Resonant secondary light emission from Plasmonic Au nanostructures at high electron temperatures created by pulsed-laser excitation

Jingyu Huang, Wei Wang, Catherine J. Murphy, David G. Cahill

Research output: Contribution to journalArticle

Abstract

Plasmonic nanostructures are of great current interest as chemical sensors, in vivo imaging agents, and for photothermal therapeutics. We study continuous-wave (cw) and pulsed-laser excitation of aqueous suspensions of Au nanorods as a model system for secondary light emission from plasmonic nanostructures. Resonant secondary emission contributes significantly to the background commonly observed in surface-enhanced Raman scattering and to the light emission generated by pulsed-laser excitation of metallic nanostructures that is often attributed to two-photon luminescence. Spectra collected using cw laser excitation at 488 nm show an enhancement of the broad spectrum of emission at the electromagnetic plasmon resonance of the nanorods. The intensity of anti-Stokes emission collected using cw laser excitation at 785 nm is described by a 300 K thermal distribution of excitations. Excitation by subpicosecond laser pulses at 785 nm broadens and increases the intensity of the anti-Stokes emission in a manner that is consistent with electronic Raman scattering by a high-temperature distribution of electronic excitations predicted by a two-temperature model. Broadening of the pulse duration using an etalon reduces the intensity of anti-Stokes emission in quantitative agreement with the model. Experiments using a pair of subpicosecond optical pulses separated by a variable delay show that the timescale of resonant secondary emission is comparable to the timescale for equilibration of electrons and phonons.

Original languageEnglish (US)
Pages (from-to)906-911
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number3
DOIs
StatePublished - Jan 21 2014

Fingerprint

secondary emission
light emission
pulsed lasers
electron energy
continuous wave lasers
excitation
nanorods
Raman spectra
pulses
electronics
pulse duration
phonons
temperature distribution
luminescence
electromagnetism
augmentation
sensors
photons
lasers
electrons

Keywords

  • Electron-hole pairs
  • Gold nanorods
  • Surface-enhanced Raman scattering background

ASJC Scopus subject areas

  • General

Cite this

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title = "Resonant secondary light emission from Plasmonic Au nanostructures at high electron temperatures created by pulsed-laser excitation",
abstract = "Plasmonic nanostructures are of great current interest as chemical sensors, in vivo imaging agents, and for photothermal therapeutics. We study continuous-wave (cw) and pulsed-laser excitation of aqueous suspensions of Au nanorods as a model system for secondary light emission from plasmonic nanostructures. Resonant secondary emission contributes significantly to the background commonly observed in surface-enhanced Raman scattering and to the light emission generated by pulsed-laser excitation of metallic nanostructures that is often attributed to two-photon luminescence. Spectra collected using cw laser excitation at 488 nm show an enhancement of the broad spectrum of emission at the electromagnetic plasmon resonance of the nanorods. The intensity of anti-Stokes emission collected using cw laser excitation at 785 nm is described by a 300 K thermal distribution of excitations. Excitation by subpicosecond laser pulses at 785 nm broadens and increases the intensity of the anti-Stokes emission in a manner that is consistent with electronic Raman scattering by a high-temperature distribution of electronic excitations predicted by a two-temperature model. Broadening of the pulse duration using an etalon reduces the intensity of anti-Stokes emission in quantitative agreement with the model. Experiments using a pair of subpicosecond optical pulses separated by a variable delay show that the timescale of resonant secondary emission is comparable to the timescale for equilibration of electrons and phonons.",
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author = "Jingyu Huang and Wei Wang and Murphy, {Catherine J.} and Cahill, {David G.}",
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AU - Huang, Jingyu

AU - Wang, Wei

AU - Murphy, Catherine J.

AU - Cahill, David G.

PY - 2014/1/21

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N2 - Plasmonic nanostructures are of great current interest as chemical sensors, in vivo imaging agents, and for photothermal therapeutics. We study continuous-wave (cw) and pulsed-laser excitation of aqueous suspensions of Au nanorods as a model system for secondary light emission from plasmonic nanostructures. Resonant secondary emission contributes significantly to the background commonly observed in surface-enhanced Raman scattering and to the light emission generated by pulsed-laser excitation of metallic nanostructures that is often attributed to two-photon luminescence. Spectra collected using cw laser excitation at 488 nm show an enhancement of the broad spectrum of emission at the electromagnetic plasmon resonance of the nanorods. The intensity of anti-Stokes emission collected using cw laser excitation at 785 nm is described by a 300 K thermal distribution of excitations. Excitation by subpicosecond laser pulses at 785 nm broadens and increases the intensity of the anti-Stokes emission in a manner that is consistent with electronic Raman scattering by a high-temperature distribution of electronic excitations predicted by a two-temperature model. Broadening of the pulse duration using an etalon reduces the intensity of anti-Stokes emission in quantitative agreement with the model. Experiments using a pair of subpicosecond optical pulses separated by a variable delay show that the timescale of resonant secondary emission is comparable to the timescale for equilibration of electrons and phonons.

AB - Plasmonic nanostructures are of great current interest as chemical sensors, in vivo imaging agents, and for photothermal therapeutics. We study continuous-wave (cw) and pulsed-laser excitation of aqueous suspensions of Au nanorods as a model system for secondary light emission from plasmonic nanostructures. Resonant secondary emission contributes significantly to the background commonly observed in surface-enhanced Raman scattering and to the light emission generated by pulsed-laser excitation of metallic nanostructures that is often attributed to two-photon luminescence. Spectra collected using cw laser excitation at 488 nm show an enhancement of the broad spectrum of emission at the electromagnetic plasmon resonance of the nanorods. The intensity of anti-Stokes emission collected using cw laser excitation at 785 nm is described by a 300 K thermal distribution of excitations. Excitation by subpicosecond laser pulses at 785 nm broadens and increases the intensity of the anti-Stokes emission in a manner that is consistent with electronic Raman scattering by a high-temperature distribution of electronic excitations predicted by a two-temperature model. Broadening of the pulse duration using an etalon reduces the intensity of anti-Stokes emission in quantitative agreement with the model. Experiments using a pair of subpicosecond optical pulses separated by a variable delay show that the timescale of resonant secondary emission is comparable to the timescale for equilibration of electrons and phonons.

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KW - Surface-enhanced Raman scattering background

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