Clusters in intense FLASH pulses: ultrafast ionization dynamics and electron emission studied with spectroscopic and scattering techniques
Résumé
FLASH, the first FEL operating at short wavelength, has paved the way for novel types of experiments in many different scientific disciplines. Key questions for the first experiments with this new type of light source are linked to light – matter interaction and ionisation processes. This paper gives an overview of the ultrafast ionisation dynamics and electron emission of pure and doped rare gas clusters illuminated with intense short-wavelength pulses by summarizing the findings of recent years work at FLASH. Atomic clusters are ideal for investigating the light – matter interaction because their size can be tuned from the molecular to the bulk regime thus allowing to distinguish between intra and interatomic processes. The ionisation processes turned out to be strongly wavelength dependent. Plasma absorption, while dominant at 13 eV becomes insignificant at photon energies above 40 eV. The cluster ionisation and disintegration proceeds in several steps on a time scale from fs to ps. Insight into the involved processes can be obtained with ion and electron spectroscopy. The high intensity of FLASH pulses opens the door for a new imaging approach to study nanoparticles. Scattering patterns of single and few clusters can be recorded in a single shot. Initial results of scattering experiments and their comparison to Miecalculations show that two and three dimensional structural information of gas phase particles can be obtained this way.
Domaines
Physique [physics]
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PEER_stage2_10.1088%2F0953-4075%2F43%2F19%2F194011.pdf (1.29 Mo)
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