Browsing by Author "Masuhara, Hiroshi"

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A Single Large Assembly with Dynamically Fluctuating Swarms of Gold Nanoparticles Formed by Trapping Laser
(2018-09-01)
Kudo, Tetsuhiro
;
Yang, Shang-Jan
;
Masuhara, Hiroshi
;
交大名義發表
;
應用化學系
Laser trapping has been utilized as tweezers to three-dimensionally trap nanoscale objects and has provided significant impacts in nanoscience and nanotechnology. The objects are immobilized at the position where the tightly focused laser beam is irradiated. Here, we report the swarming of gold nanoparticles in which component nanoparticles dynamically interact with each other, keeping their long interparticle distance around the trapping laser focus at a glass/solution interface. A pair of swarms are directionally extended outside the focal spot perpendicular to the linear polarization like a radiation pattern of dipole scattering, while a doughnut-shaped swarm is prepared by circularly polarized trapping laser. The light field is expanded as scattered light through trapped nanoparticles; this modified light field further traps the nanoparticles, and scattering and trapping cooperatively develop. Due to these nonlinear dynamic processes, the dynamically fluctuating swarms are evolved up to tens of micrometers. This finding will open the way to create various swarms of nanoscale objects that interact and bind through the scattered light depending on the properties of the laser beam and the nanomaterials.
A Single Spherical Assembly of Protein Amyloid Fibrils Formed by Laser Trapping
(2017-06-06)
Yuyama, Ken-ichi
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Ueda, Mariko
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Nagao, Satoshi
;
Hirota, Shun
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Sugiyama, Teruki
Protein amyloids have received much attention owing to their correlation with serious diseases and to their promising mechanical and optical properties as future materials. Amyloid formation has been conducted by tuning temperature and chemical conditions, so that its nucleation and the following growth are analyzed as ensemble dynamics. A single spherical assembly of amyloid fibrils of cytochrome c domain-swapped dimer was successfully generated upon laser trapping. The amyloid fibrillar structure was confirmed by fluorescence characterization and electron microscopy. The prepared spheres were further manipulated individually in solution to fabricate a three-dimensional microstructure and a line pattern. Amyloid formation dynamics and amyloid-based microstructure fabrication are demonstrated based on direct observation of a single spherical assembly, which foresees a new approach in amyloid studies.
Assembling and crystallization of amino acids and proteins by intense laser irradiation in solution
(2011-08-28)
Masuhara, Hiroshi
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Sugiyama, Teruki
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Yuyama, Ken-ichi
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Uwada, Takayuki
;
Miura, Atsushi
Bubble generation and molecular crystallization at solution surface by intense continuous-wave laser irradiation
(2018-08-01)
Chen, Jim Jui-Kai
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Yuyama, Ken-ichi
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Sugiyama, Teruki
;
Masuhara, Hiroshi
;
應用化學系
We demonstrate bubble generation outside the focus induced by irradiating a focused 1064 nm continuous-wave laser beam into the surface of water and L-phenylalanine H2O solutions. In the former case of water, bubbles stay at positions distant from the focus during the irradiation, and their size and location are controllable by the laser power. In the latter solution, bubbles move outward toward the surrounding area, and subsequently crystallization takes place at the focus. We discuss these behaviors from the viewpoints of the temperature elevation accompanying the decrease in air solubility as well as the optical trapping of L-phenylalanine clusters giving a single crystal. (C) 2018 The Japan Society of Applied Physics
Comparative Investigation of Ultrafast Photoinduced Processes in Salicylidene-Aminopyridine in Solution and Solid State
(2009-07-09)
Sliwa, Michel
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Mouton, Nicolas
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Ruckebusch, Cyril
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Aloise, Stephane
;
Poizat, Olivier
Photodynamics and excited-state intramolecular proton transfer (ESIPT) of N-(3,5-ditert-butylsalicylidene)-4-aminopyridine (4P) and N-(3,5-ditert-butylsalicylidene)-2-aminopyridine (2P) are studied by steady-state and transient optical spectroscopy in solution and solid state (microcrystalline powder). These two compounds are representative of anils Classes A and B, respectively. The results confirm that in solution both compounds have a similar dynamic behavior: upon excitation at 390 nm, ESIPT leads to different cis-keto* fluorescent species which relax to the photochromic trans-keto photoproduct within a few tens of picoseconds. Furthermore, for the first time, picosecond data are recorded for the two classes of anils in the solid state: in 2P, two cis-keto* fluorescent excited state species (23 and 250 ps lifetime) are relaxing exclusively to the cis-keto ground state, whereas in 4P, a single cis-keto* fluorescent species is observed which leads to the trans-keto photoproduct in 250 ps via an intermediate metastable species.
