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Title: Diffractive imaging of dissociation and ground-state dynamics in a complex molecule

Journal Article · · Physical Review A
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [7];  [7];  [7];  [4];  [1]
  1. Univ. of Nebraska, Lincoln, NE (United States). Dept. of Physics and Astronomy
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford PULSE Institute, Menlo Park CA (United States); Stanford Univ., CA (United States). Dept. of Chemistry
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford PULSE Institute, Menlo Park CA (United States)
  4. Stanford PULSE Institute, Menlo Park CA (United States)
  5. Univ. of Nebraska, Lincoln, NE (United States). Dept. of Physics and Astronomy; Univ. of York (United Kingdom). Dept. of Chemistry
  6. Stanford PULSE Institute, Menlo Park CA (United States); Univ. Potsdam, Potsdam (Germany). Inst. für Physik und Astronomie
  7. SLAC National Accelerator Lab., Menlo Park, CA (United States)
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We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules $$(C_2F_4I_2)$$ in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited-state dynamics simulations. The molecules are excited by an ultraviolet femtosecond laser pulse to a state characterized by a transition from the iodine $5p⊥$ orbital to a mixed $5p ∥ σ$ hole and $$CF^∙_2$$ antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wave packet of the dissociating iodine atom followed by coherent vibrations in the electronic ground state of the $$C_2F_4I_2$$ radical. The radical reaches a stable classical (nonbridged) structure in less than 200 fs.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Univ. of Nebraska, Lincoln, NE (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; Volkswagen Foundation
Grant/Contract Number:
AC02-05CH11231; AC02-76SF00515; SC0014170
OSTI ID:
1560631
Journal Information:
Physical Review A, Journal Name: Physical Review A Journal Issue: 2 Vol. 100; ISSN PLRAAN; ISSN 2469-9926
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

References (32)

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Photodissociation Reaction of 1,2-Diiodoethane in Solution:  A Theoretical and X-ray Diffraction Study journal November 2005
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Direct Imaging of Transient Molecular Structures with Ultrafast Diffraction journal January 2001
Imaging CF 3 I conical intersection and photodissociation dynamics with ultrafast electron diffraction journal July 2018

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