scholarly journals High-Harmonic and Terahertz Spectroscopy (HATS): Methods and Applications

2019 ◽  
Vol 9 (5) ◽  
pp. 853 ◽  
Author(s):  
Yindong Huang ◽  
Chao Chang ◽  
Jianmin Yuan ◽  
Zengxiu Zhao
Keyword(s):  
Extreme Ultraviolet ◽  
Terahertz Spectroscopy ◽  
High Harmonic ◽  
Molecular Structures ◽  
Slow Electron ◽  
Electron Dynamics ◽  
Joint Measurement ◽  
X Ray ◽  
Millimeter Wavelength ◽  
High Harmonics

Electrons driven from atom or molecule by intense dual-color laser fields can coherently radiate high harmonics from extreme ultraviolet to soft X-ray, as well as an intense terahertz (THz) wave from millimeter to sub-millimeter wavelength. The joint measurement of high-harmonic and terahertz spectroscopy (HATS) was established and further developed as a unique tool for monitoring electron dynamics of argon from picoseconds to attoseconds and for studying the molecular structures of nitrogen. More insights on the rescattering process could be gained by correlating the fast and slow electron motions via observing and manipulating the HATS from atoms and molecules. We also propose the potential investigations of HATS of polar molecules, and solid and liquid sources.

scholarly journals Table-top extreme ultraviolet second harmonic generation

2021 ◽  
Vol 7 (21) ◽  
pp. eabe2265
Author(s):  
Tobias Helk ◽  
Emma Berger ◽  
Sasawat Jamnuch ◽  
Lars Hoffmann ◽  
Adeline Kabacinski ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
First Principles ◽  
Extreme Ultraviolet ◽  
Second Harmonic ◽  
High Harmonic ◽  
Electronic Structure Calculations ◽  
Free Electron Lasers ◽  
X Ray ◽  
Structure Calculations

The lack of available table-top extreme ultraviolet (XUV) sources with high enough fluxes and coherence properties has limited the availability of nonlinear XUV and x-ray spectroscopies to free-electron lasers (FELs). Here, we demonstrate second harmonic generation (SHG) on a table-top XUV source by observing SHG near the Ti M2,3 edge with a high-harmonic seeded soft x-ray laser. Furthermore, this experiment represents the first SHG experiment in the XUV. First-principles electronic structure calculations suggest the surface specificity and separate the observed signal into its resonant and nonresonant contributions. The realization of XUV-SHG on a table-top source opens up more accessible opportunities for the study of element-specific dynamics in multicomponent systems where surface, interfacial, and bulk-phase asymmetries play a driving role.

scholarly journals High Repetition Rate and Coherent Free-Electron Laser in the X-Rays Range Tailored for Linear Spectroscopy

Instruments ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 47 ◽  
Author(s):  
Vittoria Petrillo ◽  
Michele Opromolla ◽  
Alberto Bacci ◽  
Illya Drebot ◽  
Giacomo Ghiringhelli ◽  
...  
Keyword(s):  
Free Electron ◽  
Repetition Rate ◽  
Free Electron Laser ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
High Repetition Rate ◽  
X Rays ◽  
Regenerative Amplifier ◽  
X Ray ◽  
High Repetition

Fine time-resolved analysis of matter—i.e., spectroscopy and photon scattering—in the linear response regime requires fs-scale pulsed, high repetition rate, fully coherent X-ray sources. A seeded Free Electron Laser (FEL) driven by a Linac based on Super Conducting cavities, generating 10 8 – 10 10 coherent photons at 2–5 keV with 0.2–1 MHz of repetition rate, can address this need. Three different seeding schemes, reaching the X-ray range, are described hereafter. The first two are multi-stage cascades upshifting the radiation frequency by a factor of 10–30 starting from a seed represented by a coherent flash of extreme ultraviolet light. This radiation can be provided either by the High Harmonic Generation of an optical laser or by an FEL Oscillator operating at 12–14 nm. The third scheme is a regenerative amplifier working with X-ray mirrors. The whole chain of the X-ray generation is here described by means of start-to-end simulations.

