Near-Field Vibrational Energy Transfer for Mid-Infrared Upconversion in Plasmonic Nanogaps

Fuente: arXiv
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Main Authors: Pal, Avisekh, Sajan, Anju, Sumner, Christopher, Alharbi, Eman, Theis, Wolfgang, Chikkaraddy, Rohit
Format: Preprint
Published: 2026
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_version_ 1866909056153681920
author Pal, Avisekh
Sajan, Anju
Sumner, Christopher
Alharbi, Eman
Theis, Wolfgang
Chikkaraddy, Rohit
author_facet Pal, Avisekh
Sajan, Anju
Sumner, Christopher
Alharbi, Eman
Theis, Wolfgang
Chikkaraddy, Rohit
contents Förster energy transfer underpins modern photonics, yet establishing an analogous vibrational pathway in the mid-infrared (MIR) remains highly challenging, as sub-picosecond intramolecular vibrational redistribution (IVR) suppresses intermolecular coupling. Here we demonstrate vibrational donor--acceptor transfer in the MIR and subsequent upconversion to visible luminescence enabled by sub-2 nm plasmonic nanogaps. The extreme lateral field confinement in metal--molecule--metal ring cavities defined by self-assembled molecular spacers couples efficiently to in-plane molecular dipoles. Continuous-wave MIR excitation selectively populates $-\mathrm{C}\equiv\mathrm{N}$ vibrational donors, and plasmon-enhanced near-field coupling transfers this energy to nearby electronic acceptors, generating anti-Stokes visible emission under low power densities. Upconversion efficiencies exceeding $0.3\%$ are observed, limited by competition between the plasmon-mediated transfer rate and IVR. These results show that extreme plasmonic confinement can redirect molecular vibrational relaxation pathways, opening a route toward vibrational nanophotonics, intermolecular interactions for bioimaging, and room-temperature MIR detection based on molecular degrees of freedom.
format Preprint
id arxiv_https___arxiv_org_abs_2605_19498
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Near-Field Vibrational Energy Transfer for Mid-Infrared Upconversion in Plasmonic Nanogaps
Pal, Avisekh
Sajan, Anju
Sumner, Christopher
Alharbi, Eman
Theis, Wolfgang
Chikkaraddy, Rohit
Optics
Mesoscale and Nanoscale Physics
Applied Physics
Förster energy transfer underpins modern photonics, yet establishing an analogous vibrational pathway in the mid-infrared (MIR) remains highly challenging, as sub-picosecond intramolecular vibrational redistribution (IVR) suppresses intermolecular coupling. Here we demonstrate vibrational donor--acceptor transfer in the MIR and subsequent upconversion to visible luminescence enabled by sub-2 nm plasmonic nanogaps. The extreme lateral field confinement in metal--molecule--metal ring cavities defined by self-assembled molecular spacers couples efficiently to in-plane molecular dipoles. Continuous-wave MIR excitation selectively populates $-\mathrm{C}\equiv\mathrm{N}$ vibrational donors, and plasmon-enhanced near-field coupling transfers this energy to nearby electronic acceptors, generating anti-Stokes visible emission under low power densities. Upconversion efficiencies exceeding $0.3\%$ are observed, limited by competition between the plasmon-mediated transfer rate and IVR. These results show that extreme plasmonic confinement can redirect molecular vibrational relaxation pathways, opening a route toward vibrational nanophotonics, intermolecular interactions for bioimaging, and room-temperature MIR detection based on molecular degrees of freedom.
title Near-Field Vibrational Energy Transfer for Mid-Infrared Upconversion in Plasmonic Nanogaps
topic Optics
Mesoscale and Nanoscale Physics
Applied Physics
url https://arxiv.org/abs/2605.19498