Angle-resolved photoemission study of CoSi2 nanofilms grown on Si(111) substrates

We have carried out an angle-resolved photoemission study for CoSi₂ nanofilms grown on the Si(111)-7×7 substrates. The surface of CoSi₂(111) nanofilm changes from the bulk-truncated surface to the surface with additional Si-bilayer by annealing at higher temperature above 825 K. The angle-resolved photoemission spectra of the CoSi₂ nanofilm annealed at 853 K show the spectral features originated from the surface resonance state on the CoSi₂ surface terminated by Si-bilayer. From the detailed photoemission study, we discuss the surface electronic structure in CoSi₂(111) nanofilms grown on Si(111) substrates.     

A supplement to precise asymptotics in the law of the iterated logarithm

Let <img height="14" border="0" style="vertical-align:bottom" width="101" alt="View the MathML source" title="View the MathML source" src="http://ars.els-cdn.com/content/image/1-s2.0-S0022247X04006493-si1.gif"> be a sequence of real-valued i.i.d. random variables with E(X)=0 and E(X²)=1, and set <img height="18" border="0" style="vertical-align:bottom" width="92" alt="View the MathML source" title="View the MathML source" src="http://ars.els-cdn.com/content/image/1-s2.0-S0022247X04006493-si4.gif">, n?1. This paper studies the precise asymptotics in the law of the iterated logarithm. For example, using a result on convergence rates for probabilities of moderate deviations for <img height="14" border="0" style="vertical-align:bottom" width="78" alt="View the MathML source" title="View the MathML source" src="http://ars.els-cdn.com/content/image/1-s2.0-S0022247X04006493-si6.gif"> obtained by Li et al. [Internat. J. Math. Math. Sci. 15 (1992) 481-497], we prove that, for every b&isin;(&minus;1/2,1], iv class="formula" id=">iv class="mathml"><img height="80" border="0" style="vertical-align:bottom" width="432" alt="View the MathML source" title="View the MathML source" src="http://ars.els-cdn.com/content/image/1-s2.0-S0022247X04006493-si8.gif">     

Discontinuous flow-through measurement of gamma-rays. Principles of operation and application in clinical biochemistry

Ohne Zusammenfassung

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Discontinuous flow-through measurement of gamma-rays. Principles of operation and application in clinical biochemistry

     

On the Law of The Iterated Logarithm for Rapidly Increasing Subsequences

The usual law of the iterated logarithm states that the partial sums <i>Si>_<i>ni> of independent and identically distributed random variables can be normalized by the sequence <i>ai>_<i>ni> = √<i>ni>log log <i>ni>, such that limsup_<i>ni>→∞ <i>Si>_<i>ni>/<i>ai>_<i>ni> = √2 a.s. As has been pointed out by Gut (1986) the law fails if one considers the limsup along subsequences which increase faster than exponentially. In particular, for very rapidly increasing subsequences {<i>n_ki>≥1} one has limsup_<i>ki>→∞ <i>S_nki>/<i>a_nki> = 0 a.s. In these cases the normalizing constants <i>a_nki> have to be replaced by √<i>nki> log <i>ki> to obtain a non-trivial limiting behaviour: limsup_<i>ki>→∞ <i>S_nki>/ √<i>nki> log <i>ki> = √2 a.s. We will present an intelligible argument for this structural change and apply it to related results.     

Hot electron relaxation in one-dimensional models: exact polaron dynamics versus relaxation in the presence of a Fermi sea

We present the exact solution for the time evolution of the electron and phonon momentum distribution for a one-dimensional polaron model with a<i>lineari> electronic energy dispersion. The electron momentum distribution is shown to obey a<i>Markoviani> quantum kinetic equation. Numerical results for the polaron model are compared to the corresponding exact results, when the negative momentum states are filled in the initial state. The presence of this Fermi sea modifies the dynamics except in the short time regime. The different, long time dynamics might show up in comparison of hot electron relaxation of undoped and doped semiconductors.     

Structural relaxation and viscous flow in amorphous ZrAlCu

The ternary metallic glass Zr₆₅Al_7.5Cu_27.5 offers a wide temperature range between glass transition temperature and crystallization temperature and is therefore well suited for investigation of the glass transition and the state of the super cooled liquid. The non-linear viscosity change caused by structural relaxation has been measured caused by structural relaxation has been measured using tensile creep experiments on as quenched samples. The increase of viscosity can be described by bimolecular annihilation kinetics of flow defects. The Arrhenius plot of equilibrium viscosity shows a kink at a temperature which seems to be the glass transition temperature. The activation energies of viscous flow below and above that glass transition temperature differ by nearly a factor two. Different microscopic processes responsible for viscous flow in the two regimes of temperature are therefore conceivable. This view is also encouraged by Dynamic-Mechanical-Analysis on relaxed samples, a method to examine the viscoelastic behaviour of glassy materials on different time scales and by recent diffusion measurements on a different system.     

