Femtosecond studies of nonequilibrium electronic processes in metals

Schoenlein, R. W.; Lin, Wen-Li; Fujimoto, James G.; Eesley, G. L.

doi:10.1103/physrevlett.58.1680

Cited by 678 publications

(336 citation statements)

References 10 publications

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“…12 In their model, the zero crossing corresponds to the electron energy x ͑relative to the top edge of the d band͒ at which the Fermi-Dirac distribution is unchanged by the optical excitation…”

Section: Resultsmentioning

confidence: 99%

“…Often, the transient signal is analyzed by assuming that it depends linearly upon either the transient electron ͑and lattice͒ temperature, 6,10 or the transient excess total electron energy, 11 or the transient electron occupation number. 12 However, such an assumption ͑referred to as the "linearity assumption" from hereon͒ is not self-consistent since transient reflectivity and transmission signals appear to have a different temporal shape, [13][14][15][16][17][18] and hence cannot be both proportional to the same function of time, e.g., the transient electron temperature. As has been known since the early optical thermomodulation studies of metals, 19 rigorous analysis instead requires the transient reflectivity and transmission to be properly calculated from the dependence of the complex dielectric function upon the electron occupation number.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we report optical pump and supercontinuum-probe 12,18,[20][21][22][23] measurements of the transient reflectivity response of a thin film of gold over a wide spectral range. In the wavelength domain, we observe that the point at which the transient reflectivity spectra cross zero shifts with the time delay at which they were acquired.…”

Section: Introductionmentioning

confidence: 99%

“…We show that this shift is incompatible with the arguments of Schoenlein et al that were based upon the linearity assumption. 12 Due to the presence of the shift, time resolved signals reconstructed from the spectra become bipolar at wavelengths near the zero crossing point. Sun et al also observed signals of similar bipolar shape, and interpreted them in terms of a short lived contribution from nonthermalized electrons.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic study of optically induced ultrafast electron dynamics in gold

et al. 2007

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Using a supercontinuum pulse as a probe, we have measured the transient reflectivity spectra of a thin film of gold for different values of the pump-probe time delay. The wavelength x at which the measured transient reflectivity changes sign has been found to depend upon the time delay, leading to bipolar time resolved signals. The time dependence of x has been shown to be consistent with calculations that take into account the full dependence of the reflectivity upon the electron occupation number, and to contradict qualitatively a model in which the signal is assumed to be directly proportional to the occupation number. The shift of x has been found to persist at time delays that are much longer than the time required for the electrons to thermalize. Therefore the bipolar reflectivity signals do not necessarily contain a contribution from nonthermalized electrons, as has been previously assumed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectroscopic study of optically induced ultrafast electron dynamics in gold

et al. 2007

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“…This actually means that the imaginary character of (3) inter χ as well as, more generally, the sign and modulus of both electronic contributions, are expected to undergo spectral variations, which is rarely considered in the literature. As soon as the incident wave intensity is sufficiently high, the modification of the conduction electron distribution induced by photon absorption may result in a significant modification of the optical transition spectrum [60,61]. This is the Fermi smearing, which is not a pure electronic nonlinear effect but was demonstrated by Hache and co-workers to amount to an optical Kerr effect contribution [56], that they characterized by the hot electron susceptibility, (3) hot electrons χ .…”

Section: 4mentioning

confidence: 99%

Gold nanoparticle assemblies: interplay between thermal effects and optical response

et al. 2008

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The optical response of materials based on gold nanoparticle assemblies depends on many parameters regarding both material morphology and light excitation characteristics. In this paper, the interplay between the optical and thermal responses of such media is particularly investigated under its theoretical aspect. Both conventional and original modeling approaches are presented and applied to concrete cases. We first show how the interaction of light with matrix-embedded gold nanoparticles can result in the generation of thermal excitations through different energy exchange mechanisms. We then describe how thermal processes can affect the optical response of a nanoparticle assembly. Finally, we connect both aspects and point out their involvement in the nonlinear optical response of nanocomposite media. This allows us to tackle two key issues in the field of third-order nonlinear properties of gold nanoparticles: The influence of the generalized thermal lens in the long laser pulse regime and the hot electron contribution to the gold particle intrinsic third-order susceptibility, including its spectral dispersion and intensity-dependence. Additionally, we demonstrate the possible significant influence of the heat carrier ballistic regime and phonon rarefaction in the cooling dynamics of an embedded gold nanoparticle subsequent to ultrafast pulsed laser excitation.

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