Molecular Monolayer Sensing Using Surface Plasmon Resonance and Angular Goos-Hänchen Shift.

Area of Science:

• Surface science
• Nanotechnology
• Optical physics

Background:

• Surface plasmon resonance (SPR) and angular Goos-Hänchen (GH) shift are sensitive optical techniques.
• Molecular monolayers, such as benzenethiol self-assembled monolayers (BT-SAM) on gold (Au) substrates, are crucial in various applications.
• Surface contamination can significantly affect optical measurements.

Purpose of the Study:

• To demonstrate the potential of SPR and GH shift for detecting molecular monolayers.
• To investigate the role of surface properties, specifically hydrophobicity, in molecular monolayer sensing.
• To analyze the impact of surface modification on SPR angle measurements.

Main Methods:

• Utilizing surface plasmon resonance (SPR) measurements.
• Employing angular Goos-Hänchen (GH) shift measurements, focusing on the angular component.
• Creating benzenethiol self-assembled monolayers (BT-SAM) on gold (Au) substrates for surface modification.

Main Results:

• Excitation of surface plasmons significantly enhanced the GH shift.
• The hydrophobic nature of BT-SAM on Au reduced surface contamination compared to a clean Au surface.
• A smaller SPR angle was observed for BT-SAM coated Au substrates, indicating successful surface modification and reduced contamination.

Conclusions:

• SPR and GH shift measurements show potential for molecular monolayer detection.
• Surface modification with BT-SAM enhances sensing capabilities by minimizing contamination.
• The study highlights the importance of surface properties in achieving accurate optical sensing.