Modelling ultrafast laser ablation

Rethfeld, Baerbel; Ivanov, Dmitriy S.; Garcia, Martín E.; Anisimov, S. I.

doi:10.1088/1361-6463/50/19/193001

Cited by 390 publications

(281 citation statements)

References 194 publications

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“…High‐intensity femtosecond laser irradiation primarily results in the extremely high excitation of the electronic system of solids . Fast electrons and ionization of the valence band are produced homogeneously in a target in a free‐electron laser (FEL) spot . Within femtoseconds electronic cascades finish, establishing the electronic temperature of several electron volts (1 eV = 11 605 K) in the excited region, significantly above the atomic one .…”

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confidence: 99%

Superionic State in Alumina Produced by Nonthermal Melting

Voronkov

Medvedev

Волков

2020

Physica Rapid Research Ltrs

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Density functional–based molecular dynamics reveals a transient superionic state in Al2O3 produced by nonthermal phase transition under extreme electronic excitation. At electronic temperatures above Te ≈ 2.75 eV, the oxygen sublattice exhibits fluid behavior, whereas the aluminum sublattice is in a solid state. This state exists up to Te ≈ 3.25 eV, where Al2O3 turns metallic–superionic; at Te ≈ 3.75 eV, the aluminum sublattice disorders. Quenching the superionic state under pressure >400 GPa freezes it into a metastable mixed amorphous–crystalline phase where the oxygen subsystem is disordered solid, whereas the aluminum one is ordered.

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mentioning

confidence: 99%

Superionic State in Alumina Produced by Nonthermal Melting

Voronkov

Medvedev

Волков

2020

Physica Rapid Research Ltrs

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“…Precise control of material processing is a premier example that requires a thorough knowledge of the energy deposition, energy loss channels, and the relaxation processes driven by the laser . In particular, the use of lasers with femtosecond pulses has brought a new set of fundamental questions regarding the nature of the interaction process and the evolution of the material response . Such short excitations drive a whole cascade of relaxation processes starting from the electron kinetics to the equilibration of electron and lattice temperatures, with most of the associated relaxation rates being still under debate even for noble metals .…”

Section: Introductionmentioning

confidence: 99%

“…For metals, the coupling of the laser field to the electrons is almost exclusively responsible for the absorption of the light, and the subsequent material response is thus strongly connected to the electron relaxation . The electrons are driven far out of thermal equilibrium both in their occupation numbers and the distribution functions.…”

Section: Introductionmentioning

confidence: 99%

Density response to short‐pulse excitation in gold

Ndione

Weber

Rethfeld

et al. 2019

Contributions to Plasma Physics

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We investigate the dynamics of band occupation in gold after excitation with short laser pulses. Strong non‐equilibrium distributions can be created by intra‐ and inter‐band transitions driven by the absorption of photons with different wavelengths. First, we briefly discuss how photons can be used as a probe and how electrons with non‐Fermi distributions can be described. Then we focus on the relaxation stage where a temperature has been established but the occupation numbers in the different bands are not yet in equilibrium with this newly established elevated temperature. We describe the relaxation towards a system with a common chemical potential with rate equations that also include the energy transfer to the lattice or ions. Finally, we give an outlook on the optical response of the relaxing electron system to a probe pulse of radiation.

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“…However, the patterning area and complexity in graphene-based fabrication require considerable improvement in the quality of laser pulse machining. As a result, the ablated structures and devices will obtain higher efficiency and better flexibility after ultrafast laser micromachining without the need for post-processing (Rethfeld et al, 2017;Winter et al, 2017). This type of laser has a short pulse duration and high peak power intensity, which can induce the nonlinear absorption in the material during irradiation and offers the advantages of more precise resolutions .…”

Section: Introductionmentioning

confidence: 99%

Thermally stable and uniform DNA amplification with picosecond laser ablated graphene rapid thermal cycling device

Chen

Chang

et al. 2019

Biosensors and Bioelectronics

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Rapid thermal cycling (RTC) in an on-chip device can perform DNA amplification in vitro through precise thermal control at each step of the polymerase chain reaction (PCR). This study reports a straightforward fabrication technique for patterning an on-chip graphene-based device with hole arrays, in which the mechanism of surface structures can achieve stable and uniform thermal control for the amplification of DNA fragments. A thin-film based PCR device was fabricated using picosecond laser (PS-laser) ablation of the multilayer graphene (MLG). Under the optimal fluence of 4.72 J/cm 2 with a pulse overlap of 66%, the MLG can be patterned with arrays of 250 μm 2 hole surface structures. A 354-bp DNA fragment of VP1, an effective marker for diagnosing the BK virus, was amplified on an on-chip device in less than 60 min. A thin-film electrode with the aforementioned MLG as the heater was demonstrated to significantly enhance temperature stability for each stage of the thermal cycle. The temperature control of the heater was performed by means of a developed programmable PCR apparatus. Our results demonstrated that the proposed integration of a graphene-based device and a laser-pulse ablation process to form a thin-film PCR device has cost benefits in a small-volume reagent and holds great promise for practical medical use of DNA amplification.

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Modelling ultrafast laser ablation

Cited by 390 publications

References 194 publications

Superionic State in Alumina Produced by Nonthermal Melting

Superionic State in Alumina Produced by Nonthermal Melting

Density response to short‐pulse excitation in gold

Thermally stable and uniform DNA amplification with picosecond laser ablated graphene rapid thermal cycling device

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