High-Resolution Distance Dependence Study of Surface-Enhanced Raman Scattering Enabled by Atomic Layer Deposition

Area of Science:

• Surface science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful technique for molecular detection.
• Controlling the distance between analyte and plasmonic substrate is crucial for SERS sensitivity.
• Atomic layer deposition (ALD) offers precise control over thin film deposition at the nanoscale.

Purpose of the Study:

• To investigate the distance dependence of SERS on silver film over nanospheres (AgFONs) with high resolution.
• To utilize ALD for creating controlled spacer layers and simultaneous Raman labeling.
• To explore the potential for detecting surface species at extended distances from the substrate.

Main Methods:

• High-resolution operando SERS measurements were performed.
• ALD of Al2O3 was used to create tunable spacer layers on AgFONs.
• Trimethylaluminum (TMA) served as both the ALD precursor and the Raman label.

Main Results:

• SERS intensity showed a clear nanometer-scale distance dependence, encompassing both short- and long-range effects.
• Experimental results showed excellent agreement with theoretical models incorporating short- and long-range interactions.
• The study demonstrated the capability to probe species up to ~3 nm from the AgFON surface.

Conclusions:

• ALD-enabled SERS provides a high-resolution method to study distance-dependent phenomena.
• The observed long-range SERS effect enables the detection of surface species further from the substrate.
• This technique offers new insights into ALD surface chemistry and catalytic reactions.