Physics Colloquium

Dr. Julius Schwarz

Deutsches Elektron Synchrotron DESY, Hamburg

Light-Driven Processes in Functionalized Nanoparticles - Towards femtosecond TR-XPS of 2-thiouracil-functionalized-gold-nanospheres

Abstract:

Gold nanoparticles (AuNPs) are currently tested as nanocarriers for medication in cancer treatment. They provide the advantage, that the release of the tumor fighting drug can be locally triggered in tissue by surface plasmon excitation of the AuNPs. The plasmon-mediated energy and charge transfer to the functional adsorbate molecule plays a crucial role for the photodynamic therapy. However, the microscopic mechanisms by which plasmon excitation in AuNPs promotes molecular activation under biologically relevant, long-wavelength illumination remain poorly understood. Surface plasmons can initiate chemical transformations through several concurrent pathways, including direct coupling to the plasmon, via hot charge carriers, or via local heating, each operating on distinct femtosecond-to-nanosecond timescales. Disentangling these timescales is essential to identify the dominant processes for molecular activation. Here, I present our plans to use Time-resolved X-ray photoelectron spectroscopy (TR-XPS) to disentangle the relevant processes in the case of 2-Thiouracil-functionalized AuNPs. TR-XPS results on the photochemistry of isolated 2-Thiouracil in the gas phase provide an important frame of reference for the expected AuNP interaction with the functional.