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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 3371-3371 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    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 95 (1991), S. 373-379 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The valence photoemission spectrum of Fe(CO)5 is calculated by the ADC(3) Green's function method. The overall agreement with the experiment is good. It is shown that the quasiparticle picture (QPP) for the outer and inner valence levels (except the 8a‘2 level) derived primarily from CO ligand orbitals breaks down completely due to the one-hole/two-hole–one-particle (1h/2h1p) charge transfer (CT) coupling in the bonded system. Compared to Ni(CO)4 the many-electron effect is much stronger in Fe(CO)5. In Cr(CO)6 and Fe(CO)5 the 3d shell is incompletely filled, but in contrast to Cr(CO)6 in Fe(CO)5 there is no significant contribution from the local metal excitations. It is shown that for the 8a(large-closed-square)2 level the 1h state is still more stable than the 2h1p states. Consequently the main line (with an intensity of 0.76) is interpreted as the 1h state where the screening charge resides on the bonding orbital which is more polarized toward the ligand than in the ground state. The satellites are dominated by 2h1p configurations where the bonding to antibonding shake-up excitations occur. For the other CO derived levels the strong mixing of 1h and 2h1p configurations leads to the breakdown of the QPP of the ionization and thus a distinction between main line and satellite line becomes meaningless. For most of the levels, the strong dynamical metal–ligand CT hole–particle excitations, where the creation of two holes in the same metal orbital is involved, lead to the breakdown of the QPP of the ionization. A similar strong many-electron effect is also found in Cr(CO)6. For most of the outer and inner valence levels of these molecules, the QPP of the ionization breaks down.
    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 98 (1993), S. 8070-8079 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The carbon and oxygen 1s core excitation spectra of free CO and NiCO are calculated by ab initio 1h1p/1h1p and 2h2p/2h2p configuration interaction (CI) method using an extended basis set. We employed the ground state as well as core–hole relaxed orbitals. For free CO, we obtain a reasonably good description of the electron energy loss spectroscopy (EELS) spectra. The present interpretation of the spectra agrees with others. For NiCO, we obtain a reasonably good description of the near edge x-ray absorption fine structure (NEXAFS) spectra of the CO/Ni(100) system and that of the electron energy loss spectroscopy (EELS) spectra of the gas phase Ni(CO)4 . We show the existence of the Rydberg-derived additional excited states in the NEXAFS spectra of the chemisorbed molecule and give an interpretation of these states. The disappearance of the giant shake-up satellite in the NEXAFS spectra of the adsorbate is explained in terms of the hindrance of the cooperative core–hole screening mechanism in the π* resonantly excited state. The core–hole screening mechanism in the σ* resonantly excited state is also investigated.
    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 97 (1992), S. 6953-6957 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed ab initio algebraic diagrammatic construction [ADC(3)] Green's function calculations of the valence photoemission spectra of PF3 and NiPF3. We obtained overall good agreement with experiment for both the free PF3 molecule and the PF3 molecule chemisorbed on a Ni(111) metal surface. A comparison to NiCO shows that there are certain similarities between NiPF3 and NiCO, not only in the σ donor–π acceptor bonding mechanism in the ground state, but also in the metal–ligand CT excitations associated with the creation of a valence hole in the ligand. However, it appears that the many-body effect, such as the configuration interactions in the final ionized state, seems to be weaker for NiPF3 than for NiCO, judging from the main line spectral intensity. The quasiparticle picture of the 4e level breaks down completely as in the case of the 1π level of NiCO.