Read by QxMD icon Read


A M Koushki, R Sadighi-Bonabi, M Mohsen-Nia, E Irani
In the present work, an efficient method is theoretically investigated for extending high-order harmonics and ultrashort attosecond pulse generation in N2 and CO molecules by using the time-dependent density functional theory approach. Our results show that by utilizing chirped laser field in the presence of a low frequency field, not only is the harmonic cutoff extended remarkably but also the single short quantum trajectory is selected to contribute to the harmonic spectra. When a low frequency field is added to the two-color chirped laser field, the long quantum trajectories are suppressed and only the short quantum trajectories contribute to the higher harmonic emission mechanism...
April 14, 2018: Journal of Chemical Physics
Peter M Kraus, Hans Jakob Wörner
The description of the electronic structure of molecules in terms of molecular orbitals is a highly successful concept in chemistry. However, it commonly fails if the electrons in a molecule are strongly correlated and cannot be treated as independent particles. Electron correlation is essential to understand inner-valence X-ray spectroscopies, it can drive ultrafast charge migration in molecules, and it is responsible for many exotic properties of strongly correlated materials. Time-resolved spectroscopy with attosecond resolution is generally capable of following electronic motion in real time and can thus provide experimental access to electron-correlation-driven phenomena...
April 6, 2018: Angewandte Chemie
Matteo Lucchini, Giacinto D Lucarelli, Mario Murari, Andrea Trabattoni, Nicola Fabris, Fabio Frassetto, Sandro De Silvestri, Luca Poletto, Mauro Nisoli
Sub-10-fs pulses tunable in the extreme-ultraviolet (XUV) spectral region are particularly important in many research fields: from atomic and molecular spectroscopy to the study of relaxation processes in solids and transition phase processes, from holography to free-electron laser injection. A crucial prerequisite for all applications is the accurate measurement of the temporal characteristics of these pulses. To fulfill this purpose, many phase retrieval algorithms have been successfully applied to reconstruct XUV attosecond pulses...
March 19, 2018: Optics Express
M Kozák, N Schönenberger, P Hommelhoff
Atomic motion dynamics during structural changes or chemical reactions have been visualized by pico- and femtosecond pulsed electron beams via ultrafast electron diffraction and microscopy. Imaging the even faster dynamics of electrons in atoms, molecules, and solids requires electron pulses with subfemtosecond durations. We demonstrate here the all-optical generation of trains of attosecond free-electron pulses. The concept is based on the periodic energy modulation of a pulsed electron beam via an inelastic interaction, with the ponderomotive potential of an optical traveling wave generated by two femtosecond laser pulses at different frequencies in vacuum...
March 9, 2018: Physical Review Letters
Dimitar Popmintchev, Benjamin R Galloway, Ming-Chang Chen, Franklin Dollar, Christopher A Mancuso, Amelia Hankla, Luis Miaja-Avila, Galen O'Neil, Justin M Shaw, Guangyu Fan, Skirmantas Ališauskas, Giedrius Andriukaitis, Tadas Balčiunas, Oliver D Mücke, Audrius Pugzlys, Andrius Baltuška, Henry C Kapteyn, Tenio Popmintchev, Margaret M Murnane
Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energies >1.6  keV. Here we demonstrate the use of this light for x-ray-absorption spectroscopy at the K- and L-absorption edges of solids at photon energies near 1 keV. We also report x-ray-absorption spectroscopy in the water window spectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuum with 10^{9}  photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources...
March 2, 2018: Physical Review Letters
Meng Han, Peipei Ge, Yun Shao, Qihuang Gong, Yunquan Liu
We employ attosecond angular streaking with photoelectron interferometric metrology to reveal electron sub-Coulomb-barrier dynamics. We use a weak perturbative corotating circularly polarized field (800 nm) to probe the strong-field ionization by an intense circularly polarized field (400 nm). In this double-pointer attoclock photoelectron interferometry, we introduce a spatially rotating temporal Young's two-slit interferometer, in which the oppositely modulated wave packets originating from consecutive laser cycles are dynamically prepared and interfered...
February 16, 2018: Physical Review Letters
Claudio Cirelli, Carlos Marante, Sebastian Heuser, C L M Petersson, Álvaro Jiménez Galán, Luca Argenti, Shiyang Zhong, David Busto, Marcus Isinger, Saikat Nandi, Sylvain Maclot, Linnea Rading, Per Johnsson, Mathieu Gisselbrecht, Matteo Lucchini, Lukas Gallmann, J Marcus Dahlström, Eva Lindroth, Anne L'Huillier, Fernando Martín, Ursula Keller
Electron correlation and multielectron effects are fundamental interactions that govern many physical and chemical processes in atomic, molecular and solid state systems. The process of autoionization, induced by resonant excitation of electrons into discrete states present in the spectral continuum of atomic and molecular targets, is mediated by electron correlation. Here we investigate the attosecond photoemission dynamics in argon in the 20-40 eV spectral range, in the vicinity of the 3s-1 np autoionizing resonances...
