Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation...Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation in liquid(fs-LAL)can easily break this polarization restriction to produce irregular circular-LIPSS(CLIPPS)and crisscross-LIPSS(CCLIPSS).Fs laser ablation of silicon in water shows formation of diverse LIPSS depending on ablation conditions.At a high power of 700 mW(repetition rate of 100 kHz,pulse duration of 457 fs and wavelength of 1045 nm),single/twin CLIPSS are produced at the bottom of macropores of several microns in diameter due to the formation of strong liquid vortexes and occurrence of the vortex shedding effect.Theoretical simulations validate our speculation about the formation of liquid vortex with an ultrahigh static pressure,which can induce the microstructure trenches and cracks at the sidewalls for fs-LAL of Si and tungsten(W)in water,respectively.At a low power of 50 mW,weak liquid vortexes are produced,which only give birth to curved LIPSS in the valleys of grooves.Consequently,it is deduced that liquid vortex plays a crucial role in the formation of macropores.Mountain-like microstructures induce complex fluid dynamics which can cause the formation of CCLIPSS on them.It is believed that liquid vortexes and fluid dynamics presented in this work open up new possibilities to diversify the morphologies of LIPSS formed by fs-LAL.展开更多
This review provides a discussion of the current state of research on sp-carbon chains synthesized by pulsed laser ablation in liquid.In recent years,pulsed laser ablation in liquid(PLAL)has been widely employed for p...This review provides a discussion of the current state of research on sp-carbon chains synthesized by pulsed laser ablation in liquid.In recent years,pulsed laser ablation in liquid(PLAL)has been widely employed for polyynes synthesis thanks to its flexibility with varying laser parameters,solvents,and targets.This allows the control of sp-carbon chains properties as yield,length,termination and stability.Although many reviews related to PLAL have been published,a comprehensive work reporting the current status and advances related to the synthesis of sp-carbon chains by PLAL is still missing.Here we first review the principle of PLAL and the mechanisms of formation of sp-carbon chains.Then we discuss the role of laser fluence(i.e.energy density),solvent,and target for sp-carbon chains synthesis.Lastly,we report the progress related to the prolonged stability of sp-carbon chains by PLAL encapsulated in polymeric matrices.This review will be a helpful guide for researchers interested in synthesizing sp-carbon chains by PLAL.展开更多
Multifunctional luminescent materials are attracting attention nowadays.In this work,monoclinic Gd_(2)O_(3):Er^(3+)nanoparticles,which possess up-conversion luminescence and down-conversion luminescence properties,wer...Multifunctional luminescent materials are attracting attention nowadays.In this work,monoclinic Gd_(2)O_(3):Er^(3+)nanoparticles,which possess up-conversion luminescence and down-conversion luminescence properties,were successfully synthesized by laser ablation in liquid(LAL)technique.Up-conversion luminescence and down-conversion luminescence of monoclinic Gd_(2)O_(3):Er^(3+)nanoparticles were got under the excitation of 980 nm and 379 nm,respectively.In addition,tunable luminescence was got.Furthermore,the cytotoxicity of the nanoparticles is low and the fluorescence of the nanoparticles in cell is also strong enough.The results indicate that the Gd_(2)O_(3):Er^(3+)nanoparticles synthesized by LAL technique are promising candidates for bio-imaging or other fields that require controllable fluorescence.展开更多
Near-IR(wavelength≈1μm)laser ablation of bulk,chemically-inert gold in water was compared for different laser pulse width in broad the range of 300 fs–100 ns,comparing a number of key ablation characteristics:mass ...Near-IR(wavelength≈1μm)laser ablation of bulk,chemically-inert gold in water was compared for different laser pulse width in broad the range of 300 fs–100 ns,comparing a number of key ablation characteristics:mass loss,singleshot crater volume and extinction coefficient of the generated colloidal solutions taken in the spectral ranges of interband transitions and localized plasmon resonance.Comparing to related air-based ablation results,at the given fluences laser ablation in the liquid resulted in the maximum ablation yield per unit energy and maximum NP yield per pulse and per unit energy for the picosecond lasers,occurring at subcritical peak pulse powers for laser self-focusing.The self-focusing effect was demonstrated to yield in incomplete,effectively weaker focusing in the water filaments of ultrashort laser pulses with supercritical peak powers,comparing to linear(geometrical)focusing at sub-critical peak powers.At the other,nanosecondpulse extreme the high ablation yield per pulse,but low ablation yield per unit energy and low NP yield per pulse and per unit energy were related to strong ablation plasma screening,providing mass removal according to the well-established scaling relationships for plasma.Illustrative comparison of the ablation and nanoparticle generation efficiency versus the broad fs–ns laser pulse width range was enabled in terms of productivity,economicity,and ergonomicity,using the proposed universal quantitative criteria.展开更多
基金This work was supported by the national key R&D program for internation-al collaboration under grant No.2018YFE9103900in part by the Nat-ural Science Foundation of China(NSFC)grant No.11972384 and the Guangdong MEPP Fund,grant No.GDOE[2019]A01.
