研究者詳細 - 宮崎　淳

論文 - 宮崎　淳

分割表示45 件中 21 - 40 件目／全件表示 >>

Sensitivity enhancement of photothermal microscopy with radially segmented balanced detection

Jun Miyazaki, Hiromichi Tsurui, Koshi Kawasumi, Takayoshi Kobayashi (担当区分：筆頭著者 )

OPTICS LETTERS ( OPTICAL SOC AMER ) 40 ( 4 ) 479 - 482 2015年02月 [査読有り]

A novel detection method is proposed for highly sensitive photothermal microscopic imaging. This method is based on the characteristics of an angular-dependent photothermal signal; it improves signal intensity by up to two times and rejects the intensity noise of the probe beam. The subdiffraction resolution photothermal imaging of mouse skin melanoma is demonstrated using a laser diode-based photothermal microscopy system to evaluate this method. We confirm that the signal intensity is enhanced 1.7 times compared with the conventional detection method. Moreover, the intensity noise of the laser diode used for the probe beam is effectively reduced by approximately 31 dB, even for a sample with non-uniformity of the refractive index and stationary absorption. This method is implemented by means of a commonly used balanced detector and is thus potentially useful for high-speed imaging. (C) 2015 Optical Society of America

Simultaneous dual-wavelength imaging of nonfluorescent tissues with 3D subdiffraction photothermal microscopy

Jun Miyazaki, Hiromichi Tsurui, Koshi Kawasumi, Takayoshi Kobayashi (担当区分：筆頭著者 )

OPTICS EXPRESS ( OPTICAL SOC AMER ) 23 ( 3 ) 3647 - 3656 2015年02月 [査読有り]

Multi-wavelength microscopic imaging is essential to visualize a variety of nanoscale cellular components with high specificity and high spatial resolution. However, previous techniques are based on fluorescence, and thus cannot visualize nonfluorescent species, which are much less suffered from photodamage or photobleaching and hence are intrinsically useful in wider range of optical microscopy. Here, we show that simultaneous multi-wavelength imaging of nonfluorescent species can be achieved with the use of a photothermal microscope. Dual-wavelength subdiffraction imaging of biological tissues stained with hematoxylin and eosin is demonstrated. Three-dimensional label-free imaging of mouse melanoma tissue section is also presented to demonstrate the effectiveness of the enhanced spatial resolution. Our technique can be implemented using cost-effective and compact laser diodes and is applicable for various types of both fluorescent and nonfluorescent tissues. (C) 2015 Optical Society of America

Sub-diffraction-limit imaging using mode multiplexing

Nan Wang, Jinping He, Jun Miyazaki, Hiromichi Tsurui, Takayoshi Kobayashi

Proceedings of SPIE - The International Society for Optical Engineering ( SPIE ) 9636 2015年 [査読有り]

Simultaneous two-color subtraction microscopy using mode multiplexing is realized experimentally. The samples are irradiated with single laser diode at wavelength of 445 nm. Then the beam split laser spots generate separate solid and donut spatial modes and are multiplexed with modulators for simultaneous excitation. The produced fluorescence signals are back collected and further divided into two color bands with dichroic mirrors. Then they are detected with two photomultipliers and demultiplexed in four lock-in amplifiers. Four fluorescence images are recorded in every scan and resolution enhanced images are obtained in two color channels after applying the subtraction strategy. With this method, imaging results of microspheres stained with organic dyes and mesenteric lymph nodes of a mouse labeled with quantum dots (Q525/650) are realized. Improvement of 20% ∼ 30% in resolving power of the two color channels compared with confocal microscopy is achieved in with corresponding subtraction factor of about 0.3.

