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  • 1
    Electronic Resource
    Electronic Resource
    Vibrational energy relaxation of azulene in the S2 state. II. Solvent density dependence (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4340-4348 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured the vibrational energy relaxation of azulene in the S2 state in ethane, carbon dioxide, and xenon over a wide density region by the time-resolved fluorescence spectroscopy. The reduced density of the solvent (the density divided by the critical density) has been changed from the gaslike one (lower than 0.05) to the liquidlike one (2.8 for ethane, 2.7 for carbon dioxide, and 2.0 for xenon). The density dependence of the relaxation rate is compared with that of azulene in the S0 state [D. Schwarzer, J. Troe, M. Votsmeier, and M. Zerezke, J. Chem. Phys. 105, 3121 (1996)]. Although the absolute rate largely depends on the electronic state, the density dependence of the relaxation rates is roughly the same for both electronic states, which can be considered as a side-proof of the isolated binary collision model. Possible origins for the validity of the isolated binary collision model are discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288391
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  • 2
    Electronic Resource
    Electronic Resource
    Poor intergrain connectivity of PbMo6S8 in sintered Mo-sheathed wires and the beneficial effect of hot-isostatic-pressing treatments on the transport critical current density (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1606-1613 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure of Mo-sheathed Chevrel-phase superconducting wires was investigated by high-resolution scanning electron microscopy (SEM). Excess Pb forms small nodules (10–30 nm) on the Chevrel-phase grains or wetting layers between the Chevrel grains. The critical current density Jc is strongly reduced when wetting layers are present. However, second-phase Mo exists as islands as large as 2–10 μm and has little harmful effect on Jc. Although some Mo-sheathed wires sintered at 700 °C show relatively high Jc ( ≥ 2 × 108 A/m2 at 8 T), the Chevrel phase in these wires has a very porous microstructure, and the Jc values measured with a magnetic field parallel to the current, Jc((parallel)), were only about 10% higher than the Jc values measured with a field perpendicular to the current, Jc(⊥). This clearly suggests that the transport current flows percolatively in these wires. Much denser microstructures were obtained by hot-isostatic-pressing (HIP) treatments at 1200 °C, and very high Jc values, (approximately-greater-than) 5 × 108 A/m2 at 8 T and 9.3 × 107 A/m2 at 23 T, which are of the order of the highest Jc values so far reported, were observed. High-resolution SEM observations of HIP'ed wires demonstrate that the interconnectivity between the Chevrel grains was much improved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349525
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of PrBa2Cu3Oy and PrBa2Cu3Oy/YBa2Cu3Oy epitaxial films using molecular beam epitaxy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 298-300 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using molecular beam epitaxy, we have successfully prepared PrBa2Cu3Oy (PBCO) films and PBCO/YBa2Cu3Oy (YBCO) layered structures. Epitaxial growth of these films was confirmed by in situ reflection high-energy electron diffraction. The temperature dependence of resistivity in the PBCO film showed semiconducting behavior. The lattice parameters of Pr1+xBa2−xCu3Oy films decreased when x increased and almost coincided with that of well-oxidized YBa2Cu3Oy films (y∼7) when x∼0.3. These experimental results indicate that YBCO/PBCO/YBCO multilayers are suitable for artificial layered structures of oxide superconductors, i.e., electronic devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104667
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  • 4
    Electronic Resource
    Electronic Resource
    Non-Gaussian dynamics of a dilute hard-sphere gas (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 3029-3034 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have calculated nonlinear time correlation functions of a dilute hard-sphere gas numerically by using the Monte Carlo method, to find that the single particle dynamics in a dilute hard-sphere gas does not follow the Gaussian process. The deviation of the self-part of the dynamic structure factor from a Gaussian function is observed. This non-Gaussian character corresponds to those of Lennard-Jones liquids reported by Itagaki et al. [K. Itagaki, M. Goda, and H. Yamada, Physica A 265, 97 (1999)], if we scale the time unit by the collision frequency. Further, we trapped a particle in a harmonic well and calculated the time development of its distribution, in order to clarify the effect of collisions to the solvation dynamics. Both the Gaussian and the linear response assumptions are broken, and the deviation becomes larger as the curvature of the harmonic well gets larger. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1340616
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrafast transient-absorption spectroscopy of the aqueous solvated electron (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 5996-5998 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed the first direct pump-probe transient-absorption measurements on the near-infrared (IR) band of the equilibrated aqueous solvated electron. The pump pulse was centered at 780 nm. The absorption spectrum of the excited state is observed to be red-shifted relative to the ground-state absorption. The radiationless transition from the excited state to the ground state occurs with an average time constant of 550±170 fs. In observing a subpicosecond lifetime and red-shifted absorption for the excited p-states, these experiments are in accord with a growing body of experimental and theoretical work, serving to provide a consistent picture of the photophysics of the solvated electron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464839
