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Project B.1.3

Fig. B.1.3: Schematic top-view of the world’s first UHV attosecond apparatus: the AS-3 beamline at MPQ. The back plate of the preparation chamber is rotatable so that the manipulator with the sample can be moved to different ports for target

Coherent electron dynamics and dephasing in isolated molecules and molecular nano-architectures

Here we aim at the control of electron wavepacket motion on molecular length scales and on few-femtosecond time scales where the nuclear coordinates are frozen. The studies hold promise of gaining unprecedented insight into intra- as well as inter-molecular charge and energy transport and electronic dephasing in molecules placed in different environments (cf. the selected publications for first results and methodology).

We shall address dephasing, energetic dynamics and dynamics of attosecond charge transfer in molecules and molecular nanosystems in specific environments. The understanding of these topics is important for many fields in science and technology, such as molecular electronics, solar cells and electronically stimulated materials modification. Attosecond measurement techniques to be used include few-femtosecond-UV-pump / attosecond-XUV-probe spectroscopy and triggering processes with attosecond XUV pulses and interrogating the unfolding dynamics by capturing outgoing (primary or secondary) electrons by means of attosecond streaking. The experiments are carried out in a UHV apparatus accommodating the attosecond tools and diagnostics along with complete equipment for surface preparation and characterisation (see Fig. B.1.3).

Ultrathin films with exquisite control of layer composition will be examined. Functional molecular species including photoactive or photoswitchable units and molecular wires, will be incorporated in nanoscale environments to achieve responsive assemblies and organised architectures. In particular, we shall address systems based on technologically relevant titanium oxide surfaces, e.g. employed for dye-sensitised solar cells and as catalyst supports.They will be functionalised with metal-organic complexes such as metalloporphyrins. The surface engineering will be explored by concomitant molecular-level scanning tunneling microscopy and synchrotron investigations which allow for in-depth scrutiny of order and electronic characteristics. Cooperations with M. Zharnikov (U. Heidelberg) and M. Thoss (already partner during 1st fp and now at U. Erlangen) will be continued.