Magnesium film-over-nanospheres (FONs) for surface-enhanced Raman scattering

Area of Science:

• Materials Science
• Surface Chemistry
• Spectroscopy

Background:

• Magnesium (Mg) interfacial interactions are crucial for catalysis and biomedicine.
• Plasmonic Mg research enables sensitive molecular detection via surface-enhanced Raman scattering (SERS).

Purpose of the Study:

• To investigate molecular binding on native Mg oxide surfaces using novel Mg film-over-nanospheres (FONs) as SERS substrates.
• To expand the understanding of molecular adsorption on Mg surfaces beyond previously studied molecules.

Main Methods:

• Fabrication of novel Mg film-over-nanospheres (FONs).
• Utilizing FONs as SERS substrates for molecular binding studies.
• Systematic investigation of 17 molecules with diverse functional groups.

Main Results:

• Identified binding of 4-nitrophenol (4-NP) and 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) on Mg surfaces.
• Discovered a pKa-dependent binding trend: adsorbates require dissociation and a pKa between ~4.5 and 7.5 for binding.
• Observed that diselenides and ditellurides deviate from this pKa trend.

Conclusions:

• The pKa of an adsorbate dictates its binding behavior on natively oxidized Mg surfaces.
• This research provides a foundation for chemically functionalizing Mg surfaces for plasmonic and other applications.