Confinement of Photopolymerization and Solidification with Radiation Pressure
(2011-09-21)
Ito, Syoji
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Tanaka, Yoshito
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Yoshikawa, Hiroyuki
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Ishibashi, Yukihide
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Miyasaka, Hiroshi
Controlling chemical reactions within a small space is a significant issue in chemistry, and methods to induce reactions within a desired position have various potential applications. Here we demonstrate localized, efficient photopolymerization by radiation pressure. We induced a one-photon UV polymerization of liquid acrylate solutions in the optical-trapping potential of a focused near-IR (NIR) laser beam, leading to the confinement of solidification to a minute space with dimensions smaller or equal to one-fifth of the wavelength of the NIR laser. Our approach can produce solidification volumes smaller than those achievable with conventional one-photon polymerization, thus enabling the production of tiny polymeric structures that are smaller than the diffraction limit of the trapping light. This is the first demonstration of a radiation pressure effect on a photochemical reaction.
Conformational relaxation dynamics of a poly(N-isopropylacrylamide) aqueous solution measured using the laser temperature jump transient grating method
(2012)
Inoue, Hayato
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Katayama, Kenji
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Iwai, Kaoru
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Miura, Atsushi
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Masuhara, Hiroshi
We observed phase transition and phase relaxation processes of a poly(N-isopropylacrylamide) (PNIPAM) aqueous solution using the heterodyne transient grating (HD-TG) method combined with the laser temperature jump technique. The sample temperature was instantaneously raised by about 1.0 K after irradiation of a pump pulse to crystal violet (CV) molecules for heating, and the phase transition was induced for the sample with an initial temperature just below the lower critical solution temperature (LCST); the following phase relaxation dynamics was observed. Turbidity relaxation was observed in both the turbidity and HD-TG responses, while another relaxation process was observed only in the HD-TG response, namely via the refractive index change. It is suggested that this response is due to formation of globule molecules or their assemblies since they would have nothing to do with turbidity change but would affect the refractive index, which is dependent on the molar volume of a chemical species. Furthermore, the grating spacing dependence of the HD-TG responses suggests that the response was caused by the counter propagating diffusion of the coil molecules as a reactant species and the globule molecules as a product species and the lifetime of the globule molecules ranged from 1.5 to 5 seconds. Thus, we conclude that the turbidity reflects the dynamics of aggregate conditions, not molecular conditions. The coil and globule sizes were estimated from the obtained diffusion coefficient. The sizes of the coil molecules did not change at the initial temperatures below the LCST but increased sharply as it approaches LCST. We propose that the coil-state molecules associate due to hydrophobic interaction when the initial temperature was higher than LCST minus 0.5 K and that the globule-state molecules generated from the coil-state molecules showed a similar trend in temperature. The phase transition was also induced by heating under a microscope, and the relaxation process was followed using the fluorescence peak shift of a fluorescent molecule-labeled PNIPAM. The result also supports the existence of a globule molecule or its assembly remains for several seconds in the phase relaxation.
