scholarly journals Filming movies of attosecond charge migration with high harmonic spectroscopy

2021 ◽  
Author(s):  
Lixin He ◽  
Siqi Sun ◽  
Pengfei Lan ◽  
Yanqing He ◽  
Bincheng Wang ◽  
...  
Keyword(s):  
Single Molecule ◽  
Light Emission ◽  
High Harmonic ◽  
Laser Pulses ◽  
Photochemical Reactions ◽  
Charge Migration ◽  
Real Time Visualization ◽  
Light Matter Interaction ◽  
Electron Migration ◽  
Electron Holes

Abstract Electron migration in molecules is the progenitor of chemical reactions and biological functions after light-matter interaction. Following this ultrafast dynamics, however, has been an enduring endeavor. Recently, it has been suggested that high-harmonic spectroscopy (HHS) is able to probe dynamics with attosecond temporal and sub-˚angstr¨om spatial resolution. Still, real-time visualization of single-molecule dynamics continues to be a great challenge because experimental harmonic spectra are due to the coherent averages of light emission from individual molecules of different alignments. Here we demonstrate that the uniting of machine learning (ML) algorithm and HHS in two-color laser pulses enables us to retrieve the complex amplitude and phase of harmonics from single fixed-in-space molecule. From the complex single-molecule dipoles for different harmonics, we construct a movie of electron migration after tunnel ionization of the molecules at time steps of 50 attoseconds. Moreover, the angular dependence of molecular charge migration is fully resolved. By examining the movie, we observe that electron holes do not just “migrate” along the laser direction, but may “swirl” around the atom centers. Our ML-based HHS establishes a general reconstruction scheme for studying ultrafast charge migration in molecules, paving a way for further advance in tracing and controlling photochemical reactions by femtosecond lasers.

scholarly journals Filming movies of attosecond charge migration with high harmonic spectroscopy

2021 ◽  
Author(s):  
Pengfei Lan ◽  
Lixin He ◽  
Siqi Sun ◽  
Yanqing He ◽  
Bincheng Wang ◽  
...  
Keyword(s):  
Single Molecule ◽  
Light Emission ◽  
High Harmonic ◽  
Photochemical Reactions ◽  
Hole Density ◽  
Charge Migration ◽  
Real Time Visualization ◽  
Light Matter Interaction ◽  
Electron Migration ◽  
Pump Probe Experiment

Abstract Ultrafast electron migration in molecules is the progenitor of all chemical reactions and biological functions after light-matter interaction [1–4]. Following this ultrafast dynamics, however, has been an enduring endeavor [5, 6]. Recently, it has been shown that high-harmonic spectroscopy (HHS) is able to probe dynamics with attosecond temporal and sub-angstrom spatial resolution [7–10]. Still, real-time visualization of single-molecule dynamics continues to be a great challenge because experimental harmonic spectra are due to the coherent averages of light emission from individual molecules of different alignments. Here, we show that from high harmonics generated with single-color and two-color probe lasers in a pump-probe experiment, the complex amplitude and phase of harmonics from a single fixed-in-space molecule can be reconstructed using modern machine learning (ML) algorithm. From the complex single-molecule dipoles for different harmonics, we construct a series of film clips of hole density distributions of the cation at time steps of 50 attoseconds (1 as=10^{−18} s) to make a classical “movie” of electron migration after tunnel ionization of the molecule. Moreover, the angular dependence of molecular charge migration is fully resolved. By examining these clips, we observed that holes do not just “migrate” along the laser direction, but they may “swirl” around the atom centers. The ML-based HHS proposed here establishes a general reconstruction scheme for studying ultrafast charge migration in molecules, paving a way for further advance in tracing and controlling photochemical reactions by femtosecond lasers.

scholarly journals Linewidth narrowing of aluminum breathing plasmon resonances in Bragg gratings decorated nanodisks

2021 ◽  
Author(s):  
Xiaomin Zhao ◽  
Chenglin Du ◽  
Rong Leng ◽  
Li Li ◽  
Weiwei Luo ◽  
...  
Keyword(s):  
Light Emission ◽  
Emission Control ◽  
Bragg Gratings ◽  
High Quality ◽  
Plasmon Resonances ◽  
Matter Interaction ◽  
Light Matter Interaction ◽  
Radiative Losses

Plasmon resonances with high-quality are of great importance in light emission control and light-matter interaction. Nevertheless, the inherent Ohmic and radiative losses usually hinder the plasmon performance of the metallic...

scholarly journals Electron Symmetry Breaking during Attosecond Charge Migration Induced by Laser Pulses: Point Group Analyses for Quantum Dynamics

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 205
Author(s):  
Dietrich Haase ◽  
Gunter Hermann ◽  
Jörn Manz ◽  
Vincent Pohl ◽  
Jean Christophe Tremblay
Keyword(s):  
Laser Pulse ◽  
Symmetry Breaking ◽  
Electric Fields ◽  
Quantum Dynamics ◽  
Point Group ◽  
Laser Pulses ◽  
Charge Migration ◽  
Laser Control ◽  
The One ◽  
Superposition States

