Fluorescence lifetime based characterization of active and tunable plasmonic nanostructures

Area of Science:

• Nanotechnology
• Materials Science
• Biophysics

Background:

• Plasmonic nanostructures are crucial for advanced optical devices.
• Characterizing their dynamic morphological changes at the nanoscale is challenging.
• Stimulus-responsive polymers offer tunable properties for nanostructure design.

Purpose of the Study:

• To introduce a non-contact fluorescence lifetime (FL) method for characterizing tunable plasmonic nanostructures.
• To investigate the pH-responsive behavior of polyelectrolyte multilayers (PEMs) in these nanostructures.
• To demonstrate the construction and characterization of an active, tunable plasmonic nanodevice.

Main Methods:

• Utilized fluorescence lifetime (FL) measurements for nanoscale morphological characterization.
• Employed pH-responsive polyelectrolyte multilayers (PEMs) as tunable spacer layers.
• Validated the FL method against ellipsometry and atomic force microscopy (AFM).

Main Results:

• A monolayer polycation film exhibited less hysteresis in response to pH changes compared to multilayer films.
• Characterized an active plasmonic nanostructure with Texas Red dye, pH-sensitive PEMs, and gold nanospheres.
• Demonstrated nanoscale accuracy in morphological change detection using the FL-based approach.

Conclusions:

• The FL-based method provides accurate, non-contact characterization of tunable plasmonic nanostructures.
• Stimulus-sensitive polymers, like pH-responsive PEMs, are effective for creating tunable plasmonic nanodevices.
• This work opens possibilities for developing novel active plasmonic nanodevices.