Control of Crystal Polymorph of Glycine by Photon Pressure of a Focused Continuous Wave Near-Infrared Laser Beam
(2010-02-04)
Rungsimanon, Thitiporn
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Yuyama, Ken-ichi
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Sugiyama, Teruki
;
Masuhara, Hiroshi
;
Tohnai, Norimitsu
Crystal polymorph of glycine is controlled by tuning the power of a linearly polarized continuous wave 1064-nm laser beam. Upon focusing the beam to the air/solution interface of a supersaturated glycine/D(2)O solution, it single crystal is spatiotemporally formed at a focal spot within a few seconds to a few ten of seconds. Fourier transform infrared measurement and single-crystal X-ray crystallographic analysis of the fabricated single crystal reveal that two polymorphs of alpha- and gamma-forms are prepared depending on the laser power. The probability of gamma-form are prepared depending on the laser power. The probability of gamma-form preparation, which is not available under ambient conditions arises upto 50% at 1.3 W laser power after an objective lens. The mechanism of the polymorph control is discussed in view of both photon pressure and local temperature elevation due to laser irradiation at the focal spot.
Crystal Growth and Dissolution Dynamics of L-Phenylalanine Controlled by Solution Surface Laser Trapping
(2018-11-01)
Yuyama, Ken-ichi
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Chiu, Ding-Shiang
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Liu, Yen-En
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Sugiyama, Teruki
;
Masuhara, Hiroshi
We present sequential behavior of nucleation, growth, and dissolution of an L-phenylalanine plate-like crystal which is induced by a focused continuous-wave near-infrared laser beam in unsaturated solution. Upon the laser irradiation into the air/solution interface, the single crystal is generated from the focus and continuously grows two-dimensionally while being trapped by the laser. The crystal growth is stopped when the laser power is decreased. The crystal size is kept constant for a certain time period, and then the crystal starts dissolution. The dissolution is also induced by moving the crystal from the focus at the air/solution interface. When the crystal is shifted far from the original position where the crystallization is induced, the crystal starts dissolution at a certain distant position. Based on the demonstrations of the crystal size change during the laser manipulation, we conclude that the L-phenylalanine crystal is surrounded by a highly concentrated domain of a few hundreds of micrometers consisting of L-phenylalanine liquid-like clusters.
Crystal Growth of Glycine Controlled by a Focused CW Near-infrared Laser Beam
(2009-05-05)
Sugiyama, Teruki
;
Adachi, Takuji
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Masuhara, Hiroshi
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應用化學系
;
應用化學系分子科學碩博班
Crystal growth of glycine was accelerated just by focusing a CW 1064-nm laser beam at a position adjacent to a spontaneously generated glycine crystal in D(2)O. Its rate depended on the distance between the crystal and the focal spot. Interesting crystal growth and dissolution were found, which is considered to be due to Ostwald ripening,
Crystal Growth of Lysozyme Controlled by Laser Trapping
(2014-01-01)
Tu, Jing-Ru
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Miura, Atsushi
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Yuyama, Ken-ichi
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Masuhara, Hiroshi
;
Sugiyama, Teruki
We demonstrate the growth of a tetragonal crystal of hen egg-white lysozyme (HEWL) in D2O buffer solution controlled by laser trapping with a focused continuous-wave (CW) near-infrared (NIR) laser beam. The focal spot was located at 10 mu m away from the edge of the target crystal that was generated spontaneously, and the crystal growth was observed although the focal spot size was much smaller than the distance. The growth rate of (101) and {110} faces of the tetragonal crystal was examined with various laser powers and polarizations. The rate observed under the irradiation was much different from those in spontaneous growth, namely, the growth rate of the {1 10} face showed a large decrease or increase depending on the irradiation time. The dynamics and mechanism of this unusual crystal growth behavior is discussed from the viewpoint of a large stable domain formation of the HEWL liquidlike clusters through liquid nucleation and growth and by considering the anisotropy of the cluster domain.
