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Dean Cvetko: Ultrafast dynamics of electron transfer at molecular interfacesprobed by x-ray resonant photoemission

Date: 14. 6. 2018
Source: Monday physics colloquium
Petek, 15. 6. 2018 ob 15.15 v predavalnici F-1, FMF, Jadranska 19

Ultrafast dynamics of electron transfer at molecular interfacesprobed by x-ray resonant photoemission

Dean Cvetko

Faculty for mathematics and physics, University of Ljubljana, Institut J.Stefan, Ljubljana
CNR-IOM Laboratorio Nazionale TASC @ Elettra synchrotron, Trieste, Italy

Understanding the interplay between molecular bonding and charge transfer effciency in heterojunctions is a key issue for molecular engineering and design of novel organic-based nanodevices. Experimentally, different channels for charge carrier transfer within molecular assemblies on solid surfaces can be probed by x-ray resonant photoemission (RPES). Within core-hole-clock (CHC) spectroscopy, we can address the time of charge carrier delocalization over different molecular sites with unprecedented temporal and orbital resolution. The method provides a unique way of measuring charge transfer dynamics from/to empty molecular orbitals in the core-excited molecular systems. The identification of orbital pathways for fast carrier transport may then provide a unique insight in the origin of the assembly’s conductive properties. The basics of x-ray resonant photoemission and core-hole-clock experiments aimed to measure the timescale of charge transfer in excited systems will be briefly discussed. RPES measurements with synchrotron light (Elettra light source, Trieste) tracking fast electron dynamics in a few organic and hybrid molecular systems with pi-pi and donor-acceptor molecular coupling will be presented to demonstrate the essential coupling motifs for efficient charge transport in non-covalent molecular junctions.