March 6, 2018: Nature Communications
Enrico Perfetto, Davide Sangalli, Andrea Marini, Gianluca Stefanucci
The early stage density oscillations of the electronic charge in molecules irradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond timescales. This ultrafast charge migration process is a central topic in attoscience as it dictates the relaxation pathways of the molecular structure. A predictive quantum theory of ultrafast charge migration should incorporate the atomistic details of the molecule, electronic correlations and the multitude of ionization channels activated by the broad-bandwidth XUV pulse...
March 1, 2018: Journal of Physical Chemistry Letters
Álvaro Jiménez-Galán, Gopal Dixit, Serguei Patchkovskii, Olga Smirnova, Felipe Morales, Misha Ivanov
High harmonic generation in multi-color laser fields opens the opportunity of generating isolated attosecond pulses with high ellipticity. Such pulses hold the potential for time-resolving chiral electronic, magnetization, and spin dynamics at their natural timescale. However, this potential cannot be realized without characterizing the exact polarization state of light on the attosecond timescale. Here we propose and numerically demonstrate a complete solution of this problem. Our solution exploits the extrinsic two-dimensional chirality induced in an atom interacting with the chiral attosecond pulse and a linearly polarized infrared probe...
February 27, 2018: Nature Communications
Zi-Yu Chen, Xiao-Ya Li, Bo-Yuan Li, Min Chen, Feng Liu
The production of intense isolated attosecond pulse is a major goal in ultrafast research. Recent advances in high harmonic generation from relativistic plasma mirrors under oblique incidence interactions gave rise to photon-rich attosecond pulses with circular or elliptical polarization. However, to achieve an isolated elliptical attosecond pulse via polarization gating using currently available long driving pulses remains a challenge, because polarization gating of high harmonics from relativistic plasmas is assumed only possible at normal or near-normal incidence...
February 19, 2018: Optics Express
Alexis Chacón, Camilo Ruiz
We report theoretical calculations of the delay in photoemission from CO with particular emphasis on the role of the ultrafast electronic bound dynamics. We study the delays in photoionization in the HOMO and HOMO-1 orbitals of the CO molecule by looking into the stereo Wigner time delay technique. That compares the delay in photoemission from electrons emitted to the left and right to extract structural and dynamical information of the ionization process. For this we apply two techniques: The attosecond streak camera and the time of flight technique...
February 19, 2018: Optics Express
Siqi Li, Zhaoheng Guo, Ryan N Coffee, Kareem Hegazy, Zhirong Huang, Adi Natan, Timur Osipov, Dipanwita Ray, Agostino Marinelli, James P Cryan
We present a reconstruction algorithm for isolated attosecond pulses, which exploits the phase dependent energy modulation of a photoelectron ionized in the presence of a strong laser field. The energy modulation due to a circularly polarized laser field is manifest strongly in the angle-resolved photoelectron momentum distribution, allowing for complete reconstruction of the temporal and spectral profile of an attosecond burst. We show that this type of reconstruction algorithm is robust against counting noise and suitable for single-shot experiments...
February 19, 2018: Optics Express
Konrad Hütten, Michael Mittermair, Sebastian O Stock, Randolf Beerwerth, Vahe Shirvanyan, Johann Riemensberger, Andreas Duensing, Rupert Heider, Martin S Wagner, Alexander Guggenmos, Stephan Fritzsche, Nikolay M Kabachnik, Reinhard Kienberger, Birgitta Bernhardt
Ultrafast spectroscopy with attosecond resolution has enabled the real time observation of ultrafast electron dynamics in atoms, molecules and solids. These experiments employ attosecond pulses or pulse trains and explore dynamical processes in a pump-probe scheme that is selectively sensitive to electronic state of matter via photoelectron or XUV absorption spectroscopy or that includes changes of the ionic state detected via photo-ion mass spectrometry. Here, we demonstrate how the implementation of combined photo-ion and absorption spectroscopy with attosecond resolution enables tracking the complex multidimensional excitation and decay cascade of an Auger auto-ionization process of a few femtoseconds in highly excited krypton...
