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 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 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 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 DNA skybridge: 3D structure producing a light sheet for high-throughput single-molecule imaging

2019 ◽  
Vol 47 (18) ◽  
pp. e107-e107 ◽  
Author(s):  
Daehyung Kim ◽  
Fahad Rashid ◽  
Yeonmo Cho ◽  
Manal S Zaher ◽  
I I Hwan Cho ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
High Throughput ◽  
Single Molecule ◽  
Surface Condition ◽  
3D Structure ◽  
Light Sheet ◽  
Bottom Surface ◽  
Nucleic Acid Binding ◽  
Nucleic Acid Binding Proteins ◽  
Real Time Visualization

Abstract Real-time visualization of single-proteins or -complexes on nucleic acid substrates is an essential tool for characterizing nucleic acid binding proteins. Here, we present a novel surface-condition independent and high-throughput single-molecule optical imaging platform called ‘DNA skybridge’. The DNA skybridge is constructed in a 3D structure with 4 μm-high thin quartz barriers in a quartz slide. Each DNA end is attached to the top of the adjacent barrier, resulting in the extension and immobilization of DNA. In this 3D structure, the bottom surface is out-of-focus when the target molecules on the DNA are imaged. Moreover, the DNA skybridge itself creates a thin Gaussian light sheet beam parallel to the immobilized DNA. This dual property allows for imaging a single probe-tagged molecule moving on DNA while effectively suppressing interference with the surface and background signals from the surface.

Additions and Corrections - Chemically Produced Excited States. Energy Transfer, Photochemical Reactions, and Light Emission.

1974 ◽  
Vol 96 (5) ◽  
pp. 1643-1643
Author(s):  
Emil White ◽  
Peter Wildes ◽  
Jacek Wiecko ◽  
Harold Doshan ◽  
C. Wei
Keyword(s):  
Energy Transfer ◽  
Excited States ◽  
Light Emission ◽  
Photochemical Reactions

DETECTING AND MANIPULATING SINGLE MOLECULES WITH STM

NANO ◽  
2006 ◽  
Vol 01 (01) ◽  
pp. 15-33 ◽  
Author(s):  
J. G. HOU ◽  
AIDI ZHAO
Keyword(s):  
Single Molecule ◽  
Scanning Tunneling Microscope ◽  
Light Emission ◽  
Single Molecules ◽  
Final Part ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Recent Advances ◽  
Recent Developments ◽  
Single Molecule Manipulation

Scanning tunneling microscope (STM) is a powerful and unique tool for study single molecules. We review recent advances in single-molecule characterizations including direct STM imaging and I–V spectroscopy, dI/dV spectroscopy and mapping, and d2I/dV2 spectroscopy and mapping. Some recent experiments of STM-excited single-molecule light emission are also introduced. In the final part, recent developments of single-molecule manipulation with the STM as well as the applications are discussed.

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