Ultrafast dynamics of chemical reactions by femtosecond electron diffraction and transient absorption spectroscopy

26.04.2017, 15:00

Dr. Gastón Corthey, Max Planck Institute for the Structure and Dynamics of Matter, Hamburg

Watching atoms move during a chemical reaction has always been the dream experiment in chemistry and it is now becoming feasible -even for complex systems- by the development of different experimental approaches. While optical methods like transient absorption spectroscopy (TAS) can provide very useful information about the dynamics of the electronic structure during a chemical reaction, they can only sense the geometric structure in an indirect way, since radiation with a wavelength on the order of the interatomic distances is needed. As changes in the atom positions fall in the sub-angstrom length scale, either X-rays or electrons should be used to probe the structural dynamics. And the source has to deliver pulses with duration on the order of 100 fs, the time domain for chemical reactions [1]. X-ray sources fulfilling these requirements are the free electron lasers (FELs), with kilometer-long facilities and costs on the order of 109 USD. A powerful complementary method to that -and an alternative for some cases- is the femtosecond electron diffraction (FED) technique, which can be implemented in tabletop setups, reducing the costs by four orders of magnitude with similar performance for many systems and without the radiation-induced damage issue that accompanies X-rays.In this talk, I will discuss the details of these experiments and introduce some examples on the application of femtosecond electron diffraction combined with transient absorption spectroscopy to the study of the ultrafast dynamics of chemical reactions [2] and photoinduced phase transitions [3].

[1] Miller, R. J. D. Science 2014, 343, 1108-1116.

[2] Xian, R. et al. Nat. Chem. 2017, DOI: 10.1038/NCHEM.2751

[3] Ishikawa, T.; et al. Science 2015, 350, 1501-1505.