Bulletin of the American Physical Society
2011 Annual Meeting of the Four Corners Section of the APS
Volume 56, Number 11
Friday–Saturday, October 21–22, 2011; Tuscon, Arizona
Session E1: AMO I: Ultrafast Measurements, Atomic Structure, EUV Optics |
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Chair: Arvinder Sandhu, University of Arizona Room: UA Student Union South Ballroom |
Friday, October 21, 2011 3:25PM - 3:37PM |
E1.00001: Watching the Real-time Evolution of a Laser Modified Atom Using Attosecond Pulses Niranjan Shivaram, Henry Timmers, Xiao-Min Tong, Arvinder Sandhu In the presence of even moderately strong laser fields, atomic states are heavily modified and develop rich structure. Such a laser dressed atom can be described using the Floquet theory in which the laser dressed states called Floquet states are composed of different Fourier components. In this work we use XUV attosecond pulses to excite a He atom from its ground state to near-infrared (NIR) laser dressed Floquet states, which are ionized by the dressing laser field. Quantum interferences between Fourier components of these Floquet states lead to oscillations in He ion yield as a function of time-delay between the XUV and NIR pulses. From the ion yield signal we measure the quantum phase difference between transition matrix elements to two different Fourier components as a function of both time-delay (instantaneous NIR intensity) and NIR pulse peak intensity. These measurements along with information from time-dependent Schrodinger equation simulations enable us to observe the real-time evolution of the laser modified atom as the dominant Floquet state mediating the ionization changes from the 5p Floquet state to the 2p Floquet state with increasing NIR intensity. [Preview Abstract] |
Friday, October 21, 2011 3:37PM - 3:49PM |
E1.00002: Very accurate quantum mechanical calculations on small atom with explicitly correlated Gaussian functions Keeper Sharkey Techniques and algorithms for very accurate calculations of ground and excited states of atoms with three and four electrons will be presented. The approach has been used to determine state energies and the corresponding wave functions. The effect of the finite mass of the nucleus is expicitly include in the calculations, which are done with the variational method and employ the analitical energy gradient in the optimization of the Gaussian nonlinear parameters. Some recenly obtained results for $D$ states of the Li and Be atom will be shown. [Preview Abstract] |
Friday, October 21, 2011 3:49PM - 4:01PM |
E1.00003: Control over dissociative dynamics in $O_2^+$ Henry Timmers, Niranjan Shivaram, Arvinder Sandhu We report results from a pump-probe experiment in O$_2$ in which we monitor the dissociative ionization upon interaction with a XUV attosecond pulse train in the presence of a strong IR probe field. We use the XUV attosecond pulse to excite the molecule to the ionized ($c^4\Sigma_u^-$) O$_2^+$ state and monitor the evolution of the vibrational wavepacket using a time delayed femtosecond IR pulse. We present the capability to control the dissociative ion yield of $O^+$ by controlling the intrinsic spin-orbit predissociation mechanism. Furthermore, we demonstrate the ability to control the time-of-birth position of the vibrational wavepacket as well as the wavepacket's dissociating phase. [Preview Abstract] |
Friday, October 21, 2011 4:01PM - 4:13PM |
E1.00004: Non-Specular Scattering from Black Chrome in the Extreme Ultraviolet James Vaterlaus, Quintin Nethercotte An instrument being developed at the Lawrence Livermore National Laboratory is very sensitive to extreme ultraviolet (EUV) radiation. In order to characterize EUV scattering, we are measuring and comparing non-specular intensity reflected from several black chrome plated samples provided by LLNL. The measurements are challenging because the intensity drops off very quickly for non-specular angles making it difficult to see the signal above the background levels of EUV. Doing photon counting with a very low background detector and measuring for extended periods of time, we were able to see above background signals over a large range of non-specular angles. The analysis of our data involves deconvolutions to reconstruct the original image and determine reflectance as a function of angle. We can then reconstruct the non-specular reflectance as a function of scattering angle. [Preview Abstract] |
Friday, October 21, 2011 4:13PM - 4:25PM |
E1.00005: The design and use of a planetary in a sputtering system Brett Bostrom, David Allred, R. Steven Turley Low variations in thickness over dimensions of several cm are important for preparing film suitable for optical characterization. Our group at BYU is interested in determining the XUV optical constants (at wavelengths of 5-100nm) of materials useful in XUV optics. In particular we have been studying the constants of oxides and comparing them with the constants of their parent elements. These include scandium, yttrium and uranium oxides prepared by reactively sputtering in an argon-oxygen plasma. To increase lateral thickness uniformity we have designed and implemented a system of planetary gears that increases motion over the sputtering target. Simulations predict a thickness variance of less than 3 percent over 5cm 5 cm areas. We will present the design and results of the work. [Preview Abstract] |
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