Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session L6: Strong-Field Physics at Relativistic Intensity |
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Chair: Anthony DiChiara, Ohio State University Room: Minor Hall 125 |
Thursday, May 21, 2009 2:00PM - 2:30PM |
L6.00001: Strong-field physics at relativistic intensity Invited Speaker: The dynamics of multiply charged ions is discussed in the presence of extremely intense laser pulses. Various schemes are put forward how such ions could be employed for medical applications [1] and to characterize extremely intense laser pulses. Furthermore various laser-based scenarious are presented regarding vacuum nonlinearities [2] as well as muon [3] and electron pair creation [4]. \newline [1] Y. I. Salamin, Z. Harman, C H Keitel, Phys. Rev. Lett. 100, 155004 (2008) \newline [2] A. Di Piazza, K. Z. Hatsagortsyan, C. H. Keitel, Phys. Rev. Lett. 100, 010403 (2008) \newline [3] C. M\"{u}ller, C. Deneke, C. H. Keitel, Phys. Rev. Lett. 101, 060402 (2008) \newline [4] E. L\"{o}tstedt, U. D. Jentschura, C. H. Keitel, Phys. Rev. Lett. 101, 203001 (2008). [Preview Abstract] |
Thursday, May 21, 2009 2:30PM - 3:00PM |
L6.00002: Ionization of Atoms and Small Molecules in Ultra-Strong Laser Fields Invited Speaker: The frontiers of ultraintense laser science stretch across an exceptional range of disciplines including plasma physics, fusion science, atomic physics, optical science, and attosecond physics. Today, ultrafast lasers have increased laboratory light intensities to 10$^{20}$ times the intensity of sunlight on earth and there is new interest in the ultrastrong fields at ``relativistic intensities.'' In ultrastrong fields (10$^{17}$ W/cm$^{2}$ to 10$^{20}$ W/cm$^{2})$ multi-electron events involving the correlation of four or more electrons have been measured and the entire valence shell along with several inner shell electrons may be ionized. Furthermore, after ionization in ultrastrong fields photoelectrons experience a tremendous acceleration, 10$^{24}$m/s$^{2}$ in fact at an intensity of 10$^{20}$W/cm$^{2}$. This acceleration can change the velocity of an electron from rest to a sizable fraction of speed of light c in less than a femtosecond. This talk will discuss recent extensions of our knowledge of atomic, molecular and optical physics from multi-photon and strong fields (10$^{11}$ W/cm$^{2}$ to 10$^{15}$ W/cm$^{2})$ into the new frontier of ultrastrong fields (10$^{17}$ W/cm$^{2}$ to 10$^{20}$ W/cm$^{2})$. The topics that will be discussed include the fundamental atomic ionization response including the role of the laser magnetic field and rescattering and Coulomb explosion and ionization of molecules in ultrastrong fields. This work is supported by the National Science Foundation (Grant No. 0757953). [Preview Abstract] |
Thursday, May 21, 2009 3:00PM - 3:30PM |
L6.00003: Photoemission out the side of a relativistic laser focus by individual free electrons Invited Speaker: The quantum wave packets of free electrons naturally spread, quickly reaching the scale of optical wavelengths. Moreover, an electron wave packet born through ionization in an intense laser focus is pulled apart by sharp field gradients. Different parts of the same electron wave packet may even be propelled out opposite sides of the laser focus. The question naturally arises as to how wave packets scatter laser radiation if they undergo such highly non-dipole dynamics. If one uses quantum probability current (multiplied by the electron charge) as a source current for Maxwell's equations, the radiated field is strongly suppressed by severe interferences. This approach predicts dramatic suppression of radiation scattered out the side of an intense laser focus, relative to what one would expect if electrons are treated as point charges. We present theoretical arguments and give a progress report on an experiment designed to test for this distinction in photoemission rates. The result may shed light on the fundamental question of what constitutes a quantum measurement. [Preview Abstract] |
Thursday, May 21, 2009 3:30PM - 3:42PM |
L6.00004: Relativistic MeV Photoelectrons from the Single Atom Response of Xenon to a 10$^{19}$ W/cm$^{2}$ Laser Field Nagitha Ekanayake, Anthony DiChiara, Issac Ghebregziabher, Laura Barclay, Jane Waesche, Barry Walker We present experimental photoelectron measurements from the single atom photoionization of Xe exposed to field intensities up to 1.2x10$^{19}$ W/cm$^{2}$. An ultra-strong laser field was used to ionize Xe and the resulting high energy electrons as a function of intensity, energy and angle were measured with a dynamic range of four orders of magnitude. The measurements are compared to a 3D, relativistic, semi-classical, single electron model of ionization [1]. The essential photoelectron spectrum features above 0.5 MeV, including the high energy cutoff, are in reasonable agreement with a semi-classical, relativistic 3D model of ionization. The observed energy spectrum and angular distributions at 60 keV is lower than the calculated result by an order of magnitude indicating existence of multi-electron processes which are not included in the model. This work is supported by the National Science Foundation (Grant {\#}: 0757953).\\[4pt] [1] I. Ghebregziabher and B.C. Walker, PRA 76, 023415 (2007). [Preview Abstract] |
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