The mission of the CRC 1477 LiMatI (Light-Matter Interactions at Interfaces) is the exploration of light-matter interactions at interfaces employing strong ultrafast fields and dedicated targets. We investigate how the geometrical, electronic and topological structure of light-matter systems with interfaces affect the sub-cycle emission of radiation and particles in strong fields, and how specific excitations and their transport dynamics can be controlled using interfaces with tailored optical and electronic properties. Recent progress in strong-field laser physics, integrated photonics, and condensed matter physics allows pushing light-matter interactions at surfaces and interfaces beyond previous limits, providing the basis for the challanging scientific projects within CRC LiMatI.
Strong ultrafast fields, such as intense, few-cycle or multi-color laser pulses, drive charge and energy flow in matter on the attosecond time scale. They induce nonlinear ionization and nonlinear optical response, like the generation of high harmonics. By “dedicated targets” we understand light-matter landscapes in which the physical effect or feature of interest can be best understood and analyzed, examples being composite 2D materials (to study long-living excitons), clusters on surfaces (to study directed electron emission), nanotips (to drive extreme near-field enhanced photoemission), waveguide circuits (to study topological photonics), molecular films (to study high-harmonic generation in ordered and disordered systems), nanocrystals (to study exciton-plasmon coupling), molecular networks (to study exciton migration), and single molecules embedded in 2D materials (to study single-molecule emitters for sensing purposes). The scope and scientific questions to be addressed in the first funding period of CRC 1477 LiMatI are aligned along the following four main physical scenarios.
The first scenario addresses extreme nonlinear optics at interfaces. The main goals are the generation and controlled modification of tailored interfaces with ultrashort and intense light waveforms, the characterization of their optical strong-field response and geometrical, electronic and topological features, and the development of appropriate theoretical models. The systems that will be investigated are organic molecular films on a substrate, free-standing 2D materials, and laser-induced interfaces inside and near the surface of dielectrics.
The second scenario is about the controlled particle emission from interfaces and aims at exploiting plasmonic near-field enhancement at free and deposited nanoparticles and at nanotips to control nonlinear photoemission from these structures. We will investigate the angle, energy, and laser waveform dependence of the electron emission from individual deposited nanostructures and nanotips as well as the selectivity of the nonlinear photoelectron or ion emission from aerosols in the gas phase.
The third scenario concerns waveguide circuits at interfaces that will be generated by femtosecond direct laser writing, chemical synthesis, or physical deposition methods. The central objective is the realization of artificial light-matter systems with designed linear and nonlinear optical properties to shape, enhance, and route light. The waveguide circuits are used for mimicking and exploring topological materials as well as for sensitive probing of excitonic states.
The fourth scenario considers dedicated two-dimensional hetero and molecular nanostructures and explores their implications for exciton-based energy and information transport, and sensing. We will develop theoretical concepts for describing the interface-mediated quasiparticles and use advanced fabrication methods to combine different nanomaterials into functional heterostructures, which can be accessed in near-field-based excitation schemes.
The scientific work on the research questions within CRC LiMatI is carried out in 13 interlinked research projects that are organized in the two project areas S (for “Strong Fields and Attosecond Physics”) and W (for “Weak Fields and Quasiparticles”), see orange and blue shaded regions in the figure.
Project Area S addresses strong fields and attosecond physics. It covers the scenarios of extreme nonlinear optics and controlled particle emission from interfaces. These two scenarios are closely interlinked by the common physics of light-driven non-perturbative electron dynamics and the quest for resolving the strongfield response mechanisms. While intense laser light is a prerequisite for all projects in area S, the work in Project Area W is performed with relatively weak lasers and mainly concerns the generation and transport of quasiparticles along interfaces in dedicated targets, quantum sensing using embedded molecules at interfaces, and general topological aspects in light-matter interaction. These scenarios are connected via the interface-mediated dynamics of quasiparticles and light and the objective to design and actively control functional light-matter landscapes.
In order to foster and manage the concerted research activities, common activities, such as the dissemination of obtained results, the scientific exchange with internal and external partners, the training of students, sustainable and subject-specific research data management, as well as outreach to the public, are organized in four support projects (see gray boxes in the figure).