Pump-probe spectroscopy study of ultrafast temperature dynamics in nanoporous gold

Abstract

We explore the influence of the nanoporous structure on the thermal relaxation of electrons and holes excited by ultrashort laser pulses (∼ 7 fs) in thin gold films. Plasmon decay into hot electronhole pairs results in the generation of a Fermi-Dirac distribution thermalized at a temperature Te higher than the lattice temperature T l . The relaxation times of the energy exchange between electrons and lattice, here measured by pump-probe spectroscopy, is slowed down by the nanoporous structure, resulting in much higher peak Te than for bulk gold films. The electron-phonon coupling constant and the Debye temperature are found to scale with the metal filling factor f and a twotemperature model reproduces the data. The results open the way for electron temperature control in metals by engineering of the nanoporous geometry.

Magnetoconductance and photoresponse properties of disordered NbTiN films

“…There are other optical methods to probe ultrafast dynamics of electrons, e.g., the pump-probe technique [36], secondharmonic generation [37], and two-photon emission [38]. They, however, reveal dynamics at high energies (≈1 eV) due to interaction with optical phonons.…”

Kinetic modelling of intraband carrier relaxation in bulk and nanocrystalline lead-halide perovskites

“…16,37 The fact that we observe similar cooling dynamics and a comparable carrier-phonon interaction constant in bulk and NC CsPbBr 3 tentatively implies that the additional grain boundaries in the NC sample do not strongly affect the phonon density of states, as one might expect for a nanostructured material. 38 As outlined above, our cuboidal NCs are efficiently packed, resulting in voids which are substantially smaller than the NCs themselves. Taking this, and the fact that the carrier delocalisation distance in CsPbBr 3 is estimated to be B7 nm 23 (comparable to the NC edge length), we posit that a phonon originating in a given NC has a similar pool of phonons to interact with as in the bulk material, and these phonons do not need to propagate far before encountering a carrier in an adjacent NC.…”

Thermometric Calibration of the Ultrafast Relaxation Dynamics in Plasmonic Au Nanoparticles

“…Given this, it is hardly surprising that understanding and modelling the ultrafast relaxation dynamics of impulsively-excited matter and of plasmonic NPs is a task that remains challenging to this day. 22,[26][27][28][29][30][31][32][33][34][35] Experimentally, the progresses in ultrafast optical and electronic spectroscopies have allowed, over the years, deeper and deeper insights in these complicated processes, [35][36][37][38][39][40] ultimately promoting the emergence of the above-described general picture. One crucial point is however still represented by the fact that, while T e , T l and T env are basic ingredients of theoretical models, their evaluation from experimental data is typically always indirect.…”