Esmaspäeval, 2. märtsil 2020 kell 16:15 TÜ Physicumi auditooriumis B103 (W. Ostwaldi 1, Tartu)
Kristjan Kunnus (TÜFI ajalise lahutusega röntgenspektroskoopia spetsialist, Stanfordi ülikooli PULSE instituudi järeldoktor)
Femtosecond Time-Resolved X-ray Spectroscopy and Scattering with X-ray Free Electron Lasers
X-ray Free Electron Laser (XFEL) light sources deliver high brightness and femtosecond duration X-ray pulses that have revolutionized the field of ultrafast science in the past ten years. In this talk I will discuss the current capabilities of pump-probe X-ray Emission Spectroscopy (XES) and X-ray Solution Scattering (XSS) at XFELs. Specifically, I will present results from a series of experiments where we investigated photoinduced excited state electron transfer and intersystem crossing dynamics in solvated Fe photosensitizer model complexes. These experiments track simultaneously electronic state and nuclear structure of the molecules, and allowed us to observe branching of electronic relaxation pathways and coherent nuclear wavepacket dynamics. In addition, I will discuss vibronic effects that emerge in time-resolved XES experiments and are necessary to interpret the ultrafast time-dependent signals.
Kristjan Kunnus received his B.Sc. and M.Sc. degree in Materials Science from University of Tartu, Estonia. In 2014, he received his Dr. rer. nat. degree in experimental physics from University of Potsdam in Germany for his work on soft X-ray spectroscopy of transition metal complexes in solution. His current research as a post-doctoral researcher in Stanford University and SLAC National Laboratory focuses on time-resolved X-ray experiments of photoinduced excited states dynamics in metal complexes.
Physicumi seminarid on mõeldud füüsikute ja materjaliteadlaste, aga ka teiste loodus- ja täppisteadlaste laiale ringile (alates bakalaureuse astme üliõpilastest) ning püüavad avada seda, mis mingis valdkonnas on parasjagu oluline ja uudne või kuhu teatud uurimissuund on tänaseks välja jõudnud.
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