Crystallization in Unsaturated Glycine/D(2)O Solution Achieved by Irradiating a Focused Continuous Wave Near Infrared Laser
(2010-11-01)
Rungsimanon, Thitiporn
;
Yuyama, Ken-ichi
;
Sugiyama, Teruki
;
Masuhara, Hiroshi
;
應用化學系
The crystallization of glycine in unsaturated solution is made possible by laser trapping of its molecular clusters due to photon pressure of a focused continuous wave near-infrared laser beam. Always one single crystal is spatiotemporally formed at a focal spot, and then it undergoes dissolution, eventually leading to repetitive crystallization and dissolution. The polymorph characterization of the crystal formed in unsaturated solution confirmed the gamma-form, which is not obtainable by conventional crystallization methods. The preparation probability of the gamma-form compared to the alpha-form is much higher than that in the supersaturated solution.
Crystallization in Unsaturated Glycine/D2O Solution Achieved by Irradiating a Focused Continuous Wave Near Infrared Laser
(2010-11-01)
Rungsimanon, Thitiporn
;
Yuyama, Ken-ichi
;
Sugiyama, Teruki
;
Masuhara, Hiroshi
;
應用化學系
The crystallization of glycine in unsaturated solution is made possible by laser trapping of its molecular clusters due to photon pressure of a focused continuous wave near-infrared laser beam. Always one single crystal is spatiotemporally formed at a focal spot, and then it undergoes dissolution, eventually leading to repetitive crystallization and dissolution. The polymorph characterization of the crystal formed in unsaturated solution confirmed the gamma-form, which is not obtainable by conventional crystallization methods. The preparation probability of the gamma-form compared to the alpha-form is much higher than that in the supersaturated solution.
Dynamic Coupling of Optically Evolved Assembling and Swarming of Gold Nanoparticles with Photothermal Local Phase Separation of Polymer Solution
(2020-07-30)
Aibara, Issei
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Huang, Chih-Hao
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Kudo, Tetsuhiro
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Bresoli-Obach, Roger
;
Hofkens, Johan
Optical trapping of gold nanoparticles (Au NPs) at a glass/solution interface initially generates a periodically aligned structure of a few NPs along the direction perpendicular to a linearly polarized laser. When the number of NPs was increased, this alignment was expanded to the outside of the irradiated focus, forming a single large assembly where the Au NPs dynamically fluctuated like a swarming of bees. The morphology was dumbbell-shape, consisting of two swarms at both sides of the focus, and its size reached about 10 mu m. This optically evolved assembling and swarming was studied in poly(N-isopropylacrylamide) (PNIPAM) solution, where liquid-liquid phase separation (LLPS) was induced by photothermal heating of the trapped Au NPs forming a microdroplet of highly concentrated PNIPAM. Dynamic coupling of the NPs assembling and swarming with the droplet formation of PNIPAM leads to cooperative optical evolution, through which the assembly was embedded in the single microdroplet.
Dynamics and Mechanism of Laser Trapping-Induced Crystal Growth of Hen Egg White Lysozyme
(2015-10-01)
Tu, Jing-Ru
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Yuyama, Ken-ichi
;
Masuhara, Hiroshi
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Sugiyama, Teruki
;
應用化學系
We propose the dynamics and mechanism of laser trapping-induced crystal growth of hen egg-white lysozyme (HEWL). A continuous-wave near-infrared laser beam is used as a trapping light source and focused at a point 10 mu m away from a target tetragonal HEWL crystal that is spontaneously generated in solution. Laser trapping of HEWL liquid-like clusters in solution increases local concentration in the focus, where the free motion and orientation of the clusters are strongly restricted, and the clusters show high rigidity and ordering. The cluster association and reorientation at the micrometer-sized focus is evolved to a large highly concentrated domain of the clusters, where the specific target crystal is grown. Initially, the high rigidity and ordering of the clusters strongly suppress the crystal grow rate compared to spontaneous crystal growth. Continuous laser trapping at the of the initially formed domain, however, leads to the transition to another domain with different concentration, rigidity, and ordering of the clusters, which surprisingly enhances the crystal growth rate. More interestingly, the clusters in both domains have anisotropic features reflecting the laser polarization direction, which also contributes to the crystal growth.
