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Title: Ultrafast X-ray Transient Absorption Spectroscopy of Gas-Phase Photochemical Reactions: A New Universal Probe of Photoinduced Molecular Dynamics

Abstract

Time-resolved spectroscopic investigations of light-induced chemical reactions with universal detection capitalize recently on single-photon molecular probing using laser pulses in the extreme ultraviolet or X-ray regimes. Direct and simultaneous mappings of the time-evolving populations of ground-state reactants, Franck-Condon (FC) and transition state regions, excited-state intermediates and conical intersections (CI), and photoproducts in photochemical reactions utilize probe pulses that are broadband and energy-tunable. The limits on temporal resolution are set by the transit- or dwell-time of the photoexcited molecules at specific locations on the potential energy surface, typically ranging from a few femtoseconds to several hundred picoseconds. Femtosecond high-harmonic generation (HHG) meets the stringent demands for a universal spectroscopic probe of large regions of the intramolecular phase-space in unimolecular photochemical reactions. Extreme-ultraviolet and soft X-ray pulses generated in this manner with few-femtosecond or sub-femtosecond durations have enormous bandwidths, allowing the probing of many elements simultaneously through excitation or ionization of core-electrons, creating molecular movies that shed light on entire photochemical pathways. At free electron lasers (FELs), powerful investigations are also possible, recognizing their higher flux and tunability but more limited bandwidths. Femtosecond time-resolved X-ray transient absorption spectroscopy, in particular, is a valuable universal probe of reaction pathways that maps changes viamore » the fingerprint core-to-valence resonances. The particular power of this method over valence-ionization probes lies in its unmatched element and chemical-site specificities. The elements carbon, nitrogen, and oxygen constitute the fundamental building blocks of life; photochemical reactions involving these elements are ubiquitous, diverse, and manifold. However, table-top HHG sources in the "water-window" region (280-550 eV), which encompasses the 1s-absorption edges of carbon (284 eV), nitrogen (410 eV), and oxygen (543 eV), are far from abundant or trivial. Recent breakthroughs in the laboratory have embraced this region by using long driving-wavelength optical parametric amplifiers coupled with differentially pumped high-pressure gas source cells. This has opened avenues to study a host of photochemical reactions in organic molecules using femtosecond time-resolved transient absorption at the carbon K-edge. In this Account, we summarize recent efforts to deploy a table-top carbon K-edge source to obtain crucial chemical insights into ultrafast, ultraviolet-induced chemical reactions involving ring-opening, nonadiabatic excited-state relaxation, bond dissociation and radical formation. Here, the X-ray probe provides a direct spectroscopic viewport into the electronic characters and configurations of the valence electronic states through spectroscopic core-level transitions into the frontier molecular orbitals of the photoexcited molecules, laying fertile ground for the real-time mapping of the evolving valence electronic structure. The profound detail and mechanistic insights emerging from the pioneering experiments at the carbon K-edge are outlined here. Comparisons of the experimental methodology with other techniques employed to study similar reactions are drawn, where applicable and relevant. We show that femtosecond time-resolved X-ray transient absorption spectroscopy blazes a new trail in the study of nonadiabatic molecular dynamics. Despite table-top implementations being largely in their infancy, future chemical applications of the technique will set the stage for widely applicable, universal probes of photoinduced molecular dynamics with unprecedented temporal resolution.« less

