Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session B7: Attosecond ScienceInvited
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Chair: Carlos Trallero, Kansas State University Room: 313 |
Tuesday, June 6, 2017 10:30AM - 11:00AM |
B7.00001: Laser-Induced Electron Wave Packets as a Sub-nanometer and Sub-femtosecond Probe Invited Speaker: Louis DiMauro Over the last fifteen years, the tailoring of a light field for manipulating the dynamics of a system at the quantum level has taken a prevalent role in modern atomic, molecular and optical physics. As first described by Keldysh, the ionization of an atom by an intense laser field will evolve depending upon the light characteristics and atomic binding energy. Numerous experiments have thoroughly investigated the dependence of the intensity and pulse duration on the ionization dynamics of inert gas atoms. However, exploration of the wavelength dependence has been mainly limited to wavelengths less than 1 $\mu $m, or in the language of Keldysh to the multiphoton or mixed ionization regime. It is now technically possible to perform more thorough test, and exploit the scaling laws at wavelengths greater than 1 $\mu $m. In addition, excitation with mid-infrared light augments a variety of atomic systems which will tunnel ionize, as well as posing different model atomic structure, e.g. one- and two-electron like systems. This talk will examine the implication of the strong-field scaling as it pertains to the production of high-energy particles, the generation of attosecond pulses and particularly, to the topic of strong-field molecular imaging. [Preview Abstract] |
Tuesday, June 6, 2017 11:00AM - 11:30AM |
B7.00002: New generation attosecond light sources Invited Speaker: Zenghu Chang Millijoule level, few-cycle, carrier-envelope phase (CEP) stable Ti:Sapphire lasers centered at 800 nm have been the workhorse for the first generation attosecond light sources in the last 16 years. The spectral range of isolated attosecond pulses with sufficient photon flux for time-resolved pump-probe experiments has been limited to extreme ultraviolet (10 to 150 eV). The shortest pulses achieved are 67 as. It was demonstrated in 2001 that the cutoff photon energy of the high harmonic spectrum could be extended by increasing the center wavelength of the driving lasers. In recent years, mJ level, two-cycle, carrier-envelope phase stabilized lasers at 1.6 to 2.1 micron have been developed by implementing Optical Parametric Chirped Pulse Amplification (OPCPA) techniques. Recently, when long wavelength driving was combined with polarization gating, isolated soft x-rays in the water window (280-530 eV) were generated in our laboratory. The number of x-ray photons in the 120--400 eV range is comparable to that generated with Ti:Sapphire lasers in the 50 to 150 eV range. The ultrabroadband isolated x-ray pulses with 53 as duration were characterized by attosecond streaking measurements. The new generation attosecond soft X-ray sources open the door for studying electron dynamics with element specificity through core to valence transitions. [Preview Abstract] |
Tuesday, June 6, 2017 11:30AM - 12:00PM |
B7.00003: Phase-sensitive Photoelectron Metrology Invited Speaker: Paul Hockett Photoionization is an interferometric process, in which multiple paths can contribute to the final continuum photoelectron state. At the simplest level, interferences between different final angular momentum states are manifest in the energy and angle resolved photoelectron spectra: metrology schemes making use of these interferograms are thus phase-sensitive, and provide a powerful route to detailed understanding of photoionization [1]. At a more complex level, such measurements can also provide a powerful probe for other processes of interest, for example: (a) dynamical process in time-resolved measurements, such as rotational, vibrational and electronic wavepackets, and (b) in order to understand and develop control schemes [1]. In this talk recent work in this vein will be discussed, touching on ``complete" photoionization studies of atoms and molecules with shaped laser pulses [1,2] and XUV [3], metrology schemes using Angle-Resolved RABBIT, and molecular photoionization dynamics in the time-domain (Wigner delays) [4]. [1] Hockett, P. et. al. (2015). Phys. Rev. A, 92, 13412. [2] Hockett, P. et. al. (2014). Phys. Rev. Lett., 112, 223001. [3] Marceau, C. et. al. (2017). Submitted. DOI: 10.6084/m9.figshare.4480349. [4] Hockett, P. et. al. (2016). J. Phys B, 49, 95602. [Preview Abstract] |
Tuesday, June 6, 2017 12:00PM - 12:30PM |
B7.00004: Do nuclei move on an attosecond timescale in strong-field photodissociation? Invited Speaker: B.D. Esry Without the ready availability of single attosecond pulses with sufficient energy to perform pump-probe experiments, the push to measure electronic dynamics on its natural timescale of attoseconds has enlisted less direct measurements. Photoionization ``time delays'', in particular, have been measured and calculated to be on the attosecond timescale and thus have attracted considerable attention. The ultimate goal of such attosecond-scale measurements is the molecular movie\,---\,{\em i.e.}, making movies of the electronic motion during chemical reactions. It has been universally assumed, however, that any measured attosecond timescales in observables relate exclusively to electronic dynamics, even during a reaction which necessarily includes nuclear motion. I will explore some of the limits of this assumption and highlight a few specific cases where it fails, emphasizing in the process that phases should be favored over ``time delays''. [Preview Abstract] |
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