Frequency domain approach for time-resolved pump-probe microscopy using intensity modulated laser diodes

J. Miyazaki, K. Kawasumi, T. Kobayashi (担当区分：筆頭著者 )

REVIEW OF SCIENTIFIC INSTRUMENTS ( AMER INST PHYSICS ) 85 ( 9 ) 093703 2014年09月 [査読有り]

We present a scheme for time-resolved pump-probe microscopy using intensity modulated laser diodes. The modulation frequencies of the pump and probe beams are varied up to 500 MHz with fixed frequency detuning typically set at 15 kHz. The frequency response of the pump-probe signal is detected using a lock-in amplifier referenced at the beat frequency. This frequency domain method is capable of characterizing the nanosecond to picosecond relaxation dynamics of sample species without the use of a high speed detector or a high frequency lock-in amplifier. Furthermore, as the pump-probe signal is based on the nonlinear interaction between the two laser beams and the sample, our scheme provides better spatial resolution than the conventional diffraction-limited optical microscopes. Time-resolved pump-probe imaging of fluorescence beads and aggregates of quantum dots demonstrates that this method is useful for the microscopic analysis of optoelectronic devices. The system is implemented using compact and low-cost laser diodes, and thus has a broad range of applications in the fields of photochemistry, optical physics, and biological imaging. (C) 2014 AIP Publishing LLC.

Sub-10 fs spectroscopy of K-TCNQ crystal for observation of intramolecular vibration modulation in melting of the Peierls dimer

Kazuaki Nakata, Eiji Tokunaga, Juan Du, Bing Xue, Jun Miyazaki, Keisuke Seto, Takayoshi Kobayashi

PHYSICAL REVIEW B ( AMER PHYSICAL SOC ) 90 ( 8 ) 2014年08月 [査読有り]

K-TCNQ crystals show photoinduced phase transition (PIPT) between a Mott insulator and a spin Peierls (SP) phase, having T-c = 395 K (= and the crystal has T-c = 395 K of the PIPT). We report the intra-molecular vibrations in the excited K-TCNQ crystal after impulsive excitation using a sub 9.4 fs pulse laser in the reflection spectrum. The frequencies of the vibrations are close to the Raman frequencies of molecules. The frequencies increase with melting of the SP phase, and then decrease with rearrangement of the dimerization. In addition, the frequencies of the vibrations are time-resolved to be modulated by the intermolecular optical phonon with 510 fs period corresponding to 65 cm(-1). This modulation is associated with the periodical change of coupling strengths of intermolecular charge transfer and/or the dipolar coupling between the counterpart molecules in the neighboring chains.

Optimal detection angle in sub-diffraction resolution photothermal microscopy: application for high sensitivity imaging of biological tissues

J. Miyazaki, H. Tsurui, K. Kawasumi, T. Kobayashi (担当区分：筆頭著者 )

OPTICS EXPRESS ( OPTICAL SOC AMER ) 22 ( 16 ) 18833 - 18842 2014年08月 [査読有り]

We evaluated the optimal detection angle for maximizing the signal to noise ratio (SNR) in sub-diffraction resolution photothermal microscopy. The angular dependent photothermal signal was calculated based on scattering theory using the temporally modulated Yukawa potential, and its detection angle and modulation frequency dependencies were analyzed. We verified the theoretical findings by imaging gold nanoparticles using laser diode based photothermal microscopy with balanced detection scheme. High-sensitivity (SNR similar to 40) photothermal biological imaging of a mouse brain was also demonstrated.

Resolution improvement in laser diode-based pump-probe microscopy with an annular pupil filter

Jun Miyazaki, Koshi Kawasumi, Takayoshi Kobayashi (担当区分：筆頭著者 )

OPTICS LETTERS ( OPTICAL SOC AMER ) 39 ( 14 ) 4219 - 4222 2014年07月 [査読有り]

We experimentally demonstrate the use of annular beams to improve lateral resolution in laser-diode-based pump-probe microscopy. We found that the width of the point-spreading function in the case of the annular pump-probe beams is 162 nm, which is 30% smaller than that of the circular beams (232 nm). Furthermore, side lobes were efficiently suppressed at the focal plane since the pump-probe signal is proportional to the product of the two beam intensities. This scheme is demonstrated for the photothermal signal of nonfluorescent gold nanoparticles and the stimulated emission signal of fluorescence beads. (C) 2014 Optical Society of America

Sub-diffraction resolution pump-probe microscopy with shot-noise limited sensitivity using laser diodes

Jun Miyazaki, Hiromichi Tsurui, Akiko Hayashi-Takagi, Haruo Kasai, Takayoshi Kobayashi (担当区分：筆頭著者 )

