Phase transitions in femtosecond laser ablation

Povarnitsyn, M. E.; Khishchenko, K. V.; Levashov, P. R.

doi:10.1016/j.apsusc.2008.07.199

Cited by 61 publications

(31 citation statements)

References 16 publications

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“…The model accounts for such processes as laser light absorption, plume expansion, thermal conductivity, two-temperature effects, phase transitions, material decomposition, etc. In particular, the dynamics of the DP ablation is investigated in details and is shown to play a crucial role in the considered phenomenon.The hydrodynamic model [12,13] was developed and previously used for the investigation of a SP ablation of metals. The main advantages of the model are in the treatment of metastable phases and in the used multiphase wide-range equation of state [13].…”

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confidence: 99%

“…In particular, the dynamics of the DP ablation is investigated in details and is shown to play a crucial role in the considered phenomenon.The hydrodynamic model [12,13] was developed and previously used for the investigation of a SP ablation of metals. The main advantages of the model are in the treatment of metastable phases and in the used multiphase wide-range equation of state [13]. The validity of the model was confirmed by the comparison with the experimentally-obtained ablation depth for several metals [14].…”

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Suppression of Ablation in Femtosecond Double-Pulse Experiments

et al. 2009

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We report the physical reasons of a curious decrease in the crater depth observed for long delays in experiments with femtosecond double pulses. Detailed hydrodynamic modeling demonstrates that the ablation mechanism is dumped when the delay between the pulses exceeds the electron-ion relaxation time. In this case, the interaction of the second laser pulse with the expanding target material leads to the formation of the second shock wave suppressing the rarefaction wave created by the first pulse. The evidence of this effect follows from the pressure and density profiles obtained at different delays after the first laser pulse.PACS numbers: 52.38. Mf, 79.20.Ds, 42.25.Bs, 72.15.Cz During last decade, femtosecond laser systems have found numerous applications in different areas, such as laser material treatment, nano-optics, and surface analysis [1]. One of the particularly promising applications of ultrashort laser pulses is laser-induced breakdown spectroscopy (LIBS) [2], or a remote technique that can be used to instantly analyze different materials. The advantages of ultrashort laser pulses were demonstrated in several LIBS experiments resulting in a considerably improved spectral resolution. To further increase the accuracy of the analysis, several special configurations were proposed enhancing the intensity of the plume emission. One of the promising schemes is based on double pulse (DP) laser set-ups [3][4][5]. In addition, experiments with several delayed femtosecond pulses were shown to be advantageous in laser machining [6], thin film modification [7] and in fast ion production [8].Performing DP femtosecond experiments for different metals, several authors [3, 5, 9] surprisingly noticed a monotonic decrease in the resulting crater depth with the increase in the delay τ delay between the laser pulses. This effect was observed both under vacuum [5,9] and in air [3]. In the experiments [5] with copper targets, for instance, the laser fluence of each pulse was set to be F single = 2 J/cm 2 . When the delay between the pulses was much shorter than the electron-ion relaxation time τ ei in the target material (τ delay ≪ τ ei , where τ ei ≈ 10 ps for copper [10]) the crater depth was the same as in the case of a single pulse (SP) with the laser fluence 2 × F single = 4 J/cm 2 . For the delays approaching the electron-ion relaxation time (τ delay ∼ τ ei ), the crater depth monotonically decreased. Finally, for longer delays (τ delay ≫ τ ei ) the crater depth was found to be even smaller than that obtained with a SP at the fluence F single , see Fig. 1. Similar behavior was also obtained for aluminum [3], gold [5] and nickel [9] thus indicating the common physical effect. The dashed (blue) curve in Fig. 1 is just a prediction for long delays, which have not been yet achieved in the DP experiments. This case will be discussed at the end of the letter.Recently, several explanations of the unusual dependency of the crater depth on the delay were proposed. In particular, the temperature dependence of the heat condu...

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Suppression of Ablation in Femtosecond Double-Pulse Experiments

et al. 2009

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“…Thereby, a one-dimensional single-fluid twotemperature Lagrangian model is used with two energy equations for both electronic and ionic subsystems [10,17,18]. The two-temperature multi-phase EOS for Al [19,20] with special treatment of metastable states and a Thomas-Fermi expression for thermal electrons [21] supplements the model. The Thomas-Fermi expression takes into account ionization and explicitly calculates the degree of ionization of the electronic gas.…”

Section: Hydrodynamic Two-temperature Modelmentioning

confidence: 99%

Simulation of ablation and plume dynamics under femtosecond double-pulse laser irradiation of aluminum: Comparison of atomistic and continual approaches

Fokin

Povarnitsyn

Levashov

2017

Applied Surface Science

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“…As a femtosecond laser pulse impacts the metal surface, the lattice temperature in the surface layer increases at the rate of 10 14 K/s and exceeds 10 3 K on a subnanosecond time scale [13]. Due to such a quick increase of the surface temperature a thin surface layer undergoes transition to a superheated liquid, which boils explosively [14]. The depth of the liquid layer according to molecular dynamic simulations is approximately several tens of nanometers [13] and 100-200 nm according to simulations based on the two-temperature model [14]; the lateral dimension is close to the laser spot diameter, which is several tens of micrometers.…”

Section: Introductionmentioning

confidence: 98%

“…Due to such a quick increase of the surface temperature a thin surface layer undergoes transition to a superheated liquid, which boils explosively [14]. The depth of the liquid layer according to molecular dynamic simulations is approximately several tens of nanometers [13] and 100-200 nm according to simulations based on the two-temperature model [14]; the lateral dimension is close to the laser spot diameter, which is several tens of micrometers. Thus the system at hand is a thin two-dimensional layer of superheated liquid, which undergoes rapid explosive boiling and resolidification.…”

Section: Introductionmentioning

confidence: 99%

Self-organized nanopatterns in thin layers of superheated liquid metals

Gurevich

2011

Phys. Rev. E

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In this paper experimental observations of self-organized patterns in resolidified thin films of liquid superheated metals are reported. The superheated melt layers represent an example of a system driven far from equilibrium, which undergoes explosive boiling and solidifies afterward. The melts appear in the course of single-shot femtosecond laser heating of metal samples. Self-organized cells, solitonlike structures, periodic stripes, and transient patterns are observed. Pattern properties and mechanisms leading to the pattern formation as well as possible applications for nanotechnology are discussed.

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Phase transitions in femtosecond laser ablation

Cited by 61 publications

References 16 publications

Suppression of Ablation in Femtosecond Double-Pulse Experiments

Suppression of Ablation in Femtosecond Double-Pulse Experiments

Simulation of ablation and plume dynamics under femtosecond double-pulse laser irradiation of aluminum: Comparison of atomistic and continual approaches

Self-organized nanopatterns in thin layers of superheated liquid metals

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