The ...

Two-photon single and double ionization of helium by ultrashort laser pulses is explored with accurate time-dependent theoretical methods. Core excited resonances are revealed in the two-photon single ionization cross sections. In two-photon double ionization, electron angular distributions reveal that subfemtosecond pulses can change the competition ...

We predict new end-of-pulse behavior in high-field atomic double ionization. Calculations of atomic electron trajectories in short intense laser pulses confirm our analysis of elliptical polarization. We exhibit a four-band structure in ion momentum distributions under various ellipticities, and predict that sequential and nonsequential ...

When an electron from a diatomic molecule undergoes tunneling-rescattering ionization, a novel form of destructive interference can be realized that involves all four geometric orbits that are available to the electron when it is freed, because both ionization and rescattering may take place at the same or at different centers. We find experimentally and confirm theoretically that in ...

We investigate the ratio of double to single ionization of He in an intense laser field based on the rescattering model. Folding the rescattering energy spectra with the electron impact inelastic cross sections, we obtain the probability of double ionization due to the nonsequential ionization process. Our results are in reasonable ...

Numerical integration of the time-dependent Schroedinger equation for two three-dimensional electrons reveals the behavior of helium in the presence of strong 390 nm and 800 nm light. Non-sequential double ionization is seen to take place predominantly at times when the electric-field component of the light reaches its peak value. ...

The effect of initial longitudinal velocity of the first tunneling electron on the nonsequential double-ionization (NSDI) process is studied using a semiclassical model. Our analysis shows that nonzero initial longitudinal velocity affects two distinct typical trajectories [single-return collision (SRC) and multiple-return collision (MRC)] in the NSDI ...

The influence of carrier-envelope phase (CEP) of a few-cycle laser pulse on non-sequential double ionization (NSDI) of an atom is investigated by applying the three-dimensional semi-classical re-scattering method. The asymmetric momentum distribution of the double-charged ion parallel to the laser polarization, which depends on the ...

Using a semiclassical rescattering model, we investigate the nonsequential double ionization (NSDI) process of diatomic molecules aligned parallel and perpendicular to the intense linearly polarized field. It is shown that a simple hydrogen-molecule-like model can simulate a nitrogen molecule effectively by giving the alignment dependence of the ratio of ...

We identify the phase-space structures that regulate atomic double ionization in strong ultrashort laser pulses. The emerging dynamical picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons, and leads to verifiable predictions on the characteristic features of the "knee", a hallmark of the ...

We identify the phase-space structures that regulate atomic double ionization in strong ultrashort laser pulses. The emerging dynamical picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons, and leads to verifiable predictions on the characteristic features of the 'knee', a hallmark of the ...

We identify the phase-space structures that regulate atomic double ionization in strong ultrashort laser pulses. The emerging dynamical picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons, and leads to verifiable predictions on the characteristic features of the �knee�, a hallmark of the ...

We introduce a unified and simplified theory of atomic double ionization. Our results show that at high laser intensities (I>/=10(14) W/cm(2)) purely classical correlation is strong enough to account for all of the main features observed in experiments to date. PMID:15783962

We analyze two-photon double ionization of helium in both the nonsequential (??I2) regime. We show that the energy spacing ?E=E1-E2 between the two emitted electrons provides the key parameter that controls both the energy and the angular distribution and reveals the universal features present in both the ...

We apply a recently developed ab initio numerical framework to calculate (generalized) total cross sections for the process of nonsequential (direct) two-photon double ionization of the hydride ion (H?), at photon energies ranging from 7.75 to 10.5 eV. The total cross section is about an order of magnitude larger than the corresponding one obtained for ...

We report on a kinematically complete experiment on nonsequential double ionization of He by 25 fs 800 nm laser pulses at 1.5 PW/cm{sup 2}. The suppression of the recollision-induced excitation at this high intensity allows us to address in a clean way direct (e,2e) ionization by the recolliding electron. In contrast with earlier experimental results, but ...

Double resonance spectroscopy via theEF ^1?g^+ ,v'EF=6,J' state has been used to probe the H(n=1) + H(n=3) dissociation threshold region with quantum state selectivity and high energy resolution. Above threshold the continuum is detected by ionizing H(n=3) to produce H^+, which is then detected by using a time-of-flight mass ...

Both uncorrelated ('sequential') and correlated ('nonsequential') processes contribute to the double ionization of the helium atom in strong laser pulses. The double ionization probability has a characteristic 'knee' shape as a function of the intensity of the pulse. We investigate the phase-space dynamics of this system, specifically ...

We have studied the dynamical behavior of laser emission in optically pumped GaAs/AlGaAs lasers with picosecond time resolution. We find a saturation of the spontaneous emission above threshold and a homogeneous reduction of carrier lifetime down to about 70 ps. These data suggest a homogeneous gain saturation in GaAs/AlGaAs quantum well lasers, similar to ...

We present a generalized thermal model based on a finite-element code for estimating the temperature rise, associated thermal resistance, and cw optical power in a stripe-geometry double-heterostructure laser. In particular, we report the first thermal analysis of a zinc-diffused, oxide-insulated AlGaAs laser structure below and above ...

An enhancement of He(2+) yield near the appearance intensity was not observed by linearly polarized KrF laser light (248 nm), whereas a significant enhancement was observed by linearly polarized Ti:sapphire laser light (745 nm). These results are consiste...

