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Chemical interface damping for propagating surface plasmon polaritons in gold nanostripes

Authors :
Gregory V. Hartland
Brendan S. Brown
Source :
The Journal of chemical physics. 152(2)
Publication Year :
2020

Abstract

Leakage radiation microscopy has been used to examine chemical interface damping (CID) for the propagating surface plasmon polariton (PSPP) modes of Au nanostripes—nanofabricated structures with heights of 40 or 50 nm, widths between 2 and 4 µm, and 100 µm lengths. Real space imaging was used to determine the propagation lengths LSPP of the leaky PSPP modes, and back focal plane measurements generated ω vs k dispersion curves, which yield the PSPP group velocities vg. The combination of these two experiments was used to calculate the PSPP lifetime via T1 = LSPP/vg. The difference in T1 times between bare and thiol coated nanostripes was used to determine the dephasing rate due to CID ΓCID for the adsorbed thiol molecules. A variety of different thiol molecules were examined, as well as nanostripes with different dimensions. The values of ΓCID are similar for the different systems and are an order-of-magnitude smaller than the typical values observed for the localized surface plasmon resonances (LSPRs) of Au nanoparticles. Scaling the measured ΓCID values by the effective path length for electron-surface scattering shows that the CID effect for the PSPP modes of the nanostripes is similar to that for the LSPR modes of nanoparticles. This is somewhat surprising given that PSPPs and LSPRs have different properties: PSPPs have a well-defined momentum, whereas LSPRs do not. The magnitude of ΓCID for the nanostripes could be increased by reducing their dimensions, principally the height of the nanostructures. However, decreasing dimensions for the leaky PSPP mode increases radiation damping, which would make it challenging to accurately measure ΓCID.

Details

ISSN :
10897690
Volume :
152
Issue :
2
Database :
OpenAIRE
Journal :
The Journal of chemical physics
Accession number :
edsair.doi.dedup.....bdd3fce89e45659993aaa7e2a4194ec5