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

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Sye, Kori Marie

Contributors dc:contributor

• Vura-Weis, Josh
• Fout, Alison R
• Han, Hee-Sun
• Backlund, Mikael

• extreme ultraviolet spectroscopy
• transient M-edge spectroscopy
• solution-phase XUV absorption
• stacked iron porphyrin
• Fe(IV)oxo
• excited state dynamics

Statement dc:rights

• Copyright 2021 Kori Sye

Language dc:language

en

Handle dc:identifier

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

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/112994