We report on first proof-of-principles results on non-sequential double ionization of argon and neon achieved by using a newly developed long-cavity Ti:sapphire femtosecond oscillator with a pulse duration of 45 fs and a repetition of 6.2 MHz combined with a dedicated reaction microscope. Under optimized experimental conditions, peak intensities larger ...

In the interaction of intense laser fields with atoms, even subtle details of single ionization and high-harmonic generation can be well described in the so-called single-active-electron approximation where just one electron reacts to the laser field. Therefore, the surprisingly high efficiency of laser-induced nonsequential multiple ionization (where two or more electrons are ...

We report calculations of double-ionization energy spectra and momentum distributions of laser-driven helium due to few-cycle pulses of wavelength 195 nm. The results are obtained from full-dimensional numerical integration of the two-electron time-dependent Schr�dinger equation. A momentum-space analysis of doubly ionizing wavepackets shows that the concentric-ring ...

Long wavelength lasers allow access to tunneling ionization due to concomitantly large ponderomotive energies. Rescattering is known to occur when a tunnel ionized photoelectron is driven back by the field and collides with the parent ion. In this picture the wavelength of the laser field provides a `control knob' for rescattering since the cycle averaged kinetic energy of a free electron is ...

A systematic study is reported on the convergence of computed triply differential cross sections for photo-double ionization of helium at 20 and 25 eV above threshold, obtained using the hyperspherical R matrix with semiclassical outgoing waves method. Such a study has become feasible due to an essential improvement in the ...

... Technical Reports - Scientific and technical (S&T) reports conveying results of Defense ... Title : Nonsequential Computation and Laws of Nature. ...

The multiconfigurational time-dependent Hartree-Fock method (MCTDHF) is applied for simulations of the two-photon ionization of helium. We present results for the single and double ionizations from the ground state for photon energies in the nonsequential regime and compare them to direct solutions of the Schro?dinger equation using the time-dependent ...

The multiconfigurational time-dependent Hartree-Fock method (MCTDHF) is applied for simulations of the two-photon ionization of helium. We present results for the single and double ionizations from the ground state for photon energies in the nonsequential regime and compare them to direct solutions of the Schr�dinger equation using the time-dependent ...

Triple differential cross sections (TDCS) for two-photon double ionization of helium are calculated using the method of exterior complex scaling both above and below the threshold for sequential ionization (54.4 eV). It is found that sequential ionization produces characteristic behavior in the TDCS that identifies that process when it is in competition with ...

The threshold law of the titled process, which is of the same form as that for electron-impact ionization of H, can experimentally be contaminated by simultaneous single photodetachment and Rydberg excitation of the residual atom, followed by ionization of the Rydberg atom by (room-temperature) blackbody photons. This gives a signal indistinguishable from direct double ...

This pair of experiments investigates strong-field behavior of an atom and of a molecule, observing these phenomena through collection of detailed spectral information under the necessary parameters. We first investigate the double-ionization of an argon atom; inelastic collisions between the ion and the laser-driven electron may provide an explanation of the unexpectedly high ...

We consider the classical dynamics of a two-electron system subjected to an intense bichromatic linearly polarized laser pulse. By varying the parameters of the field, such as the phase lag and the relative amplitude between the two colors of the field, we observe several trends from the statistical analysis of a large ensemble of trajectories initially in the ground-state energy of the helium ...

We consider the classical dynamics of a two-electron system subjected to an intense bichromatic linearly polarized laser pulse. By varying the parameters of the field, such as the phase lag and the relative amplitude between the two colors of the field, we observe several trends from the statistical analysis of a large ensemble of trajectories initially in the ground-state energy of the helium ...

We investigate the nonsequential double ionization (NSDI) of Ar and Ne based on quantitative rescattering theory (QRS). According to QRS theory, each elementary NSDI process can be calculated by multiplying the returning electron wave packet with appropriate differential electron-ion scattering cross sections. We include (e, 2e) and electron-impact ...

Single-shot carrier-envelope-phase (CEP) tagging is combined with a reaction mircoscope (REMI) to investigate CEP-dependent processes in atoms. Excellent experimental stability and data acquisition longevity are achieved. Using this approach, we study the CEP effects for nonsequential double ionization of argon in 4-fs laser fields at 750 nm and an ...

We study the correlated two-electron momentum spectra of the nonsequential double ionization (NSDI) of an atom in an intense laser field based on the recently developed quantitative rescattering (QRS) theory. According to the rescattering model, an electron that was released earlier in the laser pulse may return to collide again with the target ion. NSDI ...

We have investigated the correlated electron dynamics in nonsequential double ionization (NSDI) of helium by the orthogonally polarized two-color pulses that consisted of an 800-nm and a 400-nm laser fields using the classical ensemble model. Depending on the relative phase of the two-color field, the electron momentum distributions along the polarization ...

High precision photoelectron energy and angular distributions in helium and neon atoms for a broad intensity range reflect the change in the continuum dynamics that occurs as the ionization process evolves into the pure tunneling regime. Elastic rescattering of the laser-driven free electron from its parent ion core leaves a distinct signature on the spectra, providing a direct quantitative test ...

High precision photoelectron energy and angular distributions in helium and neon atoms for a broad intensity range reflect the change in the continuum dynamics that occurs as the ionization process evolves into the pure tunneling regime. Elastic rescattering of the laser-driven free electron from its parent ion core leaves a distinct signature on the spectra, providing a direct quantitative test ...

