Formation of normal surface plasmon modes in small sodium nanoparticles

Area of Science:

• Condensed matter physics
• Materials science
• Nanotechnology

Background:

• Surface plasmon resonance (SPR) is crucial for nanoplasmonic devices.
• Understanding plasmon modes in metal nanoclusters is key to designing advanced nanodevices.

Purpose of the Study:

• To investigate the formation and characteristics of surface plasmon modes in sodium nanoclusters.
• To determine the size-dependent behavior of localized surface plasmon resonance (LSPR), surface plasmon polariton (SPP), and volume plasmon (VP) excitations.
• To explore the potential of composite nanostructures for tunable plasmonic properties.

Main Methods:

• Utilized the G0W0 approximation for theoretical calculations.
• Analyzed the loss function Im[ε-1] to identify plasmon modes.
• Investigated spherical sodium nanoclusters and silicon-sodium composite nanoparticles.

Main Results:

• In small sodium nanoparticles (<2 nm), LSPR dominates.
• For larger particles (≥2 nm), SPP and VP resonances emerge alongside LSPR.
• A size range of 0.7-3.7 nm is identified as a lower limit for SPP-based nanodevices.
• Composite silicon-sodium nanoparticles selectively suppress LSPR while preserving SPP modes.

Conclusions:

• Sodium nanoclusters exhibit distinct plasmon modes dependent on size.
• SPP excitations become significant in larger nanoclusters, relevant for nanodevice operation.
• Composite nanostructures offer a pathway to selectively tune plasmonic characteristics for tailored nanoplasmonic devices.