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical equilibrium in fluids from the gaseous to liquid states: Solvent density dependence of the dimerization equilibrium of 2-methyl-2-nitrosopropane in carbon dioxide, chlorotrifluoromethane, and trifluoromethane (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 3085-3091 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the dimerization equilibrium of 2-methyl-2-nitrosopropane in carbon dioxide (CO2), chlorotrifluoromethane (CClF3), and trifluoromethane (CHF3) at 60 °C from the gaseous to liquid states. The dimerization equilibrium constants are not monotone functions of the solvent density in all solvent fluids. The density dependence of the equilibrium constant shows two inversions: The equilibrium constants in CO2 and CHF3 increase with increasing solvent density up to ρr(approximately-equal-to)0.3, where ρr is the reduced density by the critical density of solvent, whereas the equilibrium constant in CClF3 shows little dependence on the solvent density in this density region. From ρr(approximately-equal-to)0.3 to about 1.4, the equilibrium constants decrease with increasing solvent density. In the higher-density region, the equilibrium constants increase again. We measured the equilibrium constants in CClF3 and CHF3 at 35 °C, and obtain the density dependence of the equilibrium constant which is almost the same as that at 60 °C. The effects of the temperature and the solvent species on the equilibrium constant are larger in the low-density region than in the high-density region. The differences between the low- and high-density regions suggest that the energetic factor is dominant in the low-density region, and that the packing effect is dominant in the high-density region. The experimental results are qualitatively reproduced by a simple reaction model where two spherical molecules dimerize in a fluid composed of spherical molecules, although the reaction model overestimates the equilibrium constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461953
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical equilibrium in simple fluids: Solvent density dependence of the dimerization equilibrium of 2-methyl-2-nitrosopropane in argon and xenon (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 3824-3829 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the dimerization equilibrium of 2-methyl-2-nitrosopropane (MNP) at 60 and 35 °C in argon and xenon up to densities about twice the critical density of the solvent. With an increase in the solvent density, the dimerization equilibrium constant at 60 °C decreases in the low-density region, whereas it increases in the high-density region. The inversion of the density dependence occurs around ρr(approximately-equal-to)0.8 in argon and ∼1.4 in xenon, where ρr means the density reduced by the critical density of the solvent fluid. The equilibrium constant in xenon at 35 °C increases with increasing solvent density in the low-density region (ρr〈∼0.5), while it decreases in the medium-density region (0.5〈ρr〈1.5). The equilibrium constant in argon at 35 °C has a similar density dependence to that at 60 °C. The internal energy change for the dimerization shows a large density dependence in the low-density region of xenon, while it changes little with density in argon. The theoretical calculation by the Percus–Yevick (PY) approximation for a simple reaction model gives a poor result for the density dependence of the equilibrium constant, although the temperature dependence of the equilibrium constant is reproduced qualitatively. The calculation for a more realistic model including the molecular anisotropy of MNP suggests that the density dependence at the low-density limit is sensitive to the interaction model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461887
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrafast Transient Absorption Spectroscopy of the Solvated Electron in Water (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 3450-3458 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100064a029
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  • 9
    Electronic Resource
    Electronic Resource
    Vibrational energy relaxation of azulene in the S2 state. I. Solvent species dependence (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 2772-2783 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured the time-resolved fluorescence spectra of azulene in the S2 state in compressed gases and in liquids. We have found that the band shape of the fluorescence changes significantly in the earlier time scale after the photoexcitation when large excess energy (about 6500 cm−1) is given. The change of the band shape is similar both in the compressed gases and in the liquids, although the time scales of the change are quite different. We have measured the excitation energy dependence of the fluorescence band shape of the isolated molecule separately, and shown that the time dependence of the fluorescence band shape in gases and liquids corresponds to the vibrational energy relaxation in the S2 state. Comparing with the excitation energy dependence of the fluorescence band shape of the isolated molecule, we have succeeded in determining the transient vibrational excess energy. The vibrational energy relaxation rates in the S2 state are 1–2 times faster than those in the ground state both in compressed gases and in liquids. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1305822
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  • 10
    Electronic Resource
    Electronic Resource
    ERRATUM (2003)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 33 (2003), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2222.2003.01668.x
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