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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - FASTQUANTUM (Ultrafast Sepctroscopy of Quantum Structures)

Teaser

Summary

Nanoscopic or microscopic structures with their physical properties strongly affected by confinement effects are called quantum structures. This projects aims for the investigation of ultrafast dynamics in different kinds of quantum structures, namely, semiconductor nanocrystals and metal nanoparticles, their combination to complex nanohybrids, nanowires, nanosheets, as well as nanoemitters in optical cavities. The understanding of the fundamental ultrafast processes will help to further improve the quantum structures and to further pave the way for their application in optical or opto-electric devices. Besides this, the action intended to train the applicant in the ultrafast spectroscopy by hands-on experience on the most sophisticated ultrafast setups. The gained knowledge shall be transferred to his European host organisation. It should strengthen the scientific network of the researcher, and initiate further collaborations.

Work performed

During the outgoing phase of the project, ultrafast-laser spectroscopy was performed in the expert-research group of Prof. Kambhampati at McGill University, Montreal, Canada. The quantum structures under investigations were different kinds of spherical semiconductor nanocrystals, anisotropic semiconductor nanorods, gold nanoparticles, as well as semiconductor-metal hybrid structures. Most of these structures were synthesized in the researcherâ€™s home group in Hamburg, Germany. The researcher gained in-depth knowledge of ultrafast-spectroscopy instrumentation. He worked closely together with a PhD student of the Canadian group who also continued the work when the researcher returned to Europe.
During the incoming phase of the project, in the group of Prof. Mews in Hamburg, Germany, the researcher worked on the analysis of data obtained in experiments in Canada, on modelling of the investigated systems, on the fabrication and characterization of new systems, and on ultrafast spectroscopy in a new laboratory in Hamburg.

Exploitation and dissemination of the direct scientific results obtained during the project took place and will take place mainly via publications in peer-reviews journals.
Unit now, four papers were accepted. A first paper in the Journal of Physical Chemistry C on few-layer graphene sheets as highly efficient fuel-cell electrodes emerged in the Hamburg group under the supervision of the researcher during the outgoing phase. A second paper published in Langmuir reports on a new fabrication route for thin silica shells around semiconductor nanorods. The need of these was experienced by difficulties that arouse during ultrafast spectroscopy measurements on earlier nanostructures with thicker shells. A third paper published in ACS Photonics is about plasmonic nanoantennas and their influence on the charge-carrier recombination dynamics in quantum wells. A fourth paper published in ACS Nano shows the influence of surface charges on the photoluminescence energy and dynamics of semiconductor dot-in-rod nanocrystals. Ultrafast spectroscopy of dot-in-rod nanocrystals performed in Canada shined new lights on electron delocalization and gain in these structures. Results were disseminated via a conference contribution and further work should lead to a publication.
Transient absorption spectroscopy experiments performed in Hamburg on gold nanorods revealed interesting first results on the complex melting process of these structures upon optical pumping. We hope to disseminate these results in the future. The scientific results of the whole project were also disseminated in two invited seminar talks presented by the researcher.

Final results

The action already impacts the human resources and skills at the European host organisation via the researcherâ€™s roles as a supervisor, lecturer, and member of the committee of the degree course Nanoscience. During his research stay in Canada, the researcher got an in-depth insight into the structure of the North American university system as well as into the curricula of students of chemistry and physics. This information already gives new impulses to the researcherâ€™s teaching activity.