Search Results - (Author, Cooperation:M. Spencer)
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1Latest Papers from Table of Contents or Articles in PressSarah Ellen Johnston, Natalia Shorina, Ekaterina Bulygina, Taisya Vorobjeva, Anna Chupakova, Sergey I. Klimov, Anne M. Kellerman, Francois Guillemette, Alexander Shiklomanov, David C. Podgorski, Robert G. M. Spencer
Wiley-Blackwell
Published 2018Staff ViewPublication Date: 2018-03-06Publisher: Wiley-BlackwellPrint ISSN: 0148-0227Topics: BiologyGeosciencesPublished by: -
2Latest Papers from Table of Contents or Articles in PressYinghui Wang, Yunping Xu, Robert G. M. Spencer, Phoebe Zito, Anne Kellerman, David Podgorski, Wenjie Xiao, Dandan Wei, Harunur Rashid, Yuanhe Yang
Wiley-Blackwell
Published 2018Staff ViewPublication Date: 2018-03-09Publisher: Wiley-BlackwellPrint ISSN: 0148-0227Topics: BiologyGeosciencesPublished by: -
3Latest Papers from Table of Contents or Articles in PressToyota, M., Spencer, D., Sawai-Toyota, S., Jiaqi, W., Zhang, T., Koo, A. J., Howe, G. A., Gilroy, S.
American Association for the Advancement of Science (AAAS)
Published 2018Staff ViewPublication Date: 2018-09-14Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyGeosciencesComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: BotanyPublished by: -
4Latest Papers from Table of Contents or Articles in PressTu, C. C., Arnolds, K. L., O'Connor, C. M., Spencer, J. V.
The American Society for Microbiology (ASM)
Published 2018Staff ViewPublication Date: 2018-02-14Publisher: The American Society for Microbiology (ASM)Print ISSN: 0022-538XElectronic ISSN: 1098-5514Topics: MedicinePublished by: -
5Latest Papers from Table of Contents or Articles in PressMariȷn Bauters, Travis W. Drake, Hans Verbeeck, Samuel Bode, Pedro Herve–Fernandez, Phoebe Zito, David C. Podgorski, Faustin Boyemba, Isaac Makelele, Landry Cizungu Ntaboba, Robert G. M. Spencer, Pascal Boeckx
National Academy of Sciences
Published 2018Staff ViewPublication Date: 2018-01-17Publisher: National Academy of SciencesPrint ISSN: 0027-8424Electronic ISSN: 1091-6490Topics: BiologyMedicineNatural Sciences in GeneralPublished by: -
6Latest Papers from Table of Contents or Articles in PressA. Steele ; F. M. McCubbin ; M. Fries ; L. Kater ; N. Z. Boctor ; M. L. Fogel ; P. G. Conrad ; M. Glamoclija ; M. Spencer ; A. L. Morrow ; M. R. Hammond ; R. N. Zare ; E. P. Vicenzi ; S. Siljestrom ; R. Bowden ; C. D. Herd ; B. O. Mysen ; S. B. Shirey ; H. E. Amundsen ; A. H. Treiman ; E. S. Bullock ; A. J. Jull
American Association for the Advancement of Science (AAAS)
Published 2012Staff ViewPublication Date: 2012-05-26Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: Carbon/*analysis ; Crystallization ; Extraterrestrial Environment ; *Mars ; *Meteoroids ; Organic Chemicals/*analysis ; Oxidation-Reduction ; Oxides/analysis ; Polycyclic Hydrocarbons, Aromatic/*analysis/chemistry ; Silicates/*chemistry ; Spectrum Analysis, RamanPublished by: -
7Articles: DFG German National LicensesPerks, E. R. ; Cadle, D. R. ; Boulton, T. B. ; Swaine, M. Spencer
Oxford, UK : Blackwell Publishing Ltd
Published 1968Staff ViewISSN: 1365-2044Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineType of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesCadle, D. R. ; Boulton, T. B. ; Swaine, M. Spencer
Oxford, UK : Blackwell Publishing Ltd
Published 1968Staff ViewISSN: 1365-2044Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineType of Medium: Electronic ResourceURL: -
9Latest Papers from Table of Contents or Articles in PressRobert H. Wilson, Elena Martin-Avila, Carly Conlan, Spencer M. Whitney
