1,721,333 research outputs found
Supergain transistors on high-purity float-zone silicon substrate
No full textSince float-zone (FZ) silicon has lower contamination and longer minority carrier lifetime than those in Czochralski silicon and other semiconductor materials, it has potential advantages to fabricate a bipolar junction transistor on the FZ substrate to achieve high gain at very low current levels. In this report, the authors present preliminary experimental results on supergain bipolar junction transistors fabricated on unusual FZ refined high-resistivity silicon substrate and by ion implantation technology. A phosphorus-doped polycrystalline silicon backside gettering layer has been employed to preserve the long carrier lifetime of the high-purity FZ silicon. Bipolar junction transistors have demonstrated high current gain, more than 3300 for ultralow base current levels of 10 pA in this study. Possible applications of high-purity FZ silicon on some advanced semiconductor devices and circuits are discussed in this letter. (C) 2003 American Institute of Physics
Frontier Detectors for Frontier Physics - Proceedings of the 7th Pisa Meeting on Advanced Detectors, La Biodola, Isola d'Elba, Italy, May 25-31, 1997
No full textAbsolute excited state molecular geometries revealed by resonance Raman signals
Full text linkUltrafast reactions activated by light absorption are governed by multidimensional excited-state (ES) potential energy surfaces (PESs), which describe how the molecular potential varies with the nuclear coordinates. ES PESs ad-hoc displaced with respect to the ground state can drive subtle structural rearrangements, accompanying molecular biological activity and regulating physical/chemical properties. Such displacements are encoded in the Franck-Condon overlap integrals, which in turn determine the resonant Raman response. Conventional spectroscopic approaches only access their absolute value, and hence cannot determine the sense of ES displacements. Here, we introduce a two-color broadband impulsive Raman experimental scheme, to directly measure complex Raman excitation profiles along desired normal modes. The key to achieve this task is in the signal linear dependence on the Frank-Condon overlaps, brought about by non-degenerate resonant probe and off-resonant pump pulses, which ultimately enables time-domain sensitivity to the phase of the stimulated vibrational coherences. Our results provide the tool to determine the magnitude and the sensed direction of ES displacements, unambiguously relating them to the ground state eigenvectors reference frame
Frontier detectors for frontier physics - Proceedings of the 8th Pisa Meeting on Advanced Detectors La Biodola, Isola d' Elba, Italy, May 21-27, 2000
No full textProceedings of the 9th Pisa Meeting on Advanced Detectors - La Biodola, - Isola d'Elba, Italy, May 25-31, 2003
No full textA MODERN APPARATUS FOR THE STUDY OF THE KOKBARO SYSTEM FROM THE PHI(1020) PRODUCED IN E+E-
No full textSnapshots of sub-picosecond dynamics in heme-proteins captured by Femtosecond Stimulated Raman Scattering
No full textThe reaction pathway in photoexcited hemeproteins (ligand dissociation, energy redistribution and structural dynamics) has been unraveled by Femtosecond Stimulated Raman Scattering. The possible existence of short living intermediates as opposed to vibrational relaxation is discussed. © 2014 OSA
Energy flow between spectral components in 2D broadband stimulated Raman spectroscopy
Full text linkWe introduce a general theoretical description of non resonant impulsive femtosecond stimulated Raman spectroscopy in a multimode harmonic model. In this technique an ultrashort actinic pulse createscoherences of low frequency modes and is followed by a paired narrowband Raman pulse and abroadband probe pulse. Using closed-time-path-loop (CTPL) diagrams, the response on both the redand the blue sides of the broadband pulse with respect to the narrowband Raman pulse is calculated, theprocess couples high and low frequency modes, which share the same ground state. The transmittedintensity oscillates between the red and the blue side, while the total number of photons is conserved.The total energy of the probe signal is periodically modulated in time by the coherence created in the lowfrequency modes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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