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  • 1
    Electronic Resource
    Electronic Resource
    Orange-green emission from porous Si coated with Ge films: The role of Ge-related defects (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 707-709 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence (PL) spectra of porous Si (PS) coated with Ge films were examined using the 514.5 nm line of Ar+ laser. A new orange-green PL band, centered at 2.25 eV, was observed with full-width at half-maximum of ∼0.1 eV, in addition to the reported PL bands at 3.1, 2.0, and 1.72 eV. With increasing the thickness of Ge layer coated, the new PL band remains unchanged in peak energy but drops abruptly in intensity. Spectral analysis and some experimental results from Raman scattering and x-ray diffraction indicate that Ge-related defects at the interfaces between PS and the Ge nanocrystals embedded in the pores are responsible for the orange-green PL band. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370790
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  • 2
    Electronic Resource
    Electronic Resource
    Optical fiber velocimetry: A technique for measuring velocity in two-dimensional flows (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 3215-3222 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article we describe a new technique, optical fiber velocimetry (OFV), to instantaneously measure two components of velocity at a point in freely suspended flowing liquid films. The technique relies on the measurement of displacements of an optical fiber tip which is coupled to the flowing film. The deflection of the fiber tip is proportional to the velocity and it behaves as a simple harmonic oscillator. Thus the low frequency response of the fiber gives direct measurements of the flow velocity. A statistical test using data acquired simultaneously by the fiber and by a laser Doppler velocimeter shows good agreement between the two techniques. Velocity power spectra measured in the wake of a von Karman street and in two-dimensional (2D) grid turbulence using the OFV also compare favorably with the laser Doppler velocimeter. The OFV technique is simple and robust, allowing it to be used in a wide variety of flows that have strong 2D characteristics. New prospects of using multiple fibers to measure circulation and velocity correlations at several separated spatial points are discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149086
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  • 3
    Electronic Resource
    Electronic Resource
    Shear flow in a two-dimensional Couette cell: A technique for measuring the viscosity of free-standing liquid films (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 5603-5608 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A two-dimensional shear viscometer has been constructed and tested using free-standing liquid soap films. The viscometer, which is an analog of a three-dimensional Couette cell, consists of an inner rotating disk and an outer stationary ring. The viscosity of the liquid films can be reliably obtained by measuring either the transient response of the disk upon a stepwise increment of the applied stress on the disk, or by measuring the strain-stress relation in the steady state. The design can be easily modified to accommodate other types of flow which are useful for investigating hydrodynamic and rheological behavior in a variety of thin films, such as liquid crystal and polymer films. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146027
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  • 4
    Electronic Resource
    Electronic Resource
    Raman scattering by longitudinal acoustic phonons in metallic W/Ti Fibonacci superlattice (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4063-4066 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman scattering from longitudinal acoustic phonons in W/Ti Fibonacci superlattice is studied. Doublet peaks which result from the folded longitudinal acoustic phonons appear in the Raman spectra as expected. Based on the Kronig–Penney model or the Rytov model, both the normal-mode frequencies and scattering intensities are numerically calculated by using a transfer-matrix method. Noticeable agreement is obtained between the results of quantitative calculations and experimental data. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363368
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  • 5
    Electronic Resource
    Electronic Resource
    Chemical relaxation in a chemiosmotic-coupled system: driving the calcium adenosine triphosphatase with bacteriorhodopsin (1987)
    s.l. : American Chemical Society
    Biochemistry 26 (1987), S. 6914-6918 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00396a008
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  • 6
    Electronic Resource
    Electronic Resource