February 19, 2018: Nature Communications
Jiancai Xu, Baifei Shen, Xiaomei Zhang, Yin Shi, Liangliang Ji, Lingang Zhang, Tongjun Xu, Wenpeng Wang, Xueyan Zhao, Zhizhan Xu
Extreme-ultravoilet (XUV) attosecond pulses with durations of a few tens of attosecond have been successfully applied for exploring ultrafast electron dynamics at the atomic scale. But their weak intensities limit the further application in demonstrating nonlinear responses of inner-shell electrons. Optical attosecond pulses will provide sufficient photon flux to initiate strong-field processes. Here we proposed a novel method to generate an ultra-intense isolated optical attosecond pulse through relativistic multi-cycle laser pulse interacting with a designed gas-foil target...
February 8, 2018: Scientific Reports
Johannes Passig, Sergey Zherebtsov, Robert Irsig, Mathias Arbeiter, Christian Peltz, Sebastian Göde, Slawomir Skruszewicz, Karl-Heinz Meiwes-Broer, Josef Tiggesbäumker, Matthias F Kling, Thomas Fennel
The original PDF version of this Article contained an error in Equation 1. The original HTML version of this Article contained errors in Equation 2 and Equation 4. These errors have now been corrected in both the PDF and the HTML versions of the Article.
February 7, 2018: Nature Communications
Kaijun Yuan, Andre Dieter Bandrauk
Charge migration is a fundamental and important process in the photo-chemistry of molecules which has been explored by time-resolved photoelectron angular distributions. A scheme based on UV pump and polarized soft x-ray probe techniques shows that photoelectron diffraction effects enable us to reconstruct electronic coherences encoding the information of the charge migration with extreme time resolutions. We discuss how probe pulse helicity influences the probing photoelectron spectra in the presence of molecular nonspherical Coulomb potentials...
February 6, 2018: Journal of Physical Chemistry. A
Meng Li, Guizhong Zhang, Xuelian Kong, Tianqing Wang, Xin Ding, Jianquan Yao
In this paper, we report our numerical simulation on the symmetry distortion and mechanism of the vortex-shaped momentum distribution of hydrogen atom by taking into account of the dynamic Stark effect. By deploying the strong field approximation (SFA) theory, we performed extensive simulation on the momentum pattern of hydrogen ionized by two time-delayed oppositely circularly polarized attosecond pulses. We deciphered that this distortion is originated from the temporal characteristics of the dynamic Stark phase which is nonlinear in time...
January 22, 2018: Optics Express
Chunyang Zhai, Xiaofan Zhang, Xiaosong Zhu, Lixin He, Yinfu Zhang, Baoning Wang, Qingbin Zhang, Pengfei Lan, Peixiang Lu
Molecular orbital tomography (MOT) based on high-order-harmonic generation opens a way to track the molecular electron dynamics or even follow a chemical reaction. However, the real-time imaging of the evolution of electron orbitals is hampered by the multi-shot measurement of high-order harmonics. Here, we report a single-shot MOT scheme with orthogonal two-color (OTC) fields. This scheme enables the tomographic imaging of molecular orbital with single-shot measurement in experiment, owing to the two-dimensional manipulation of the electron motion in OTC fields...
February 5, 2018: Optics Express
E Conejero Jarque, J San Roman, F Silva, R Romero, W Holgado, M A Gonzalez-Galicia, B Alonso, I J Sola, H Crespo
Gas-filled hollow-core fiber (HCF) pulse post-compressors generating few- to single-cycle pulses are a key enabling tool for attosecond science and ultrafast spectroscopy. Achieving optimum performance in this regime can be extremely challenging due to the ultra-broad bandwidth of the pulses and the need of an adequate temporal diagnostic. These difficulties have hindered the full exploitation of HCF post-compressors, namely the generation of stable and high-quality near-Fourier-transform-limited pulses. Here we show that, independently of conditions such as the type of gas or the laser system used, there is a universal route to obtain the shortest stable output pulse down to the single-cycle regime...
February 2, 2018: Scientific Reports
Marieke F Jager, Christian Ott, Christopher J Kaplan, Peter M Kraus, Daniel M Neumark, Stephen R Leone
We present an extreme ultraviolet (XUV) transient absorption apparatus tailored to attosecond and femtosecond measurements on bulk solid-state thin-film samples, specifically when the sample dynamics are sensitive to heating effects. The setup combines methodology for stabilizing sub-femtosecond time-resolution measurements over 48 h and techniques for mitigating heat buildup in temperature-dependent samples. Single-point beam stabilization in pump and probe arms and periodic time-zero reference measurements are described for accurate timing and stabilization...
January 2018: Review of Scientific Instruments
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"