We study elastic scattering and impact ionization by returning electrons induced in a strong laser field based on the recently developed quantitative rescattering theory. The high-energy angle-resolved photoelectron spectra of molecules in strong fields are attributed to elastic scattering of the returning electrons with the parent ion. We demonstrate that the high-energy photoelectron spectra can ...

Recently published data concerning a contemporary well-behaved cw stripe-geometry injection laser was accompanied by the assertion that above threshold both the junction voltage and the spontaneous emission exhibit ''complete saturation''. This paper shows by detailed analysis of the data that in fact the small ...

An original architecture of an active fiber allowing a nearly diffraction-limited beam to be produced is demonstrated. The active medium is a double-clad large-mode-area photonic-bandgap fiber consisting of a 10,000 ppm by weight Yb(3+)-doped core surrounded by an alternation of high- and low-index layers constituting a cylindrical photonic crystal. The periodic cladding ...

We present a semi-microscopic model for the double charge exchange (DCX) reaction (..pi../sup +/, ..pi../sup -/) to the ground state of the final nucleus at medium and low energies. We separate the DCX amplitude into a sequential and a non-sequential part, with pions distorted by the full ..delta..-hole optical potential and medium corrections to the ...

... Title : Use of Non-Sequential Techniques in the Analysis of Power Potential at Storage Projects. Descriptive Note : Technical paper,. ...

... WERE DETERMINED SUCH AS SIGNAL DURATION, AE COUNTS (OSCILLATIONS ABOVE THRESHOLD), RISE TIME, AND PEAK AMPLITUDE. ...

A model is presented for the steady state operation of polymer light-emitting electrochemical cells (LECs). An LEC consists of a luminescent and ionically conducting polymer, with an ionic salt added to provide ions necessary for p-type and n-type doping, sandwiched between two electrodes. Upon applying a sufficiently large voltage bias, the ions are spatially separated forming an electrical ...

Four-wave-mixing (FWM) phase conjugation was investigated in materials that can operate at diode-laser wavelengths. Investigated were atomic cesium vapor, bulk GaAs, multiquantum well (MQW) GaAs/AlGaAs, and intracavity FWM in diode laser waveguides operating above threshold. Conjugate reflectivities up to 154% were observed in cesium for c-w pumping at ...

In this paper we investigate the single and double ionization signals of H2 molecules, with fixed and moving nuclei, as a function of laser intensity, for two different values of laser wavelength ( ?=390nm and ?=780nm ), using an approach for evaluating the ionization signals which allows the investigation of relatively long-lasting pulses. The He system is first ...

We investigate the possibility to deduce momentum space properties from time-dependent density functional calculations. Electron and ion momentum distributions after double ionization of a model helium atom in a strong few-cycle laser pulse are studied. We show that, in this case, the choice of suitable functionals for the observables is considerably more important than the ...

Using a novel split-mirror set-up attached to a Reaction Microscope at the Free electron LASer in Hamburg (FLASH) we demonstrate an XUV-pump -- XUV-probe ((hbar omega = 38 eV) experiment by tracing the ultra-fast nuclear wave-packet motion in the D2+ (1s sigma g-state) with<10 fs time resolution. Comparison with time-dependent calculations yields excellent agreement with the measured ...

Electron energy distributions of singly and doubly ionized helium in an intense 390 nm laser field have been measured at two intensities (0.8 PW/cm2 and 1.1 PW/cm2, where PW is defined as 10(15) W/cm2). Numerical solutions of the full-dimensional time-dependent helium Schr�dinger equation show excellent agreement with the experimental measurements. The high-energy portion of the two-electron ...

In recent combined experimental and theoretical study we have explored nonsequential double ionization of neon and argon atoms in the infrared light field (800nm) below the recollision threshold. We find that the two-electron correlation dynamics depends on atomic structure- "side-by-side emission" (correlation) for Ne and "back-to-back emission" ...

Two-photon double ionization of He is studied at the Free Electron Laser in Hamburg (FLASH) by inspecting He2+ momentum (\\vec P({\\rm{He}}^{2 + } )) distributions at 52 eV photon energy. We demonstrate that recoil ion momentum distributions can be used to infer information about highly correlated electron dynamics and find the first experimental evidence for 'virtual ...

Above 54.4 eV, two-photon double ionization of helium isdominated by a sequential absorption process, producing characteristicbehavior in the single and triple differential cross sections. We showthat the signature of this process is visible in the nuclear recoil crosssection, integrated over all energy sharings of the ejected electrons,even below the threshold for the ...

The dissociative double ionization and multi-photon ionization of 1-bromo-2-chloroethane (BCE) irradiated by the 800 nm femtosecond laser field have been investigated by dc-slice imaging technology. The charged parent ion ratio [BCE(2+)]?[BCE(+)] was measured, and the corresponding ionization process including non-sequential double ...

Electron beam induced structural transformations are investigated in single-wall carbon nanotubes (SWNTs), double-wall carbon nanotubes (DWNTs) and crossed nanotube junctions. The nanotubes studied here are synthesized by the chemical vapor deposition method. The response of the nanotubes to an electron beam is found to be influenced by the presence of coatings of amorphous ...

Studies of nonlinear laser-matter interaction have been so far limited to wavelengths from the near ultraviolet to infrared, because of the low brightness of currently available sources outside this range. However nonlinear processes in the VUV/Soft X-ray domain would initiate multiphoton innershell spectroscopy, XUV nonlinear optics and applications of such processes to metrology. The probability ...