Efficient Optical Trapping of CdTe Quantum Dots by Femtosecond Laser Pulses
(2014-12-11)
Chiang, Wei-Yi
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Okuhata, Tomoki
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Usman, Anwar
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Tamai, Naoto
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Masuhara, Hiroshi
The development in optical trapping and manipulation has been showing rapid progress, most of it is in the small particle sizes in nanometer scales, substituting the conventional continuous-wave lasers with high-repetition-rate ultrashort laser pulse train and nonlinear optical effects. Here, we evaluate two-photon absorption in optical trapping of 2.7 nm-sized CdTe quantum dots (QDs) with high-repetition-rate femtosecond pulse train by probing laser intensity dependence of both Rayleigh scattering image and the two-photon-induced luminescence spectrum of the optically trapped QDs. The Rayleigh scattering imaging indicates that the two-photon absorption (TPA) process enhances trapping ability of the QDs. Similarly, a nonlinear increase of the two-photon-induced luminescence with the incident laser intensity fairly indicates the existence of the TPA process.
Enhanced optical confinement of dielectric nanoparticles by two-photon resonance transition
(2017-01-01)
Kittiravechote, Aungtinee
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Usman, Anwar
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Masuhara, Hiroshi
;
Liau, Ian
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應用化學系
Despite a tremendous success in the optical manipulation of microscopic particles, it remains a challenge to manipulate nanoparticles especially as the polarizability of the particles is small. With a picosecond-pulsed near-infrared laser, we demonstrated recently that the confinement of dye-doped polystyrene nanobeads is significantly enhanced relative to bare nanobeads of the same dimension. We attributed the enhancement to an additional term of the refractive index, which results from two-photon resonance between the dopant and the optical field. The optical confinement is profoundly enhanced as the half-wavelength of the laser falls either on the red side, or slightly away from the blue side, of the absorption band of the dopant. In contrast, the ability to confine the nanobeads is significantly diminished as the half-wavelength of the laser locates either at the peak, or on the blue side, of the absorption band. We suggest that the dispersively shaped polarizability of the dopant near the resonance is responsible to the distinctive spectral dependence of the optical confinement of nanobeads. This work advances our understanding of the underlying mechanism of the enhanced optical confinement of doped nanoparticles with a nearinfrared pulsed laser, and might facilitate future research that benefits from effective sorting of selected nanoparticles beyond the limitations of previous approaches.
Evolving Crystal Morphology of Potassium Chloride Controlled by Optical Trapping
(2020-03-26)
Cheng, An-Chieh
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Masuhara, Hiroshi
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Sugiyama, Teruki
;
交大名義發表
;
應用化學系
Dynamic morphology evolution of potassium chloride (KCl) crystals was demonstrated by surface optical trapping with a focused continuous-wave near-infrared laser. Optical trapping at an air/solution interface triggered the crystallization, and then, the dynamic change in crystal morphology was observed in real time. We observed three different crystal morphologies of needle, rectangle, and cubic at the early stage of crystallization. As the laser power increases, the probability of generation of a cubic crystal increases, especially upon the irradiation with linear polarization. We also found laser polarization-dependent morphology evolution by the continuous irradiation to the generated crystals. Upon linearly polarized laser irradiation, the stepwise morphology evolves from needle to rectangle, and eventually to cubic, which is an equilibrium shape of KCl crystals. Meanwhile, circularly polarized laser irradiation only induced morphology evolution from needle to rectangle, without morphology change into cubic, because the rectangle crystal was dissolved while the crystal was rotating. It was made possible to observe such a unique morphological evolution due to the spatiotemporal controllability of our crystallization method. The dynamics and mechanism of these intriguing phenomena are discussed from the perspective of a dense cluster domain formed by optical trapping before nucleation.
Exploratory Research on Time- and Space-Resolved Spectroscopy and Chemistry
(2015-12-01)
Masuhara, Hiroshi
;
應用化學系
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應用化學系分子科學碩博班
;
Department of Applied Chemistry
;
Institute of Molecular science
Exploratory Research on Time- and Space-Resolved Spectroscopy and Chemistry
(2015-12)
Masuhara, Hiroshi
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
;
Institute of Molecular science