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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 152-159 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Ionization efficiency curves (IECs) were measured for Lin(OH)n−1 (n=2–5) clusters generated by reactions of laser-ablated lithium metal with water vapor, using photoionization time-of-flight mass spectrometry. The measured IECs are well-reproduced with a simulation involving Franck–Condon factors, enabling to identify the global-minimum structure of the clusters predicted in our theoretical study [Tanaka et al., J. Chem. Phys. 113, 1821 (2000)]. Hyperlithiated structures (HLS), in which an excess electron is delocalized, are identified for the cluster with n=2 and 3, while electron-localized or segregated structure (ELS) are for those with n=3–5. Adiabatic ionization energies were determined as 4.053±0.003 eV for HLS of Li2OH, 3.687±0.003 eV for HLS of Li3(OH)2, 4.133±0.003 eV for ELS of Li3(OH)2, and 3.418±0.009 eV for ELS of Li4(OH)3. The ionization energy of Li5(OH)4 was determined as 3.60±0.11 eV by a linear extrapolation of IEC. For Li3(OH)2, the energetics of two lowest-energy isomers is discussed based on the observed abundance ratio. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 1821-1830 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Density functional theory (DFT) calculations at the Becke three parameter hybrid functional with the Lee–Yang–Parr nonlocal correlation functional (B3LYP)/6-311+G(d,p) level are performed to study the stability and structures of lithium-excess lithium hydroxide clusters Lin(OH)n−1 (n=2–5). These small clusters are stable toward the dissociation to liberate one lithium atom and each of the clusters has structural isomers differing in the stability. The result of calculations implies that the most stable isomer of the clusters with n=2 and 3 have a "hyperlithiated" electronic structure, in which the excess electron fully delocalizes over all of the lithium atoms in the cluster, while the most stable isomer of the clusters with n=4 and 5 in which the excess electron localizes on a specific site has a "segregated" electronic structure composed of the metallic and ionic parts. Vertical ionization energies of the isomers of these clusters calculated by ab initio MO theory at the coupled cluster singles and doubles calculation including a perturbational estimate of the triples excitations [CCSD(T)] and second-order perturbation theory Møller–Plesset (MP2)/6-311+G(d,p) levels depend on the structure; e.g., around 5 eV for the planar isomers, approximately 4.2 eV for the "Li-tail" isomers with one terminal lithium atom, and 3.5 eV or less for the other isomers. The structure dependence of ionization energies reflects a feature of the singly occupied molecular orbital (SOMO) which accommodates the excess electron. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1600-0714
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: A peripheral ameloblastoma with atypical features occurring on the left maxillary alveolar ridge of 40-year-old man is described, along with an immunohistochemical profile of its cytokeratin (CK). The lesion apparently originated from the surface gingival epithelium. The tumor nests or strands were highly cellular with a variable degree of squamous differentiation and microcyst formation. Occasional mitotic figures and dystrophic calcification, both of which are not seen in conventional ameloblastomas, were also observed. The tumor infiltrated deep into the alveolar mucosa, including the periodontal ligament, and showed histological and topographical evidence of atypism, resulting in resorption of the underlying alveolar bone. On the CK immunohistochemistry, CK19 was demonstrated in all the types of neoplastic epithelia, including microcyst-forming cells, densely packed round or spindle cells within the tumor nests, cells with squamous metaplasia, and peripheral tall columnar cells. The CK immunohistochemical findings suggest the lesion’s cell of odontogenic origin; they may reflect an immature phenotypic expression of cell differentiation in the odontogenic epithelia during the tumor growth in the gingival mucosa.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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