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 2767-2771 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed ab initio two hole one particle (2h1p) CI and algebraic diagrammatic construction [ADC(3)] Green's function calculations of the valence photoemission spectrum of PdN2. The spectral features obtained by two different reliable methods are similar. However, they disagree with the experimental spectrum of N2/Pd(111) system. The 1π and 5σ ionization peaks are interpreted to be so well separated (1.6 eV) according to the experimental assignment, but the present theoretical result shows that despite a much weaker metal–ligand bonding, they are almost degenerate as in the case of the CO/Ni, CO/Pd, and N2/Ni systems. The basic spectral features and the relative positions of the 1π and 5σ levels do not change much with an increase of the metal–ligand bond length (weaker bonding strength). This shows that further detailed experimental study of the valence photoemission spectrum of the N2/Pd system is needed. The many-body effects such as the breakdown of the quasiparticle picture for the ionization is much stronger in NiN2 that in PdN2, despite the widely held assumption that weak coupling leads to increased many-body effects. It is shown that the change of the valence spectral features of the adsorbate depends on a subtle change of the electronic structure of the substrate metal atom rather than the metal–ligand bond strength.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 8120-8127 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: To investigate the dependence of ligand core-hole spectra on the electronic structure of the metal, we performed the ab initio 2h2p/3h2p configuration interaction (CI) calculation of the core-hole spectra of PdCO and Pd2CO molecules, using an extended basis set. The main line is the one-hole state and takes a much larger intensity than for NiCO and NiN2 but still smaller than for free CO. As in the case of NiCO and NiN2, for both PdCO and Pd2CO the π charge-transfer shakeup satellite of a small intensity is obtained. The most striking spectral feature of PdCO and Pd2CO which differs from NiCO and NiN2 is the absence of the 5 eV giant σ shakeup satellite in the carbon spectra of PdCO and Pd2CO. For PdCO the corresponding oxygen satellite of small intensity is shifted toward the higher energy (around 8 eV). This oxygen satellite is missing in Pd2CO. For the core-hole spectra of the CO/Pd(100) system which are not available, we expect satellite lines of small intensity around 10 eV. The absence and enhancement of the giant satellite in the core-hole spectra for the CO/Ni, N2/Ni, and CO/Pd systems are explained in terms of the different degree of the dσ-s hybrid and s-d promotion in the ground and ionized states.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: With successful conditioning, the beam lifetime of the SORTEC SR ring extended over 50 h at our nominal beam current of 200 mA. The conditioning and the results are discussed from the point of (i) optimization of operating point, (ii) high vacuum, and (iii) effective removal of the produced ion.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1620-1622 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Acoustic phase conjugate waves at 10 MHz were generated with PZT piezoelectric ceramics as highly nonlinear media. Phase conjugate power reflectivity was 10−3, which was 102 times higher than the conventional values with LiNbO3.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 29-31 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The acoustic phase conjugate wave was generated at 56 MHz by nonlinear electroacoustic interaction in LiNbO3 and its field was visualized with the schlieren technique. The field distribution of the phase conjugate wave was observed to be very close to that of the incident wave, and the time-reversal property of the phase conjugate waves was experimentally confirmed for the first time.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 5 (1994), S. 72-79 
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The mechanical properties of a composite material rely not only on the volume fraction, orientation and properties of the individual constituents, but upon their bonding interactions as well. This study examines the role of bonding between the mineral and organic constituents of bovine compact bone. Intact and completely demineralized samples were tested in tension following treatment in varying ionic strength sodium chloride or phosphate ion containing buffers to examine the interfacial bonding forces between bone's constituents. Phosphate ion treatment caused a reduction in the mechanical properties of intact samples but not in the demineralized samples. A sodium chloride solution with ionic strength equal to that of the phosphate ion buffer did not alter the mechanical properties of the intact or demineralized samples. Ash weight analysis, calcium probe measurements and SDS-gel electrophoresis indicated intact samples were not demineralized nor were bone structural proteins removed during treatment. Data suggest that the reduction in the mechanical properties of intact samples with phosphate ion treatment was due to an alteration in the interfacial bonding between the mineral and organic constituents of bone. Phosphate ions can compete with the negative domains of organic constituents for calcium binding sites of bone mineral and thereby interrupt or partially debond the interactions between the mineral and organic constituents of bone.
    Type of Medium: Electronic Resource
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