Quantum simulations of the electron dynamics of oriented benzene and Mg-porphyrin driven by short (<10 fs) laser pulses yield electron symmetry breaking during attosecond charge migration. Nuclear motions are negligible on this time domain, i.e., the point group symmetries G = D6h and D4h of the nuclear scaffolds are conserved. At the same time, the symmetries of the one-electron densities are broken, however, to specific subgroups of G for the excited superposition states. These subgroups depend on the polarization and on the electric fields of the laser pulses. They can be determined either by inspection of the symmetry elements of the one-electron density which represents charge migration after the laser pulse, or by a new and more efficient group-theoretical approach. The results agree perfectly with each other. They suggest laser control of symmetry breaking. The choice of the target subgroup is restricted, however, by a new theorem, i.e., it must contain the symmetry group of the time-dependent electronic Hamiltonian of the oriented molecule interacting with the laser pulse(s). This theorem can also be applied to confirm or to falsify complementary suggestions of electron symmetry breaking by laser pulses.

scholarly journals Characterizing the carrier-envelope phase stability of mid-infrared laser pulses by high harmonic generation in solids

2020 ◽  
Vol 28 (12) ◽  
pp. 17161
Author(s):  
A. Leblanc ◽  
P. Lassonde ◽  
Gilles Dalla-Barba ◽  
E. Cormier ◽  
H. Ibrahim ◽  
...  
Keyword(s):  
Harmonic Generation ◽  
Phase Stability ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Laser Pulses ◽  
Infrared Laser ◽  
Mid Infrared ◽  
Carrier Envelope Phase

scholarly journals Single occupancy spectroelectrochemistry of freely diffusing flavin mononucleotide in zero-dimensional nanophotonic structures

2015 ◽  
Vol 184 ◽  
pp. 101-115 ◽  
Author(s):  
Lawrence P. Zaino ◽  
Dane A. Grismer ◽  
Donghoon Han ◽  
Garrison M. Crouch ◽  
Paul W. Bohn
Keyword(s):  
Electron Transfer ◽  
Single Molecule ◽  
Light Emission ◽  
Fluorescence Emission ◽  
Flavin Mononucleotide ◽  
Wide Field ◽  
Potential Sweep ◽  
Potential Control ◽  
Fluorescence Measurements ◽  
Electron Transfer Properties

Zero-mode waveguides (ZMW) have the potential to be powerful confinement tools for studying electron transfer dynamics at single molecule occupancy conditions. Flavin mononucleotide contains an isoalloxazine chromophore, which is fluorescent in the oxidized state (FMN) while the reduced state (FMNH2) exhibits dramatically lower light emission, i.e. a dark-state. This allows fluorescence emission to report the redox state of single FMN molecules, an observation that has been used previously to study single electron transfer events in surface-immobilized flavins and flavoenzymes, e.g. sarcosine oxidase, by direct wide-field imaging of ZMW arrays. Single molecule electron transfer dynamics have now been extended to the study of freely diffusing molecules using fluorescence measurements of Au ZMWs under single occupancy conditions. The Au in the ZMW serves both as an optical cladding layer and as the working electrode for potential control, thereby accessing single molecule electron transfer dynamics at μM concentrations. Consistent with expectations, the probability of observing single reduced molecules increases as the potential is scanned negative, Eappl < Eeq, and the probability of observing emitting oxidized molecules increases at Eappl > Eeq. Different single molecules exhibit different electron transfer properties as reflected in the position of Eeq and the distribution of Eeq among a population of FMN molecules. Two types of actively-controlled electroluminescence experiments were used: chronofluorometry experiments, in which the potential is alternately stepped between oxidizing and reducing potentials, and cyclic potential sweep fluorescence experiments, analogous to cyclic voltammetry, these latter experiments exhibiting a dramatic scan rate dependence with the slowest scan rates showing distinct intermediate states that are stable over a range of potentials. These states are assigned to flavosemiquinone species that are stabilized in the special environment of the ZMW nanopore.

scholarly journals High harmonic generation in two-dimensional Mott insulators

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Christopher Orthodoxou ◽  
Amelle Zaïr ◽  
George H. Booth
Keyword(s):  
Quantum Monte Carlo ◽  
Strong Field ◽  
High Harmonic ◽  
Mean Field ◽  
Laser Pulses ◽  
Two Dimensions ◽  
Mott Insulators ◽  
Strongly Correlated ◽  
Two Dimensional ◽  
Mean Field Model

AbstractWith a combination of numerical methods, including quantum Monte Carlo, exact diagonalization, and a simplified dynamical mean-field model, we consider the attosecond charge dynamics of electrons induced by strong-field laser pulses in two-dimensional Mott insulators. The necessity to go beyond single-particle approaches in these strongly correlated systems has made the simulation of two-dimensional extended materials challenging, and we contrast their resulting high-harmonic emission with more widely studied one-dimensional analogues. As well as considering the photo-induced breakdown of the Mott insulating state and magnetic order, we also resolve the time and ultra-high-frequency domains of emission, which are used to characterize both the photo-transition, and the sub-cycle structure of the electron dynamics. This extends simulation capabilities and understanding of the photo-melting of these Mott insulators in two dimensions, at the frontier of attosecond non-equilibrium science of correlated materials.

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