The building blocks of matter, electrons, and atomic nuclei, relentlessly move on a time scale much faster than what our senses manage to grasp.
Their spatial distribution and evolution over time dictate a large portion of the chemical and physical properties of organic and inorganic substances. Detecting and understanding such ultrafast evolution is the very complex task pursued by time-resolved spectroscopy.
As a photographer that “freezes” a fast object by taking a picture with a short and bright flash, time-resolved spectroscopy probes matter with ultrashort bunches of photons and detects how it responds on the same time scale.
Nuclei move on temporal scales of tens to hundreds of femtoseconds (1 femtosecond = 10-15 s) hence their evolution can be captured using femtosecond light pulses. Laser sources providing such pulses exist since the ‘80s and enabled the development of femtochemistry, i.e. the discipline studying chemical reactions on their natural temporal scale. However, the other constituents of matter – electrons – are thousand-times lighter and faster than nuclei. Understanding their behavior in atoms and molecules is crucial as well since they mediate light-matter interaction and are the main actors in chemical bonds. Electrons move on time scales of tens to hundreds of attoseconds (1 attosecond = 10-18 s) thus eluding femtosecond spectroscopic tools.
Only on the verge of the new millennium novel optical techniques came to the fore, enabling the generation of attosecond bursts of extreme ultraviolet light. These tools enabled a novel spectroscopic discipline, Attosecond Science.
Nowadays Attosecond Science discloses the intimate mechanisms of matter by elucidating how electrons behave on their own temporal scale inside atoms, molecules, and condensed matter.
Our group contributes to this exciting research in the following areas:
- Attosecond Technology
Attosecond technology, enabling the generation of isolated attosecond light pulses and attosecond pulse trains, is the core of Attosecond Science. Attosecond technology exploits the extremely nonlinear optical effect of High-order Harmonic Generation.
- Electron dynamics in atoms and molecules
Attosecond pulses are used in time-resolved spectroscopy for their ability to excite and probe matter on the temporal scales typical of electron dynamics. This ability discloses unresolved aspects of atomic and molecular physics.
- X-ray spectroscopy in solids
Ultrafast XUV and X-Ray spectroscopy allows the study of light-matter interaction with an unprecedented temporal and spatial resolution with the further advantages of being element-selective and oxidation- and spin-state specific. X-ray measurements at atom-specific absorption edges allow the investigation of both the electronic and the structural environment of the probed atom, providing a local probe of the dynamics under study.