OPTICS EXPRESS ( OPTICAL SOC AMER ) 22 ( 8 ) 9024 - 9032 2014年04月 [査読有り]

We demonstrate the use of intensity-modulated laser diodes to implement pump-probe microscopy and achieved sub-diffraction resolution imaging with shot-noise limited sensitivity with a scheme of balanced detection. This technique has several applications for various types of induced transmission change, including excited-state absorption, ground state absorption bleaching and stimulated emission. By using our technique, biological imaging of mouse T cells and the axons of neurons in the cerebral cortex was demonstrated. (C) 2014 Optical Society of America

Quantifying exciton hopping in disordered media with quenching sites: Application to arrays of quantum dots

Jun Miyazaki (担当区分：筆頭著者,　責任著者 )

PHYSICAL REVIEW B ( AMER PHYSICAL SOC ) 88 ( 15 ) 155302 2013年10月 [査読有り]

We present an analytical method for quantifying exciton hopping in an energetically disordered system with quenching sites. The method is subsequently used to provide a quantitative understanding of exciton hopping in a quantum dot (QD) array. Several statistical quantities that characterize the dynamics (survival probability, average number of distinct sites visited, average hopping distance, and average hopping rate in the initial stage) are obtained experimentally by measuring time-resolved fluorescence intensities at various temperatures. The time evolution of these quantities suggests in a quantitative way that at low temperature an exciton tends to be trapped at a local low-energy site, while at room temperature, exciton hopping occurs repeatedly, leading to a large hopping distance. This method will serve to facilitate highly efficient optoelectronic devices using QDs such as photovoltaic cells and light-emitting diodes, since exciton hopping is considered to strongly influence their operational parameters. The presence of a dark QD (quenching site) that exhibits fast decay is also quantified.

Electronic Excited State and Vibrational Dynamics of Water Solution of Cytosine Observed by Time-resolved Transient Absorption Spectroscopy with Sub-10fs Deep Ultraviolet Laser Pulses

Jun Miyazaki, Yuichiro Kida, Takayoshi Kobayashi (担当区分：筆頭著者 )

XVIIITH INTERNATIONAL CONFERENCE ON ULTRAFAST PHENOMENA ( E D P SCIENCES ) 41 05017 2013年 [査読有り]

Site-selective spectroscopic study on the dynamics of exciton hopping in an array of inhomogeneously broadened quantum dots

Jun Miyazaki, Shuichi Kinoshita (担当区分：筆頭著者,　責任著者 )

PHYSICAL REVIEW B ( AMER PHYSICAL SOC ) 86 ( 3 ) 035303 2012年07月 [査読有り]

We investigate the dynamics of exciton hopping in a CdSe/ZnS quantum dot (QD) array composed of an inhomogeneously broadened ensemble. Time- and spectrally resolved fluorescence intensities are measured by varying the excitation photon energy at the absorption edge. This method allows us to observe fluorescence from only the subdistribution of the QD ensemble, thereby allowing the dynamics of exciton hopping, which depends on the initial (donor) exciton energy, to be elucidated. Experimental results along with numerical calculations using a model of a coupled QD array show that when high-energy QDs are selectively excited, exciton energy transfer occurs repeatedly to a site of low energy, leading to a large exciton hopping length. In contrast, when the low-energy end of the QD ensemble is excited, the exciton tends to be trapped in the initial QD. Furthermore, from the analysis of the decay time of fluorescence intensities, it is suggested that there are dark QDs associated with the defect and/or off state of blinking QDs in the ensemble and energy transfer to such a site is mainly followed by quenching.

Temperature-Dependent Exciton Hopping in an Array of Inhomogeneously Broadened Quantum Dots

Jun Miyazaki, Shuichi Kinoshita (担当区分：筆頭著者,　責任著者 )

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN ( PHYSICAL SOC JAPAN ) 81 ( 7 ) 074708 2012年07月 [査読有り]

The dynamics of exciton hopping in an array of inhomogeneously broadened CdSe/ZnS quantum dot (QD) ensembles is examined by measuring time-and spectrally resolved fluorescence intensities. We have found a decrease in the fluorescence decay time as well as a dynamic redshift of the fluorescence spectrum originating from exciton transfer. Both show the characteristic temperature dependence reflecting the peculiar exciton dynamics in the QD ensemble. We propose a model of coupled QD arrays where inhomogeneous distribution and dark QDs that are related to a long-lasting off-state of blinking QDs are taken into account. Experimental results together with numerical calculations based on this model suggest that at low temperatures, an exciton transfers to a local low-energy site and tends to be trapped, whereas at high temperatures, thermally activated hopping of the exciton occurs repeatedly. Furthermore, we show that the decay time decrease of the QD array is attributable to exciton hopping to dark QDs.

