PhD, The Graduate University for Advanced Studies, Mar. 2009

近接場光化学

光学応答理論

励起状態

近接場光学

分子物理学

クラスター化学

錯体化学

触媒化学

Nanotechnology/Materials, Fundamental physical chemistry

Bachelor's degree program, School of Science

Master's degree program, Graduate School of Chemical Sciences and Engineering

Doctoral (PhD) degree program, Graduate School of Chemical Sciences and Engineering

Mar. 2026, プラズモニック化学研究会, 第6回プラズモニック化学研究会若手奨励賞
双極子近似を超えた光-分子相互作用の第一原理計算手法の開発とプラズモニック化学への応用

Jun. 2023, APNFO14, Best Poster Award in The 14th Asia-Pacific Conference on Near-Field Optics
Near-field Raman spectroscopy with multipolar Hamiltonian and real-time-TDDFT
Takeshi Iwasa

Oct. 2021, 第7回北海道大学部局横断シンポジウム, ベストポスター賞
「双極子近似を超えた光学応答理論開発と光STM-TERSへの応用」
岩佐豪, Japan society, Japan, 34006646;30404721;30404720;30404717

May 2015, 第18回理論化学討論会, 優秀講演賞
「非一様電場と分子振動の相互作用と近接場赤外吸収分光への応用」
岩佐豪, Japan society, Japan

Local structures and catalytic N2O decomposition properties of Ni1−xCuxCo2O4
Satoshi Hinokuma; Nino Uchiyama; Tetsuya Taketsugu; Takeshi Iwasa
Scientific Reports, 16, 1, Springer Science and Business Media LLC, 21 Apr. 2026, [Peer-reviewed], [Last author]
Scientific journal

Thiophenol-based Designer Enzymes for Asymmetric Hydrogen/Deuterium Atom Transfer
Kano, Ryusei; Oohora, Koji; Iwasa, Takeshi; Poggetti, Valeria; Roelfes, Gerard; Hayashi, Takashi
Journal of the American Chemical Society, 2026, [Peer-reviewed]

Interplay between Spectroscopic Measurement Techniques and Computational Chemistry for Catalytic Ammonia Combustion
Satoshi HINOKUMA; Takeshi IWASA
Journal of the Japan Petroleum Institute, 68, 6, 235, 243, Japan Petroleum Institute, 01 Nov. 2025, [Peer-reviewed], [Invited], [Last author, Corresponding author]
English, Scientific journal, 30404716;46315024;46315025

Theoretical Study of Near-Field-Induced Local Excitation Dynamics
Daisuke Nishizawa; Tetsuya Taketsugu; Takeshi Iwasa
Chemistry Letters, Oxford University Press (OUP), 23 May 2025, [Peer-reviewed], [Invited], [Last author, Corresponding author], [International Magazine]
Scientific journal, Abstract

Near-field optics provides a revolutionary pathway to achieve high spatial resolution beyond the diffraction limit, which is unattainable with conventional optics. Furthermore, the strong localization of near-field light induces spatially non-uniform interactions with molecules, enabling access to forbidden quantum states and allowing for the control of light at the single-molecule level. To describe such non-uniform interactions between near-field light and molecules, we have developed a theoretical framework that goes beyond the dipole approximation. In this highlight review, we present the theoretical and computational frameworks developed primarily based on the multipolar Hamiltonian, along with a recent study that explores the electron dynamics of a single molecule induced by near-field excitation.

A nearly perfect icosahedral Ir@Au₁₂ superatom with superior photoluminescence obtained by ligand engineering
Katsuya Mutoh; Teppei Yahagi; Shinjiro Takano; Sonomi Kawakita; Takeshi Iwasa; Tetsuya Taketsugu; Tatsuya Tsukuda; Takuya Nakashima
Chemical Science, Royal Society of Chemistry (RSC), Mar. 2025, [Peer-reviewed]
Scientific journal, Heterometal doping and the introduction of surface ligands drastically alter the optical and photophysical properties of gold-based superatoms by modulating their electronic structures and the excited state dynamics. In this...