Improvement of amorphous silicon n-i-p solar cells by incorporating double-layer hydrogenated nanocrystalline silicon structure

We develop a double-layer p-type hydrogenated nanocrystalline silicon (p-nc-Si:H) structure consisting of a low hydrogen diluted i/p buffer layer and a high hydrogen diluted p-layer to improve the hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells. The electrical, optical and structural properties of p-nc-Si:H films with different hydrogen dilution ratio (R_H) are investigated. High conductivity, low activation energy and wide band gap are achieved for the thin films. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) analyses indicate that the thin films contain nanocrystallites with grain size around 3-5 nm embedded in the amorphous silicon matrix. By inserting a p-nc-Si:H buffer layer at the i/p interface, the overall performance of the solar cell is improved significantly compared to the bufferless cell. The improvement is correlated with the reduction of the density of defect states at the i/p interface.     

Optical Properties of Zinc-Blende InGaN/GaN Quantum Well Structures and Comparison with Experiment

Optical properties of zinc-blende InGaN/GaN Q W structures are investigated using the multiband effective-mass theory. The transition wavelength values at 300 K ranged from 440 to 570nm in the investigated range of the In composition and the well width. The theoretical wavelengths show reasonable agreement with the experimental results. The optical gain decreases with the increasing well width. This is mainly due to the reduction in the quasi-Fermi-level separation because the optical matrix element increases with the well width.     

Kinks and waterfalls in the dispersion of ARPES features

In this paper we use a generic form for the Green function G(k, ω) in a correlated metal, already proven successful in describing ARPES line shapes [1]. The associated many body self-energy function has only a single pole. We now investigate, whether this generic model can be used all the way to the limit of strong correlations and, when applied to ARPES intensities, whether it is able to explain some of the ubiquitous dispersive crossover phenomena that have been attributed to dynamical, i.e.: ω-dependent effects. We argue that a quantitative interpretation of experimental data requires to calculate extrema not only in the momentum distribution curve but also in the energy distribution curve. In passing, we give a formula for the extrema in the latter distribution that is valid for the general G(k, ω) in a many body system. To our knowledge, this is a new formula, not found in the literature. The investigation of the generic model proceeds on two levels: on the one hand, we explore the rich variety of crossovers that can be predicted and linked to well defined features in the complex ω-plain. On the other hand, we show that the generic one-pole self-energy can be viewed as a projection on the low energy sector of a microscopic solution, belonging to a lattice model of interacting fermions. To obtain approximate microscopic solutions, we use our continued fraction method [2] and [3]. As an explicit example, we study the projection for the case of a hole doped Hubbard model in infinite dimension. A discussion section gives examples, how the generic model is able to cope with the ubiquity of the crossover phenomena, also in finite dimension and beyond the Hubbard model.     

Ergodicity and transience of SDEs driven by -stable processes with Markovian switching

In this paper, we focus on ergodicity and transience of SDEs driven by symmetric ipt><img src="/na101/home/literatum/publisher/tandf/journals/content/gapa20/2018/gapa20.v097.i07/00036811.2017.1307966/20180625/images/gapa_a_1307966_ilm0004.gif" alt=" />ipt><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" alt=" class="no-mml-formula" data-formula-source="{"type" : "image", "src" : "/na101/home/literatum/publisher/tandf/journals/content/gapa20/2018/gapa20.v097.i07/00036811.2017.1307966/20180625/images/gapa_a_1307966_ilm0004.gif"}" />-stable processes (ipt><img src="/na101/home/literatum/publisher/tandf/journals/content/gapa20/2018/gapa20.v097.i07/00036811.2017.1307966/20180625/images/gapa_a_1307966_ilm0005.gif" alt=" />ipt><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" alt=" class="no-mml-formula" data-formula-source="{"type" : "image", "src" : "/na101/home/literatum/publisher/tandf/journals/content/gapa20/2018/gapa20.v097.i07/00036811.2017.1307966/20180625/images/gapa_a_1307966_ilm0005.gif"}" />) with Markovian switching. Some sufficient conditions for ergodicity of several classes of stable processes with Markovian switching are given. Furthermore, an almost necessary and sufficient condition for ergodicity of Ornstein–Uhlenbeck type driven by symmetric ipt><img src="/na101/home/literatum/publisher/tandf/journals/content/gapa20/2018/gapa20.v097.i07/00036811.2017.1307966/20180625/images/gapa_a_1307966_ilm0006.gif" alt=" />ipt><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" alt=" class="no-mml-formula" data-formula-source="{"type" : "image", "src" : "/na101/home/literatum/publisher/tandf/journals/content/gapa20/2018/gapa20.v097.i07/00036811.2017.1307966/20180625/images/gapa_a_1307966_ilm0006.gif"}" />-stable processes with Markovian switching is presented. As applications, some examples are provided to illustrate our results.