HHGhole2 · High-harmonic spectroscopy for core-hole dynamics
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2016-12-05 → 2018-12-04
- EU contribution
- €158,122
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
High-harmonic spectroscopy for core-hole dynamics
X-ray photons strongly interact with core electrons, exciting them into unoccupied valence or continuum states. The core-hole state left behind decays very fast (few femtoseconds) via the rearrangement of electrons in the system to fill the core hole. This ultrafast core rearrangement can induce the emission of a photon (fluorescence) or an electron (Auger process). These mechanisms are universal and play also a fundamental role in radiation damage of physical systems of interest, as biomolecules. Hence, it is timely to study molecular core-hole dynamics. To achieve the complete understanding of the core-hole dynamics one needs to follow the time-evolution of the intermediate states. Here we use high-order harmonic spectroscopy (HHS) to study core-hole dynamics. In HHS, an intense infrared source is used to probe the system after the pump pulse (here an x-ray pulse). The non-linear interaction with the IR field results in a complex harmonic spectrum that encodes the transient dynamics. This technique has been proven to resolve molecular dynamics with attosecond resolution. Conclusions of the action: The MC researcher obtained a tenure-track position and we needed to terminate the contract 10 months before expected. However, we have made enormous progress towards the final goal of developing a numerical code to calculate the HHG spectroscopy for core-hole molecular dynamics. 1) The first step was to develop a time-dependent code to simulate the core-hole dynamics in molecular systems. Based on this theory, we started to implement the numerical code. These calculations allow the possibility to obtain the x-ray absorption spectrum of a static state. We collaborated with experimentalists that performed x-ray absorption spectroscopy measurements in synchrotron facilities [JACS 139, 12907 (2017) and Chem. Eur. J. 24, 6464 (2018)]. Then we implemented the time-propagation program to describe the response of the molecule interacting with x rays. We obtain interesting results for charge migration induced by the x rays. 2) We started to work on the implementation of calculating the HHG spectrum of the evolving system, within the Strong-Field Approximation (SFA). We started with the simple molecule, hydrogen molecular ion (a complete solution of the Time-Dependent Schrödinger Equation (TDSE) is possible). First calculations look promising, when we compared the time-dependent SFA (td-SFA) with the TDSE. Also, we adopted the code to also consider two-dimensional materials to broaden the applications.
Data: CORDIS, © European Union
Project objective
Nowadays x rays play a unique role in understanding the electronic and nuclear structure of atoms, molecules, materials, or systems in solutions, and also in following their fundamental transient dynamics. X-ray applications have high impact on society, ranging from medical and security to cutting-edge research on Physics, Chemistry, Biology, and Material Science. The advent of X-Ray Free Electron Lasers (XFELs) is a giant step in the advance of x-ray techniques, adding a high degree of coherence compared to synchrotron sources, and delivering pulses with enough intensity to develop novel techniques without precedents. A prominent example is the study of biomolecular systems with coherent diffractive imaging.Coherent diffractive imaging, among other applications, requires the sample to absorb a significant number of photons, limited by the inflicted damage. Radiation damage is, in fact, far from well understood due to the complexity of the physical processes that are in play. It is also a universal phenomenon, with important consequences in biological systems. Hence, radiation damage has become one of the most interesting fundamental problems to investigate.In this project we propose to develop novel approaches to time-resolve radiation damage processes in molecules by using High-Harmonic Spectroscopy (HHS). HHS is a technique that has already been used to study molecular valence dynamics with atomic spatial resolution and attosecond time resolution, and we plan to extend this method. Hence, this proposal aims to develop numerical methods for feasible experiments at XFELs by combining the expertise of the host group (well recognized by developing theoretical methods for High-Harmonic phenomena) and the Experienced Researcher (coming from a leading US group in radiation damage research at XFELs), with support of a European experimental group led by Prof. Jon Marangos (at Imperial College London, a world leading group in HHS) where a secondment will take place.
Original text from CORDIS.
Participants
- UNIVERSIDAD DE SALAMANCA · SalamancaCoordinatorSpain
Links
Data: CORDIS, © European Union