Quantitative Ultrafast Electron‐Temperature Dynamics in Photo‐Excited Au Nanoparticles

Sygletou, Maria; Benedetti, Stefania; Ferrera, Marzia; Pierantozzi, Gian Marco; Cucini, Riccardo; Valle, Giuseppe Della; Carrara, Pietro; Vita, Alessandro De; Bona, A. di; Torelli, Piero; Catone, Daniele; Panaccione, G.; Canepa, M.; Bisio, Francesco

doi:10.1002/smll.202100050

Cited by 8 publications

(7 citation statements)

References 73 publications

(98 reference statements)

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“…In particular, for the smallest particles, the observed heating is less than the uncorrected simulated one. A modification of cooling originating from a slow electron–phonon coupling in gold, − which would modify temperature rise and therefore dissipation via cooling during electron–phonon coupling, has been neglected at this point as the effect would be small. The resolution effect is taken into account when determining an effective slope of temperature (lattice expansion) versus applied fluence.…”

Section: Resultsmentioning

confidence: 99%

“…This is, however, not completely unexpected and has been reported earlier. ,, Werner et al attribute this to the particular way that electron heat capacity is changed upon inter- versus intraband excitation. Furthermore, the bleaching effect at the plasmon resonance of gold colloids has been extensively studied in transient absorption spectroscopy. ,,, Typical experiments excite the suspension at either 400 or 532 nm with femtosecond pulses and record the transient absorption change across the spectrum. The change of the plasmon resonance helped to discern the effects of plasmon dephasing, electron–electron thermalization, and electron cooling via electron–phonon coupling .…”

Section: Discussionmentioning

confidence: 99%

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Low Efficiency of Laser Heating of Gold Particles at the Plasmon Resonance: An X-ray Calorimetry Study

et al. 2022

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Laser excitation of nanoparticles provides an appealing tool for particle engineering as well as nanoscale-localized photothermal material modification. In the case of plasmonic nanoparticles like gold, mostly on-resonant excitation is used as it appears to be the most efficient channel for laser heating. Yet, as will be shown in this paper, in the case of an excitation with picosecond pulse duration a drastic reduction of the energy uptake efficiency of gold nanoparticles is observed at on-resonant excitation with 532 nm compared to interband excitation at 400 nm. This observation is found irrespective of varied gold nanoparticle size or different synthesis methods. Based on the nanocalorimetry of laser-excited suspended gold nanoparticles with time-resolved X-ray scattering the transient particle temperature, heat-induced relaxation and particle expansion and nonreversible particle transformations were disentangled. At first glance, the lower heating efficiency appears related to ultrafast plasmon bleaching and its recovery in the picosecond range. Yet, following a caloric heat balance a significant residual dissipation channel remains in the case of on-resonant excitation, which is absent at interband excitation. Consequently, photothermal applications may suffer from lower heat generation at the expense of irreversible channels.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Low Efficiency of Laser Heating of Gold Particles at the Plasmon Resonance: An X-ray Calorimetry Study

et al. 2022

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“…We propose an approach that offers the opportunity to ground the study of plasmonic dynamics with an unprecedented detail of physical evidence, resolving the dynamics of the electronic states in momentum space and the coupling of charge excitations to phonons: this provides a direct response to the needs of hybrid plasmonics as foreseen by Linic et al [3] Here, we study a heterostructure of Au nanoislands on WSe 2 (Figure 1a) with angle-resolved photoemission spectroscopy (ARPES) and time-resolved ARPES (tr-ARPES) that give access to equilibrium and excited electronic states with momentum resolution [17,27,28] (Figure 1b), capture excitons in the TMD [29] and detect the dynamic hot-carrier distributions in the nanometal. [30] To fully unfold the dynamics of the system we investigate also the complementary subsystem, the lattice, by femtosecond electron diffraction (FED) [31][32][33] (Figure 1c), determining the coupling of electronic excitations to phononic states.…”