The American Society for Biochemistry and Molecular Biology (ASBMB)
Published 2018Staff ViewPublication Date: 2018-01-06Publisher: The American Society for Biochemistry and Molecular Biology (ASBMB)Print ISSN: 0021-9258Electronic ISSN: 1083-351XTopics: BiologyChemistry and PharmacologyPublished by: -
10Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2018-06-05Publisher: Nature Publishing Group (NPG)Electronic ISSN: 2045-2322Topics: Natural Sciences in GeneralPublished by: -
11Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2018-05-18Publisher: Institute of Physics Publishing (IOP)Electronic ISSN: 1748-0221Topics: PhysicsPublished by: -
12Articles: DFG German National LicensesStaff View
ISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Electron tunneling spectroscopy has been used to study the phonon modes of the GaAs electrode and the AlGaAs barrier of single barrier GaAs/AlGaAs/GaAs heterostructures. The barriers were spiked doped with Si or Be to determine whether defects or impurities in the barrier have an effect on the measured line shapes. The phonon line shapes and intensities have been observed to change after shining light on the devices to photoionize defects in the barrier. The results demonstrate that the charge state of defects in a heterostructure barrier can affect the interaction between a tunneling electron and the phonon modes of a tunnel barrier.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesFlannery, C. ; Mizugai, Y. ; Steinfeld, J. I. ; Spencer, M. N.
College Park, Md. : American Institute of Physics (AIP)
Published 1990Staff ViewISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: Rotational relaxation times in ozone–ozone collisions have been measured for selected rovibrational levels using the time-resolved infrared double-resonance technique. Rotationally inelastic processes account for at least 90% of the measured pressure-broadening rate. The rotational-state dependence of the relaxation cross sections is in good accord with the collision models used in current theories of pressure broadening. The V–V energy transfer rate between symmetric and asymmetric stretching modes of ozone has also been measured; the V–V cross section is approximately 15 A(ring)2, about an order of magnitude smaller than that for rotational energy transfer.Type of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesStaff View
ISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Surface potentials on GaN epilayers and Al0.35Ga0.65N/GaN heterostructures have been studied by scanning Kelvin probe microscopy (SKPM) in conjunction with noncontact atomic force microscopy. The dependence of the surface potential on doping in GaN films, as well as the variation of surface potential with Al0.35Ga0.65N barrier layer thickness has been investigated. The bare surface barrier height (BSBH), as measured by SKPM, is observed to decrease from ∼1. 40±0.1 eV to ∼0.60±0.1 eV with increasing doping in the GaN epilayers. Schottky barrier height calculated from the measurements of BSBH on n-GaN agrees very well with results from previous studies. We have also estimated the surface state density for GaN based on the measured values of BSBH. The semiconductor "work function" at the Al0.35Ga0.65N surface (in heterostructure samples) is observed to decrease by ∼0.60 eV with increase in barrier layer thickness from ∼50 to ∼440 Å. A simple model considering the presence of a uniform density of charged acceptors in the Al0.35Ga0.65N layer is proposed to explain the observed decreasing trend in work function. © 2001 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesSu, C. M. ; Wuttig, Manfred ; Fekade, A. ; Spencer, M.
