Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session C7: Focus Session: Strong Field Plasmonics and Control |
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Chair: Uwe Thumm, Kansas State University Room: 303 |
Tuesday, June 4, 2013 2:00PM - 2:30PM |
C7.00001: Controlling dielectrics with the electric field of light Invited Speaker: Mark Stockman |
Tuesday, June 4, 2013 2:30PM - 2:42PM |
C7.00002: Unveiling the critical role of phase in optimal control pulses H.U. Jang, J. Lee, G.-Y. Chen, W.T. Hill, III Theory purports optimal control problems either have a perfect control solution or no solution. Experimental searches often produce multiple solutions that are not the same. This apparent inconsistency has inhibited a quantitative description of how an optimal pulse (OP) achieves its goal. We now have evidence that suggests the relative phase between the components of OPs (temporal and spectral), which has garnered little attention in optimal control discussions, is a key to solving this paradox. Exploiting an ability to adjust the relative phase (RP), intensity and temporal separation (TS) of a pair of peaks independently, we have compared OP solutions generated by closed-loop searches to a two-peak optimization adjusting only RP and TS. Three distinct phenomena concomitant with strong-field enhanced ionization of three-atom systems were monitored -- propensity for bending, explosion strength and branching into degenerate channels. In all cases, the response was altered significantly when RP and TS were varied. Multiple specific values for the (RP, TS)-pair were found to produce optimal responses. The optimal values were consistent with those associated with the OP solutions producing the same result, possibly explaining the paradox. Results and ramification will be presented. [Preview Abstract] |
Tuesday, June 4, 2013 2:42PM - 2:54PM |
C7.00003: Isotope effect in carrier-envelop phase control of electron localization in dissociating hydrogen molecules Igor Litvinyuk, Han Xu, Dane Laban, William Wallace, Dave Kielpinski, Robert Sang, Tianyu Xu, Feng He We study dissociation of light (H$_{2})$ and heavy (D$_{2})$ hydrogen by few-cycle near-infrared (800 nm) laser pulses with stable carrier-envelop phase (CEP) using Reaction Microscope. We observe significant (40 percent for H$_{2})$ CEP-dependent asymmetry in low energy (below 2 eV per fragment) dissociation channels for both molecules. By using a 50:50 mixture of light and heavy hydrogen in the target jet we can compare the spectra for the two isotopes obtained at exactly the same experimental conditions including CEP. We observe marked differences between the two molecules indicating that nuclear mass strongly affects the dynamics of electron localization. We also perform theoretical calculations using a one-dimensional two-level model, with theoretical results being in good agreement with the experimental data. [Preview Abstract] |
Tuesday, June 4, 2013 2:54PM - 3:06PM |
C7.00004: Control of decoherence accompanying Raman transitions by odd and even chirps of optical frequency combs Svetlana Malinovskaya We discuss femtosecond Raman type techniques to control molecular vibrations by implementing phase modulated optical frequency combs. These techniques make use of multiple two-photon resonances induced by optical frequencies present in the comb. They provide a tool to study the details of molecular dynamics in systems with decoherence. We analyze the spectral properties of odd and even chirps of the optical frequency comb in the form of sine and cosine functions and the effects they cause on the population transfer. We show that the odd chirp leads to population transfer in the presence of decoherence while the even chirp maximizes coherence between the initial and the final state. The results justify the importance of the parity of the chirp in achieving the desired quantum yield [1].\\[4pt] [1] S.A. Malinovskaya, S.L. Horton, ``Impact of Decoherence on Internal State Cooling using Optical Frequency Combs,'' J. Opt. Soc. Am. B (2013). [Preview Abstract] |
Tuesday, June 4, 2013 3:06PM - 3:36PM |
C7.00005: Strong-Field Above Threshold Photoemission from Sharp Metal Tips Invited Speaker: Peter Hommelhoff . [Preview Abstract] |
Tuesday, June 4, 2013 3:36PM - 3:48PM |
C7.00006: Using attosecond high-harmonics to probe dynamics near conical intersections Henry Timmers, Niranjan Shivaram, Chen-Ting Liao, Arvinder Sandhu Conical intersections provide a highly efficient means for electronic relaxation in excited polyatomic molecules. However, the experimental time-resolved studies of non-adiabatic couplings and dynamics associated with conical intersections have been limited. Here, we present the results of an attosecond, XUV pump - IR probe experiment to resolve the non-adiabatic dynamics of the CO$_2$ molecular ion in the vicinity of a conical intersection. We use 11th harmonic in the XUV pulse train to create a wavepacket in the two lowest excited states of CO$_2^+$. The IR pulse samples the evolution of this wavepacket and results in formation of O$^+$ and CO$^+$ ions along different dissociation pathways. We observe coherent oscillations in the fragmentation yield which can be attributed to the vibronic coupling mechanism of the conical intersection. [Preview Abstract] |
Tuesday, June 4, 2013 3:48PM - 4:00PM |
C7.00007: Sub-femtosecond Control of Hydrogen-Bond Rearrangement Ali S. Alnaser, K. Betsch, M. K\"ubel, R. Siemering, B. Bergues, N.G. Kling, I. Ben-Itzhak, Y. Deng, Z.A. Alahmed, A.M. Azzeeer, R. Moshammer, J. Ulrich, U. Kleineberg, R. de Vivie-Riedle, F. Krausz, M.F. Kling We present experimental and theoretical data supporting a new and very general coherent control scheme, where the directional hydrogen migration in hydrocarbon molecules is initiated via light-driven attosecond electron motion. The strong coupling between electron and nuclear motions allows for efficient control of both electrons and heavier nuclei within the wave cycle of near-single-cycle laser pulses. We show that the waveform of the near-single-cycle laser pulses can be tailored to preferentially steer protons to different sites of the hydrocarbons prior to the molecular disintegration by the strong laser fields. [Preview Abstract] |
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