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We report a source of free electron pulses based on a field emission tip irradiated by a low-power femtosecond laser. The electron pulses are shorter than 70 fs and originate from a tip with an emission area diameter down to 2 nm. Depending…

Quantum Physics · Physics 2007-05-23 Peter Hommelhoff , Yvan Sortais , Anoush Aghajani-Talesh , Mark A. Kasevich

Signatures of stochastic effects in the radiation of a relativistic electron beam interacting with a counterpropagating superstrong short focused laser pulse are investigated in a quantum regime when the electron's radiation dominates its…

Plasma Physics · Physics 2016-12-21 Jian-Xing Li , Yue-Yue Chen , Karen Z. Hatsagortsyan , Christoph H. Keitel

In this work we report ab initio calculations for the $H_2^+$ molecule interacting with ultrashort intense laser pulses. We analyse several observables that can, in principle, be available experimentally, in order to get a deeper…

Atomic Physics · Physics 2017-05-25 R. E. F. Silva

Helium nanodroplets are ideal model systems to unravel the complex interaction of condensed matter with ionizing radiation. Here we study the effect of purely elastic electron scattering on angular and energy distributions of photoelectrons…

We explore photo-electron spectra (PES) and photo-electron angular distributions (PAD) of C$_{60}$ with time-dependent density functional theory (TDDFT) in real time. To simulate experiments in gas phase, we consider isotropic ensembles of…

Atomic and Molecular Clusters · Physics 2014-12-12 C. -Z. Gao , P. Wopperer , P. M. Dinh , E. Suraud , P. -G. Reinhard

Techniques in time- and angle-resolved photoemission spectroscopy have facilitated a number of recent advances in the study of quantum materials. We review developments in this field related to the study of incoherent nonequilibrium…

Strongly Correlated Electrons · Physics 2016-10-04 Christopher L. Smallwood , Robert A. Kaindl , Alessandra Lanzara

Photoelectron emission from excited states of laser-dressed atomic helium is analyzed with respect to laser intensity-dependent excitation energy shifts and angular distributions. In the two-color XUV (exteme ultra\-violet) -- IR (infrared)…

In this paper we discuss a method for nondestructive measurements of the longitudinal profile of sub-picosecond electron bunches for X-Ray Free Electron Lasers (XFELs). The method is based on the detection of the Coherent Synchrotron…

Accelerator Physics · Physics 2007-05-23 G. A. Geloni , E. L. Saldin , E. A. Schneidmiller , M. V. Yurkov

We demonstrate the breakdown of molecular-frame dynamics induced by the uncoupling of molecular rotation from electronic motion in molecular Rydberg states. We observe this non-Born-Oppenheimer regime in the time domain through…

Atomic and Molecular Clusters · Physics 2017-07-05 Lucas J. Zipp , Adi Natan , Philip H. Bucksbaum

The rotational echo response of molecules is found to strongly depend on the delay between the two ultrashort laser pulses, as opposed to two-level systems. We study this dependence experimentally and theoretically and show that by…

Quantum Physics · Physics 2018-12-12 Dina Rosenberg , Ran Damari , Sharly Fleischer

The effect of screening by atomic electrons on the behavior of electron and positron wave functions in the continuous spectrum at small distances is studied. It is shown that these asymptotics are affected not only by the static potential…

Atomic Physics · Physics 2025-01-28 P. A. Krachkov , A. I. Milstein

Measurements and calculations of the absolute carrier-envelope phase (CEP) effects in the photodissociation of the simplest molecule, H2+, with a 4.5-fs Ti:Sapphire laser pulse at intensities up to (4 +- 2)x10^14 Watt/cm^2 are presented.…

Chemical Physics · Physics 2013-09-23 T. Rathje , A. M. Sayler , S. Zeng , P. Wustelt , H. Figger , B. D. Esry , G. G. Paulus

The quality of electron bunches accelerated by laser wakefields is highly dependant on the temporal and spatial features of the laser driver. Analysis of experiments performed at APOLLON PW-class laser facility shows that spatial…

We study optical spectra of finite electronic quantum systems at frequencies smaller than the plasma frequency using a quasi-classical approach. This approach includes collective effects and enables us to analyze how the nature of the…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 M. Santer , B. Mehlig

We study spectral properties of quantum radiation of ultimately short duration. In particular, we introduce a continuous multimode squeezing operator for the description of subcycle pulses of entangled photons generated by a coherent-field…

We report two schemes to generate perfect anisotropy in the photoelectron angular distribution of a randomly oriented ensemble of polyatomic molecules. In order to exert full control over the anisotropy of photoelectron emission, we exploit…

Quantum Physics · Physics 2020-02-24 R. Esteban Goetz , Christiane P. Koch , Loren Greenman

We investigate the photoionization spectrum of helium by attosecond XUV pulses both in the spectral region of doubly excited resonances as well as above the double ionization threshold. In order to probe for convergence, we compare three…

Asymmetric molecules look different when viewed from one side or the other. This difference influences the electronic structure of the valence electrons, thereby giving stereo sensitivity to chemistry and biology. We show that attosecond…

The pronounced dependence of the nonlinear parameters of both dielectric and semiconductor materials on the wavelength, and the nonlinear interaction between the ultra-short laser pulse and the material requires precise control of the…

Laser-plasma accelerators can produce ultra short electron bunches in the femtosecond to picosecond duration range, resulting in high peak dose rates in comparison with clinical accelerators. This peculiar characteristic motivates their…