scholarly journals Ultrafast Hole Deformation Revealed by Molecular Attosecond Interferometry

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yindong Huang ◽  
Jing Zhao ◽  
Zheng Shu ◽  
Yalei Zhu ◽  
Jinlei Liu ◽  
...  
Keyword(s):  
Wave Packet ◽  
Terahertz Spectroscopy ◽  
Strong Field ◽  
High Harmonic ◽  
Photochemical Reactions ◽  
Pulse Generation ◽  
Joint Measurement ◽  
Electron Wave Packet ◽  
Rotational Wave ◽  
And Control

Understanding the evolution of molecular electronic structures is the key to explore and control photochemical reactions and photobiological processes. Subjected to strong laser fields, electronic holes are formed upon ionization and evolve in the attosecond timescale. It is crucial to probe the electronic dynamics in real time with attosecond-temporal and atomic-spatial precision. Here, we present molecular attosecond interferometry that enables the in situ manipulation of holes in carbon dioxide molecules via the interferometry of the phase-locked electrons (propagating in opposite directions) of a laser-triggered rotational wave packet. The joint measurement on high-harmonic and terahertz spectroscopy (HATS) provides a unique tool for understanding electron dynamics from picoseconds to attoseconds. The optimum phases of two-color pulses for controlling the electron wave packet are precisely determined owing to the robust reference provided with the terahertz pulse generation. It is noteworthy that the contribution of HOMO-1 and HOMO-2 increases reflecting the deformation of the hole as the harmonic order increases. Our method can be applied to study hole dynamics of complex molecules and electron correlations during the strong-field process. The threefold control through molecular alignment, laser polarization, and the two-color pulse phase delay allows the precise manipulation of the transient hole paving the way for new advances in attochemistry.

scholarly journals Angular dispersion enhanced prebunch for seeding ultrashort and coherent EUV and soft X-ray free-electron laser in storage rings

2019 ◽  
Vol 26 (3) ◽  
pp. 677-684 ◽  
Author(s):  
Xiaofan Wang ◽  
Chao Feng ◽  
Tao Liu ◽  
Zhen Zhang ◽  
Cheng-Ying Tsai ◽  
...  
Keyword(s):  
Storage Ring ◽  
Free Electron ◽  
Peak Power ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Angular Dispersion ◽  
Effective Technique ◽  
X Ray ◽  
Output Stability ◽  
Longitudinal Coherence

Prebunching is an effective technique to reduce the radiation saturation length and to improve the longitudinal coherence and output stability in storage-ring-based free-electron lasers (FELs). A novel technique is proposed which uses angular dispersion to enhance the high-harmonic bunching with very small laser-induced energy spread. This technique can effectively reduce the radiation saturation length without significantly reducing the peak power of the FEL. Numerical simulations demonstrate that this technique can be used for the generation of 100 MW scale level, fully temporal coherent femtosecond extreme-ultraviolet and soft X-ray radiation pulses through a 10 m-long undulator based on a diffraction-limited storage ring.

scholarly journals Spectrally resolved wavefront characterization of broadband ultrafast high-harmonic pulses

2019 ◽  
Vol 205 ◽  
pp. 01022
Author(s):  
Jansen G.S.M. ◽  
Freisem L. ◽  
Rudolf D. ◽  
Eikema K.S.E. ◽  
Witte S.
Keyword(s):  
Harmonic Generation ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Single Camera ◽  
High Harmonics ◽  
Spectrally Resolved

We demonstrate a sensor that measures wavefronts of multiple extreme ultraviolet wavelengths simultaneously. By incorporating transmission gratings into the apertures of a Hartmann mask, we can record wavefront information for series of discrete harmonics from a high-harmonic generation source in a single camera exposure, without the need for scanning parts. Wavefronts of up to nine high harmonics at 25-49 nm wavelength are retrieved, and ultrafast spatiotemporal couplings can be detected.

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

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