Remote Excitation of Tip-Enhanced Photoluminescence with a Parallel AgNW Coupler

Area of Science:

• Nanoscale optical microscopy
• Spectroscopy
• Materials science

Background:

• Tip-enhanced photoluminescence (TEPL) microscopy correlates nanoscale imaging with photoluminescent spectra.
• Far-field excitation in TEPL is limited by diffraction-limited background fluorescence, hindering spatial resolution.
• Tip-enhanced Raman scattering (TERS) offers high resolution but has a lower scattering cross-section than fluorescence.

Purpose of the Study:

• To overcome the spatial resolution limitations of conventional TEPL microscopy.
• To develop a method for minimizing background fluorescence in nanoscale photoluminescence measurements.
• To demonstrate the capability of the new technique for analyzing material heterogeneity.

Main Methods:

• Developed remote excitation TEPL (RE-TEPL) by spatially separating excitation and detection.
• Evaluated two probe designs: gold nanoparticles on a silver nanowire and two offset parallel silver nanowires.
• Utilized simulations and experimental validation for probe design assessment.

Main Results:

• The two offset parallel silver nanowire coupler system demonstrated higher coupling efficiency.
• Successfully applied RE-TEPL spectral mapping to a MoSe2/WSe2 lateral heterostructure.
• Revealed spatial heterogeneity at the heterojunction with enhanced spatial resolution.

Conclusions:

• RE-TEPL effectively minimizes far-field background contributions, enhancing spatial resolution in photoluminescence microscopy.
• The silver nanowire coupler system is a promising design for advanced nanoscale optical characterization.
• RE-TEPL provides a powerful tool for investigating nanoscale variations in complex material systems.