A systematic study is reported on the convergence of computed triply differential cross sections for photo-double ionization of helium at 20 and 25 eV above threshold, obtained using the hyperspherical R matrix with semiclassical outgoing waves method. Such a study has become feasible due to an essential improvement in the description ...

We investigate the role of electron correlation in the two-photon double ionization of helium for ultrashort pulses in the extreme ultraviolet (XUV) regime with durations ranging from a hundred attoseconds to a few femtoseconds. We perform time-dependent ab initio calculations for pulses with mean frequencies in the so-called 'sequential' regime ...

High precision photoelectron energy and angular distributions in helium and neon atoms for a broad intensity range reflect the change in the continuum dynamics that occurs as the ionization process evolves into the pure tunneling regime. Elastic rescattering of the laser-driven free electron from its parent ion core leaves a distinct signature on the spectra, providing a direct quantitative test ...

Two-photon double ionization of the helium atom was the subject of early experiments at FLASH and will be the subject of future benchmark measurements of the associated electron angular and energy distributions. As the photon energy of a single femtosecond pulse is raised from the threshold for two-photon double ionization at 39.5 eV to beyond the ...

1. In anaesthetized cats, graded electrical stimulation of the inferior alveolar nerve at just above threshold for the largest afferent fibres caused inhibition of jaw-closer motoneurones. Stimulus strength had to be increased to 1.5 times threshold with double shocks to cause reflex contraction of the digastric muscle. 2. Inhibition ...

Forty-seven strip-buried-heterostructure (Al,Ga)As lasers have been examined for pulsations and absorbing defects in the active volume. All 18 pulsating lasers were found to have defects while only one of the 29 nonpulsating lasers had a visible defect. These results show conclusively that absorbing defects can cause pulsations in double-heterostructure injection lasers and ...

We have studied InGaAs/InAsPSb double heterojunction, oxide stripe lasers grown by hydride vapor phase epitaxy. At 80 K the threshold current density is 0.4 kA/cm{sup 2}, the staturated output power is about 4 mW, and the differential quantum efficiency just above threshold is 20% per facet. The output wavelength increases from 2.44 ...

A novel approach to achieving robust single-spatial-mode operation of cladding-pumped fiber lasers with multimode cores is reported. The approach is based on the use of a fiber geometry in which the core has a helical trajectory within the inner cladding to suppress laser oscillation on higher-order modes. In a preliminary proof-of-principle study, efficient single-mode operation of a ...

We address the influence of the molecular orbital geometry and of the molecular alignment with respect to the laser-field polarization on laser-induced nonsequential double ionization of diatomic molecules for different molecular species, namely N2 and Li2. We focus on the recollision excitation with subsequent tunneling ionization (RESI) mechanism, in ...

With the classical ensemble model, we investigate the manifestations of the Coulomb tail of electron-electron interaction in nonsequential double ionization by comparing the results from the short-range electron-electron interaction with those from the Coulombic electron-electron interaction. At the intensity below the recollision threshold, the ...

An equation relating the photocurrent just above threshold to the binding energy of the solvated electron is compared to experimental data. (AIP)

Figure 9b. Laser Energy Transmission Through the Focal. Volume as a Function of Time for Power Density. Input Well Above Threshold in 3.0 Atmospheres ...

Series switching diodes triggered on by passing above threshold voltage. High-voltage switch made by

A storage-ring free-electron laser oscillator has been operated above threshold at a visible wavelength lambdaapprox. =6500 A.

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o Manufacturing Defect such as improper heat treat o Stress Corrosion cracking due to prolonged exposure to ammonium hydroxide and stresses above threshold ...

We have determined the double-to-single photoionization ratio of magnesium from 22 to 70 eV photon energy using monochromatized synchrotron radiation and the ion time-of-flight method ootnotetextR. Wehlitz, P.N. Jurani'c, and D.V. Luki'c, PRA 78, 033428 (2008). Our results compare reasonably well with recent theoretical calculations ootnotetextA.S. Kheifets and I. Bray, Phys. ...

The wavelength and intensity dependence of xenon ionization with 50 fs laser pulses has been studied using time-of-flight mass spectrometry. We compare the ion yield distribution of singly and doubly charged xenon with the Perelomov-Popov-Terent'ev (PPT) theory, Perelomov, Popov, and Terent'ev, Zh. Eksp. Teor. Fiz. 50, 1393 (1966) [Sov. Phys. JETP 23, 924 (1966)], in the regime ...

The wavelength and intensity dependence of xenon ionization with 50 fs laser pulses has been studied using time-of-flight mass spectrometry. We compare the ion yield distribution of singly and doubly charged xenon with the Perelomov-Popov-Terent�ev (PPT) theory, Perelomov, Popov, and Terent�ev, Zh. Eksp. Teor. Fiz.ZETFA70044-4510 50, 1393 (1966) PerelomovPopovTerent�ev[Sov. Phys. ...

We extend the coupled coherent-state (CCS) approach to simulate the strong-field ionization of helium atoms at long wavelengths. This approach uses a basis of trajectories guided by frozen Gaussian coherent states, sampled from a Monte Carlo distribution, as the initial states of the quantum time-dependent Schroedinger equations. The CCS trajectories move over averaged potentials, which can remove ...

