Language：English   Publishing type：Research paper (scientific journal)  

We discuss our recently reported femtosecond (fs) X-ray emission spectroscopy results on the ligand dissociation and recombination in nitrosylmyoglobin (MbNO) in the context of previous studies on ferrous haem proteins. We also present a preliminary account of femtosecond X-ray absorption studies on MbNO, pointing to the presence of more than one species formed upon photolysis.

DOI： 10.1039/d0fd00131g

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Optical Society  

DOI： 10.1364/ol.409672

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

In haemoglobin (consisting of four globular myoglobin-like subunits), the
change from the low-spin (LS) hexacoordinated haem to the high spin (HS)
pentacoordinated domed form upon ligand detachment and the reverse process upon
ligand binding, represent the transition states that ultimately drive the
respiratory function. Visible-ultraviolet light has long been used to mimic the
ligand release from the haem by photodissociation, while its recombination was
monitored using time-resolved infrared to ultraviolet spectroscopic tools.
However, these are neither element- nor spin-sensitive. Here we investigate the
transition state in the case of Myoglobin-NO (MbNO) using femtosecond Fe Kalpha
and Kbeta non-resonant X-ray emission spectroscopy (XES) at an X-ray
free-electron laser upon photolysis of the Fe-NO bond. We find that the
photoinduced change from the LS (S = 1/2) MbNO to the HS (S = 2)
deoxy-myoglobin (deoxyMb) haem occurs in ca. 800 fs, and that it proceeds via
an intermediate (S = 1) spin state. The XES observables also show that upon NO
recombination to deoxyMb, the return to the planar MbNO ground state is an
electronic relaxation from HS to LS taking place in ca. 30 ps. Thus, the entire
ligand dissociation-recombination cycle in MbNO is a spin cross-over followed
by a reverse spin cross-over process.

DOI： 10.1038/s41467-020-17923-w

arXiv

Other Link： http://arxiv.org/pdf/2005.05598v1

Language：English   Publisher：Optical Society of America  

In this study, we demonstrate the switching of the direction of the photocurrent in an n-type GaAs/Al0.3Ga0.7As modulation-doped quantum well using a polarization pulse-shaping apparatus containing a 4f setup. The right- and left-polarization-twisting pulses with a polarization rotation frequency in the THz-regime are incident on a modulation-doped quantum well. The results show that the sign of the photovoltage is dependent on the direction of rotation of the polarization-twisting pulses, which can be explained by the circular photogalvanic effect combined with the production of a classical edge photocurrent from the acceleration of free electrons in the vicinity of the sample edge by the incident optical electric field. The wide range over which the polarization-rotation frequency may be tuned makes this method a powerful tool to investigate the response of an extensive variety of materials in the THz-regime.

DOI： 10.1364/OE.27.028091

Web of Science

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.73.1.0_1276

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.73.1.0_3195

Language：Japanese   Publisher：一般社団法人 日本物理学会  

<p>1．はじめに</p><p>物理学における教育実践でアクティブラーニングの効用が盛んに言われている¹⁾．中等教育においては「主体的・対話的で深い学び」として指導要領に示されているが，大学，特に学生実験にお</p>

DOI： 10.11316/peu.24.2_59

CiNii Books

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

DOI： 10.1063/1.4989862

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.72.1.0_1340

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.72.1.0_1492

Language：Japanese  

CiNii Books

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We studied the superconducting proximity effect under photoexcitation by illuminating a superconductor/monolayer graphene/superconductor (SGS) Josephson junction with monochromatic light at a wavelength of 1.31 mu m. Although the critical current I-c can be controlled by the irradiation power P, its variation cannot be explained by modification of the carrier density, which has been reported for semiconductor- based Josephson junctions. The estimated electron temperature of graphene is proportional to P-delta, where delta similar or equal to 1/3. This relation clearly indicates that photogenerated non-equilibrium carrier dynamics are responsible for the variation of Ic with P. We suggest that the SGS junction can directly mediate interactions between the optical field and the superconducting state. (C) 2016 AIP Publishing LLC.

DOI： 10.1063/1.4940377

Web of Science

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_3183

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_1434

Language：English   Publisher：Springer-Verlag  

DOI： 10.1007/s00339-015-9420-9

Web of Science

CiNii Books

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We have successfully developed a circularly polarized near-field scanning optical microscope (NSOM) that enables us to irradiate circularly polarized light with spatial resolution below the diffraction limit. As a demonstration, we perform real-space mapping of the quantum Hall chiral edge states near the edge of a Hall-bar structure by injecting spin polarized electrons optically at low temperature. The obtained real-space mappings show that spin-polarized electrons are injected optically to the two-dimensional electron layer. Our general method to locally inject spins using a circularly polarized NSOM should be broadly applicable to characterize a variety of nanomaterials and nanostructures.

