Kalendář

In this contribution, ultrafast spectroscopy will be introduced as a probe of chemical reaction dynamics. One of the main goals of this field is to replace purely mechanistic “arrows” in organic chemistry by in-depth understanding of the reaction pathways. In fact, ultrafast spectroscopy can in principle do even more – short laser pulses can be used to shape the outcome of chemical reactions by acting like a light catalyst.

Ultrafast spectroscopy has been from the very beginning tightly connected with the development of laser sources capable of generating short laser pulses. Everything started in 1950 by the invention of flash photolysis which allowed the detection of intermediate radicals during chemical reactions. The field advanced in the 1980s by the discovery of the colliding-pulse mode-locked dye laser, which could produce laser pulses as short as 30 fs. A major breakthrough came in 1990 with the invention of the self mode-locking in Ti:sapphire-based lasers. Because of that, 10 – 20 fs pulses could be routinely produced and techniques as hollow-core fibre broadening and chirped mirror compression could shrink the pulse duration down to 4 – 5 fs.

The development from the previous years cumulated at the beginning of the 21st century by the invention of the high-harmonic generation process opening the attosecond time domain. At this time scale, only light electrons can move, which produces a totally different picture to chemical dynamics that happens in the frozen molecular frame. This new fascinating field entitled attosecond science is going to be introduced in the talk as an interesting probe of atomic and molecular system in areas previously forbidden due to insufficient time resolution. By mastering this technology, new problems like time-resolved chirality can be addressed offering novel fascinating venues in femtochemistry.