Authors:
 [1]; ORCiD logo [2]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Bristol, Bristol (United Kingdom)
  2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division
OSTI Identifier:
1580344
Grant/Contract Number:  
AC02-05CH11231; EC-0310717; 1660417; W911NF-14-1-0383
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Accounts of Chemical Research
Additional Journal Information:
Journal Volume: 51; Journal Issue: 12; Journal ID: ISSN 0001-4842
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Bhattacherjee, Aditi, and Leone, Stephen R. Ultrafast X-ray Transient Absorption Spectroscopy of Gas-Phase Photochemical Reactions: A New Universal Probe of Photoinduced Molecular Dynamics. United States: N. p., 2018. Web. doi:10.1021/acs.accounts.8b00462.
Bhattacherjee, Aditi, & Leone, Stephen R. Ultrafast X-ray Transient Absorption Spectroscopy of Gas-Phase Photochemical Reactions: A New Universal Probe of Photoinduced Molecular Dynamics. United States. https://doi.org/10.1021/acs.accounts.8b00462
Bhattacherjee, Aditi, and Leone, Stephen R. 2018. "Ultrafast X-ray Transient Absorption Spectroscopy of Gas-Phase Photochemical Reactions: A New Universal Probe of Photoinduced Molecular Dynamics". United States. https://doi.org/10.1021/acs.accounts.8b00462. https://www.osti.gov/servlets/purl/1580344.
@article{osti_1580344,
title = {Ultrafast X-ray Transient Absorption Spectroscopy of Gas-Phase Photochemical Reactions: A New Universal Probe of Photoinduced Molecular Dynamics},
author = {Bhattacherjee, Aditi and Leone, Stephen R.},
abstractNote = {Time-resolved spectroscopic investigations of light-induced chemical reactions with universal detection capitalize recently on single-photon molecular probing using laser pulses in the extreme ultraviolet or X-ray regimes. Direct and simultaneous mappings of the time-evolving populations of ground-state reactants, Franck-Condon (FC) and transition state regions, excited-state intermediates and conical intersections (CI), and photoproducts in photochemical reactions utilize probe pulses that are broadband and energy-tunable. The limits on temporal resolution are set by the transit- or dwell-time of the photoexcited molecules at specific locations on the potential energy surface, typically ranging from a few femtoseconds to several hundred picoseconds. Femtosecond high-harmonic generation (HHG) meets the stringent demands for a universal spectroscopic probe of large regions of the intramolecular phase-space in unimolecular photochemical reactions. Extreme-ultraviolet and soft X-ray pulses generated in this manner with few-femtosecond or sub-femtosecond durations have enormous bandwidths, allowing the probing of many elements simultaneously through excitation or ionization of core-electrons, creating molecular movies that shed light on entire photochemical pathways. At free electron lasers (FELs), powerful investigations are also possible, recognizing their higher flux and tunability but more limited bandwidths. Femtosecond time-resolved X-ray transient absorption spectroscopy, in particular, is a valuable universal probe of reaction pathways that maps changes via the fingerprint core-to-valence resonances. The particular power of this method over valence-ionization probes lies in its unmatched element and chemical-site specificities. The elements carbon, nitrogen, and oxygen constitute the fundamental building blocks of life; photochemical reactions involving these elements are ubiquitous, diverse, and manifold. However, table-top HHG sources in the "water-window" region (280-550 eV), which encompasses the 1s-absorption edges of carbon (284 eV), nitrogen (410 eV), and oxygen (543 eV), are far from abundant or trivial. Recent breakthroughs in the laboratory have embraced this region by using long driving-wavelength optical parametric amplifiers coupled with differentially pumped high-pressure gas source cells. This has opened avenues to study a host of photochemical reactions in organic molecules using femtosecond time-resolved transient absorption at the carbon K-edge. In this Account, we summarize recent efforts to deploy a table-top carbon K-edge source to obtain crucial chemical insights into ultrafast, ultraviolet-induced chemical reactions involving ring-opening, nonadiabatic excited-state relaxation, bond dissociation and radical formation. Here, the X-ray probe provides a direct spectroscopic viewport into the electronic characters and configurations of the valence electronic states through spectroscopic core-level transitions into the frontier molecular orbitals of the photoexcited molecules, laying fertile ground for the real-time mapping of the evolving valence electronic structure. The profound detail and mechanistic insights emerging from the pioneering experiments at the carbon K-edge are outlined here. Comparisons of the experimental methodology with other techniques employed to study similar reactions are drawn, where applicable and relevant. We show that femtosecond time-resolved X-ray transient absorption spectroscopy blazes a new trail in the study of nonadiabatic molecular dynamics. Despite table-top implementations being largely in their infancy, future chemical applications of the technique will set the stage for widely applicable, universal probes of photoinduced molecular dynamics with unprecedented temporal resolution.},
doi = {10.1021/acs.accounts.8b00462},
url = {https://www.osti.gov/biblio/1580344}, journal = {Accounts of Chemical Research},
issn = {0001-4842},
number = 12,
volume = 51,
place = {United States},
year = {Wed Nov 21 00:00:00 EST 2018},
month = {Wed Nov 21 00:00:00 EST 2018}
}