DOI： 10.1021/nl504767w

Web of Science

PubMed

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.69.1.4.0_703_4

CiNii Books

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.68.2.4.0_611_4

CiNii Books

Language：English   Publishing type：Research paper (international conference proceedings)  

A high resolution mapping of quantum Hall edge states has been performed by locally creating electrons with small excess energies with a near-field scanning optical microscope in a dilution refrigerator. We have observed fine structures parallel to the edge in photovoltage signals, which appear only at low temperature. The observed fine structures near sample edges have been seen to shift inward with increase in magnetic field in accordance with Chklovskii Shklovskii, and Glazman model. © 2013 AIP Publishing LLC.

DOI： 10.1063/1.4848390

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

We report on the mapping of quantum-Hall edge states by quasiresonant photovoltage measurements using a near-field scanning optical microscope. We have observed fine structures near sample edges that shift inward with an increase in magnetic field in accordance with the shift of the positions of the quantum-Hall edge states. We have found a transition from the weak disorder regime where compressible-incompressble strips are visible to the strong disorder regime where fluctuations smear out incompressible strips. © 2011 American Physical Society.

DOI： 10.1103/PhysRevLett.107.256803

Scopus

Language：English   Publishing type：Research paper (international conference proceedings)  

Compressible and incompressible strips formed near the boundary of a two-dimensional electron system were mapped out by near-field scanning optical microscope at 230 mK. Dilution-refrigerator based near-field scanning optical microscope enables us to investigate spatial properties of the electrons in semiconductor nanostructures with a subwavelength spatial resolution. We obtain real-space mapping of photovoltage in the vicinity of the edge of Hall-bar, which reflects the local chemical potential determined by the distribution of the compressible and incompressible strips. © 2011 American Institute of Physics.

DOI： 10.1063/1.3666522

Scopus

Language：English   Publishing type：Research paper (international conference proceedings)  

A real-space mapping of photovoltage near the edge of the Hall-bar of a GaAs/AlGaAs single heterojunction has been obtained using a dilution- refrigerator-based near-field scanning optical microscope in magnetic fields. The optical probe-sample surface distance dependence of photovoltage is investigated. We obtain photovoltage profile in the vicinity of the edge, which reflects the local chemical potential of the two-dimensional electron gas determined by the distribution of the compressible and incompressible strips. © 2010 World Scientific Publishing Company.

DOI： 10.1142/S0218863510005467

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

We constructed a dilution-refrigerator-based near-field scanning optical microscope (NSOM) which operates at temperatures down to 200 mK. Our NSOM enables us to investigate spatial properties of the electrons in semiconductor nanostructures with a subwavelength spatial resolution. We report on a result of the optical mapping of the boundary of a two-dimensional electron gas in a gated Hall-bar structure of a GaAs/AlGaAs modulation-doped single heterojuntion. © 2010.

DOI： 10.1016/j.phpro.2010.01.158

Scopus

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.65.1.4.0_703_1

CiNii Books

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.65.2.4.0_648_3

CiNii Books

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.64.1.4.0_687_2

CiNii Books

Language：English   Publisher：The Japan Society of Applied Physics  

We have developed a new method of fabricating nanoparticles utilizing a mechanical rubbing process. Highly ordered arraysof Au nanoparticles with a diameter of 60 nm have been fabricated on a porous anodic alumina template. Pressuremeasurements during the mechanical rubbing process confirmed that these nanoparticles were formed only by a mechanicalseparation process. Our method can be applied to fabricate nanocapsules and has a wide range of applicability to materials thathave never been controlled in the nanoscale.

DOI： 10.1143/jjap.45.8997

Web of Science

Scopus

CiNii Books

Other Link： http://hdl.handle.net/2241/99859

Event date： 2023.9

Language：English   Presentation type：Oral presentation(invited, special)  

Venue：National Yang Ming Chiao Tung Univ. Daxue Rd,1001 Science Building B-1 Large Hall, Taiwan Hsinch City, East District   Country：Taiwan, Province of China  

Event date： 2023.9

Language：English   Presentation type：Oral presentation(invited, special)  

Venue：National Yang Ming Chiao Tung Univ. Daxue Rd,1001 Science Building B-1 Large Hall, Taiwan Hsinch City, East District   Country：Taiwan, Province of China  

Event date： 2022.7

Language：English   Presentation type：Poster presentation  

Venue：Sapporo, Japan  

1. A method of adding a phase key to multiple spatial orthogonal code signal, synthesizing them into one page of optical data, and recording this in holographic memory.
2. A method in which interference fringes are formed on the camera by extracting and reproducing two specific signals during readout, and the complex amplitude signal is detected by analyzing this fringe.
　We proposed the above two methods and evaluated their reproduction accuracy.