A photoemission study of the surface carbonate species on Ag{110}

The electronic structure of the surface carbonate species adsorbed on Ag{110} has been studied with angle‐resolved photoemission using synchrotron radiation. Despite the low symmetry of the surface complex (Cs) and more than one azimuthal orientation of the vertical symmetry plane, it has been possible to assign the adsorbate‐induced levels. Recent semiempirical quantum chemical calculations have proved to be of considerable assistance in this process. The resonant behavior observed for the 3a‘ level is discussed in the context of photoelectron data for the free BF3 molecule, which is isoelectronic with CO2−3. The Cs symmetry pertaining in the present experiment is compared with the effective D3h symmetry observed in x‐ray‐absorption spectroscopy of the same system

Exciton lifetime and emission polarization dispersion in strongly in-plane asymmetric nanostructures

We present experimental and theoretical investigation of exciton recombination dynamics and the related polarization of emission in highly in-plane asymmetric nanostructures. Considering general asymmetry- and size-driven effects, we illustrate them with a detailed analysis of InAs/AlGaInAs/InP elongated quantum dots. These offer a widely varied confinement characteristics tuned by size and geometry that are tailored during the growth process, which leads to emission in the application-relevant spectral range of 1.25-1.65 {\mu}m. By exploring the interplay of the very shallow hole confining potential and widely varying structural asymmetry, we show that a transition from the strong through intermediate to even weak confinement regime is possible in nanostructures of this kind. This has a significant impact on exciton recombination dynamics and the polarization of emission, which are shown to depend not only on details of the calculated excitonic states but also on excitation conditions in the photoluminescence experiments. We estimate the impact of the latter and propose a way to determine the intrinsic polarization-dependent exciton light-matter coupling based on kinetic characteristics.Comment: 11 pages, 8 figure