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Wave function engineering has become a powerful tool to tailor the optical properties of semiconductor colloidal nanocrystals. Core–shell systems allow to design the spatial extent of the electron (e) and hole (h) wave functions in the conduction- and valence bands, respectively. However, tuning the overlap between the e- and h-wave functions not only affects the oscillator strength of the coupled e–h pairs (excitons) that are responsible for the light emission, but also modifies the e–h exchange interaction, leading to an altered excitonic energy spectrum. Here, we present exciton lifetime measurements in a strong magnetic field to determine the strength of the e–h exchange interaction, independently of the e–h overlap that is deduced from lifetime measurements at room temperature. We use a set of CdTe/CdSe core/shell heteronanocrystals in which the electron–hole separation is systematically varied. We are able to unravel the separate effects of e–h overlap and e–h exchange on the exciton lifetimes, and we present a simple model that fully describes the recombination lifetimes of heteronanostructures (HNCs) as a function of core volume, shell volume, temperature, and magnetic fields.

The thermal motion of polymer chains in a crowded environment is anisotropic and highly confined. Whereas theoretical and experimental progress has been made, typically only indirect evidence of polymer dynamics is obtained either from scattering or mechanical response. Toward a complete understanding of the complicated polymer dynamics in crowded media such as biological cells, it is of great importance to unravel the role of heterogeneity and molecular individualism. In the present work, we investigate the dynamics of synthetic polymers and the tube-like motion of individual chains using time-resolved fluorescence microscopy. A single fluorescently labeled polymer molecule is observed in a sea of unlabeled polymers, giving access to not only the dynamics of the probe chain itself but also to that of the surrounding network. We demonstrate that it is possible to extract the characteristic time constants and length scales in one experiment, providing a detailed understanding of polymer dynamics at the single chain level. The quantitative agreement with bulk rheology measurements is promising for using local probes to study heterogeneity in complex, crowded systems.

Light emission of semiconductor nanocrystals is a complex process, depending on many factors, among which are the quantum mechanical size confinement of excitons (coupled electron–hole pairs) and the influence of confined phonon modes and the nanocrystal surface. Despite years of research, the nature of nanocrystal emission at low temperatures is still under debate. Here we unravel the different optical recombination pathways of CdSe/CdS dot-in-rod systems that show an unprecedented number of narrow emission lines upon resonant laser excitation. By using self-assembled, vertically aligned rods and application of crystallographically oriented high magnetic fields, the origin of all these peaks is established. We observe a clear signature of an acoustic-phonon assisted transition, separated from the zero-phonon emission and optical-phonon replica, proving that nanocrystal light emission results from an intricate interplay between bright (optically allowed) and dark (optically forbidden) exciton states, coupled to both acoustic and optical phonon modes.

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The formation of micrometer‐sized, highly ordered porphyrin rings on surfaces has been investigated. The porphyrin‐based nanoarchitectures are formed by deposition from evaporating solutions through a surface dewetting process which can be tuned by variations in the substitution pattern of the molecules used, the coating of the surface and the conditions under which the evaporation takes place. Control over the combined self‐assembly and surface dewetting results in nanorings possessing a defined internal architecture. The ordering of the molecules within the rings has been studied by a variety of microscopy techniques (TEM, AFM, fluorescence microscopy) and the exact ordering of the porphyrins within the rings has been quantified.

The formation of micrometer-sized, highly ordered porphyrin rings on surfaces has been investigated. The porphyrin-based nanoarchitectures are formed by deposition from evaporating solutions through a surface dewetting process which can be tuned by variations in the substitution pattern of the molecules used, the coating of the surface and the conditions under which the evaporation takes place. Control over the combined self-assembly and surface dewetting results in nanorings possessing a defined internal architecture. The ordering of the molecules within the rings has been studied by a variety of microscopy techniques (TEM, AFM, fluorescence microscopy) and the exact ordering of the porphyrins within the rings has been quantified.

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Click chemistry is used to construct a novel lipase–BSA hetero-dimer, in which the latter protein acts as a foot enabling the anchoring of the enzyme onto the surface for single enzyme studies.

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