Fundamental aspects of light scattering and optical Kerr effect spectroscopy

S. Kinoshita, Y. Sakai, J. Miyazaki, J. Watanabe

EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS ( SPRINGER HEIDELBERG ) 209 ( 1 ) 1 - 100 2012年06月 [査読有り]

We describe the principles of two spectroscopic methods of non-resonance light scattering (LS) and optical-Kerr-effect (OKE) spectroscopies in detail, and review basic but truly important phenomena observed by these two methods. Particularly, we focus on the following three experiments: 1) Response functions determined by frequency-domain LS and time-domain OKE spectroscopies, almost completely agree with each other, indicating that the quantum-mechanical fluctuation-dissipation theorem (QM-FDT) holds well in this system. 2) Femtosecond time responses of liquids clearly show an initial rise process even though they show an exponential response at a later time. This indicates that the Debye relaxation model does not hold in such an early time region. 3) From the measurement of the Stokes and anti-Stokes LS intensity ratios, it is found that the LS spectra of relaxation modes in liquids and solids are symmetric with respect to the spectral origin of the scattered light and hence the ratio does not satisfy the Boltzmann distribution rule expected from QM-FDT. These experimental results which contain apparently contradictory data are closely related with the nature of relaxation modes examined, which more or less assume a macroscopic character, and also with the physical basis of relaxation, which is inevitably connected to the observation problem of quantum mechanics. We discuss these points in relation to the physical reality of macroscopic quantity.

The weak iridescent feather color in the Jungle Crow Corvus macrorhynchos

Eunok Lee, Jun Miyazaki, Shinya Yoshioka, Hang Lee, Shoei Sugita

ORNITHOLOGICAL SCIENCE ( ORNITHOLOGICAL SOC JAPAN, UNIV TOKYO, SCH AGR ) 11 ( 1 ) 59 - 64 2012年06月 [査読有り]

We investigated the origin of the iridescent violet-bluish feathers of the adult Jungle Crow, Corvus macrorhynchos, using microscopic and optical techniques. A single layer of melanin granules was found below the surface of the barbules in the feathers of male crows. Although the barbule microstructure was clearly sexually dimorphic, neither the appearance nor the optical measurements were notably different between the sexes, which indicated that the single layer of melanin granules did not contribute to the iridescent color of the feathers. We also found a thin layer, which we refer to as the epicuticle, at the surfaces of the barbules of both male and female feathers, indicating thin-film interference as the most likely cause of the iridescent color. We investigated this possibility by measuring reflection patterns and spectra. Our results suggest that the weak violet-bluish feather color of the feathers of the Jungle Crow is caused by thin-film interface due to the presence of an epicuticle on the feather barbules.

Non-radiative exciton recombination through excitation energy transfer in quantum dot clusters

Jun Miyazaki, Shuichi Kinoshita, Takashi Jin (担当区分：筆頭著者,　責任著者 )

JOURNAL OF LUMINESCENCE ( ELSEVIER SCIENCE BV ) 131 ( 3 ) 539 - 542 2011年03月 [査読有り]

Excitation energy transfer (EET) processes in CdSe/CdZnS quantum dot (QD) clusters have been investigated in this study by measuring their time-resolved and spectrally resolved fluorescence intensities. The contributions of radiative and non-radiative exciton recombination through EET are evaluated, where the latter is expected to occur in a large class of QD ensembles because of the presence of nonluminescent QDs. It appears that the fluorescence decay in larger QDs serving as acceptor does not show an initial rise, in addition the lifetime of the acceptor QD is independent of the excitation wavelength, suggesting that an EET is followed mostly by non-radiative recombination. (C) 2010 Elsevier B.V. All rights reserved.

