Search results for "F10"
showing 10 items of 51 documents
Focus on the Essential: Extracting the Decisive Energy Barrier of a Complex Process
2019
Molecular processes at surfaces can be composed of a rather complex sequence of steps. The kinetics of even seemingly simple steps are demonstrated to depend on a multitude of factors, which prohibits applying a simple Arrhenius law. This complexity can make it challenging to experimentally determine the kinetic parameters of a single step. However, a molecular-level understanding of molecular processes such as structural transitions requires elucidating the atomistic details of the individual steps. Here, a strategy is presented to extract the energy barrier of a decisive step in a very complex structural transition by systematically addressing all factors that impact the transition kineti…
[Cu(bpy)(P^P)]+ containing light-emitting electrochemical cells: improving performance through simple substitution
2014
Light-emitting electrochemical cells (LECs) containing [Cu(POP)(N^N)][PF6] (POP = bis(2-diphenylphosphinophenyl)ether, N^N = 6-methyl- or 6,6′-dimethyl-2,2′-bipyridine) exhibit luminance and efficiency surpassing previous copper(i)-containing LECs.
Luminescent copper(i) complexes with bisphosphane and halogen-substituted 2,2′-bipyridine ligands
2018
Heteroleptic [Cu(P^P)(N^N)][PF6] complexes, where N^N is a halo-substituted 2,2'-bipyridine (bpy) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9- dimethylxanthene (xantphos) have been synthesized and investigated. To stabilize the tetrahedral geometry of the copper(I) complexes, the steric demands of the bpy ligands have been increased by introducing 6- or 6,6'-halo-substituents in 6,6'-dichloro-2,2'-bipyridine (6,6'-Cl2bpy), 6-bromo-2,2'- bipyridine (6-Brbpy) and 6,6'-dibromo-2,2'-bipyridine (6,6'-Br2bpy). The solid-state structures of [Cu(POP)(6,6'-Cl2bpy)][PF6], [Cu(xantphos)(6,6'-Cl2bpy)][PF6].CH2Cl2, [Cu(POP)(6-Brbpy)][PF6] and [Cu(xantp…
Invariant Jordan curves of Sierpinski carpet rational maps
2015
In this paper, we prove that if $R\colon\widehat{\mathbb{C}}\to\widehat{\mathbb{C}}$ is a postcritically finite rational map with Julia set homeomorphic to the Sierpi\'nski carpet, then there is an integer $n_0$, such that, for any $n\ge n_0$, there exists an $R^n$-invariant Jordan curve $\Gamma$ containing the postcritical set of $R$.
Probabilities of large values for sums of i.i.d. non-negative random variables with regular tail of index $-1$
2021
Let $\xi_1, \xi_2, \dots$ be i.i.d. non-negative random variables whose tail varies regularly with index $-1$, let $S_n$ be the sum and $M_n$ the largest of the first $n$ values. We clarify for which sequences $x_n\to\infty$ we have $\mathbb P(S_n \ge x_n) \sim \mathbb P(M_n \ge x_n)$ as $n\to\infty$. Outside this regime, the typical size of $S_n$ conditioned on exceeding $x_n$ is not completely determined by the largest summand and we provide an appropriate correction term which involves the integrated tail of $\xi_1$.
Offshoring along the production chain
2009
Recent contributions on offshoring often assume that firms can freely split their production process into separate steps which can be ranked according to the cost savings from producing abroad. We replace this assumption by the notion of a technologically determined sequence of production steps. In our model, cost savings from offshoring fluctuate along the production chain, and moving unfinished goods across borders causes transport costs. We show that, in such a setting, firms may refrain from offshoring even if relocating individual steps would be advantageous in terms of offshoring costs, or they may offshore (almost) the entire production chain to save transport costs. Small variations…
Highly luminescent perovskite–aluminum oxide composites
2015
In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence.
Origin of the Enhanced Photoluminescence Quantum Yield in MAPbBr 3 Perovskite with Reduced Crystal Size
2018
Methylammonium lead bromide perovskite (MAPbBr3) has been widely investigated for applications in visible perovskite light-emitting diodes (LEDs). Fine-tuning of the morphology and of the crystal size, from the microscale down to the quantum confinement regime, has been used to increase the photoluminescence quantum yield (PLQY). However, the physical processes underlying the PL emission of this perovskite remain unclear. Here, we elucidate the origin of the PL emission of polycrystalline MAPbBr3 thin films by different spectroscopic techniques. We estimate the exciton binding energy, the reduced exciton effective mass, and the trap density. Moreover, we confirm the coexistence of free carr…
Equilibrium measures for uniformly quasiregular dynamics
2012
We establish the existence and fundamental properties of the equilibrium measure in uniformly quasiregular dynamics. We show that a uniformly quasiregular endomorphism $f$ of degree at least 2 on a closed Riemannian manifold admits an equilibrium measure $\mu_f$, which is balanced and invariant under $f$ and non-atomic, and whose support agrees with the Julia set of $f$. Furthermore we show that $f$ is strongly mixing with respect to the measure $\mu_f$. We also characterize the measure $\mu_f$ using an approximation property by iterated pullbacks of points under $f$ up to a set of exceptional initial points of Hausdorff dimension at most $n-1$. These dynamical mixing and approximation resu…
Functorial Test Modules
2016
In this article we introduce a slight modification of the definition of test modules which is an additive functor $\tau$ on the category of coherent Cartier modules. We show that in many situations this modification agrees with the usual definition of test modules. Furthermore, we show that for a smooth morphism $f \colon X \to Y$ of $F$-finite schemes one has a natural isomorphism $f^! \circ \tau \cong \tau \circ f^!$. If $f$ is quasi-finite and of finite type we construct a natural transformation $\tau \circ f_* \to f_* \circ \tau$.