Cryogenic XPS Study of Metal Oxide/Water Interfaces
EMSL Project ID
19843
Abstract
The object of this research is to investigate the generation of charge at the metal oxide/water interface using the cryogenic capabilities of the PHI Quantum 2000 XPS of the Interfacial and Nanoscale Science Facility. The cryogenic XPS technique is a powerful method that can obtain the composition of solid/solution interfaces equilibrated at room temperature by analyzing fast-frozen wet solids at liquid nitrogen temperature. In this project the centrifuged pastes of hematite colloidal aqueous suspensions will be used to investigate the effects of pH and ionic strength on the water, hydroxyl, sodium and chloride composition of the surface. These analyses will address important issues regarding the generation of charge at solid/solution interfaces including (1) the possible correlation between the generation of surface hydroxyls with the adsorption of counterions, (2) the hydration state of counterions as well as (3) the surface coverage of counterions. The study of shifts in binding energies of the O 1s spectra in the sample heated to room temperature will also enable the study of the 'built-in' electric potential of the solid/solution interface arising from the charge surface functional groups.This research will also provide the Interfacial and Nanoscale Science Facility the opportunity to test the assumptions behind the cryogenic XPS technique by attempting to reproduce data obtained with a sample previously analysed on a Kratos Axis Ultra electron spectrometer at Umeå University (Sweden).
Project Details
Project type
Large-Scale EMSL Research
Start Date
2006-10-01
End Date
2008-11-11
Status
Closed
Released Data Link
Team
Principal Investigator