Optical properties of liquid carbon measured by femtosecond spectroscopy

Reitze, D. H.; Ahn, Hyeyoung; Downer, Michael

doi:10.1103/physrevb.45.2677

Cited by 152 publications

(89 citation statements)

References 52 publications

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“…It is worth noting that at a fluence lower than the surface damage threshold, the incident femtosecond laser will be simply reflected. 27 There is no surface melting occurring, and thereby, the surface damaged threshold is the lower limit fluence for nanojoining. By scanning the surface, it is not challenged to generate nanowelded films in a large area.…”

Section: Plasmonic Properties Of Welded Nanoparticlesmentioning

confidence: 99%

“…27 As the electronlattice thermal coupling time (typical a few picoseconds) is much longer than the laser pulse width, the electrons do not have enough time to transfer energy to the lattice. At a fluence larger than the surface damage threshold, 27 electrons are excited, ejected, and thereby weaken the chemical bonds of lattice atoms, resulting in "melting" of surface atoms, which is a nonthermal phenomenon.…”

mentioning

confidence: 99%

“…At a fluence larger than the surface damage threshold, 27 electrons are excited, ejected, and thereby weaken the chemical bonds of lattice atoms, resulting in "melting" of surface atoms, which is a nonthermal phenomenon. 5,[27][28][29] This melting also occurs only on the surface to a nanoscale depth without damaging the bulk and, thus, can be used for welding of nanoparticles. 5 …”

mentioning

confidence: 99%

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Femtosecond laser welded nanostructures and plasmonic devices

Peng

Alarifi

et al. 2012

Journal of Laser Applications

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Nanojoining, a burgeoning research area, becomes a key manufacturing of complicated nanodevices with functional prefabricated components. In this work, various nanojoining methods are first reviewed. For nanojoining of Ag/Au nanoparticles, three methods are investigated comparatively. Thermal annealing shows a two-step solid state diffusion mechanism. Laser annealing by millisecond pulses displays the thermal activated solid state diffusion. Meanwhile, two effects have been identified in femtosecond laser irradiation with different laser intensities: photofragmentation at rather high intensity (∼1014 W/cm2) and nanojoining at low intensity (∼1010 W/cm2). The photofragmentation forms a large number of tiny nanoparticles with an average size of 10 nm. Control over irradiation conditions at intensities near 1010 W/cm2 results in nanojoining of most of the nanoparticles. This nanojoining is obtained through a nonthermal melting and a surface fusion welding. Joined Au nanoparticles are expected to have numerous applications, such as probes for surface enhance Raman spectroscopy.

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Section: Plasmonic Properties Of Welded Nanoparticlesmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Femtosecond laser welded nanostructures and plasmonic devices

Peng

Alarifi

et al. 2012

Journal of Laser Applications

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“…In this experiment, only a fraction of the energy was effectively used to stimulate the phase transition and, later, it was shown how a faster heating system can improve the excitation efficiency. The natural evolution of this concept is the use of an ultrafast pump-probe technique, an approach followed, e.g., by Reitze et al [11], who measured the transient optical reflectivity and transmissivity in photo-excited graphite and diamond, finding evidence of an ultrafast metallization of the sample (ascribed to a solid-liquid transition). However, the effects of the surface plasma screening, inherently related to the use of an optical probe, raised some questions regarding the probe's sensitivity to bulk properties.…”

Section: Introductionmentioning

confidence: 99%

Transient EUV Reflectivity Measurements of Carbon upon Ultrafast Laser Heating

et al. 2017

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Time resolved extreme ultraviolet (EUV) transient reflectivity measurements on non-equilibrium amorphous carbon (a-C) have been carried out by combining optical and free electron laser (FEL) sources. The EUV probing was specifically sensitive to lattice dynamics, since the EUV reflectivity is essentially unaffected by the photo-excited surface plasma. Data have been interpreted in terms of the dynamics of an expanding surface, i.e., a density gradient rapidly forming along the normal surface. This allowed us to determine the characteristic time (τ 1 ps) for hydrodynamic expansion in photo-excited a-C. This finding suggests an extremely narrow time window during which the system can be assumed to be in the isochoric regime, a situation that may complicate the study of photo-induced metastable phases of carbon. Data also showed a weak dependence on the probing EUV wavelength, which was used to estimate the electronic temperature (T e ≈ 0.8 eV) of the excited sample. This experimental finding compares fairly well with the results of calculations, while a comparison of our data and calculations with previous transient optical reflectivity measurements highlights the complementarities between optical and EUV probing.

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“…Experimentally, electron-hole plasmas are generated by irradiating solids with strong laser pulses, and the threshold for dielectric breakdown has been measured [18][19][20][21][22][23][24][25][26][27] . To describe the phenomena, model approaches such as a rate equation for electronic excitations have been developed [28][29][30][31][32][33] .…”

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confidence: 99%

Time-dependent density functional theory for strong electromagnetic fields in crystalline solids

et al. 2012

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We apply the coupled dynamics of time-dependent density functional theory and Maxwell equations to the interaction of intense laser pulses with crystalline silicon. As a function of electromagnetic field intensity, we see several regions in the response. At the lowest intensities, the pulse is reflected and transmitted in accord with the dielectric response, and the characteristics of the energy deposition is consistent with two-photon absorption. The absorption process begins to deviate from that at laser intensities ∼ 10 13 W/cm 2 , where the energy deposited is of the order of 1 eV per atom. Changes in the reflectivity are seen as a function of intensity. When it passes a threshold of about 3 × 10 12 W/cm 2 , there is a small decrease. At higher intensities, above 2 × 10 13 W/cm 2 , the reflectivity increases strongly. This behavior can be understood qualitatively in a model treating the excited electron-hole pairs as a plasma.

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Optical properties of liquid carbon measured by femtosecond spectroscopy

Cited by 152 publications

References 52 publications

Femtosecond laser welded nanostructures and plasmonic devices

Femtosecond laser welded nanostructures and plasmonic devices

Transient EUV Reflectivity Measurements of Carbon upon Ultrafast Laser Heating

Time-dependent density functional theory for strong electromagnetic fields in crystalline solids

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