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Works referenced in this record:

Breakdown of the dipole approximation in soft-X-ray photoemission
journal, October 1999


Imaging Molecular Motion: Femtosecond X-Ray Scattering of an Electrocyclic Chemical Reaction
journal, June 2015


Acetylacetone photodynamics at a seeded free-electron laser
journal, January 2018


From nanosecond to femtosecond science
journal, March 1999


Laser Coulomb explosion imaging for probing ultra-fast molecular dynamics
journal, June 2006


Ultrafast transient absorption spectroscopy: principles and application to photosynthetic systems
journal, July 2009


Looking at Photoinduced Charge Transfer Processes in the IR: Answers to Several Long-Standing Questions
journal, January 2017


Femtosecond Time-Resolved Photoelectron Spectroscopy
journal, April 2004


Electrochemistry and Electrogenerated Chemiluminescence of BODIPY Dyes
journal, March 2012


Ultrafast Molecular Reaction Dynamics in Real-Time Progress Over a Decade
journal, October 1990


Direct Observation of the Transition State
journal, March 1995


Capturing Ultrafast Quantum Dynamics with Femtosecond and Attosecond X-ray Core-Level Absorption Spectroscopy
journal, January 2013


Ultrafast X-Ray Spectroscopy of Conical Intersections
journal, June 2018


Roadmap of ultrafast x-ray atomic and molecular physics
journal, January 2018


Spatiotemporal isolation of attosecond soft X-ray pulses in the water window
journal, March 2015


Heterogeneous Photochemistry in the Atmosphere
journal, February 2015


Analysis of Femtosecond Dynamic Absorption Spectra of Nonstationary States
journal, October 1992


Femtosecond x-ray spectroscopy of an electrocyclic ring-opening reaction
journal, April 2017


Direct Observation of Ground-State Product Formation in a 1,3-Cyclohexadiene Ring-Opening Reaction
journal, January 2015


Ultrafast Intersystem Crossing in Acetylacetone via Femtosecond X-ray Transient Absorption at the Carbon K-Edge
journal, November 2017


53-attosecond X-ray pulses reach the carbon K-edge
journal, August 2017


Photoinduced Heterocyclic Ring Opening of Furfural: Distinct Open-Chain Product Identification by Ultrafast X-ray Transient Absorption Spectroscopy
journal, September 2018


Self-Referenced Coherent Diffraction X-Ray Movie of Ångstrom- and Femtosecond-Scale Atomic Motion
journal, October 2016


Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption
journal, June 2017


Electron-Withdrawing Effects in the Photodissociation of CH 2 ICl To Form CH 2 Cl Radical, Simultaneously Viewed Through the Carbon K and Chlorine L 2,3 X-ray Edges
journal, September 2018


Bioinorganic Photochemistry:  Frontiers and Mechanisms
journal, June 2005


Tabletop imaging of structural evolutions in chemical reactions demonstrated for the acetylene cation
journal, July 2014


Chemical Reactions Produced by Very High Light Intensities
journal, October 1949


Transition state region in the A-Band photodissociation of allyl iodide—A femtosecond extreme ultraviolet transient absorption study
journal, March 2016


Femtosecond Time-Resolved Photoelectron Imaging
journal, May 2006


Direct Observation of the Transition-State Region in the Photodissociation of CH 3 I by Femtosecond Extreme Ultraviolet Transient Absorption Spectroscopy
journal, December 2015


Tracing the 267 nm-Induced Radical Formation in Dimethyl Disulfide Using Time-Resolved X-ray Absorption Spectroscopy
journal, February 2019


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