Optical force and torque in near-field excitation of C3H6: A first-principles study using RT-TDDFT
Risa Amano; Daisuke Nishizawa; Tetsuya Taketsugu; Takeshi Iwasa
The Journal of Chemical Physics, 161, 12, AIP Publishing, 26 Sep. 2024, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
Scientific journal, Optical trapping is an effective tool for manipulating micrometer-sized particles, although its application to nanometer-sized particles remains difficult. The field of optical trapping has advanced significantly, incorporating more advanced techniques such as plasmonic structures. However, single-molecule trapping remains a challenge. To achieve a deeper understanding of optical forces acting on molecular systems, a first-principles approach to analyze the optical force on molecules interacting with a plasmonic field is crucial. In our study, the optical force and torque induced by the near-field excitation of C3H6 were investigated using real-time time-dependent density functional theory calculations on real-space grids. The near field from the scanning tunneling probe was adopted as the excitation source for the molecule. The optical force was calculated using the polarization charges induced in the molecule based on Lorentz force. While the optical force and torque calculated as functions of the light energy were in moderate agreement with the oscillator strengths obtained from the far-field excitation of C3H6, a closer correspondence was achieved with the power spectrum of the induced dipole moment using near-field excitation. Time-domain analysis of the optical force suggests that the simultaneous excitation of multiple excited states generally weakens the force because of mismatches between the directions of the induced polarization and the electric field. This study revealed a subtle damping mechanism for the optical force arising from intrinsic electronic states and the influence of beating.

Near-field induced local excitation dynamics of Na10 and Na10–N2 from real-time TDDFT
Daisuke Nishizawa; Risa Amano; Tetsuya Taketsugu; Takeshi Iwasa
The Journal of Chemical Physics, 161, 5, 054309, AIP Publishing, 05 Aug. 2024, [Peer-reviewed], [Invited], [Last author, Corresponding author]
Scientific journal, Electron dynamics of the Na10 chain and the Na10–N2 complex locally excited by an atomistic optical near-field are investigated using real-time time-dependent density functional theory calculations on real-space grids. Ultrafast laser pulses were used to simulate the near-field excitation under on- and off-resonance conditions. Off-resonance excitation did not lead to the propagation of the excitation through the Na10 chain. In contrast, under the resonance conditions, the excited state is delocalized over the entire Na chain. Analysis of the local dipole moment of each atom in Na10 indicates that this behavior is consistent with the transition density. Adding an N2 molecule to the opposite end of the local excitation region results in energy transfer via the Na10 chain. The energy transfer efficiency of the N2 molecule is well correlated with the absorption spectrum of Na10. The present study paves the way for realizing remote excitation and photonic devices at the atomic scale.

Generalized Transition Moment and Oscillator Strength for Optimal Control of Excited States Using Near-Field Light
Takeshi Iwasa
The Journal of Physical Chemistry Letters, 15, 18, 4775, 4781, American Chemical Society (ACS), 26 Apr. 2024, [Peer-reviewed], [Lead author, Last author, Corresponding author]
Scientific journal, 46315025;46315024;42090519;34006646;46315036

Key factors for connecting silver-based icosahedral superatoms by vertex sharing
Sayuri Miyajima; Sakiat Hossain; Ayaka Ikeda; Taiga Kosaka; Tokuhisa Kawawaki; Yoshiki Niihori; Takeshi Iwasa; Tetsuya Taketsugu; Yuichi Negishi
Communications Chemistry, 6, 1, Springer Science and Business Media LLC, 28 Mar. 2023, [Peer-reviewed], [Invited], [Corresponding author], [International Magazine]
Scientific journal, Abstract

Metal nanoclusters composed of noble elements such as gold (Au) or silver (Ag) are regarded as superatoms. In recent years, the understanding of the materials composed of superatoms, which are often called superatomic molecules, has gradually progressed for Au-based materials. However, there is still little information on Ag-based superatomic molecules. In the present study, we synthesise two di-superatomic molecules with Ag as the main constituent element and reveal the three essential conditions for the formation and isolation of a superatomic molecule comprising two Ag_13−xM_x structures (M = Ag or other metal; x = number of M) connected by vertex sharing. The effects of the central atom and the type of bridging halogen on the electronic structure of the resulting superatomic molecule are also clarified in detail. These findings are expected to provide clear design guidelines for the creation of superatomic molecules with various properties and functions.

Excited States of Metal-Adsorbed Dimethyl Disulfide: A TDDFT Study with Cluster Model
Keijiro Toda; Yoshihiro Hirose; Emiko Kazuma; Yousoo Kim; Tetsuya Taketsugu; Takeshi Iwasa
The Journal of Physical Chemistry A, 126, 26, 4191, 4198, American Chemical Society ({ACS}), 07 Jul. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, The optical near field refers to a localized light field near a surface that can induce photochemical phenomena such as dipole-forbidden transitions. Recently, the photodissociation of the S–S bond of dimethyl disulfide (DMDS) was investigated using a scanning tunneling microscope with far- and near-field light. This reaction is thought to be initiated by the lowest-energy highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) transition of the DMDS molecule under far-field light. In near-field light, photodissociation proceeds at lower photon energies than in far-field light. To gain insight into the underlying mechanism, we theoretically investigated the excited states of DMDS adsorbed on Cu and Ag surfaces modeled by a tetrahedral 20-atom cluster. The frontier orbitals of the molecule were delocalized by the interaction with the metal, resulting in narrowing of the HOMO–LUMO gap energy. The excited-state distribution was analyzed using the Mulliken population analysis, decomposing molecular orbitals into metal and DMDS fragments. The excited states of the intra-DMDS transitions were found over a wider energy range, but at low energies, their oscillator strengths were negligible, which is consistent with the experimental results. Sparse modeling analysis showed that typical electronic transitions differed between the higher and lower excited states. If these low-lying excited states are efficiently excited by near-field light with different selection rules, the S–S bond dissociation reaction can proceed., 34006646;30404717;30404716;30404718

