Plasmon Dynamics in Colloidal Cu<sub>2–<i>x</i></sub>Se Nanocrystals

Scotognella, Francesco; Valle, Giuseppe Della; Kandada, Ajay Ram Srimath; Dorfs, Dirk; Zavelani‐Rossi, M.; Conforti, Matteo; Miszta, Karol; Comin, Alberto; Korobchevskaya, Kseniya; Lanzani, Guglielmo; Manna, Liberato; Tassone, F.

doi:10.1021/nl202390s

Cited by 162 publications

(230 citation statements)

References 44 publications

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“…12) exhibit a common general trend with two well separated temporal dynamics: a short--time dynamics, on the time--scale of few ps, and a long--time dynamics, on the time scale of hundred ps. These distinct temporal behaviours have been attributed to the dynamical features of the two fundamental processes of carrier--phonon interaction and phonon--phonon interaction respectively [52,69], similarly to what observed in gold and silver nanoparticles. Actually, when the pump pulse is in the infrared region of the spectrum, the initial Fermi distribution of free carriers of the systems is strongly perturbed by pump absorption; the pump pulse creates energetic carriers that are ments; 19 this material is also blue, but the l absorption has not been discussed in the emonstrate in this communication that (W 24 O 68 ) can support strong LSPRs and account for a strong absorption feature ed edge of the visible to the near-IR (NIR).…”

Section: Ultrafast Plasmon Response In Semiconductor Nanocrystalsmentioning

confidence: 64%

Plasmonics in heavily-doped semiconductor nanocrystals

et al. 2013

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Abstract:Heavily--doped semiconductor nanocrystals characterized by a tunable plasmonic band have been gaining increasing attention recently. Herein, we introduce this type of materials focusing on their structural and photo--physical properties. Beside their continuous--wave plasmonic response, depicted both theoretically and experimentally, we also review recent results on their transient ultrafast response. This was successfully interpreted by adapting models of the ultrafast response of noble metal nanoparticles. IntroductionThe optical features exhibited by metallic nano--systems have been the subject of an intensive theoretical and experimental research, resulting in applications in several fields, from surface--enhanced spectroscopy, to biological and chemical nano--sensing [1]. Such developments are primarily due to the localized surface plasmon resonance (LSPR), which results in intense optical absorption and scattering as well as sub--wavelength localization of large electrical fields in the vicinity of the nano--object [2--10]. The plasmonic response of these metallic nanostructures is strongly dependent on the type of metal of which they are made, on the dielectric function of the surrounding medium, on the particle shape and, even if to a lesser extent, on the particle size. Nanoparticles of several metals, such as Ag, Au, Cu and Pt, exhibiting plasmonic response in the ultraviolet and in the visible regions of the spectrum have been successfully synthesized in the past decades [11--15]. Elongated metallic nanoparticles have been shown to exhibit plasmonic response in the near infrared, due to excitation of the longitudinal plasmon mode [16--18]. It has been recently reported that direct optical excitation of the metal by intense femtosecond laser pulses induces an ultra--fast modulation of the plasmonic resonance, which can be used for ultra--fast modulation of signals [19], paving the way to ultrafast active plasmonics. A quantitative investigation of such dynamical features is therefore crucial for the development of a new generation of ultra--fast nano--devices. Pump--probe spectroscopy, giving access to the electronic excitation and subsequent relaxation processes in the material, is to date the most suitable tool for the experimental study of the ultrafast dynamical features exhibited by plasmonic nanostructures. So far, several noble metal structures have been investigated, including spherical nanoparticles [20--22] and nanorods [23], revealing that the physical processes of excitation and relaxation are actually similar to those observed in bulk (i.e. in thin films) metallic systems, that are the electron--electron, the electron--phonon and the phonon--phonon interactions [24,25].

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Section: Ultrafast Plasmon Response In Semiconductor Nanocrystalsmentioning

confidence: 64%

Plasmonics in heavily-doped semiconductor nanocrystals

et al. 2013

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“…Therefore, it is not surprising that they could also be modelled by the TTM. 74 The results by Scotognella et al 22 By means of broadband pump-probe spectroscopy they found that the shape and the relaxation dynamics of the LSPR have strong analogies with those of noble metal NCs. 74 Broadly speaking, when the photon energy of the pump beam is below the onset of interband transitions, the optical properties are dominated by intra-band transitions and the interband ones only contribute with an offset to the dielectric permittivity.…”

Section: 7174-76mentioning

confidence: 99%

“…6c and d). 74 This model was initially developed in order to rationalize the transient optical response of metals, after the absorption of sub-picosecond laser pulses, 74 and it considers electrons and phonons as two thermal reservoirs in thermodynamic equilibrium. Although this assumption is not strictly valid until the electrons have reached internal equilibrium (about 200 fs after laser excitation) the TTM could qualitatively reproduce the transient optical response of metal NCs.…”

Section: 7174-76mentioning

confidence: 99%

“…74 Broadly speaking, when the photon energy of the pump beam is below the onset of interband transitions, the optical properties are dominated by intra-band transitions and the interband ones only contribute with an offset to the dielectric permittivity. 74 In this case the pump energy is entirely absorbed by the free carriers, leading to the formation of a non-thermal hot electron population, which thermalizes to a Fermi-Dirac distribution after a few hundreds of femtoseconds. 21 On the picosecond time scale, the electrons exchange energy with the lattice.…”

Section: 7174-76mentioning

confidence: 99%

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New materials for tunable plasmonic colloidal nanocrystals

2014

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We present a review on the emerging materials for novel plasmonic colloidal nanocrystals. We start by explaining the basic processes involved in surface plasmon resonances in nanoparticles and then discuss the classes of nanocrystals that to date are particularly promising for tunable plasmonics: nonstoichiometric copper chalcogenides, extrinsically doped metal oxides, oxygen-deficient metal oxides and conductive metal oxides. We additionally introduce other emerging types of plasmonic nanocrystals and finally we give an outlook on nanocrystals of materials that could potentially display interesting plasmonic properties.

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“…[8,9] Others have shown similar LSPRs in nanocrystals of copper(I) selenide and copper(I) telluride. [10][11][12][13][14][15][16] LSPR tunability by variation of the copper vacancy concentration has also been demonstrated by the Alivisatos and Manna groups: the greater the vacancy concentration, the higher the LSPR frequency. [9,10] Metal nanoparticles do not possess such tunability, as their free carrier concentrations are large and difficult to perturb appreciably.…”

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confidence: 69%