Influence of hematite crystal face on organic ligand surface interactions with iron oxide/water interfaces studied using sum frequency generation spectroscopy
EMSL Project ID
51493
Abstract
The proposed work will examine the interfacial phenomena of the organic ligands methanol and acetohydroxamic acid (aHa) at the hematite/water interface and the molecular structure at organic/aqueous interface using the nonlinear optical spectroscopy technique sum frequency generation (SFG). A variety of hematite crystal faces and electrolyte compositions will be explored. Experiments will monitor the change in the organic ligand structure as the organic ligand is exposed to iron oxide/water interfaces at varying pH and ligand concentrations. These studies will provide direct evidence of surface coverage, structure and kinetics of complexation and dissolution. Polarization and phase measurements will be conducted to examine adsorbate surface orientation. Results from such experiments on aqueous organic ligand-iron oxide interfaces will provide crucial information about biogeochemical iron and carbon cycling, leading to improved global models. The SFG experiments will be conducted in the Environmental Spectroscopy Laboratory at EMSL, using thin-film hematite samples fabricated by EMSL. This work is dependent on access to the Deposition and Microfabrication and Nonlinear Spectroscopy capabilities at EMSL. Hematite thin films (~20 nm thick) will be deposited onto transparent substrates using Pulsed Laser Deposition (PLD) for use in the SFG experiments (various crystal faces of hematite will be fabricated). PLD is not available at the University of Puget Sound. The thin film is required to avoid absorption of the laser light and burning of the sample while maintaining optical reflectivity. The SFG experiments must be conducted at EMSL, as the Environmental Spectroscopy Laboratory houses the most convenient SFG spectrometers to the University of Puget Sound, and the only high-resolution SFG spectrometer currently available for public use in the United States.
Project Details
Start Date
2020-06-01
End Date
2020-09-30
Status
Closed
Released Data Link
Team
Principal Investigator