... the order of the retrieval is nonsequential. ... system. ... in information management systems [1]. It has been applied to organize and present EPA ...

National Marine Fisheries Service - 2nd Quarter 2009 FMP Stock Jurisdiction Overfishing? (Is Fishing Mortality above Threshold?) Overfished? (Is Biomass below Threshold?) Approaching Overfished Jurisdiction Overfishing? (Is Fishing Mortality above Threshold?) Overfished? (Is Biomass below Threshold

An injection laser is automatically stabilized so that the laser operates above threshold when the laser current is modulated. The invention makes use of the fact that the laser junction voltage saturates at currents above the threshold. A signal which modulates the laser current and causes the laser current to fall below the threshold level therefore ...

The authors study the longitudinal mode discrimination above threshold in both distributed feedback lasers with one external reflector and those with phase-shifted grating structures. By numerically solving a pair of coupled mode equations, they show that when these types of lasers have nonsaturable index coupling, they lose their mode discrimination at ...

of the ionized electron wave packet calculated at a delay of 120 ps for ionization of Xe atoms preparedAbove-threshold ionization in a strong dc electric field Y. Ni,1 S. Zamith,1,2 F. L�pine,1 T received 3 November 2007; published 18 July 2008 High-lying Rydberg states of Xe have been ionized using

and the electron energy is Ee mec2 . It should be noted that this free-wave acceleration of ionized electronsAbove Threshold Ionization in Tightly Focused, Strongly Relativistic Laser Fields A. Maltsev and T September 2002; published 5 February 2003) The dynamics of electrons ionized from high charge states

A technique for calculating above-threshold bound-bound transitions of an atomic optical electron, based on the use of generalized Sturm expansion of the Green's function for a potential with a Coulomb asymptotics has been developed within the model-potential method. The dynamic polarizabilities of alkali-metal and noble gas atoms are calculated in the frequency range ...

BackgroundThe majority of relations between proteins can be represented as a conventional sequential alignment. Nevertheless, unusual non-sequential alignments with different connectivity of the aligned fragments in compared proteins have been reported by many researchers. It is interesting to understand those non-sequential alignments; are they unique, ...

This work investigates the linewidth enhancement factor (alpha-factor) and stability of an optically-injected InAs/InGaAs quantum-dot Fabry-Perot laser. Using the injection-locking technique, the above threshold alpha-factor is measured to be as low as 0.6 at 1.3X the threshold current. The below threshold alpha-factor is also measured using the ...

Electron impact ionization has been studied in PH/sub 3/ and in a mixture of PH/sub 3/ and PD/sub 3/ as a function of electron energy up to 180 eV, with a double focusing mass spectrometer. Absolute partial ionization cross sections have been obtained in PH/sub 3/ for the production of the parent ion PH/sup +//sub 3/, for the fragment ions PH/sup +//sub 2/, PH/sup +/, P/sup ...

Experience shows that the ability to make measurements in any new time regime opens new areas of science. Currently, experimental probes for the attosecond time regime (10(-18) 10(-15) s) are being established. The leading approach is the generation of attosecond optical pulses by ionizing atoms with intense laser pulses. This nonlinear process leads to the production of high harmonics during ...

Metastable channel of doubly ionized carbon monoxide, CO{sup 2+}, was scantly seen in previous strong-field experiments at the visible wavelength region, but was commonly observed using single high-energy photon or electron excitation. For the first time with near-IR ultrashort-pulse radiation, we observe an abundance of CO{sup 2+}. We show that CO{sup 2+} results from ...

We calibrate the distorted wave Born approximation (DWBA) for electron impact excitation processes empirically. Differential cross sections (DCSs) for the excitation of the 2p53s, 2p53p, 2p54s and 2p54p configurations of Ne and the 3p54s and 3p54p configurations of Ar by electron impact are calculated using DWBA for incident energies between 20 and 100 eV. The calculated results are compared with ...

Using a frequency-domain theory, we demonstrate that an angle-resolved high-order above-threshold ionization (HATI) spectrum carries three pieces of important information: the fingerprint of the molecular wave function in the direct above-threshold-ionization amplitude, the geometrical structure of the molecule in the potential scattering between two plane ...

Using a frequency-domain theory, we demonstrate that an angle-resolved high-order above-threshold ionization (HATI) spectrum carries three pieces of important information: the fingerprint of the molecular wave function in the direct above-threshold-ionization amplitude, the geometrical structure of the molecule in the potential scattering between two plane ...

Using a triatomic molecular model, we show that the interference pattern in the high-order above-threshold ionization (HATI) spectrum depends dramatically on the charge distribution of the molecular ion. Therefore the charge distribution can be considered a crucial factor for imaging a molecular geometric structure. Based on this study, a general destructive interference ...

Using a triatomic molecular model, we show that the interference pattern in the high-order above-threshold ionization (HATI) spectrum depends dramatically on the charge distribution of the molecular ion. Therefore the charge distribution can be considered a crucial factor for imaging a molecular geometric structure. Based on this study, a general destructive interference ...

We describe first-principles in-plane calculations of nonsequential triple ionization of atoms in a linearly polarized intense laser pulse. In a fully classically correlated description, all three electrons respond dynamically to the nuclear attraction, the pairwise e-e repulsions, and the laser force throughout the duration of a 780 nm laser pulse. ...

