Attochemistry Regulation of Charge Migration
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Engineering topics
Jones, Robert R.
Publications and source records attributed to Jones, Robert R..
Characterizing particle-like charge-migration dynamics with high-order harmonic sideband spectroscopy
Here, we introduce high-order harmonic sideband spectroscopy and show that it can be a robust probe of charge migration (CM) in a halogenated carbon-chain molecule. We simulate both the CM and high-order harmonic generation (HHG) dynamics using ab initio time-dependent density-functional theory. We find that CM dynamics initiated along the molecular backbone induces sidebands in the HHG spectrum driven by a delayed laser pulse that is polarized perpendicular to the molecular axis. Monitoring the spectrum as either the HHG laser frequency or the relative delay is scanned allows for the extraction of detailed information about the time-domain characteristics of the CM process.
74 ATOMIC AND MOLECULAR PHYSICS↗
Manipulating and Probing Ultrafast Atomic and Molecular Dynamics (Final Report)
This program has focused on the exploration and control of dynamics in atoms, small molecules, clusters, and micro- or nano-structures following ultrafast excitation and/or driven by strong oscillating fields. In our principal experiments, gas phase atoms and molecules were exposed to short pulses of electromagnetic radiation with frequencies ranging from THz into the XUV spectral regions, and with durations from picoseconds to attoseconds. The pulses coherently induce and/or probe dynamics in the electronic, vibrational, and rotational degrees of freedom of the targets. The overarching goal of the various projects has been to exploit strong-field processes and/or implement novel ultrafast techniques for manipulating and probing coherent electronic and nuclear motion. Typically, the relevant system evolution occurs over attosecond to picosecond timescales. In doing so, we have gained a more complete picture of correlated multi-particle dynamics in atoms, molecules, and other complex systems and expanded the toolbox of useful techniques for manipulating and probing those dynamics. Grant funds were primarily used to: (i) pay salaries and fringe benefits for the PI and postdocs and stipends, tuition, and health care costs for graduate students; (ii) cover travel expenses for the PI, postdocs, and students to attend and participate in professional meetings, conferences, and workshops; and (iii) purchase research materials, supplies, and equipment required for experiments. The research resulted in the publication of 24 peer reviewed articles (including 1 in Nature Physics, 2 in Nature Communications, 7 in Physical Review Letters, and 12 in Physical Review A), and 4 PhD dissertations. The specific results from different funding periods are summarized separately in the main report.
74 ATOMIC AND MOLECULAR PHYSICS↗
Molecular Modes of Attosecond Charge Migration
Here, first-principles calculations are employed to elucidate the modes of attosecond charge migration (CM) in halogenated hydrocarbon chains. We use constrained density functional theory (DFT) to emulate the creation of a localized hole on the halogen and follow the subsequent dynamics via time-dependent DFT. We find low-frequency CM modes (~ 1 eV) that propagate across the molecule and study their dependence on length, bond order, and halogenation. We observe that the CM speed (~ 4Å/ fs) is largely independent of molecule length, but is lower for triple-bonded versus double-bonded molecules. Additionally, as the halogen mass increases, the hole travels in a more particlelike manner as it moves across the molecule. These heuristics will be useful in identifying molecules and optimal CM detection methods for future experiments, especially for halogenated hydrocarbons which are promising targets for ionization-triggered CM.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Multidimensional molecular high-harmonic spectroscopy: A road map for charge migration studies
This work discusses recent experimental and theoretical analyses of high-harmonic spectroscopy in small molecules, with the aim of characterizing charge migration. We discuss the formulation of molecular high-harmonic spectra followed by methods to extract molecular-target-specific information, both in experiments and ab initio simulations. We present measured and simulated high-harmonic spectra from carbon dioxide and carbonyl sulfide to illustrate the necessity for multidimensional analyses for high-harmonic spectroscopies that include both the spectral amplitude and phase. Leveraging these results, we examine how such multidimensional analyses pave the way for the study of charge migration with high-harmonic spectroscopy and illustrate the beneficial role a static molecular feature can play when probing dynamics. Finally, we briefly expand our scope with an outlook on the critical role of integrating theoretical and experimental approaches, beyond just high-harmonic spectroscopy, for the development of versatile harmonic spectroscopic probes of charge migration.
74 ATOMIC AND MOLECULAR PHYSICS↗