„Ultrafast dynamics in light-excited transition metal complexes revealed with hard X-ray spectroscopy” – seminarium ACMiN

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Akademickie Centrum Materiałów i Nanotechnologii AGH zaprasza na seminarium, które odbędzie się 17 grudnia 2015 r. o godz. 15.00.

 

Referat pt. „Ultrafast dynamics in light-excited transition metal complexes revealed with hard X-ray spectroscopy” wygłosi dr Gyorgy Vankó (Head of the X-ray Spectroscopy Group, MTA Wigner Research Centre for Physics, Hungary).

 

Miejsce: ul. Kawiory 30, bud. D-16, sala audytoryjna ACMiN (1.02A).

 

W 2018 r. regularną pracę rozpocznie europejski laser rentgenowski (European X-FEL), który pozwoli na detekcję widm dyfrakcyjnych i spektroskopowych w czasie jednego femtosekundowego impulsu. Polscy naukowcy będą mieli zapewniony dostęp do tego urządzenia. Dlatego już dziś warto gromadzić pomysły na jego wykorzystanie. Dr Vankó zaprezentuje wyniki pionierskich badań spektroskopowych wykonanych z użyciem lasera rentgenowskiego LCLS (Standford), których wyniki zostały opublikowane w „Nature" i „Nature Communications".

 

„Ultrafast dynamics in light-excited transition metal complexes revealed with hard X-ray spectroscopy”

 

Photo-induced transformations of molecular systems are ubiquitous in various branches of chemistry, physics, molecular biology, and materials science. They are essential in photosynthesis and photocatalysis, and have high potential for molecular storage or switching devices, and light-harvesting systems. In order to design better performing functional molecules, it is inevitable to unveil the elementary steps and the formation of transient species in related molecular reactions, phase transitions or biochemical function. However, the traditional tool set of pump-probe experiments has several limitations, preventing us from capturing many relevant details needed to fully understand the underlying ultrafast dynamics.

 

In principle all X-ray spectroscopy and scattering tools can be utilized to probe the ultrafast dynamics in pump-probe experiments. Nevertheless, synchrotron-based studies make use of picosecond-long pulses, and thus lack the necessary time resolution to unveil the ultrafast processes. The intense femtosecond X-ray pulses of X-ray free electron lasers permit us to exploit the X-ray spectroscopy tools with the appropriate time resolution, offering direct access to the changes in the charge, spin and nuclear degrees of freedom during the elementary physical processes of a chemical reaction, photophysical transformation, or biological function. We report on the implementation of hard X-ray spectroscopies in such time-resolved experiments, as well as their combination with X-ray diffuse scattering, which allows us to simultaneously address both the electronic and structural dynamics.

 

Results obtained on light-excited transition-metal-based model systems for photoswitchable or light-harvesting functional molecules will be shown as examples.

 

Mr. Vankó has recorded hundreds of Mössbauer spectra in the laboratory of prof. Attila Vértes, at the Eötvös University, Budapest, to receive his PhD. During this time he amused himself with learning other techniques, which opened his eyes to synchrotron radiation facilities. The enthusiast and (that time) young fellow seeked a postdoc position at the ESRF, where he later became a beamline scientist on the Inelastic Scattering Beamline ID16. After almost seven years at the ESRF, he managed to become a user and returned to his home country, where he has built own research group that explore electronic and structural dynamics on the fs to ps time scales by means of X-ray free electron lasers. He has been awarded grants from ERC-StGX-cited! „Electronic transitions and bistability: states, switches, transitions and dynamics studied with high-resolution X-ray spectroscopy (2010–2015)", and “Lendület” Programme: „Functional molecules caught in the act: Electronic structure – function relationships studied by femtosecond spectroscopy (2013–2018)".

 

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