    Light emission properties of crystalline SiO2 coated with LiNbO3/LiTaO3 multilayers (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3278-3280 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence (PL) properties of the crystalline SiO2 coated with LiNbO3/LiTaO3 multilayers were studied using the 514.5 nm line excitation. The 2.25 eV PL band observed at room temperature can be Gaussian divided into two subbands at 2.19 and 2.30 eV, which can be clearly resolved in the 77 K PL spectrum. The 2.30 eV band is z polarized with a polarization degree of 0.25 and its intensity has a linear dependence on the excitation power. No similar behavior was observed for the 2.19 eV band. Spectral analysis indicates that the two PL bands arise from optical transitions of the self-trapped excitons and E′ defect pairs in the crystalline SiO2 surface, which are induced by the photorefractive effect of the coated multilayers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123319
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  • 7
    Electronic Resource
    Electronic Resource
    X-ray diffraction study of alternating nanocrystalline silicon/amorphous silicon multilayers (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 838-840 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural properties of alternating nanocrystalline silicon/amorphous silicon multilayers with visible light emission at room temperature were examined by means of x-ray diffraction. According to the linewidths and intensities of the diffraction peaks in the low- and high-angle ranges, we have determined the effective interface thickness, the mean crystallite sizes, and the internal strains, which are closely related to the photoluminescence in this material. In addition, the existence of the voids or holes was also observed, indicating that the improved electrical properties of this kind of hydrogenated nanocrystalline materials are due to the inhomogeneous structure of the material. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118219
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  • 8
    Electronic Resource
    Electronic Resource
    Phonon properties and microstructure of annealed LiTaO3:Nd (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 2401-2403 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Phonon properties and microstructure of annealed Nd-doped LiTaO3 (LT:Nd) were examined by means of Raman scattering and infrared spectra. Raman spectra show the splitting of A1(TO) mode at 204 cm−1 and the appearance of an additional shoulder peak at ∼208 cm−1, indicating that the homogeneous distribution of Nd ions leads to the structural recovery of partial oxygen octahedra centered with Li and Ta ions, but the microstructural deviation from original LT trigonal system still exists. The enhancement of E(TO) mode intensities and the reduction of A1(TO) mode intensities in the A1+E symmetry spectrum are mainly attributed to the microstructural deviation of LT:Nd and the changed photorefractive effect due to annealing. Infrared spectra in the OH stretching region suggest that the changed photorefractive effect arises from the displacements of positive ions along the optical z axis. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118884
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  • 9
    Electronic Resource
    Electronic Resource
    Annealing temperature dependence of Raman scattering in Ge+-implanted SiO2 films (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2704-2706 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have examined the Raman spectra of violet and infrared emitting Ge+-implanted SiO2 films with special emphasis upon annealing temperature (AT) dependence of Raman scattering. We found that the complete spectrum mainly consists of three bands at 220–280, 300, and 430 cm−1, corresponding to scattering of Ge-related components, Ge nanocrystallites, and localized Si–Si optical phonons in the Ge neighborhoods, respectively. The Ge crystalline band shows an obvious AT dependence. The theoretical result from the phonon confinement model can predict its linewidth change with AT, but cannot explain its constant peak frequency. Based on the experimental result from x-ray diffraction, we attributed the discrepancy mainly to the compressive stress exerted on Ge nanocrystallites, which leads to the upshift of Ge crystallite peak thereby basically compensating the downshift caused by the confinement on phonon frequency. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366089
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  • 10
    Electronic Resource
    Electronic Resource
    Scanning tunneling microscopy investigations of the local structure of Tl2Ba2CaCu2O8 single crystals (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2129-2131 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The in-plane structure of single-crystal samples of Tl2Ba2CaCu2O8 has been imaged at room temperature using a scanning tunneling microscope. Atomic-resolution surface images exhibit areas in which the structure has tetragonal symmetry (peak spacing 2.5±0.2 A(ring)) and regions in which the structure is distorted from tetragonal symmetry. The lattice spacing indicates that the observed structure corresponds to the in-plane thallium and oxygen positions. The observation of both sites also suggests that the Tl-O band makes a significant contribution to the density of states near the Fermi level. In addition, a weak one-dimensional superlattice (period 10±0.5 A(ring)) which shows short-range order has been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102345
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