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  • American Institute of Physics (AIP)  (9)
  • Institute of Electrical and Electronics Engineers  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Reflection of low energy hydrogen from carbon at oblique incidence (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6609-6615 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The particle reflection coefficient is determined experimentally and by computer simulation for the bombardment of two different kinds of carbon with deuterium at normal and oblique incidence in the energy range from 1 keV down to 33 eV. Highly oriented pyrolytic graphite (HOPG) and EK98 graphites served as targets, the former as an example with a relatively flat surface, the latter with a rough surface topography. The experimental technique is based on the measurement of the trapped amount by nuclear reaction analysis using the reaction d(3He,p)α; protons are detected with a surface barrier detector. It is found that the usual assumption of complete trapping at low fluences is not fulfilled at low energies (≤100 eV). This is demonstrated by measuring the decrease of the implanted amount of deuterium with further bombardment of protons at the same energy. This loss of implanted atoms can be described by an exponential function which can be used to determine the correct trapping coefficient and from this the correct particle reflection coefficient. The experimentally determined particle reflection coefficients for HOPG agree reasonably well with data calculated with the Monte Carlo program TRIM.SP (version TRVMC); only at the lowest energy of 50 eV the experimental values are somewhat higher at intermediate angles of incidence than the calculated ones. The rough surface of EK98 is investigated with a scanning tunneling microscope. It is found that this surface can be described by a fractal surface of dimension 2.05. For this surface agreement of the experimental values with those calculated with the program VFTRIM (based on TRIM.SP, assuming a fractal surface) is found. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359071
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  • 2
    Electronic Resource
    Electronic Resource
    Material gain of bulk 1.55 μm InGaAsP/InP semiconductor optical amplifiers approximated by a polynomial model (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 618-620 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report material gain measurements of bulk 1.55 μm InGaAsP/InP performed at constant temperature and carried out over a large range of carrier densities and a large spectral region. In addition, a polynomial model for the material gain is proposed that not only fits the experimental data well over the whole measured range but also shows stable convergence in simulation tools when carrier densities exceed the usual range. To get reliable parameters for the model we eliminated temperature effects arising from different current biases and performed material-gain measurements over the largest possible carrier density range. The material-gain model realized is used in semiconductor optical amplifier simulation tools. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371909
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  • 3
    Electronic Resource
    Electronic Resource
    Room-temperature low-threshold low-loss continuous-wave operation of 2.26 μm GaInAsSb/AlGaAsSb quantum-well laser diodes (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1581-1583 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained single- and triple-quantum-well (SQW and TQW), large optical cavity GaInAsSb/AlGaAsSb/GaSb laser diodes emitting at 2.26 μm are investigated. Internal loss coefficients as low as 5 and 7.7 cm−1 for the SQW and TQW, respectively, and relatively high internal quantum efficiencies of 65% (SQW) and 69% (TQW) were obtained. Extrapolated threshold current densities for infinite cavity lengths of 55 and 150 A/cm2 have been deduced for the SQW and TQW, respectively. These values scale very well with the number of QWs and are among the lowest reported for diode lasers in this wavelength range. A differential quantum efficiency as high as 50% and a total power efficiency of 23% were achieved at 280 K. The temperature dependence of the threshold current density revealed a high characteristic temperature of 110 K. Single-ended output powers of 240 mW in continuous-wave mode and exceeding 0.5 W in pulsed operation were obtained for a TQW laser with high-reflection/antireflection coated facets at 280 K, mounted substrate-side down. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1308537
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  • 4
    Electronic Resource
    Electronic Resource
    Calculation of shapes of dipolar domains in two-dimensional films: Effect of dipole tilt (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 9788-9794 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dispersed domains in two-dimensional two-phase systems often exhibit complex and intriguing morphologies. For many of these systems, it is possible to predict the shape of such a domain through an evaluation of the free energy. In this paper, we extend our previous numerical technique for calculating domain shapes by allowing for titled dipoles; the original technique assumed dipole moments oriented normal to the system plane. The solution diagram is presented in the vicinity of the primary shape transition for varying tilt angles. We find that circular domains are only stable in the absence of dipole tilt. Moreover, we find that the discontinuous transition found when the dipoles are vertical gives way to continuous elongation with increasing dipole tilt. Interestingly, it appears that the critical angle is independent of domain size. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469943
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  • 5
    Electronic Resource
    Electronic Resource
