Nanoscale hydrodynamic instability in a molten thin gold film induced by femtosecond laser ablation

Emel’yanov, V. I.; Zayarniy, D.A.; Ионин, А. А.; Kiseleva, Irina; Kudryashov, S. I.; Makarov, Sergey; Nguyen, Thi Hoai Thu; Rudenko, A. A.

doi:10.1134/s0021364014090057

Cited by 30 publications

(26 citation statements)

References 17 publications

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“…If we suppose that the hardly probable case of full freezing of the jet in Fig. 5 c will nevertheless takes place, then this will contradict to the experimental observations [ 1,7,9,17,23,24] where never such large ratios of a length of a jet to a bump separation radius r sep have been obtained. Development of the very long jet in the case # 31 presented in Table 1 and in Fig.…”

Section: Figcontrasting

confidence: 44%

“…Velocity distribution v norm( r, t =0) mainly follows the fluence distribution ( 1) if the film/substrate adhesion is weak. It is known that a gold film used in experiments [ 17,23,24] is weakly coupled to a glass substrate. We have v norm( r ,0)∝ F ( r ) ( 1) everywhere inside the circle r < r sep with the exception of the vicinity of ring r = r sep. Velocity v norm( r sep,0)=0 at the ring for the small but finite adhesion, while the distribution F ( r ) ( 1) exponentially damps out but remains non-zero.…”

Section: Previous Theoretical Suggestionsmentioning

confidence: 99%

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Solitary Nanostructures Produced by Ultrashort Laser Pulse

Inogamov¹,

Zhakhovsky²,

Хохлов³

et al. 2017

Nano Online

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which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. AbstractLaser-produced surface nanostructures show considerable promise for many applications while fundamental questions concerning the corresponding mechanisms of structuring are still debated. Here, we present a simple physical model describing those mechanisms happened in a thin metal film on dielectric substrate irradiated by a tightly focused ultrashort laser pulse. The main ingredients included into the model are (i) the film-substrate hydrodynamic interaction, melting and separation of the film from substrate with velocity increasing with increase of absorbed fluence; (ii) the capillary forces decelerating expansion of the expanding flying film; and (iii) rapid freezing into a solid state if the rate of solidification is comparable or larger than hydrodynamic velocities. The developed model and performed simulations explain appearance of microbump inside the focal spot on the film surface. The model follows experimental findings about gradual transformation of the bump from small parabolic to a conical shape and to the bump with a jet on its tip with increasing fluence. Disruption of the bump as a result of thinning down the liquid film to a few interatomic distances or due to mechanical break-off of solid film is described together with the jetting and formation of one or many droplets. Developed theory opens door for optimizing laser parameters for intended nanostructuring in applications.

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Section: Figcontrasting

confidence: 44%

Section: Previous Theoretical Suggestionsmentioning

confidence: 99%

Solitary Nanostructures Produced by Ultrashort Laser Pulse

Inogamov¹,

Zhakhovsky²,

Хохлов³

et al. 2017

Nano Online

View full text Add to dashboard Cite

show abstract

“…Obviously, the broader molten pools obtained in the film at lower NA & 0.15 ( Fig. 3) result in broader and higher transient melt bumps [24] that can withstand higher excursions of the molten film near the substrate and its accompanying hydrodynamic instabilities [25]. For comparison, the narrower molten pools obtained in the film at higher NA & 0.8 result in narrower melt bumps [24], which are more sensitive to any transient surface deformations and thus are less stable even at the same deposited surface energy densities (Fig.…”

Section: Resultsmentioning

confidence: 98%

Single-shot front-side nanoscale femtosecond laser ablation of a thin silver film

et al. 2014

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Nano-and microscale holes, as well as related sub-ablative nanospikes and sub-micron bumps, were produced in a 30-nm thick silver film on a silica substrate by single femtosecond laser pulses with variable pulse energies, focused by different strong focusing optics. Characteristic laser energy deposition dimensions exceed the expected focal spots by nearly 2 microns, indicating the considerable lateral thermal transport in the film, while the effective hole formation thresholds decrease versus increasing numerical aperture of focusing optics. Morphologies of the sub-ablative solidified surface nanostructures and numerical estimates of deposited volume energy density undermine blowing-off the molten film due to subsurface boiling and near-critical phase explosion at lower and higher sub-threshold fluences, respectively.

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“…It is shown that in the case of experimental interest [15][16][17] film separated from the substrate and forms a swelling on the substrate. An explanation of the vibrational motion and delamination of the film is given.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 1 shows the overall picture of detachment of the film from the substrate and forming a dome-shaped swelling of the film. In the experiments [15][16][17] using gold film thickness of 10-100 nm. This film was coated with a thick (many microns) glass substrate.…”

Section: Introductionmentioning

confidence: 99%