Section: Introductionmentioning

confidence: 99%

Observation of Multi‐Directional Energy Transfer in a Hybrid Plasmonic–Excitonic Nanostructure

et al. 2023

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Hybrid plasmonic devices involve a nanostructured metal supporting localized surface plasmons to amplify light–matter interaction, and a non‐plasmonic material to functionalize charge excitations. Application‐relevant epitaxial heterostructures, however, give rise to ballistic ultrafast dynamics that challenge the conventional semiclassical understanding of unidirectional nanometal‐to‐substrate energy transfer. Epitaxial Au nanoislands are studied on WSe2 with time‐ and angle‐resolved photoemission spectroscopy and femtosecond electron diffraction: this combination of techniques resolves material, energy, and momentum of charge‐carriers and phonons excited in the heterostructure. A strong non‐linear plasmon–exciton interaction that transfers the energy of sub‐bandgap photons very efficiently to the semiconductor is observed, leaving the metal cold until non‐radiative exciton recombination heats the nanoparticles on hundreds of femtoseconds timescales. The results resolve a multi‐directional energy exchange on timescales shorter than the electronic thermalization of the nanometal. Electron–phonon coupling and diffusive charge‐transfer determine the subsequent energy flow. This complex dynamics opens perspectives for optoelectronic and photocatalytic applications, while providing a constraining experimental testbed for state‐of‐the‐art modelling.

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“…Leaving the bottom configuration aside (the environment is inhomogeneous in this case), we observe that the LSPR in the sandwich case is strongly redshifted with respect to the simple theoretical expectations, and that the LSPR dependence on the permittivity is much stronger. The general redshift is easily interpreted as a result of the mutual NP electromagnetic interaction [83], whereas we suggest that the strong variation of the LSPR wavelength in the 5.5<ε 1<6 range is related to the peculiar characteristics of the embedding medium, that, while preserving the LSPR, is nonetheless an electrical conductor [84].…”

Section: (Ab))mentioning

confidence: 80%

Tunable optical and plasmonic response of Au nanoparticles embedded in Ta-doped TiO2 transparent conducting films

Mancarella

Sygletou

Bricchi

et al. 2022

Phys. Rev. Materials

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Localised Surface Plasmon Resonances (LSPR) are fascinating optical phenomena occurring in metal nanostructures, like gold nanoparticles (Au NPs). Plasmonic excitation can be tailored efficiently in the visible range by acting on size, shape and NP surrounding, whereas carrier density is fixed, thus restricting the LSPR modulation. Transparent Conductive Oxides (TCOs), on the other hand, are gaining increasing interest for their transparency, charge carrier tunability and plasmonic features in the infrared. The combination of these two materials into a metal-TCO nanocomposite can give access to unique electrical and optical characteristics, to be tailored in view of the desired optoelectronic application. In this study Au NPs and Ta-doped TiO2 TCO films have been merged with the aim to master the Au plasmon resonance by acting on the dielectric properties of the surrounding TCO. Morphology, structure and electrical properties have been investigated as well, in order to understand the optical response of the nano-systems. The role of the embedding geometry has been explored, revealing that the largest LSPR shift (550-760 nm) occurs when the nanoparticles are sandwiched in the middle of the film, and not at the "bottom" of the film (substrate/film interface). Ta doping in the TCO has been varied (5-10% at. and bare TiO2) to induce a permittivity change of the matrix. As a result, Au LSPR is clearly blue-shifted when decreasing the dielectric permittivity at higher Ta content in the sandwich configuration. Despite the non-optimal electrical performance caused by defectivity of the films, Au-Ta:TiO2 multifunctional nanocomposites are promising candidates for their optical behavior as highly tunable plasmonic conductive metamaterials for advanced light management.

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Quantitative Ultrafast Electron‐Temperature Dynamics in Photo‐Excited Au Nanoparticles

Cited by 8 publications

References 73 publications

Low Efficiency of Laser Heating of Gold Particles at the Plasmon Resonance: An X-ray Calorimetry Study

Low Efficiency of Laser Heating of Gold Particles at the Plasmon Resonance: An X-ray Calorimetry Study

Observation of Multi‐Directional Energy Transfer in a Hybrid Plasmonic–Excitonic Nanostructure

Tunable optical and plasmonic response of Au nanoparticles embedded in Ta-doped TiO2 transparent conducting films

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