University of Illinois Urbana-Champaign

Development of solution-phase extreme ultraviolet spectroscopy and photophysics of μ-oxo-bridged Fe(III)porphyrins

Sye, Kori Marie

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https://hdl.handle.net/2142/112994

Description

Title
Development of solution-phase extreme ultraviolet spectroscopy and photophysics of μ-oxo-bridged Fe(III)porphyrins
Author(s)
Sye, Kori Marie
Issue Date
2021-07-09
Director of Research (if dissertation) or Advisor (if thesis)
Vura-Weis, Josh
Doctoral Committee Chair(s)
Vura-Weis, Josh
Committee Member(s)
  • Fout, Alison R
  • Han, Hee-Sun
  • Backlund, Mikael
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • extreme ultraviolet spectroscopy
  • transient M-edge spectroscopy
  • solution-phase XUV absorption
  • stacked iron porphyrin
  • Fe(IV)oxo
  • excited state dynamics
Abstract
A sample delivery method is developed to extend the field of transient M-edge x-ray absorption spectroscopy to study molecular complexes in the solution-phase. A gas-accelerated liquid sheet method is adapted to operate in the vacuum conditions needed for XUV transmission. Gas-generated liquid sheet of chlorinated solvents transmissible to XUV photons are characterized and stabilized under vacuum conditions. A method for measuring the thickness of a liquid sheet in situ is described and the high-pressure pumping system for generating the liquid sheet is detailed. The instrument for M-edge absorption spectroscopy is adapted to handle the gas load for the vacuum chambers. The first transmission spectrum of XUV in the energy of 40-90 eV is collected through a flowing liquid sheet of dichloroethane. It is determined that with the noise level present in the liquid sheet, a transient spectrum of a liquid sheet containing FeTPPCl could be collected with a reasonable signal to noise ratio. However, it is found that the liquid sheet of an iron monoporphyrin was unstable in the XUV sample chamber under high vacuum conditions. The transient M-edge absorption spectroscopy technique is also used to probe the excited state dynamics of an iron stacked porphyrin, (TPPFe)2O, oxidation catalyst in the solid state. The relaxation pathway upon photoexcitation at several pump wavelengths is studied to determine the stability and lifetime of the catalytically active Fe(IV)oxo intermediate state. With a combination of optical and XUV absorption techniques, it is found that upon excitation, the stacked porphyrin formed an Fe(II)/Fe(III) containing LMCT state which decays in less than 1 ps. The remaining excited states of the stacked porphyrin are XUV dark and are identified as a relaxing through the pathway containing an Fe(III)TPP+ and Fe(III)TPPO- subunits with the charges on the porphyrin ligand. It is found that the Fe(IV)oxo intermediate state is not observed in these studies and is likely a small percentage of the relaxation pathway.
Graduation Semester
2021-08
Type of Resource
Thesis
Permalink
http://hdl.handle.net/2142/112994
Copyright and License Information
Copyright 2021 Kori Sye

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