[S.l.] : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Chemical vapor deposited 3C-SiC films were micromachined into free standing cantilevers and their anelastic and elastic properties were determined by a vibrating reed technique. Despite a high density of defects, epitaxial 3C-SiC exhibits extremely high mechanical Q which is essential for resonator sensors and actuators. An anelastic relaxation peak was found with an associated activation energy of 0.94 eV. Doping caused splitting of this peak. The mechanism of the mechanical relaxation peak is discussed in relation to defect movement under stress. Young's modulus of epitaxial undoped 3C-SiC was found to be 694 GPa, p-doping reduced it to 474 Gpa. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesSu, C. M. ; Fekade, A. ; Spencer, M. ; Wuttig, Manfred
[S.l.] : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: The internal stresses in chemical-vapor-deposited 3C-SiC films were studied by a vibrating membrane technique. The differential thermal expansivity of 3C-SiC films was investigated by the change of the internal stress as a function of temperature. It was found that the internal stress of the films is dominated by thermal stresses and its magnitude depends both on doping and the film thickness. While p doping substantially increases the stress, increasing the film thickness reduces the stress of the SiC layer. The thermal expansivity of the SiC layer shows a lower value which is significantly less than that of bulk 3C-SiC and tends to approach the expansivity of the Si substrate. It is proposed that the stress dependence of the SiC films on doping and film thickness is the result of the film morphology which is heavily faulted for very thin films and more perfect as the film thickness increases. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesScott, C. J. ; Tang, X. ; Spencer, M. G.
Woodbury, NY : American Institute of Physics (AIP)
Published 1991Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: A bilayer LaB6/Au, laser driven, photoelectron source for high-speed pulsed electron applications has been investigated. Preliminary results show the cathode operating at a quantum efficiency of 1.4×10−5 when illuminated with a mode-locked, frequency quadrupled Nd:YAG, 266 nm laser source. The measured current output at a pressure of 1×10−5 Torr was found to be three times larger than a single-layer gold photocathode structure.〈lz〉 〈lz〉 〈lz〉 〈lz〉Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesTadayon, Bijan ; Tadayon, Saied ; Spencer, M. G. ; Harris, G. L. ; Rathbun, L. ; Bradshaw, J. T. ; Schaff, W. J. ; Tasker, P. J. ; Eastman, L. F.
Woodbury, NY : American Institute of Physics (AIP)
Published 1988Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: The GaAs-Al-GaAs structure is grown using migration-enhanced epitaxy (MEE) method at low temperature on a molecular beam epitaxy machine. With MEE the interdiffusion between Al and GaAs is reduced by a large amount, and the morphology is improved by a large degree. Still, Raman spectrum indicates poor crystallinity for the GaAs of the top layer. The effect of different annealing temperatures on the interdiffusion is also studied.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesTadayon, Bijan ; Tadayon, Saied ; Schaff, W. J. ; Spencer, M. G. ; Harris, G. L. ; Tasker, P. J. ; Wood, C. E. C. ; Eastman, L. F.
Woodbury, NY : American Institute of Physics (AIP)
Published 1989Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: Be-doped GaAs layers were grown by the migration-enhanced epitaxy (MEE) method at 300 °C. The MEE layers showed practically no electrical activation. Rapid thermal annealing on the MEE layers resulted in mobility and hole concentration comparable to those of conventional molecular beam epitaxy (MBE) layers grown at 600 °C. Secondary-ion mass spectroscopy showed that the Be diffusion in annealed MEE layers was much smaller than that in conventional MBE layers, especially for highly doped layers. Raman spectroscopy and 4 K photoluminescence were also performed. The MEE method can replace the conventional MBE method for device applications which require high hole concentration with small diffusion.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesMagno, R. ; Shelby, R. ; Kennedy, T. A. ; Spencer, M. G.
[S.l.] : American Institute of Physics (AIP)
Published 1989Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Deep-level transient spectroscopy has been used to study metastable defects in Be-doped Alx Ga1−x As grown by molecular-beam epitaxy. The metastability manifests itself by the appearance of different spectra depending upon whether the sample is cooled from a high temperature with zero bias or a reverse bias applied to it. The defects are found in concentrations of 1015 cm−3 in a sample doped with 1018 Be cm−3 and in much lower concentrations in a 1017 Be cm−3 sample. Isochronal annealing experiments indicate that the defect is multistable and that it is best modeled as a mobile interstitial which can reside at several sites near an acceptor. The activation energies for these defects are between 0.2 and 0.5 eV above the valence band.Type of Medium: Electronic ResourceURL: