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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 7901-7909 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a new complex-scaling Fourier-grid Hamiltonian (CSFGH) method for accurate and efficient determination of laser-induced (multichannel) molecular resonance states without the use of basis set expansions. The method requires neither the computation of potential matrix elements nor the imposition of boundary conditions, and the eigenvectors provide directly the values of the resonance wave functions at the space grid points. The procedure is particularly valuable for excited-state problems where basis set expansion methods face the challenge. The simplicity and usefulness of the CSFGH method is demonstrated by a case study of the intensity-dependent complex quasivibrational energy eigenvalues (ER, −Γ/2) and eigenvectors associated with multiphoton and above-threshold dissociation of H+2 ions in the presence of intense laser fields (I=1012–1014 W/cm2 ).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6233-6239 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The S-matrix version of the Kohn variational principle is used to obtain a very effective method for quantum scattering calculations. The approach is especially useful for the nonlocal (i.e., exchange) interactions that arise in chemically reactive scattering (and also in electron–atom/molecule scattering). The particular version developed in this paper has a more general structure than an earlier one by Miller and Jansen op de Haar [J. Chem. Phys. 86, 6213 (1987)], and applications to an elastic scattering problem, and also to three-dimensional H+H2 reactive scattering, show that it is also more useful in practice.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 3225-3238 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a practical nonperturbative method for exact treatment of intensity-dependent generalized nonlinear optical susceptibilities χ(ω) in intense polychromatic fields, valid for arbitrary laser intensities, detunings, and relaxation. By means of the many-mode Floquet theory, the time-dependent Liouville equation can be transformed into an equivalent time-independent infinite-dimensional Floquet–Liouville supermatrix (FLSM) eigenvalue problem. It is then shown that the nonlinear optical susceptibilities χ(ω) can be completely determined simply from the supereigenvalues and eigenfunctions of the Floquet–Liouvillian LˆF. In addition to this exact FLSM approach, we have also presented higher-order perturbative results, based on the extension of the Salwen's nearly degenerate perturbation theory, appropriate for somewhat weaker fields and near-resonant multiphoton processes, but beyond the conventional perturbative or rotating wave approximation (RWA). In the case of two-level systems, for example, the implementation of Salwen's method in the time-independent LˆF allows the reduction of the infinite-dimensional FLSM into a 4×4 dimensional effective Hamiltonian, from which essential analytical formulas for intensity-dependent χ(ω) can be obtained. These methods are applied to a detailed study of intensity-dependent spectral line shapes (such as hole burning and extra resonance peaks at the line center, and the effects of saturation, detuning, and radiative and collisional damping, etc.) and subharmonic structures in nonlinear multiple wave mixings χ[(m+1)ω1−mω2] for two-level systems in intense linearly polarized bichromatic fields.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 3898-3904 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A diffusion quantum Monte Carlo method, based on a trial wave function, built from floating spherical Gaussian orbitals and geminals, is reported. The ability to precisely sample the Gaussian function by using the Ornstein–Uhlenbeck random walks process, to treat electron correlation effect explicitly, and to apply the Hellmann–Feynman theorem are the important consequences of this approach. Floating functions, which remedy deficiency of electron density around nuclei, satisfy the Hellmann–Feynman theorem. Gaussian geminals, which correlate the electron pair directly, are used to treat correlation energy and to improve the quality of the trial wave function. Applying this type of trial wave function, within fixed-node approximation, in diffusion quantum Monte Carlo (QMC) calculation of ground state energies of lithium hydride molecule, provides very good estimates of the electronic energy and dipole moment. We also compare the results with several previous QMC results and experiments. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 208 (1993), S. 64-68 
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2234-2236 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bulk Y-Ba-Cu-O samples containing Si with nominal compositions of Y:Ba:Cu:Si=1:2:3:x (x=0.2, 0.4, and 0.6) have been prepared by adding SiO2 to the source materials. After a relatively short heat treatment, the resistance transition characteristics of the samples were found to improve as the SiO2 content was increased. Results from ac susceptibility measurements also showed improved values as the SiO2 content was increased. However, as the solid-state reaction was carried out at a lower temperature but for a longer time, the sample resistance increased and the superconductivity was found to degrade.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 1403-1411 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We extend the inhomogenous-differential-equation (IDE) approach of Dalgarno and Lewis for a detailed study of two-photon dissociation (TPD) of HD+ from high vibrational levels of the 1sσg electronic state. Contrary to the H+2 case, where the TPD cross sections σ(2)L are largest near TPD thresholds and decrease monotonically with increasing photon energy, the HD+ cross sections are characterized by rich resonant and interference structures. We present σ(2)L results for TPD from the initial vi =6, 8, 10, 12, 14, 16, and ji=0 levels as well as from vi=14, ji=0, 2, 4 levels for a wide range of wavelengths of linearly polarized radiation accessible by CO2 and CO lasers. It is found that while there are four TPD pathways, the channel 1sσg(vi ji)→ω 1sσg(v, j=ji±1) →ω2pσu(k, j f=j±1) dominates the two-photon process in most of the cases we have studied. Further, the results show that σ(2)L increases rather rapidly as the initial vibrational quantum number vi increases, indicating that the hereronuclear diatomic molecules in high vibrational levels can be efficiently two-photon dissociated by IR lasers. Consequently molecular structures near the dissociation limit may be conveniently probed by two-photon spectroscopy—as has indeed been demonstrated recently by experiments. Our σ(2)L results thus provide complementary information to the HD+ spectroscopic data obtained recently by Carrington et al.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 660-662 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the effects of high-temperature anneals on sequentially deposited TlBaCaCu films in an environment containing O2 and TlOx . From Auger electron spectroscopy depth profiles, it was found that Tl was quite volatile and can be easily eliminated from the thin films after a short treatment at 830 °C. However, the Tl can be incorporated in the films after appropriate treatment.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7414-7421 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The photoresponses of Pb doped 2223 phase BiSrCaCuO films to low power 5 mm cw radiation were measured at temperatures near Tc. To identify the involved detection mechanisms, dependence of responsivity on temperature, supplied current, radiation power, and film granularity were investigated. At temperatures in the vicinity of the transition to the normal state, good agreement was obtained with the responses derived from a bolometric model. At temperatures below the transition, a nonbolometric response mode was found to occur when the film was biased into a partially resistive regime. Transient measurements were carried out showing a response time for this mode of at least 5 orders of magnitude smaller than that of the bolometric response. Further characteristics inherent to the nonbolometric mode include square law detection, nonlinear current dependence, and short wavelength cutoff. In addition, a correlation between responsivity and film granularity was established. For strongly granular films with an active area of 300×1800 μm2, a detectivity D* of about 1.1×108 cm Hz1/2/W was typically achieved at a modulation frequency of 5 kHz. Consistency of the experimental results with the sub-gap responses of Josephson arrays is discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Histopathology 47 (2005), S. 0 
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In this Expert Opinion we have invited articles from two leading groups, to discuss serous borderline tumours (serous tumours of low malignant potential) of the ovary from their own perspectives. Controversy remains over heterogeneity within this group of tumours and their relationship to ovarian cancer. Our authors discuss the histopathological classification of these tumours in relation to morphological appearances, molecular and clinical data. The significance of a micropapillary pattern is discussed, and issues related to extra-ovarian implants.
    Type of Medium: Electronic Resource
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