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  • 1
    Electronic Resource
    Electronic Resource
    A 16 cm broad-beam ion source for ion-beam etching of quartz wafers : Proceedings of the 6th international conference on ion sources (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1009-1011 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broad-beam ion source is developed for ion-beam etching of quartz wafers, which are used in resonators with a high basic frequency of the order of magnitude of 1 GHz. The improvement of uniformity of the extracted ion beam is investigated. The double-grid multiple-aperture ion optics is adopted, in which perveance is matched by varying both the aperture diameters and spaces between grids. The configuration of the magnetic field is optimized. Measured at the target of 12 cm from the grids, the area of uniform region (nonuniformity 〈5%) is approximately equal to the area of the bored region of the grids (12 cm diam) and 1/1.78 of the cross-section area of the anode (16 cm diam). A broad beam of 100–1000 eV and 0.1–2.0 mA/cm2 is extracted from the source to fulfill the requirement of the etching process. Without any cooling system, the ion source is installed in vacuum chamber. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146799
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    Paper (German National Licenses)
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  • 2
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    Synaptic devices based on purely electronic memristors (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-01-06
    Description: Memristive devices have been widely employed to emulate biological synaptic behavior. In these cases, the memristive switching generally originates from electrical field induced ion migration or Joule heating induced phase change. In this letter, the Ti/ZnO/Pt structure was found to show memristive switching ascribed to a carrier trapping/detrapping of the trap sites (e.g., oxygen vacancies or zinc interstitials) in ZnO. The carrier trapping/detrapping level can be controllably adjusted by regulating the current compliance level or voltage amplitude. Multi-level conductance states can, therefore, be realized in such memristive device. The spike-timing-dependent plasticity, an important Hebbian learning rule, has been implemented in this type of synaptic device. Compared with filamentary-type memristive devices, purely electronic memristors have potential to reduce their energy consumption and work more stably and reliably, since no structural distortion occurs.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 3
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    Multiple stimulated emission fluorescence photoacoustic sensing and spectroscopy (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-07-07
    Description: Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitation spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 4
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    Analysis of stimulated Raman photoacoustics in frequency domain: A feasibility study (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-08-27
    Description: The frequency domain analysis of stimulated Raman Photoacoustic (PA) induced by laser pulses with Gaussian and rectangular temporal profiles is presented. Utilizing the pulsed laser with nanosecond and microsecond pulse width with Gaussian temporal profile, the frequency component of the PA signals cannot be differentiated between the stimulated Raman PA and the linear optical absorption PA, which is limited by the response bandwidth of biological tissue. When the laser pulses with rectangular temporal profile are used, we deduced the PA expression and numerically derived its frequency spectrum. The frequency components of PA signal induced by the stimulated Raman phonons is more than that induced by optical absorption in some low frequency ranges, which is inside the bandwidth of tissue system. Therefore, stimulated Raman PA signal can be distinguished from the linear optical absorption PA signal in frequency domain. Numerical simulations were conducted in this paper to demonstrate the proposition and feasibility of stimulated Raman PA in frequency domain, which will be experimentally validated in future work.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 5
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    Microstructure and dielectric properties of (Nb + In) co-doped rutile TiO2 ceramics (2014)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2014-08-19
    Description: The (Nb + In) co-doped TiO 2 ceramics recently attracted considerable attention due to their colossal dielectric permittivity (CP) (∼100,000) and low dielectric loss (∼0.05). In this research, the 0.5 mol. % In-only, 0.5 mol. % Nb-only, and 0.5–7 mol. % (Nb + In) co-doped TiO 2 ceramics were synthesized by standard conventional solid-state reaction method. Microstructure studies showed that all samples were in pure rutile phase. The Nb and In ions were homogeneously distributed in the grain and grain boundary. Impedance spectroscopy and I-V behavior analysis demonstrated that the ceramics may compose of semiconducting grains and insulating grain boundaries. The high conductivity of grain was associated with the reduction of Ti 4+ ions to Ti 3+ ions, while the migration of oxygen vacancy may account for the conductivity of grain boundary. The effects of annealing treatment and bias filed on electrical properties were investigated for co-doped TiO 2 ceramics, where the electric behaviors of samples were found to be susceptible to the annealing treatment and bias field. The internal-barrier-layer-capacitance mechanism was used to explain the CP phenomenon, the effect of annealing treatment and nonlinear I-V behavior for co-doped rutile TiO 2 ceramics. Compared with CaCu 3 Ti 4 O 12 ceramics, the high activation energy of co-doped rutile TiO 2 (3.05 eV for grain boundary) was thought to be responsible for the low dielectric loss.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 6
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    Anomalous specific heats of metallic nanocrystals induced by surface oxidation (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-11-24
    Description: Although the low-temperature specific heat in metallic nanocrystals has been extensively demonstrated to be always enhanced due to the surface phonon softening, it is revealed here to be anomalously depressed by the surface oxidation so that the excess specific heat can be either positive or negative as a function of temperature with respect to the counterparts of the bulk crystals. The background mechanism has been theoretically deduced to well explain these experimental phenomena by calculating and comparing the vibrational densities of states (VDOS) of face-centered-cubic-aluminum (fcc-Al) and amorphous-alumina (a-Al 2 O 3 ) nanoparticles. Different from fcc-Al nanocrystals, both the surface and volume VDOSs g(ω) of a-Al 2 O 3 nanoparticles are scaled as g(ω) ∼ ω 1.5 at the low-frequency limit (ω). The effective spatial dimension for the a-Al 2 O 3 surfaces and volume as well as the fcc-Al surfaces is thus assumed to be between 2D and 3D while it is 3D for the fcc-Al volume. The specific heat of a-Al 2 O 3 @Al nanoparticles is consequently revealed to show a different T -dependent feature from those of both pure metallic nanocrystals and bulk crystals at low temperatures.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics (AIP)
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