Exciton Binding Energies in Conjugated Polyelectrolyte Films

Molecular design: The electronic structure of conjugated polyelectrolytes as a function of ionization potential (IP) and electron affinity (EA) is determined using X‐ray absorption and emission spectroscopy (see figure). Different functional groups give rise to dissimilar transport gaps and exciton binding energies.

     

Photophysical and biological investigation of novel luminescent Ru(II)-polypyridyl-1,8-naphthalimide Tröger's bases as cellular imaging agents

The synthesis and photophysical properties of 1 and 2, two Ru(II)-polypyridyl based-1,8-naphthalimide Tr?ger's bases, are described; these were found to stabilize double stranded DNA, undergo rapid cellular uptake, displaying good luminescence without affecting cell viability even after 24 hours of incubation.     

The Entropy of a Binary Hidden Markov Process

The entropy of a binary symmetric Hidden Markov Process is calculated as an expansion in the noise parameter ε. We map the problem onto a one-dimensional Ising model in a large field of random signs and calculate the expansion coefficients up to second order in ε. Using a conjecture we extend the calculation to 11th order and discuss the convergence of the resulting series     

Eisen und Stahl

Ohne Zusammenfassung     

An analytical view of ionic liquids

Within the last decade, ionic liquids have come to the fore as environmentally-responsible designer solvents. But what are ionic liquids and what can they offer the analytical scientist? This article addresses these questions and chronicles recent progress made in the application of ionic liquids toward analytical problem-solving. While further progress is required before ionic liquids become mainstream analytical solvents, results to date commend their use in various modes of chemical analysis. It is our aim that the findings reported herein draw other researchers into this area and encourage the increased application of ionic liquids in this manner.     

Ir6In32S21, a polar,metal-rich semiconducting subchalcogenide

Subchalcogenides are uncommon, and their chemical bonding results from an interplay between metal–metal and metal–chalcogenide interactions. Herein, we present Ir₆In₃₂S₂₁, a novel semiconducting subchalcogenide compound that crystallizes in a new structure type in the polar P31m space group, with unit cell parameters a = 13.9378(12) Å, c = 8.2316(8) Å, α = β = 90°, γ = 120°. The compound has a large band gap of 1.48(2) eV, and photoemission and Kelvin probe measurements corroborate this semiconducting behavior with a valence band maximum (VBM) of −4.95(5) eV, conduction band minimum of −3.47(5) eV, and a photoresponse shift of the Fermi level by ∼0.2 eV in the presence of white light. X-ray absorption spectroscopy shows absorption edges for In and Ir do not indicate clear oxidation states, suggesting that the numerous coordination environments of Ir₆In₃₂S₂₁ make such assignments ambiguous. Electronic structure calculations confirm the semiconducting character with a nearly direct band gap, and electron localization function (ELF) analysis suggests that the origin of the gap is the result of electron transfer from the In atoms to the S 3p and Ir 5d orbitals. DFT calculations indicate that the average hole effective masses near the VBM (1.19m_e) are substantially smaller than the average electron masses near the CBM (2.51m_e), an unusual feature for most semiconductors. The crystal and electronic structure of Ir₆In₃₂S₂₁, along with spectroscopic data, suggest that it is neither a true intermetallic nor a classical semiconductor, but somewhere in between those two extremes.

Subchalcogenides are uncommon, and their chemical bonding results from an interplay between metal–metal and metal–chalcogenide interactions.     

Simultaneous two-component determinations by phase-resolved fluorescence spectrometry

Three approaches to phase-resolved fluorimetric determination of mixtures of 1,4-bis(5-phenyloxazol-2-yl)benzene and its dimethyl derivatives are compared, including the use of measurements at the detector phase angles required to null the phase resolved intensity contribution of each component and the use of measurements at multiple detector phase angles which are either used in an indirect-nulling method or in simultaneous-equation approach. Best results were obtained using the latter method with eight detector phase angles, and both the indirect-nulling and simutaneous-equation methods were generally superior to the method involving measurements at the “nulling” detector phase angles.