Extracting continuum electron dynamics from high harmonic emission from molecules.

Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA.
Physical Review Letters (Impact Factor: 7.73). 03/2012; 108(13):133901. DOI: 10.1103/PhysRevLett.108.133901
Source: PubMed

ABSTRACT We show that high harmonic generation is the most sensitive probe of rotational wave packet revivals, revealing very high-order rotational revivals for the first time using any probe. By fitting high-quality experimental data to an exact theory of high harmonic generation from aligned molecules, we can extract the underlying electronic dipole elements for high harmonic emission and uncover that the electron gains angular momentum from the photon field.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We theoretically investigate high-order harmonic generation from H2+ in an infrared laser field. Our numerical simulations show that a highly efficient plateau structure exists in the molecular harmonic spectrum. Under the action of the infrared laser pulse, the bound electronic wave packet in a potential well has enough time to tunnel through the effective potential barrier, which is formed by the molecular potential and the infrared laser field, and then recombine with the neighboring nucleus emitting a harmonic photon. During the entire dynamic process, because the wave packet is mainly located in the effective potential, the diffusion effect is of no significance, and thus a highly efficient harmonic plateau can be achieved. Specifically, the cut-off frequency of the plateau is linearly scaled with the peak amplitude of the infrared laser electric field, which may open another route to examine the internuclear distance of the molecule. Furthermore, one may detect the molecular bond lengths using the harmonic plateau.
    Chinese Physics B 03/2013; 22(3):033203. · 1.39 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: High-order harmonic generation in an atomic or molecular gas is a promising source of sub-femtosecond vacuum ultraviolet coherent radiation for transient scattering, absorption, metrology and imaging applications. High harmonic spectra are sensitive to Ångstrom-scale structure and motion of laser-driven molecules, but interference from radiation produced by random molecular orientations obscures this in all but the simplest cases, such as linear molecules. Here we show how to extract full body-frame high harmonic generation information for molecules with more complicated geometries by utilizing the methods of coherent transient rotational spectroscopy. To demonstrate this approach, we obtain the relative strength of harmonic emission along the three principal axes in the asymmetric-top sulphur dioxide. This greatly simplifies the analysis task of high harmonic spectroscopy and extends its usefulness to more complex molecules.
    Nature Communications 02/2014; 5:3190. · 10.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We experimentally and theoretically analyze the manifestations of quantum interference and multiple ionization channels (multiple orbitals) in high-harmonic spectra of aligned N2O molecules. Increasing the probe wavelength from 1.17 to 1.46 μm, we demonstrate the gradual disappearance of multielectron effects and quantitatively explain the observation through calculations. We thus identify a minimum in the high-harmonic spectrum of N2O caused only by its structure. By comparing its position with that measured in the isoelectronic CO2 molecule for similar axis distributions, we find a difference of 10 eV, confirmed by ab initio quantum scattering calculations. Quantum interference in photorecombination is thus shown to be sensitive to subtle differences in the valence orbital structure of molecules with nearly identical lengths. This property may find applications in time-resolved studies.
    Physical Review A 03/2013; · 2.99 Impact Factor

Full-text (2 Sources)

Available from
Nov 30, 2014