Eight sets of studies are reported that support a model my colleagues and I have developed which views WM as a system consisting of those long-term memory traces active above threshold, the procedures and skills necessary to achieve and maintain that acti...

Results are reported from sixteen different sets of studies on a model of working memory capacity. We see WM as a system consisting of those long-term memory traces active above threshold, the procedures and skills necessary to achieve and maintain that a...

HAL-US) were each detected above thresholds in two of the samples from grid wells, and radon (proposed alternative MCL-US) was detected above the threshold in one sample from a...

The buildup of single-mode laser oscillations is investigated for the 0.633-micrometer transition of a helium-neon laser at levels of relative excitation significantly above threshold using a fast intra-cavity chopper. The time response agrees with theory...

Using approximate solutions for over-coupled (KL > 1) distributed feedback lasers above threshold and a small-signal perturbation analysis, the frequency and damping of DFL relaxation oscillations are calculated. (Author)

Cross sections and reaction rates of (?,n) reactions have been measured close above threshold with the photoactivation technique. The experimental data for 186W, 190,192,198Pt, 196,198,204Hg, 197Au, and 204Pb show good agreement with theoretical predictions.

Anisotropy parameters and cross section ratios of two-color two-photon above threshold ionization sidebands from argon are measured using photoelectron velocity map imaging with the selected 13th or 15th high-order harmonics in a perturbative 800 nm dressing field. A new data analysis technique determines accurate anisotropy parameters of the photoelectron ...

We have found that nanosecond optical parametric oscillators pumped well above threshold by single longitudinal mode pulse produce signal and idler light that is nearly purely phase modulated, even for unseeded operation.

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We present a method for the calculation of multiphoton ionization, including above-threshold ionization and autoionization, which goes beyond the one-electron approximation. We illustrate the method with examples of calculations in He and Mg.

Laser induced material modifications in the bulk and on the surface of KDP (KH2PO4) and DKDP (70-80% deuterated KDP) are studied using fluorescence imaging and spectroscopy. Photoluminescence is observed at damaged regions following above threshold exposu...

Pure iron in the form of a shielded electrode facing upward was anodically polarized in hydrochloric, perchloric, and sulfuric acid solutions. Ferrous salt films formed in all three electrolytes at potentials and current densities above threshold values d...

Under SARA Title III, Section 313, manufacturers (SIC Codes 2000-3999) that have greater than 10 employees and use listed toxic chemicals (currently, the list covers 302 chemicals and 20 chemical categories) above threshold quantities are required to comp...

A general theory of the effects of Coulomb excitation of a deep hole state in a solid on the subsequent soft-x-ray emission line shape is given. For excitation energies well above threshold it is shown that the emission corresponds to the decay of a nonre...

The connection between internal conversion of a nuclear transition and EXAFS is pointed out. A prediction is made of sizable variations of lifetimes of nuclear states depending on the surrounding material environment, provided that the transition energy is just above threshold and the internal conversion coefficient is appreciable. 12 refs., 2 figs.

Vacuum polarization of nonconformal and conformal fields would render the de Sitter solution quasistable. An inhomogeneous perturbation above threshold could trigger a transition to the scalaron stage. Particle creation in curvature fluctuations could result in a homogeneous transition.

The dependence on cavity Q of the intensity of a single-mode laser above threshold is examined for the quantum and semi-classical theories due to Scully and Lamb, and Stenholm and Lamb, respectively. The two theories predict different functional dependenc...

Bridging the Gap between Data Warehouses and Business Processes A Business Intelligence Perspective. For instance, if a BI process is used to intelligently control the production process based on the currently to intelligently adjust business process behavior across the entire enterprise. Value of Order Above Threshold

Sep 15, 2001 ... Typical of McLuhan's style, his main ideas are developed from a number of different perspectives in a non-sequential fashion. ...

... Whatever the level of training, however, the inherent non-sequential nature of simulation training more naturally supports the development of higher ...

... One non-sequential text was presented in each block of four texts, ,ith its position in the block being randomly determined. ...

Since the first reported Nd:YAG solar laser, researchers have been exploiting parabolic mirrors and heliostats for enhancing laser output performance. We are now investigating the production of an efficient solar-pumped laser for the reduction of magnesium from magnesium oxide, which could be an alternative solution to fossil fuel. Therefore both high conversion efficiency and excellent beam ...

The theoretical model proposed in the paper explains the influence of an inhomogeneous laser radiation in the junction plane upon the behavior of the first derivative I dV/dI above threshold. These inhomogeneities are connected with the existence of lateral modes. Calculations are carried out for modes represented by trigonometric functions for a buried or ...

Photoelectron energy spectra for ionization in a strong laser field are calculated within the Floquet framework, for a one-electron model of argon and for other model potentials. The results indicate that, at least for linear polarization and not too short pulse durations, the plateau enhancements dominating high-order above-threshold ionization in rare gases originate from ...

First experiments on atomic photoionization and molecular dissociation have been performed by taking advantage of the unprecedented characteristics of the free electron laser in Hamburg (FLASH) combined with a separate near-infrared (NIR) femtosecond laser. In a series of two-colour experiments, the photoionization of rare gases in the presence of a strong NIR dressing field as well as the ...

We theoretically study the spin-polarized transport through double barrier magnetic tunnel junction (DBMTJ) consisting of the quantum dot sandwiched by two ferromagnetic (FM) leads. The tunneling current through the DBMTJ is evaluated based on the Keldysh nonequilibrium Green's function approach. The self-energy and Green's function of the dot are analytically obtained via the ...

