Probing adsorption on a nanoscale: field desorption microspectroscopy

Area of Science:

• Surface Science
• Materials Science
• Analytical Chemistry

Background:

• Characterizing atomic-scale surface interactions is crucial for understanding material properties.
• Traditional methods often lack the spatial resolution to probe individual adsorption sites.
• Field ion microscopy offers high spatial resolution but typically lacks detailed energy analysis.

Purpose of the Study:

• To develop and present a technique for spatially resolved energy analysis of field desorbed ions on the nanometer scale.
• To correlate measured kinetic energies of field ions with binding energies of adsorbed species.
• To demonstrate the technique's capability in detecting weakly adsorbed species and determining binding energies in coadsorption systems.

Main Methods:

• Combining a field ion microscope with a probe-hole and an energy analyzer.
• Spatially resolved energy analysis of ions field desorbed from adsorbent surfaces at the nm-scale.
• Utilizing a thermionic cycle to relate kinetic ion energies to binding energies of adsorbed species.

Main Results:

• Successful detection of weakly adsorbed carbon monoxide (CO) species on Pt(111), analogous to high-pressure adsorption.
• First determination of binding energies for lithium (Li) adatoms in a Li-O-W(112) coadsorption system across various coverages.
• Demonstration of the technique as a serviceable micro-spectroscopy for nanoscale surface analysis.

Conclusions:

• The developed technique enables nm-scale spatially resolved energy analysis of field desorbed ions.
• This method provides physically meaningful binding energies for adsorbed species, advancing surface science.
• The technique is effective for studying complex coadsorption systems and weakly bound adsorbates.