    Calculation of shapes of dipolar domains in insoluble monolayers: Analysis of shape stability and transitions (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 8399-8407 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dispersed domains in two-phase systems often exhibit complex and intriguing morphologies. For many of these systems, it is possible to predict the shape of such a domain through an evaluation of the free energy. In this paper, we present a numerical technique to calculate domain shapes through a variational approach. This is a significant extension to previous work which has primarily involved examining free energies of specific classes of shapes. The solution diagram is presented in the neighborhood of the first four bifurcations from a circle and the affect of domain size is examined. We find the only stable domain shapes are circular or bilobed. More importantly, we find that the transition between these two shapes is discontinuous, contrary to the findings of previous shape studies. Examining the free energy functional in the neighborhood of stable solutions, we find that, in general, domain shape calculations are best applied to small nonelongated domains. Finally, we present graphical differentiation, a numerical technique we developed to enable solution of the problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466787
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  • 6
    Electronic Resource
    Electronic Resource
    Ground state dynamics of NO3: Multimode vibronic borrowing including thermal effects (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 899-911 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The X 2A2' band of the photoelectron spectrum of NO−3 is theoretically calculated in the framework of a multimode vibronic coupling model. Linear coupling between and within the X 2A2' and the B 2E' electronic states of NO3 is found to be the important mechanism governing the dynamics. The necessary coupling constants are obtained from the ionization potentials of NO−3 calculated at different geometries using ab initio Green's functions. Comparison of the theoretical with experimental results [A. Weaver, D. W. Arnold, S. E. Bradforth, and D. M. Neumark, J. Chem. Phys. 94(3), 1740 (1991)] for the PE spectrum shows good agreement if a temperature of the NO−3 anion of 455 K in the experiment is assumed. A general theoretical treatment of thermal effects in vibronically coupled electronic states is presented. The ground electronic state potential surface of NO3 is discussed in the framework of the vibronic coupling model. A shallow minimum at a C2v geometry with a barrier height of 0.006 eV relative to the minimum energy D3h configuration is found. It is too weak to deform the effective geometry of the molecule from D3h to C2v. Mode-mode coupling is found to play a relevant role in the ground electronic state of NO3, in general.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466572
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  • 7
    Electronic Resource
    Electronic Resource
    Rovibronic coupling in the Na3 B system (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 8932-8942 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rovibronic spectrum of the Na3 B system is computed taking into account full rovibronic coupling between different vibronic states. The rovibronic coupling matrix elements are calculated using the vibronic states following from a pseudo Jahn–Teller model for the vibronic dynamics in the B system. Comparison with results of optical–optical double resonance measurements [W. E. Ernst and S. Rakowsky, Can. J. Phys. 72, 1307 (1994)] shows good agreement. In particular, certain properties of the Coriolis splittings, so far explained by an ad hoc spin–rotation interaction, are now well understood as the consequence of rovibronic coupling between two vibronic states. A general discussion of rovibronic dynamics on electronic potential energy surfaces with three equivalent minima is presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471627
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular rotations in vibronically coupled systems (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 4938-4963 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new general method to compute rovibronic energy levels and eigenstates in molecules with possibly strong vibronic coupling is presented. The method can be applied to arbitrary coupling mechanisms of electronic potential energy surfaces and is not limited to a special type of molecule. Explicit criteria for the applicability of the method are derived. To investigate different types of rovibronic interactions, parameter studies for linear and bilinear E×ε Jahn–Teller systems are performed. As an application to a real molecule we investigate the rotational structure of the Li3 electronic A state. A variety of possible nontrivial effects is found which cannot be explained by rotational–vibrational coupling on a single electronic potential energy surface. Attention is paid to construct explicit effective Hamiltonians describing the findings. The rovibronic motion on potential surfaces with equivalent minima is also discussed in this context. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472345
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  • 9
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    Imaging of phase change materials below a capping layer using correlative infrared near-field microscopy and electron microscopy (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-10-13
    Description: Phase Change Materials (PCM) show two stable states in the solid phase with significantly different optical and electronic properties. They can be switched reversibly between those two states and are promising candidates for future non-volatile memory applications. The development of phase change devices demands characterization tools, yielding information about the switching process at high spatial resolution. Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) allows for spectroscopic analyses of the different optical properties of the PCMs on the nm-scale. By correlating the optical s-SNOM images with transmission electron microscopy images of the same sample, we unambiguously demonstrate the correlation of the infrared optical contrast with the structural state of the phase change material. The investigated sample consists of sandwiched amorphous and crystalline regions of Ag 4 In 3 Sb 67 Te 26 below a 100   nm thick ( ZnS ) 80 − ( SiO 2 ) 20 capping layer. Our results demonstrate the sensitivity of s-SNOM to small dielectric near-field contrasts even below a comparably thick capping layer ( 100   nm ).
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 10
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    Accurate Estimation of Atmospheric Water Vapor Using GNSS Observations and Surface Meteorological Data (2015)
    Institute of Electrical and Electronics Engineers
    Details
    Publication Date: 2015-07-01
    Print ISSN: 0196-2892
    Electronic ISSN: 1558-0644
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Institute of Electrical and Electronics Engineers
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