Analysis of excitation energy transfer in quantum dot clusters in the presence of nonluminescent dots

Jun Miyazaki, Shuichi Kinoshita, Takashi Jin (担当区分：筆頭著者,　責任著者 )

PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 8, NO 1 ( WILEY-V C H VERLAG GMBH ) 8 ( 1 ) 54 - 57 2011年 [査読有り]

We studied the excitation energy transfer (EET) process in CdSe/CdZnS quantum dot (QD) clusters by measuring time-and spectrally-resolved fluorescence intensities. Radiative and non-radiative exciton recombinations that occurs after EET were evaluated: the latter occurred in a large class of QD ensembles because of the presence of nonluminescent (dark) QDs. Numerical simulation confirmed the effect of the dark QDs on time-dependent fluorescence intensities, and the results were compared with that of the experiment. Nonradiative recombination occurring after EET was found to be dominant in the low quantum yield of QDs. The EET rate as a function of QD energy was successfully calculated on the basis of these findings. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Fluorescent Platinum Nanoclusters: Synthesis, Purification, Characterization, and Application to Bioimaging

Shin-Ichi Tanaka, Jun Miyazaki, Dhermendra K. Tiwari, Takashi Jin, Yasushi Inouye

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION ( WILEY-V C H VERLAG GMBH ) 50 ( 2 ) 431 - 435 2011年 [査読有り]

Stabilized Michelson Interferometer for Active Phase Locking of Nanosecond Pulse Pair

Jun Miyazaki, Shuichi Kinoshita (担当区分：筆頭著者,　責任著者 )

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN ( PHYSICAL SOC JAPAN ) 79 ( 8 ) 084301-1-5 2010年08月 [査読有り]

An actively stabilized Michelson interferometer with a long optical-path-length difference is developed to generate a phase-locked pulse pair on the order of nanoseconds. A rigid frame and a piezoelectric feedback loop enable us to stabilize an interferometer to the optical-path-length difference of up to 5.8 m within lambda/20 for 1 h. It is demonstrated that this interferometer is useful for generating a phase-tunable pulse pair up to an interval of 19 ns, which opens new possibilities for measuring the longtime coherence in the nanosecond region in the field of coherent control spectroscopy.

A quantum dot-based ratiometric pH sensor

Takashi Jin, Akira Sasaki, Masataka Kinjo, Jun Miyazaki

CHEMICAL COMMUNICATIONS ( ROYAL SOC CHEMISTRY ) 46 ( 14 ) 2408 - 2410 2010年 [査読有り]

Physics of structural colors

S. Kinoshita, S. Yoshioka, J. Miyazaki

REPORTS ON PROGRESS IN PHYSICS ( IOP PUBLISHING LTD ) 71 ( 7 ) 076401-1-30 2008年07月 [査読有り]

In recent years, structural colors have attracted great attention in a wide variety of research fields. This is because they are originated from complex interaction between light and sophisticated nanostructures generated in the natural world. In addition, their inherent regular structures are one of the most conspicuous examples of non-equilibrium order formation. Structural colors are deeply connected with recent rapidly growing fields of photonics and have been extensively studied to clarify their peculiar optical phenomena. Their mechanisms are, in principle, of a purely physical origin, which differs considerably from the ordinary coloration mechanisms such as in pigments, dyes and metals, where the colors are produced by virtue of the energy consumption of light. It is generally recognized that structural colors are mainly based on several elementary optical processes including thin-layer interference, diffraction grating, light scattering, photonic crystals and so on. However, in nature, these processes are somehow mixed together to produce complex optical phenomena. In many cases, they are combined with the irregularity of the structure to produce the diffusive nature of the reflected light, while in some cases they are accompanied by large-scale structures to generate the macroscopic effect on the coloration. Further, it is well known that structural colors cooperate with pigmentary colors to enhance or to reduce the brilliancy and to produce special effects. Thus, structure-based optical phenomena in nature appear to be quite multi-functional, the variety of which is far beyond our understanding. In this article, we overview these phenomena appearing particularly in the diversity of the animal world, to shed light on this rapidly developing research field.

　前のページ - 次のページ　

1
2
3