Doping‐Mediated Energy‐Level Engineering of M@Au ₁₂ Superatoms (M=Pd, Pt, Rh, Ir) for Efficient Photoluminescence and Photocatalysis
Haru Hirai; Shinjiro Takano; Takuya Nakashima; Takeshi Iwasa; Tetsuya Taketsugu; Tatsuya Tsukuda
Angewandte Chemie International Edition, 61, 36, Wiley, 17 Jun. 2022, [Peer-reviewed]
Scientific journal

Structural Characterization of Nickel-Doped Aluminum Oxide Cations by Cryogenic Ion Trap Vibrational Spectroscopy
Ya-Ke Li; Mark C. Babin; Sreekanta Debnath; Takeshi Iwasa; Sonu Kumar; Tetsuya Taketsugu; Knut R. Asmis; Andrey Lyalin; Daniel M. Neumark
The Journal of Physical Chemistry A, 125, 43, 9527, 9535, American Chemical Society (ACS), 24 Oct. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
Scientific journal, 30404716

Barium Oxide Encapsulating Cobalt Nanoparticles Supported on Magnesium Oxide: Active Non-Noble Metal Catalysts for Ammonia Synthesis under Mild Reaction Conditions
Katsutoshi Sato; Shin-ichiro Miyahara; Kotoko Tsujimaru; Yuichiro Wada; Takaaki Toriyama; Tomokazu Yamamoto; Syo Matsumura; Koji Inazu; Hirono Mohri; Takeshi Iwasa; Tetsuya Taketsugu; Katsutoshi Nagaoka
ACS Catalysis, 11, 21, 13050, 13061, 13 Oct. 2021, [Peer-reviewed]
English, Scientific journal

A comparative study of structural, electronic, and optical properties of thiolated gold clusters with icosahedral vs face-centered cubic cores
Maho Miyamoto; Tetsuya Taketsugu; Takeshi Iwasa
The Journal of Chemical Physics, 155, 9, 094304, 094304, AIP Publishing, 07 Sep. 2021, [Peer-reviewed], [Invited], [Last author, Corresponding author]
Scientific journal

[Ag23Pd2(PPh3)10Cl7]0: A new family of synthesizable bi-icosahedral superatomic molecules
Sakiat Hossain; Sayuri Miyajima; Takeshi Iwasa; Ryo Kaneko; Taishu Sekine; Ayaka Ikeda; Tokuhisa Kawawaki; Tetsuya Taketsugu; Yuichi Negishi
The Journal of Chemical Physics, 155, 2, 024302, 024302, AIP Publishing, 14 Jul. 2021, [Peer-reviewed], [Invited], [Corresponding author]
Scientific journal

Photoluminescence of Doped Superatoms M@Au12 (M = Ru, Rh, Ir) Homoleptically Capped by (Ph2)PCH2P(Ph2): Efficient Room-Temperature Phosphorescence from Ru@Au12
Shinjiro Takano; Haru Hirai; Takuya Nakashima; Takeshi Iwasa; Tetsuya Taketsugu; Tatsuya Tsukuda
Journal of the American Chemical Society, 143, 28, 10560, 10564, American Chemical Society (ACS), 07 Jul. 2021, [Peer-reviewed]
Scientific journal