文摘Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation in liquid(fs-LAL)can easily break this polarization restriction to produce irregular circular-LIPSS(CLIPPS)and crisscross-LIPSS(CCLIPSS).Fs laser ablation of silicon in water shows formation of diverse LIPSS depending on ablation conditions.At a high power of 700 mW(repetition rate of 100 kHz,pulse duration of 457 fs and wavelength of 1045 nm),single/twin CLIPSS are produced at the bottom of macropores of several microns in diameter due to the formation of strong liquid vortexes and occurrence of the vortex shedding effect.Theoretical simulations validate our speculation about the formation of liquid vortex with an ultrahigh static pressure,which can induce the microstructure trenches and cracks at the sidewalls for fs-LAL of Si and tungsten(W)in water,respectively.At a low power of 50 mW,weak liquid vortexes are produced,which only give birth to curved LIPSS in the valleys of grooves.Consequently,it is deduced that liquid vortex plays a crucial role in the formation of macropores.Mountain-like microstructures induce complex fluid dynamics which can cause the formation of CCLIPSS on them.It is believed that liquid vortexes and fluid dynamics presented in this work open up new possibilities to diversify the morphologies of LIPSS formed by fs-LAL.
基金funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program ERC Consolidator Grant(ERC Co G2016 Esp LORE grant agreement No.724610,website:www.esplore.polimi.it)
文摘This review provides a discussion of the current state of research on sp-carbon chains synthesized by pulsed laser ablation in liquid.In recent years,pulsed laser ablation in liquid(PLAL)has been widely employed for polyynes synthesis thanks to its flexibility with varying laser parameters,solvents,and targets.This allows the control of sp-carbon chains properties as yield,length,termination and stability.Although many reviews related to PLAL have been published,a comprehensive work reporting the current status and advances related to the synthesis of sp-carbon chains by PLAL is still missing.Here we first review the principle of PLAL and the mechanisms of formation of sp-carbon chains.Then we discuss the role of laser fluence(i.e.energy density),solvent,and target for sp-carbon chains synthesis.Lastly,we report the progress related to the prolonged stability of sp-carbon chains by PLAL encapsulated in polymeric matrices.This review will be a helpful guide for researchers interested in synthesizing sp-carbon chains by PLAL.
文摘Multifunctional luminescent materials are attracting attention nowadays.In this work,monoclinic Gd_(2)O_(3):Er^(3+)nanoparticles,which possess up-conversion luminescence and down-conversion luminescence properties,were successfully synthesized by laser ablation in liquid(LAL)technique.Up-conversion luminescence and down-conversion luminescence of monoclinic Gd_(2)O_(3):Er^(3+)nanoparticles were got under the excitation of 980 nm and 379 nm,respectively.In addition,tunable luminescence was got.Furthermore,the cytotoxicity of the nanoparticles is low and the fluorescence of the nanoparticles in cell is also strong enough.The results indicate that the Gd_(2)O_(3):Er^(3+)nanoparticles synthesized by LAL technique are promising candidates for bio-imaging or other fields that require controllable fluorescence.
基金the Ministry of Science and Higher Education of the Russian Federation(Project No.075-152020-775)。
文摘Near-IR(wavelength≈1μm)laser ablation of bulk,chemically-inert gold in water was compared for different laser pulse width in broad the range of 300 fs–100 ns,comparing a number of key ablation characteristics:mass loss,singleshot crater volume and extinction coefficient of the generated colloidal solutions taken in the spectral ranges of interband transitions and localized plasmon resonance.Comparing to related air-based ablation results,at the given fluences laser ablation in the liquid resulted in the maximum ablation yield per unit energy and maximum NP yield per pulse and per unit energy for the picosecond lasers,occurring at subcritical peak pulse powers for laser self-focusing.The self-focusing effect was demonstrated to yield in incomplete,effectively weaker focusing in the water filaments of ultrashort laser pulses with supercritical peak powers,comparing to linear(geometrical)focusing at sub-critical peak powers.At the other,nanosecondpulse extreme the high ablation yield per pulse,but low ablation yield per unit energy and low NP yield per pulse and per unit energy were related to strong ablation plasma screening,providing mass removal according to the well-established scaling relationships for plasma.Illustrative comparison of the ablation and nanoparticle generation efficiency versus the broad fs–ns laser pulse width range was enabled in terms of productivity,economicity,and ergonomicity,using the proposed universal quantitative criteria.
