Starts 22 May 2025 11:00
Ends 22 May 2025 13:00
Central European Time
CMSP Seminar (Experimental Lecture Series): Observing photo-induced dynamics via time-resolved photoemission spectroscopies
Luigi Stasi Seminar Room (Leonardo Building)
Roberto Costantini
(University of Trieste)
Abstract:
In optoelectronics and photochemistry, the ability to investigate the response of organic molecules, low-dimensional materials, and hybrid interfaces to optical excitation is a critical advantage. These systems may represent new platforms for developing the next generation of environmentally sustainable devices and catalysts; to optimize their performance and functionality, it is thus essential to thoroughly understand the charge generation mechanisms within these materials. Thanks to the recent advancements in experimental capabilities and in the generation of ultra-short X-ray pulses, it is now possible to observe such photo-induced dynamics with chemical selectivity using time-resolved X-ray spectroscopies.
At the ANCHOR-SUNDYN endstation of the ALOISA beamline at the Elettra synchrotron, we employ both synchrotron radiation and optical laser pulses to probe photoexcited systems. This versatile toolkit enables in-depth characterization of electronic energy level alignment and photo-induced processes. Specifically, laser-based techniques such as two-photon photoemission provide real-time insights into exciton dynamics, while synchrotron-based X-ray probes offer access to the core levels, albeit with lower temporal resolution. This presentation will highlight results obtained from studies on molecular thin films and heterojunctions using complementary optical and X-ray techniques to characterize the dynamics of the excited states, as well as the physical properties of the systems at equilibrium. In particular, we show how the interface morphology influences energy level alignment, which in turn governs the relaxation pathways of excited carriers.
In optoelectronics and photochemistry, the ability to investigate the response of organic molecules, low-dimensional materials, and hybrid interfaces to optical excitation is a critical advantage. These systems may represent new platforms for developing the next generation of environmentally sustainable devices and catalysts; to optimize their performance and functionality, it is thus essential to thoroughly understand the charge generation mechanisms within these materials. Thanks to the recent advancements in experimental capabilities and in the generation of ultra-short X-ray pulses, it is now possible to observe such photo-induced dynamics with chemical selectivity using time-resolved X-ray spectroscopies.
At the ANCHOR-SUNDYN endstation of the ALOISA beamline at the Elettra synchrotron, we employ both synchrotron radiation and optical laser pulses to probe photoexcited systems. This versatile toolkit enables in-depth characterization of electronic energy level alignment and photo-induced processes. Specifically, laser-based techniques such as two-photon photoemission provide real-time insights into exciton dynamics, while synchrotron-based X-ray probes offer access to the core levels, albeit with lower temporal resolution. This presentation will highlight results obtained from studies on molecular thin films and heterojunctions using complementary optical and X-ray techniques to characterize the dynamics of the excited states, as well as the physical properties of the systems at equilibrium. In particular, we show how the interface morphology influences energy level alignment, which in turn governs the relaxation pathways of excited carriers.