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Attosecond spectroscopy of molecules in gas and liquid phase

Contact: MARROUX Hugo, ,, +33 1 69 08 17 55
The student will use attosecond laser techniques to study ultrafast dynamics of molecules in liquid and gas phase. Inner level photoionization will be used to study in real time: diffusion/rearrangement/electron transfer dynamics, as well as solvation effects.
Possibility of continuation in PhD: Oui
Deadline for application:21/04/2023

Full description:
In recent years, the generation of sub-femtosecond pulses, known as attoseconds (1 as=10-18 s), has made spectacular progress. These ultrashort pulses open new perspectives for the exploration of matter on a timescale that was previously inaccessible. Their generation is based on the strong non-linear interaction of short (~20 femtoseconds) and intense infrared (IR) laser pulses with atomic or molecular gases. This produces high order harmonics of the fundamental frequency, over a wide spectral range (160-10 nm) covering the extreme ultraviolet (UVX). This high energy radiation is able to ionize electrons located in the inner layers of molecules. In the time domain, this coherent radiation appears as pulses of ~100 attoseconds duration [1].

With these attosecond pulses, it becomes possible to study the fastest dynamics in matter, those associated with electrons, which naturally occur on this timescale. Attosecond spectroscopy thus allows the study of fundamental processes such as photoionization and addresses questions such as : how long does it take to pull an electron out of an atom or molecule? These questions have become hot topics in the scientific community but have so far been studied in isolated systems, in the gas phase [2,3]. Advanced sampling technologies now allow us to study these electronic dynamics in a solvated medium where the behavior of electrons on these attosecond timescales is unknown. What energy or electron transfers take place in 10-18 seconds? Can we measure electron scattering effects in a liquid? These questions are a new challenge for our field on the experimental and theoretical level.

The objective of this thesis is first to implement attosecond techniques established in gas phase to the liquid phase. Two complementary detections will be used, photoelectron detection and transient absorption. By combining the information obtained by each technique, we will be able to measure the scattering of the photoelectron after its creation but also the fate of the ionized molecule: rearrangements/electron transfers, solvation effects.

The experimental work will include the development and the implementation of a beamline, installed on the FAB100 laser of the ATTOLab Excellence Equipment, allowing: i) the generation of attosecond radiation; ii) its characterization by quantum interferometry; iii) its use in photoionization and absorption spectroscopy. Theoretical aspects will also be developed. The student will be trained in ultrafast optics, atomic and molecular physics, quantum chemistry, and will acquire a broad mastery of XUV and charged particle spectroscopy techniques. Knowledge in optics, nonlinear optics, atomic and molecular physics is a prerequisite.
The thesis work could lead to experimental campaigns in French and associated European laboratories (Hamburg-DESY).

References :
[1] Y. Mairesse, et al., Science 302, 1540 (2003)
[2] V. Gruson, et al., Science 354, 734 (2016)
[3] A. Autuori, et al., Science Advances 8, eabl7594 (2022)
Technics/methods used during the internship:
Intense femtosecond laser, optical post-compression, molecular gas jets, liquid jet, vacuum technology, interferometry, spectrometry of XUV photons, electron spectrometry, transient absorption

Tutor of the internship

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