STROBE Seminar: Leo Hamerlynck, “Label-free measurement of nanoscale energy flow using time-resolved scattering microscopy”
Title: Label-free measurement of nanoscale energy flow using time-resolved scattering microscopy
Presenter: Leo Hamerlynck, Graduate Student, University of California Berkeley
Abstract: From photo-generated heat and charge carriers in metals and semiconductors to excited chlorophyll molecules in plants’ photosynthetic membranes, understanding how energy flows through and is dissipated by systems with nanoscale heterogeneity is of great interest for emerging energy technologies, including photovoltaics, transistors, and artificial photosynthesis. The dynamics of charge carrier migration following photoexcitation take place over sub-picosecond to nanosecond timescales and nanometer length scales. Imaging such a wide variety of energy carriers in such varied materials calls for a microscopy modality with high temporal resolution and spatial sensitivity without the need for labeling. Time-resolved interferometric scattering microscopy (stroboSCAT), developed in the Ginsberg Lab, ticks many of these boxes, relying on interference between light scattered by a sample and light reflected by the substrate to achieve high sensitivity at low fluences. In stroboSCAT, a pump-probe technique, a diffraction-limited volume is excited by a focused optical pump and imaged some time later by a widefield probe pulse. The technique allows direct imaging of excitons, heat, and any other energy carriers that alter the local polarizability and thus the scattering cross-section of the sample. Using this technique, the Ginsberg Group has studied exciton migration in hybrid organic-inorganic perovskites and organic semiconductors, charge and heat migration in silicon and 2D transition metal dichalcogenides, and subdiffusive heat transfer in gold nanocrystal films, and more, revealing insights into the role of nanoscale heterogeneity on energy transfer.
Bio: Leo Hamerlynck is a fifth-year graduate student in Prof. Naomi Ginsberg’s lab at UC Berkeley. At Berkeley, Leo has studied energy transfer in proteins involved in photosynthesis through time-resolved spectroscopy and microscopy in order to understand what gives rise to its excellent energy transfer efficiency. Leo has used ultrafast transient absorption anisotropy measurements to understand the impacts of different types of disorder on intra-protein energy transfer in a model light-harvesting complex based on TMV. Leo’s recent work focuses on applying stroboSCAT to intact thylakoid membranes to investigate inter-protein energy transfer in photosynthesis.