Rational Topological Design for Fluorescence Enhancement upon Aggregation of Distyrylfuran Derivatives

A series of 2,5‐distyrylfuran derivatives bearing pentafluorophenyl‐ and cyanovinyl units have been synthesized for aggregation‐induced emission (AIE). The effect of the type and extent of the supramolecular connections on the AIE of the furan derivatives were examined and correlated with their X‐ray crystal structures. It was found that the simultaneous presence of cyano and perfluorophenyl units strongly enhances the fluorescence upon aggregation. Single‐crystal X‐ray diffraction analysis confirmed that C?H???F, F???F, C?H???nitrile, Ar???Ar_F (Ar=aryl, Ar_F=fluoroaryl), and nitrile???Ar_F intra‐ and intermolecular interactions drive the topology of the molecule and that solid‐state supramolecular contacts favor AIE of the furan derivatives.     

Nitride-based photodetectors: from visible to X-ray monitoring

The performance of nitride-based photodetectors is investigated beyond the usual near-UV (400–300 nm) and mid-UV (300–200 nm) operation ranges. The responses of metal–semiconductor–metal (MSM) photodiodes were analyzed in the vacuum–UV and soft X-ray regions. To interpret the results, the absorption properties and the attributes of each of the photons with energies for producing multiple electron–hole pairs were considered. The soft X-ray characterization showed that in-plane MSMs worked efficiently up to photon energies of 600 eV. Above this value, the absorption decrease makes the diffusion length and layer thickness become critical parameters for the detector behavior. To perform detection in the violet and near-UV, InGaN-based photoconductors were fabricated and spectrally characterized. The devices presented abrupt wavelength cut-offs, demonstrating that the InGaN compositional fluctuations were tolerable up to In contents of 10% for fabricating selective photodetectors. Back-face illumination allowed us to obtain bandpass detectors for these spectral ranges.     

Monitoring and control of industrial downstream processing of sugar beet molasses

In present work the determination of several amino acids during the industrial chromatographic desugarisation of molasses is presented. The use of innovative biosensor systems for highly specific detection of serine is described. Using two-dimensional fluorescence spectrometry, a non-invasive method for the determination of several product fractions could be established in an industrial chromatographic procedure.     

HgTe/CdTe superlattices grown by molecular beam epitaxy

In this paper we present results concerning the optical absorption in HgTe-CdTe superlattices. We confirm the narrowing of the superlattice band-gap (the increase of cut-off wavelength, λ_c) compared to the band gap of the equivalent Hg_1?xCd_xTe alloy. We show also, as predicted by the theory, an increase of the cut-off wavelength of the superlattice when the HgTe layer thickness increases. At 300K, the agreement between theory and experiment is fairly good if we consider the onset of the absorption. The λ_c tail shifting towards shorter wavelengths could be explained by the interdiffusion between HgTe and CdTe layers. At 30K, no important change in the I.R. absorption is noticed for all the superlattices.We present for the first time a superlattice exhibiting an absorption in the 8–12 μm window.We have carried out Hall measurements on several superlattices and present for the first time transport properties on these alternate microstructures. The most important features concern the unexpected and not yet understood very high hole mobilities at 10K.