Ultrafast nonequilibrium stress generation in gold and silver

Wright, Oliver B.

doi:10.1103/physrevb.49.9985

Cited by 222 publications

(182 citation statements)

References 26 publications

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“…This result maybe due to ultrafast electron-phonon dynamics within the gold film. In particular, Wright observed that under intense ultrafast optical excitation, the non-instantaneous decay of the hot electrons will create an extended phonon pulse within the gold film 50 . If we assume that the electron phonon coupling time is 5 ps 16 this increases the effective film thickness to 65nm.…”

Section: Strain Reconstructionmentioning

confidence: 99%

Reconstructing longitudinal strain pulses using time-resolved x-ray diffraction

et al. 2013

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Time-resolved x-ray diffraction is a very powerful tool for visualizing transient one-dimensional crystalline strains, ranging from crystal growth to shockwave production. In this work, we use picosecond x-ray diffraction to visualize transient strain formation from nanometer scaled laser excited gold films into crystalline substrates. We show that there is a direct correspondence between the measured time-resolved x-ray diffraction pattern and the transient acoustic wave, providing a straightforward method to make a reconstruction of the transient strain. In addition, we discuss real-world experimental constraints that place limits on the validity of the reconstructed transient acoustic wave.

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Section: Strain Reconstructionmentioning

confidence: 99%

Reconstructing longitudinal strain pulses using time-resolved x-ray diffraction

et al. 2013

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“…[1][2][3][4][5] Subpicosecond light pulses are typically used to generate and detect ϳ10-1000 GHz longitudinal acoustic strain pulses. The acoustic strain pulse shape depends on the optoacoustic generation and the acoustic propagation, related, respectively, to the electron and phonon scattering mechanisms.…”

mentioning

confidence: 99%

Tomographic reconstruction of picosecond acoustic strain propagation

Tomoda

Matsuda

Wright

et al. 2007

Applied Physics Letters

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By means of an ultrafast optical technique, picosecond acoustic strain pulses in a transparent medium are tomographically visualized. The authors reconstruct strain pulses in Au-coated glass from time-domain reflectivity changes as a function of the optical angle of incidence, with ϳ1 ps temporal and ϳ100 nm spatial resolutions. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2432238͔ Laser picosecond acoustics is well adapted to the investigation of thin films and nanostructures. 1-5 Subpicosecond light pulses are typically used to generate and detect ϳ10-1000 GHz longitudinal acoustic strain pulses. The acoustic strain pulse shape depends on the optoacoustic generation and the acoustic propagation, related, respectively, to the electron and phonon scattering mechanisms. 1,4,6,7 Measuring the strain pulse shape is therefore useful for studying these mechanisms. In some materials it is possible to measure the strain pulse shape near a free surface by monitoring either surface displacements through beam deflection or changes in the phase of the optical reflectance. 2,8 However, no existing method can continuously monitor picosecond strain pulse shapes during propagation. Stimulated by progress in lower frequency acoustic tomography, 9 we present a method to achieve this.Our sample consists of a thin metal film ͑with complex dielectric constant 2 ͒ deposited on a transparent substrate ͑with real 1 ͒, both materials being isotropic. For s-polarized probe light incidence at angle from the substrate side, the optical amplitude reflection coefficient r 0 ͑also termed the optical reflectance͒ can be expressed as 10 r 0 = cos − ͱ 2 / 1 − sin 2 cos + ͱ 2 / 1 − sin 2 . ͑1͒If 1 is slightly perturbed by a ͑anisotropic͒ longitudinal strain distribution 33 ͑z , t͒ ͑ϳ10 −5 here͒ in the depth ͑z͒ direction, the reflectance is changed: 11-13where variations in 2 and the effect of the finite substrate thickness have been ignored. Here, is the ͑central͒ wavelength of the probe light, P 12 ‫ץ=͑‬ 1 / ‫ץ‬ 33 ͒ is a photoelastic constant, and z = 0 at the 1-2 interface. Equation ͑2͒, which generalizes the formula derived in the past for reflectance changes at normal incidence, 1,11 is an example of an inhomogeneous Fredholm integral. 14 We calculate 33 ͑z , t͒ in the transparent substrate at a given time t from the observed reflectivity variation ␦R 0 / R 0 =2 Re͑␦r 0 / r 0 ͒ as a function of by solving the inverse problem ͑where R 0 = ͉r 0 ͉ 2 ͒. 14,15 ͑A similar approach involving optical phase variations should be feasible.͒ A polished 10 mm radius hemisphere of BK7 glass, whose flat surface is coated with a thin polycrystalline Au film of thickness of 600 nm, is mounted on a rotation stage to set ͑see Fig. 1͒. A photodetector is mounted on a separate coaxial rotation stage set to 2 . Visible s-polarized pump light pulses of duration of ϳ100 fs, repetition rate of 82 MHz, wavelength of 415 nm, and pulse energy of 1.1 nJ from the second harmonic of a Ti:sapphire mode-locked laser are used to illuminate an ϳ20 m diameter ͓full ...

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“…When electrons and the lattice are not in thermal equilibrium, the classical thermoelastic theory can't describe generation and evolution of the stress. The microscopic process of generation of nonequilibrium stresses is related to the instantaneous temperature change of electrons and the lattice [19] and can be described by:…”

Section: Ultrafast Mechanical Responsesmentioning

confidence: 99%

“…Since the thermal conductivity of metals is closely related to their electric conductivity [5,18], the size effect on thermal responses of metals is also an important problem in the field of microscale energy transport. In addition, the ultrashort pulse laser usually induces ultrafast mechanical responses in metals [1,4,[19][20][21][22][23][24][25]. Thus, another important problem is the size effect on mechanical responses of nanostructures.…”

Section: Introductionmentioning

confidence: 99%

Investigation of thermomechanical responses in ultrafast laser heating of metal nanofilms

Zhou

2011

Thin Solid Films

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The present work uses two-temperature model and Cattaneo's constitutive model to study the thermomechanical responses and the size effect on energy transport during ultrafast laser heating of Au nanofilms. It is shown that the grain size effects on thermophysical properties, heat transport and thermal stresses are rather evident when the average grain diameter is less than the electron mean free path. The study on heat transport shows that there are two heat waves propagating in the lattice during nonequilibrium heating of films. It is found that the classical thermoelastic theory can not reveal the generation of the ultrafast thermal stresses during nonequilibrium heating; however, it can approximately describe the stress evolution in the stage of thermal equilibrium.

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Ultrafast nonequilibrium stress generation in gold and silver

Cited by 222 publications

References 26 publications

Reconstructing longitudinal strain pulses using time-resolved x-ray diffraction

Reconstructing longitudinal strain pulses using time-resolved x-ray diffraction

Tomographic reconstruction of picosecond acoustic strain propagation

Investigation of thermomechanical responses in ultrafast laser heating of metal nanofilms

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