Template free synthesis of free-standing silver nanowhisker and nanocrown superlattice by interfering femtosecond laser irradiation

Nakata, Yoshiki; Miyanaga, Noriaki; Momoo, Kazuma; Hiromoto, Takuya

doi:10.7567/jjap.53.096701

“…In past interference femtosecond laser processing experiments, metal lattice nanowhiskers 11 , 12 and nanodrops 13 , 14 , grating 15 , 16 , embedded grating inside an active medium 17 and a photonic crystal device 18 have been fabricated; however, any spiral formations on these nanostructures have not been observed yet. If spirality and chirality could be accomplished using this method, a number of spiral and chiral structures could be fabricated in precise lattice simultaneously, and the effect of the spirality or chirality would be greatly enhanced, leading to an acceleration in the investigation and practical application of these structures.…”

Section: Introductionmentioning

confidence: 99%

Parallel fabrication of spiral surface structures by interference pattern of circularly polarized beams

Nakata

¹

,

Yoshida

²

,

Miyanaga

³

2018

Sci Rep

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Mass migration of photo-isomeric azo-polymers occurs according to the light intensity gradient, and the morphological surface structure can be fabricated by the artificial distribution of light by applying the interference properties of coherent laser light. Recently, the optical radiation force has played an important role in the morphology for dielectric targets, and chiral structures have been fabricated according to the spirally gathering force distribution that arises due to the electric susceptibility. On the contrary, interference laser processing has been applied to process the surface or interior of the material, and nano- or micro-structures in the lattice have been fabricated in a single exposure to the interference pattern. The unit structures are mostly axisymmetric nanowhiskers, nanodrops and nanobumps, among others. In this experiment, interference laser processing of an azo-polymer dielectric target using a circularly polarised continuous-wave (CW) laser was examined, and a spiral structure was successfully fabricated. From the viewpoint of laser processing method, an optical spiral radiation force was introduced in interference laser processing for the first time.

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“…In the past experiment with Au and Ag thin film targets, we have selectively fabricated metal nanowhiskers [ 12 , 15 ] and nanocrowns [ 15 , 16 ], as shown in the inserted pictures in Figure 8 b,c, respectively. Usually, nanowhiskers and nanodrops [ 13 , 25 ] are formed as shown in Figure 8 b, but nanocrowns are formed as shown in Figure 8 c when the film thickness is relatively thin or the interference pattern has a wider period, i.e., when the spot size is relatively large [ 15 , 16 ]. In the former case, a nanodot is formed by surface tension and deposited onto the receiver substrate, which was shown in the previous paper using Au donor film [ 17 ].…”

Section: Resultsmentioning

confidence: 99%

“…( c ) nanodots are ejected in a splashy manner. Insets in each illustration are copied from our past experiments [ 12 , 13 , 15 , 16 ].…”

Section: Figurementioning

confidence: 99%

“…The mechanism involves the liquid behavior of solute metals and their freezing, called the solid–liquid–solid (SLS) mechanism [ 12 ]. Here, SLS enables the fabrication of a variety of nanostructures other than nanodots using LIDT, such as the nanobump [ 13 ], nanodrop [ 13 , 14 ], nanowhisker [ 12 , 15 ], nanocrown [ 15 , 16 ], etc. Furthermore, we have investigated interference laser processing for two decades.…”

Section: Introductionmentioning

confidence: 99%

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Laser-Induced Transfer of Noble Metal Nanodots with Femtosecond Laser-Interference Processing

Nakata

¹

,

Tsubakimoto

²

,

Miyanaga

³

et al. 2021

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Noble metal nanodots have been applied to plasmonic devices, catalysts, and highly sensitive detection in bioinstruments. We have been studying the fabrications of them through a laser-induced dot transfer (LIDT) technique, a type of laser-induced forward transfer (LIFT), in which nanodots several hundred nm in diameter are produced via a solid–liquid–solid (SLS) mechanism. In the previous study, an interference laser processing technique was applied to LIDT, and aligned Au nanodots were successfully deposited onto an acceptor substrate in a single shot of femtosecond laser irradiation. In the present experiment, Pt thin film was applied to this technique, and the deposited nanodots were measured by scanning electron microscopy (SEM) and compared with the Au nanodots. A typical nanodot had a roundness fr=0.98 and circularity fcirc=0.90. Compared to the previous experiment using Au thin film, the size distribution was more diffuse, and it was difficult to see the periodic alignment of the nanodots in the parameter range of this experiment. This method is promising as a method for producing large quantities of Pt particles with diameters of several hundred nm.

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“…In these experiments, spiralling on an azopolymer occurred due to the optical radiation force induced by a circularly polarized Gaussian beam. On the other hand, interference pattern processing methods can form nanometre- or micron-sized structures such as nanowhiskers 8 , 9 , nanodrops 10 , 11 , grating 12 , 13 , and grating inside an active medium 14 , 15 , which have been fabricated with a single laser beam exposure. By combining these techniques, a chiral structure in an array was successfully fabricated by using an interference pattern of circularly polarized 6-beams facing each other symmetrically 16 .…”

Section: Introductionmentioning

confidence: 99%

Simulation of optical radiation force distribution in interference patterns and necessary conditions for chiral structure formation on dielectrics

Nakata

¹

,

Tsubakimoto

²

,

Shiraga

³

et al. 2022

Sci Rep

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0

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A chiral structure is formed by the optical radiation force induced by a circularly polarized light that has spin angular momentum; chiral structures are expected to be used for light control devices and molecular chirality discrimination devices. In this paper, we clarify the relationship between the differences in the distributions of the optical radiation force and the possibility of formation of chiral structures. We first simulate the optical radiation force distribution in the case of a Gaussian beam that successfully forms a chiral structure. Given a vector $${\varvec{r}}$$ r with a centre of the light spot $$\mathrm{O}$$ O and polar coordinates $$R(\left|{\varvec{r}}\right|, \theta )$$ R ( r , θ ) , and an optical radiation force vector $${\varvec{F}}$$ F at $$R$$ R , the angle $${\theta }^{\mathrm{^{\prime}}}=\mathrm{\angle }({\varvec{r}}, {\varvec{F}})$$ θ ′ = ∠ ( r , F ) and $$\left|{\varvec{F}}\right|$$ F must be constant with respect to the declination angle $$\theta$$ θ for a chiral structure to form. These conditions are fulfilled in the case of a 6-beam interference pattern, but not in the case of a 4-beam interference pattern, which is consistent with the result that no chiral structure is formed in the latter case. The equations derived for simulation of optical radiation force distribution can be used for any optical intensity distribution, and will be of great help in the research of any dielectrics deformation.

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Template free synthesis of free-standing silver nanowhisker and nanocrown superlattice by interfering femtosecond laser irradiation

Cited by 16 publications

References 25 publications

Parallel fabrication of spiral surface structures by interference pattern of circularly polarized beams

Parallel fabrication of spiral surface structures by interference pattern of circularly polarized beams

Laser-Induced Transfer of Noble Metal Nanodots with Femtosecond Laser-Interference Processing

Simulation of optical radiation force distribution in interference patterns and necessary conditions for chiral structure formation on dielectrics

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