Critical petermann K factor for intensity noise squeezing

We investigate the impact of the Petermann-excess-noise factor K>/=1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest Petermann factor significantly impedes squeezing, which becomes impossible when K>/=1.5. This appears as a serious limitation for obtaining sub-shot-noise light from practical semiconductor lasers. We present experimental evidence for our theory.     

The transition from As-doped GaN, showing blue emission, to GaNAs alloys in films grown by molecular beam epitaxy

We have studied the transition from As-doped GaN showing strong blue emission (2.6 eV) at room temperature to the formation of GaN_1−xAs_x alloys for films grown by plasma-assisted molecular beam epitaxy. We have demonstrated that with increasing N-to-Ga ratio there is first an increase in the intensity of blue emission at about 2.6 eV and then a transition to the growth of GaN_1−xAs_x alloy films. We present a model based on thermodynamic considerations, which can explain how this might occur.     

Diffuse measures and nonlinear parabolic equations

Given a parabolic cylinder Q = (0, T) × Ω, where W ì \mathbb R^N{\Omega\subset \mathbb {R}^N} is a bounded domain, we prove new properties of solutions of

On a Class of Solutions to the Generalized Derivative Schrödinger Equations

In this work we shall consider the initial value problem associated to the generalized derivative Schrödinger (gDNLS) equations and Following the argument introduced by Cazenave and Naumkin we shall establish the local well-posedness for a class of small data in an appropriate weighted Sobolev space. The other main tools in the proof include the homogeneous and inhomogeneous versions of the Kato smoothing effect for the linear Schrödinger equation established by Kenig-Ponce-Vega.     

Molecular and Electronic‐Structure Basis of the Ambipolar Behavior of Naphthalimide–Terthiophene Derivatives: Implementation in Organic Field‐Effect Transistors

A new family of naphthalimide‐fused thienopyrazine derivatives for ambipolar charge transport in organic field‐effect transistors is presented. Their electronic and molecular structures were elucidated through optical and vibrational spectroscopy aided by DFT calculations. The results indicate that these compounds have completely planar molecular skeletons which promote good film crystallinity and low reorganization energies for both electron and hole transport. Their performance in organic field‐effect transistors is compared with twisted and planar naphthaleneamidine monoimide‐fused terthiophenes in order to understand the origin of ambipolarity in this new series of molecular semiconductors.     

Importance of Pd and Pt excited states in N2O capture and activation: A comparative study with Rh and Au atoms

Nitrous oxide (N₂O) is an intermediate compound formed during catalysis occurring in automobile exhaust pipes. In this work, the N₂O capture and activation by Pt and Pd atoms in the ground and excited states of many multiplicities are studied. Pt and Pd + N₂O reactions are studied at multireference second‐order perturbation level of theory using C_s symmetry. The PtN₂O (¹A′, ⁵A′, and ⁵A″) species are spontaneously created from excited states. Only the ⁵A′ and ⁵A″ states exhibit N₂O activation reaction paths when N₂O approaches Pt end‐on by the N or O atoms side or side‐on yielding NO or N₂ as products, respectively. Pt⁺ cations ground and excited states, capture N₂O, although only Pt⁺ (⁶A′ and ⁶A″) states show N₂O activation yielding O and N₂ as products. In the Pd atom case, PdN₂O (¹A′ and ⁵A″) species are also spontaneously created from excited states. The ⁵A″ state exhibits N₂O activation yielding N₂ + O as products. Pd⁺ cations in both ground and excited states capture N₂O; however, only the [PdN₂O]⁺ (⁴A′, ⁴A″, ⁶A′, and ⁶A″) states in side‐on approaches and (⁶A′) in end‐on approach activate the N₂O and yield the N₂ bounded to the metal and O as product. The results obtained in this work are discussed and compared with previous calculations of Rh and Au atoms. The reaction paths show a metal–gas dative covalent bonding character. Löwdin charge population analyses for Pt and Pd active states show a binding done through charge donation and retrodonation between the metals and N₂O. © 2013 Wiley Periodicals, Inc.     

Poly(phenylene oxide); electropolymerization on mild steel and anticorrosive properties of the layer: A new corrosion test

The electropolymerization of phenyl salicylate by cyclic potential sweeps over mild steel gives rise to the formation of a poly(phenylene oxide) (PPO) film. In order to study the anticorrosive properties of PPO a new rapid corrosion test has been devised.