Femtosecond Studies of Nonequilibrium Electronic Processes in Metals

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

doi:10.1007/978-3-642-82918-5_71

Cited by 39 publications

(52 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a remedy, using a similar model, we derived in [4,5] an extended version of the TTM (referred to below as the eTTM) whereby the early stages of the thermalization of the electron subsystem are accounted for via the total energy of the nonthermal electrons; the latter is then characterized by a fast rise time and slow decay time, corresponding to the thermalization of the electron subsystem 1 ,2 . This derivation confirmed the phenomenological model presented much earlier in [19,20]. In contrast to the TTM, the eTTM allows the electron subsystem to be non-thermal, and only assumes (by adopting the relaxation time approximation, RTA) that the electron subsystem can be described by some temperature -the one to which the electron system would have relaxed if it was isolated from the photons and phonons, see discussion in [4,5].…”

Section: Introductionsupporting

confidence: 78%

Ultrafast Dynamics of Optically Induced Heat Gratings in Metals

Sivan

Spector

2020

ACS Photonics

View full text Add to dashboard Cite

Diffusion of heat in metals is a fundamental process which, surprisingly, received only a little attention from the research community. Here, we study heat diffusion on the femtosecond and few picoseconds time scales. Specifically, we identify the underlying time scales responsible for the generation and erasure of optically-induced transient Bragg gratings in metal films. We show that due to a interplay between the temporally and spatially nature of the thermo-optic response, heat diffusion affects the temperature dynamics in a partially indirect, and overall non-trivial way. Further, we show that heat diffusion affects also the nonlinear response in a way that was not appreciated before.1 In comparison, the source in the TTM has just the temporal profile of the absorbed power. 2 Note that the eTTM does not capture the increase of rate of energy transfer to the lattice during the thermalization time, as discussed in [18]; however, this effect should have, at most, a modest quantitative effect on the issues discussed in the current work.

show abstract

Section: Introductionsupporting

confidence: 78%

Ultrafast Dynamics of Optically Induced Heat Gratings in Metals

Sivan

Spector

2020

ACS Photonics

View full text Add to dashboard Cite

show abstract

“…Monte Carlo simulations demonstrated that the relaxation time τ generally decreases with the laser fluence [63]. Note that the sensitivity of the electron relaxation time on the laser fluence explains why early experimental investigations, occuring at low excitation levels, reported nonthermal character of the electron distribution [59,60,[64][65][66][67]. At higher excitations, the electron cooling down is relatively well described by the twotemperature model [63,[68][69][70].…”

Section: B Discussionmentioning

confidence: 91%

Enhanced Heat Transfer with Metal-Dielectric Core-Shell Nanoparticles

et al. 2020

View full text Add to dashboard Cite

Heat transfer from irradiated metallic nanoparticles is relevant to a broad array of applications ranging from water desalination to photoacoustics. The efficacy of such processes relies on the ability of these nanoparticles to absorb the pulsed illuminating light and to quickly transfer energy to the environment. Here we show that compared to homogeneous gold nanoparticles having the same size, gold-silica core-shell nanoparticles enable heat transfers to liquid water that are faster. We reach this conclusion by considering both analytical and numerical calculations. The key factor explaining enhanced heat transfer is the direct interfacial coupling between metal electrons and silica phonons. We discuss how to obtain fast heating of water in the vicinity of the particle and show that optimal conditions involve nanoparticles with thin silica shells irradiated by ultrafast laser pulses. Our findings should serve as guides for the optimization of thermoplasmonic applications of core-shell nanoparticles.

show abstract

“…Due to the relatively facile implementation, ultrafast microscopy is now emerging as an important tool to study exciton diffusion in semiconductors, molecular solids, and 2D materials [23][24][25][26][27][28][29] . In this context, the ultrafast carrier diffusion dynamics in noble metals, such as gold, is of particular importance for heat management in nanoscale devices, as well as femtosecond laser ablation, but has thus far only been studied in the time domain [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] .…”

mentioning

confidence: 99%

Tracking ultrafast hot-electron diffusion in space and time by ultrafast thermomodulation microscopy

et al. 2019

View full text Add to dashboard Cite

The ultrafast response of metals to light is governed by intriguing nonequilibrium dynamics involving the interplay of excited electrons and phonons. The coupling between them leads to nonlinear diffusion behavior on ultrashort time scales. Here, we use scanning ultrafast thermomodulation microscopy to image the spatiotemporal hot-electron diffusion in thin gold films. By tracking local transient reflectivity with 20-nm spatial precision and 0.25-ps temporal resolution, we reveal two distinct diffusion regimes: an initial rapid diffusion during the first few picoseconds, followed by about 100-fold slower diffusion at longer times. We find a slower initial diffusion than previously predicted for purely electronic diffusion. We develop a comprehensive three-dimensional model based on a two-temperature model and evaluation of the thermo-optical response, taking into account the delaying effect of electron-phonon coupling. Our simulations describe well the observed diffusion dynamics and let us identify the two diffusion regimes as hot-electron and phonon-limited thermal diffusion, respectively.

show abstract

Femtosecond Studies of Nonequilibrium Electronic Processes in Metals

Cited by 39 publications

References 4 publications

Ultrafast Dynamics of Optically Induced Heat Gratings in Metals

Ultrafast Dynamics of Optically Induced Heat Gratings in Metals

Enhanced Heat Transfer with Metal-Dielectric Core-Shell Nanoparticles

Tracking ultrafast hot-electron diffusion in space and time by ultrafast thermomodulation microscopy

Contact Info

Product

Resources

About