Aligned silver nanorod arrays as substrates for surface-enhanced infrared absorption spectroscopy

Area of Science:

• Nanotechnology
• Spectroscopy
• Materials Science

Background:

• Surface-enhanced infrared absorption (SEIRA) spectroscopy requires suitable substrates for enhanced sensitivity.
• Silver nanostructures are known for their plasmonic properties beneficial for SEIRA.

Purpose of the Study:

• To evaluate preferentially aligned silver nanorod arrays as substrates for SEIRA spectroscopy.
• To determine the enhancement factor and detection limits of these nanorod arrays for organic molecules.

Main Methods:

• Fabrication of aligned silver nanorod arrays using oblique angle vapor deposition.
• Analysis of chemisorbed para-nitrobenzoic acid (PNBA) films using external reflection SEIRA and infrared reflection-absorption spectroscopy (IRRAS).
• Characterization of nanorod morphology and optical properties using UV/Vis/NIR spectroscopy.

Main Results:

• Silver nanorod arrays exhibited an overall enhancement factor of 31 +/- 9 for PNBA compared to a traditional Ag film.
• SEIRA intensity was observed with both p- and s-polarized light, with optimal results at high angles of incidence and p-polarization.
• A SEIRA detection limit of 0.08 ng/cm(2) was achieved.
• Demonstrated simultaneous SEIRA and surface-enhanced Raman scattering (SERS) analysis on the same substrate.

Conclusions:

• Preferentially aligned silver nanorod arrays are effective substrates for SEIRA spectroscopy.
• The enhanced performance is attributed to the nanorod array's optical properties and increased surface area.
• These nanorod substrates offer a sensitive platform for molecular detection and analysis.