We theoretically study the spin-polarized transport through double barrier magnetic tunnel junction (DBMTJ) consisting of the quantum dot sandwiched by two ferromagnetic (FM) leads. The tunneling current through the DBMTJ is evaluated based on the Keldysh nonequilibrium Green's function approach. The self-energy and Green's function of the dot are analytically obtained via the ...

We have studied the dissociative ionization behavior of Na2 molecules using two-color, three photon optical-optical double resonance enhanced excitation via the A(1)Sigma(u)(+) and the 2(1)Pi(g) states. Excess energy ranges from about 150 to about 1500 cm(-1) above threshold for dissociative ionization into ground-state Na and Na(+). ...

An electron imaging technique has been used to study the full angular distribution of valence photoelectrons produced from enantiomerically pure molecular beams of camphor when these are photoionized with circularly polarized light. In addition to the familiar ? parameter, this provides a new chiral term, taking the form of an additional cosine function in the angular distribution which ...

A theoretical analysis of laser-driven collisional ejection of inner-shell electrons is presented to explain the previously observed anomalous kilovolt L-shell x-ray emission spectra from atomic Xe cluster targets excited by intense sub-picosecond 248nrn ultraviolet radiation. For incident ponderomotively-driven electrons photoionized by strong above ...

An electronic computer procedure is described that uses an estimate of power storage available at a dam site to make estimates of average annual energy and dependable capacity using a non-sequential methodology. Comparisons of this method against the more traditional sequential routing analysis are performed.

We propose an effective medium theory to analyze the kinetics of nonsequential adsorption of colloidal particles, including transport and blocking effects, valid at all values of surface coverage. The theory is applied to the irreversible adsorption of diffusing hard disks obtaining a kinetic law, which is in excellent agreement with nonsequential computer ...

Absolute ionization cross sections have been measured for the processes N$sub 2$+e$Yields$N$sub 2$$sup +$+2e, N$sub 2$+e$Yields$N$sub 2$$sup ++$+3e, O$sub 2$+e$Yields$O$sub 2$$sup +$+2e, and O$sub 2$+e$Yields$O$sub 2$$sup ++$+3e as a function of electron energy up to 170 eV in a crossed molecule--electron beam apparatus. The ionization cross section curve for producing the singly ...

We have calculated the two-photon above-threshold-ionization cross sections of rare-gas atoms by extreme ultraviolet (xuv) photons in the extended framework of multichannel quantum defect theory. Since free-free dipole moments do not converge in the length gauge, we have made the combined use of the length gauge for small r and the acceleration gauge for large r. The ...

Polariton emission from a single GaN nanowire in the strong coupling regime has been investigated in the temperature range of 200-300 K. GaN nanowires grow in the wurtzite structure with the c-axis along the growth direction. The polariton dispersion characteristics are determined from angle-resolved reflectivity measurements. The light emission characteristics measured as a function of incident ...

Energy-dependent photoelectron angular distributions from two-color two-photon above threshold ionizations are investigated to determine the partial-wave characteristics of free-free electronic transitions in helium. Sideband photoelectron energies ranging from 0.18 to 13.0 eV are measured with different wavelengths of the perturbative infrared dressing ...

This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He{sup +2}, Ne{sup +2} and Ar{sup +2}. The ion yields for He{sup +l}, Ne{sup +l} and Ar{sup +l} agree well with the ...

Multiple ionization (MI), induced by a few EUV photons at energies of 28.2 eV, 38 eV and 44 eV from FLASH (the free-electron laser at Hamburg), has been studied for atoms (He, Ne, Ar) and N2 molecules utilizing our multi-hit coincident technology�the reaction microscope. At comparably low intensities of I cong 1011-1013 W cm?2 we find the non-sequential (NS) MI mechanism ...

We investigate the cutoff law for high-order above-threshold ionization (HATI) within a semiclassical framework. By explicitly adopting the tunneling effect and considering the initial position shift of the tunneled electron from the origin in the model, the cutoff energy position in HATI spectrum exhibits a well-defined upshift from the simple-man model prediction. The ...

Laser fluctuations are measured and characterized with a new technique based on the concept of first-passage-time distributions. This first-passage-time technique makes it possible to discern quantum noise in a dye laser even in the presence of pump fluctuations that are many orders of magnitude larger. We report new analytic and experimental results for the mean, variance, and skewness of the ...

The shot-to-shot phase fidelity of a stimulated-Brillouin-scattering phase conjugator operated many times above threshold has been found to be very sensitive to the slope of the leading edge of the input pulse. For a pulse with a rising edge that is short relative to the acoustic lifetime of the stimulated-Brillouin-scattering medium, strong random ...

A number of advances were made in improving the understanding of multimode dye laser dynamics. The source of mode-intensity fluctuations in a three-mirror, multimode dye laser has been identified in the typical operating regime well above threshold. It was found experimentally that deterministic four-wave mixing interactions are the underlying cause. We ...

Significant progress has been made in several areas. The source of mode-intensity fluctuations in a three-mirror, multimode dye laser has been identified in the typical operating regime well above threshold. It was found experimentally that deterministic four-wave mixing interactions are the underlying cause. We have also made new theoretical studies ...

A number of advances were made in improving the understanding of multimode dye laser dynamics. The source of mode-intensity fluctuations in a three-mirror, multimode dye laser has been identified in the typical operating regime well above threshold. It was found experimentally that deterministic four-wave mixing interactions are the underlying cause. We ...

