Setup for Dynamic Spectroscopy

• Subject Area: Condensed Matter Physics
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 560260003

The setup for dynamic spectroscopy is characterized by the fact that transient absorption and luminescence signals can be detected after excitation with individual, tunable high-energy femto- or nanosecond laser pulses in the ultraviolet, visible and near-infrared spectral range over a time range from sub-picoseconds to the second range. The instrument will enable the study of energy flow in novel, heterogeneous molecular complex compounds as well as in amorphous and crystalline solids by detecting emitting and non-emitting processes. The investigated material systems include: polar oxide solid solutions, core-shell nanoparticles, transition metal complex compounds, supramolecular luminescence probes and self-assembled meso- and macroporous membranes of aluminum oxide (anodic aluminum oxide, AAO). The energy transfer relevant processes are based on intramolecular, phonon-assisted, electronic (dipole-dipole interaction) and/or quantum mechanical (tunnel transport, de-localized transport) charge or energy transfer mechanisms. This is associated with relaxation times with time constants in the pico- or (sub-)nanosecond to micro- and millisecond range.To prepare reproducible initial states, femto- or nanosecond laser pulses are used, i.e. pulses with pulse durations far below the relaxation time of the studied processes. For fs pulse excitation, single pulses or double pulses with adjustable pulse delay (up to ns) can be used to study the excitation dynamics. The photon energy of the fs/ns excitation pulses is adapted to the optical absorption properties of the initial one- or two-photon transitions of the material systems in the range of 0.8 - 4.7 eV (260 - 1550 nm). Pulse energies in the microjoule (fs) or millijoule (ns) range ensure a sufficiently large population of energetically excited states including multiphoton excitation (fs). The dynamic spectroscopy setup will significantly support the research activities of four ongoing or planned third-party funded projects, including the DFG Research Unit FOR 5044 “Periodic low-dimensional defect structures in polar oxides” and the interdisciplinary DFG Research Training Group 2900 “nanomaterials@biomembranes”. It will be used as an interdisciplinary research facility by doctoral students from physics, chemistry and biology and will be embedded in the infrastructure of the CellNanOs research center and the ibiOS core facility. From the user's point of view, the measuring device is characterized by a high degree of user-friendliness and low-maintenance and low-adjustment measuring operation. It enables experimental access to solutions, thin films, surfaces and powder compacts in different measuring geometries (transmission, reflection).

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Messplatz zur Dynamischen Spektroskopie
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Universität Osnabrück
• Leader: Professor Dr. Mirco Imlau