Coherent control of ultrafast extreme ultraviolet transient absorption

2021 ◽  
Author(s):  
Peng Peng ◽  
Yonghao Mi ◽  
Marianna Lytova ◽  
Mathew Britton ◽  
Xiaoyan Ding ◽  
...  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Thomas Ding ◽  
Marc Rebholz ◽  
Lennart Aufleger ◽  
Maximilian Hartmann ◽  
Veit Stooß ◽  
...  

AbstractHigh-intensity ultrashort pulses at extreme ultraviolet (XUV) and x-ray photon energies, delivered by state-of-the-art free-electron lasers (FELs), are revolutionizing the field of ultrafast spectroscopy. For crossing the next frontiers of research, precise, reliable and practical photonic tools for the spectro-temporal characterization of the pulses are becoming steadily more important. Here, we experimentally demonstrate a technique for the direct measurement of the frequency chirp of extreme-ultraviolet free-electron laser pulses based on fundamental nonlinear optics. It is implemented in XUV-only pump-probe transient-absorption geometry and provides in-situ information on the time-energy structure of FEL pulses. Using a rate-equation model for the time-dependent absorbance changes of an ionized neon target, we show how the frequency chirp can be directly extracted and quantified from measured data. Since the method does not rely on an additional external field, we expect a widespread implementation at FELs benefiting multiple science fields by in-situ on-target measurement and optimization of FEL-pulse properties.


2020 ◽  
Vol 10 (18) ◽  
pp. 6153
Author(s):  
Alexander Magunia ◽  
Lennart Aufleger ◽  
Thomas Ding ◽  
Patrick Rupprecht ◽  
Marc Rebholz ◽  
...  

We report on numerical results revealing line-shape asymmetry changes of electronic transitions in atoms near-resonantly driven by intense extreme-ultraviolet (XUV) electric fields by monitoring their transient absorption spectrum after transmission through a moderately dense atomic medium. Our numerical model utilizes ultrashort broadband XUV laser pulses varied in their intensity (1014–1015 W/cm2) and detuning nearly out of resonance for a quantitative evaluation of the absorption line-shape asymmetry. It will be shown how transient energy shifts of the bound electronic states can be linked to these asymmetry changes in the case of an ultrashort XUV driving pulse temporally shorter than the lifetime of the resonant excitation, and how the asymmetry can be controlled by the near-resonant detuning of the XUV pulse. In the case of a two-level system, the numerical model is compared to an analytical calculation, which helps to uncover the underlying mechanism for the detuning- and intensity-induced line-shape modification and links it to the generalized Rabi frequency. To further apply the numerical model to recent experimental results of the near-resonant dressing of the 2s2p doubly excited state in helium by an ultrashort XUV free-electron laser pulse we extend the two-level model with an ionization continuum, thereby enabling the description of transmission-type (Fraunhofer-like) transient absorption of a strongly laser-coupled autoionizing state.


2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Peng Peng ◽  
Claude Marceau ◽  
Marius Hervé ◽  
P. B. Corkum ◽  
A. Yu. Naumov ◽  
...  

AbstractTransient absorption spectroscopy is utilized extensively for measurements of bound- and quasibound-state dynamics of atoms and molecules. The extension of this technique into the extreme ultraviolet (XUV) region with attosecond pulses has the potential to attain unprecedented time resolution. Here we apply this technique to aligned-in-space molecules. The XUV pulses are much shorter than the time during which the molecules remain aligned, typically $$<$$<100 fs. However, transient absorption is not an instantaneous probe, because long-lived coherences re-emit for picoseconds to nanoseconds. Due to dephasing of the rotational wavepacket, it is not clear if these coherences will be evident in the absorption spectrum, and whether the properties of the initial excitations will be preserved. We studied Rydberg states of N$${}_{2}$$2 and O$${}_{2}$$2 from 12 to 23 eV. We were able to determine the polarization direction of the electronic transitions, and hence identify the symmetry of the final states.


2016 ◽  
Vol 18 (21) ◽  
pp. 14644-14653 ◽  
Author(s):  
Adam S. Chatterley ◽  
Florian Lackner ◽  
Daniel M. Neumark ◽  
Stephen R. Leone ◽  
Oliver Gessner

Using femtosecond time-resolved extreme ultraviolet absorption spectroscopy, the dissociation dynamics of the haloalkane 1,2-dibromoethane (DBE) have been explored following strong field ionization by femtosecond near infrared pulses at intensities between 7.5 × 1013 and 2.2 × 1014 W cm−2.


2016 ◽  
Vol 33 (7) ◽  
pp. C57 ◽  
Author(s):  
Lauren J. Borja ◽  
M. Zürch ◽  
C. D. Pemmaraju ◽  
Martin Schultze ◽  
Krupa Ramasesha ◽  
...  

Author(s):  
Lennart Aufleger ◽  
Patrick Friebel ◽  
Patrick Rupprecht ◽  
Alexander Magunia ◽  
Thomas Ding ◽  
...  

Abstract We study the interaction of intense extreme ultraviolet (XUV) light with the 2s2p doubly excited state in helium. In addition to previously understood energy-level and phase shifts, high XUV intensities may lead to other absorption line shape distortions. Here, we report on experimental transient-absorption spectroscopy results on the 2s2p line width modification in helium in intense stochastic XUV fields. A few-level model simulation is realized to investigate the origins of this effect. We find that the line shape broadening is connected to the strong coupling of the ground state to the 2s2p doubly excited state which is embedded in the ionization continuum. As the broadening takes place for intensities lower than for other strong-coupling processes, e.g. observing asymmetry changes of the absorption profile, this signature can be identified already in an intermediate intensity regime. These findings are in general relevant for resonant inner shell transitions in nonlinear experiments with XUV and x-ray photon energies at high intensity.


2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Hung-Tzu Chang ◽  
Alexander Guggenmos ◽  
Christopher T. Chen ◽  
Juwon Oh ◽  
Romain Géneaux ◽  
...  

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Y. Hikosaka ◽  
T. Kaneyasu ◽  
M. Fujimoto ◽  
H. Iwayama ◽  
M. Katoh

Abstract Quantum manipulation of populations and pathways in matter by light pulses, so-called coherent control, is currently one of the hottest research areas in optical physics and photochemistry. The forefront of coherent control research is moving rapidly into the regime of extreme ultraviolet wavelength and attosecond temporal resolution. This advance has been enabled by the development of high harmonic generation light sources driven by intense femtosecond laser pulses and by the advent of seeded free electron laser sources. Synchrotron radiation, which is usually illustrated as being of poor temporal coherence, hitherto has not been considered as a tool for coherent control. Here we show an approach based on synchrotron radiation to study coherent control in the extreme ultraviolet and attosecond regime. We demonstrate this capability by achieving wave-packet interferometry on Rydberg wave packets generated in helium atoms.


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