Selectively oxidized vertical cavity surface emitting lasers (VCSELs) have been studied by spectrally resolved near-field scanning optical microscopy. We have obtained spatially and spectrally resolved images of both subthreshold emission and lasing emission from a selectively oxidized VCSEL operating at a wavelength of 850 nm. Below threshold, highly local high gain regions, emitting local ...

Selectively oxidized vertical cavity surface emitting lasers (VCSELS) have been studied by spectrally resolved near field scanning optical microscopy (NSOM). We have obtained spatially and spectrally resolved images of both subthreshold emission and lasing emission from a selectively oxidized VCSEL operating at a wavelength of 850 nm. Below threshold, highly local high gain regions, emitting local ...

We explore the effects of multiple participating final ion states during strong field ionization (SFI) and high-harmonic generation (HHG) using a two-electron two-center reduced-dimensionality model. In particular, we propose to use above threshold ionization (ATI) photoelectron spectra to identify ionic states that are active in SFI, and demonstrate the ...

A detailed eigenmode analysis of diode laser phased arrays both at and above threshold condition is presented. This analysis is based on the models developed for stripe-geometry diode lasers, in which the field equation is solved-consistently with the carrier equation by taking into account the effect of carriers on the effective refractive index and ...

Photoionization cross sections and asymmetry ({beta}) parameters for Kr 3s, 3p, and 3d subshells have been measured and calculated in the 300--1300-eV photon energy range. Good agreement between experiment and theory is found for both cross-section branching ratios and {beta} parameters. Interchannel coupling among the channels arising from 3s, 3p, and 3d subshells is found to be necessary for ...

A type of sustained oscillations that can occur in the output of semiconductor injection lasers are studied analytically. The frequency of oscillations and the conditions of instability are deduced from the nonlinear differential rate equations. This model raises the possibility that, at least in some if not many cases, the stability of a laser above ...

The cross section for the reaction p+6Li??+7Be was measured at an excess energy of 11.28 MeV above threshold by detecting the recoiling Be7 nuclei. A dedicated set of focal plane detectors was built for the magnetic spectrograph Big Karl and was used for identification and four-momentum measurement of Be7. A differential cross section of ...

Ionization of atoms is the first step in many analytical procedures. The cross section for ionizing a particular atomic shell is essential for calculating the magnitude of analytical signals. Calculations using atomic wave functions for various shells of all elements relevant for X-ray microanalysis over a range of electron energies up to 400 keV were performed. The calculations for high energies ...

Many nonlinear quantum phenomena of intense laser-atom physics can be intuitively explained with the concept of trajectory. In this paper, Bohmian mechanics (BM) is introduced to study a multiphoton process of atoms interacting with the intense laser field: above-threshold ionization (ATI). Quantum trajectory of an atomic electron in intense laser field is obtained from the ...

Many nonlinear quantum phenomena of intense laser-atom physics can be intuitively explained with the concept of trajectory. In this paper, Bohmian mechanics (BM) is introduced to study a multiphoton process of atoms interacting with the intense laser field: above-threshold ionization (ATI). Quantum trajectory of an atomic electron in intense laser field is obtained from the ...

Above-threshold ionization of atoms by XUV short laser pulses with frequencies close to the resonant 1s�2p transition is investigated. We present a theory based on a variational expression using trial wavefunctions for the final and the initial states. For the former we use a Coulomb�Volkov wavefunction, and for the latter a close-coupling solution of the time-dependent ...

In a high-intensity laser field an atom can absorb more photons than the minimum necessary for ionization. It is known as above threshold ionization (ATI). Theoretically it is the most difficult case to handle as we have to consider transitions in continuum. To study ATI we use the perturbation theory and Green's function formalism. We have derived the ...

We propose and demonstrate a new method for phaselocking the signal fields emitted above threshold by a nondegenerate, type-II optical parametric oscillator (OPO). This method is based on the observation that amplitude modulation of the pump beam produces a related modulation of the frequency difference of the OPO signals via the temperature-tuning of the ...

A non-sequential Bayesian program for diagnosing acute abdominal pain was developed using an Amdahl mainframe accessed by a Texas Instrument remote terminal. Transferring the program to a MacIntosh SE/30 using hypercard was attended by increased utilisation from 15 to 44%.

This report examines the use of non-sequential (Non-von Neumann) technology for the support of command and control applications. It has become apparent that the utilization of traditional von-Neumann computers is insufficient of many applications. The uti...

The report summarizes work of the current state-of-the-art in software engineering issues confronting the effective implementation of non-sequential architecture-based computers. Since these architectures do not conform to the model of the von Neumann mac...

1. Learning and experience, 2. What freshman actually know when they show up at school, 3. Concept mapping, 4. Non-sequential online learning strategies. Length: 25:23

We describe a Web-based application developed above a digital library of geographical resources for Singapore students preparing to take a national examination in geography. The application provides an interactive, non-sequential approach to learning that supplements textbooks.

The authors have measured the ion yields for helium and neon ionized by 120 femtosecond, 614 nanometer laser pulses with intensities up to 10{sup 16} watts per square centimeter. They have found that the He II and Ne II data exhibit features incompatible with standard nonresonant sequential ionization. These features reduce the usefulness of optical field ionization for monitoring laser intensity. ...