Single-molecule laser nanospectroscopy with micro–electron volt energy resolution
Hiroshi Imada; Miyabi Imai-Imada; Kuniyuki Miwa; Hidemasa Yamane; Takeshi Iwasa; Yusuke Tanaka; Naoyuki Toriumi; Kensuke Kimura; Nobuhiko Yokoshi; Atsuya Muranaka; Masanobu Uchiyama; Tetsuya Taketsugu; Yuichiro K. Kato; Hajime Ishihara; Yousoo Kim
Science, 373, 6550, 95, 98, American Association for the Advancement of Science (AAAS), 02 Jul. 2021, [Peer-reviewed]
Scientific journal, Ways to characterize and control excited states at the single-molecule and atomic levels are needed to exploit excitation-triggered energy-conversion processes. Here, we present a single-molecule spectroscopic method with micro–electron volt energy and submolecular-spatial resolution using laser driving of nanocavity plasmons to induce molecular luminescence in scanning tunneling microscopy. This tunable and monochromatic nanoprobe allows state-selective characterization of the energy levels and linewidths of individual electronic and vibrational quantum states of a single molecule. Moreover, we demonstrate that the energy levels of the states can be finely tuned by using the Stark effect and plasmon-exciton coupling in the tunneling junction. Our technique and findings open a route to the creation of designed energy-converting functions by using tuned energy levels of molecular systems.

Theoretical method for near-field Raman spectroscopy with multipolar Hamiltonian and real-time-TDDFT: Application to on- and off-resonance tip-enhanced Raman spectroscopy
Masato Takenaka; Tetsuya Taketsugu; Takeshi Iwasa
The Journal of Chemical Physics, 154, 2, 024104, 024104, AIP Publishing, 14 Jan. 2021, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal

Effects of support materials and Ir loading on catalytic N2O decomposition properties
Satoshi Hinokuma; Takeshi Iwasa; Yoshihiro Kon; Tetsuya Taketsugu; Kazuhiko Sato
Catalysis Communications, 149, 106208, 106208, Elsevier {BV}, Jan. 2021, [Peer-reviewed]
English, Scientific journal

N2O decomposition properties of Ru catalysts supported on various oxide materials and SnO2
Satoshi Hinokuma; Takeshi Iwasa; Yoshihiro Kon; Tetsuya Taketsugu; Kazuhiko Sato
Scientific Reports, 10, 1, 21605, 21605, Springer Science and Business Media LLC, Dec. 2020, [Peer-reviewed], [International Magazine]
English, Scientific journal, Nitrous oxide (N₂O) is a stratospheric ozone depleting greenhouse gas that has global warming potential. As the catalytic decomposition of N₂O is one of the most promising techniques for N₂O emissions abatement, in this study, for this purpose the properties of Ru supported on various oxide materials were investigated under excess O₂ conditions, and the identities of the N₂O adsorption species on the catalysts were confirmed. To clarify the correlation between the catalytic properties and N₂O decomposition activity, the supported Ru catalysts were characterised by means of powder X-ray diffraction, X-ray fluorescence measurements, energy-dispersive X-ray mapping and several gas sorption techniques. The results showed that the redox properties for Ru (RuO₂) at low temperature are closely associated with N₂O decomposition activity. The local structures, optimal Ru loading and N₂O adsorption species of the novel Ru/SnO₂ catalysts were studied and they showed high activity for N₂O decomposition.

Determining and Controlling Cu-Substitution Sites in Thiolate-Protected Gold-Based 25-Atom Alloy Nanoclusters
Sakiat Hossain; Daiki Suzuki; Takeshi Iwasa; Ryo Kaneko; Taiyo Suzuki; Sayuri Miyajima; Yuki Iwamatsu; Stephan Pollitt; Tokuhisa Kawawaki; Noelia Barrabés; Günther Rupprechter; Yuichi Negishi
The Journal of Physical Chemistry C, 124, 40, 22304, 22313, American Chemical Society (ACS), 08 Oct. 2020, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
Scientific journal

Ammonia Combustion Properties of Copper Oxides-based Honeycomb and Granular Catalysts
Satoshi HINOKUMA; Takeshi IWASA; Kento ARAKI; Yusuke KAWABATA; Shun MATSUKI; Tetsuya SATO; Yoshihiro KON; Tetsuya TAKETSUGU; Kazuhiko SATO; Masato MACHIDA
Journal of the Japan Petroleum Institute, 63, 5, 274, 281, Japan Petroleum Institute, 01 Sep. 2020, [Peer-reviewed]
Scientific journal

Photoinduced Pyramidal Inversion Behavior of Phosphanes Involved with Aggregation‐Induced Emission Behavior
Takashi Machida; Takeshi Iwasa; Tetsuya Taketsugu; Kazuki Sada; Kenta Kokado
Chemistry – A European Journal, 26, 36, 8028, 8034, Wiley, 26 Jun. 2020, [Peer-reviewed]
Scientific journal

Combined computational quantum chemistry and classical electrodynamics approach for surface enhanced infrared absorption spectroscopy
Takeshi Iwasa
The Journal of Chemical Physics, 152, 16, 164103, 164103, AIP Publishing, 30 Apr. 2020, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Single-molecule resonance Raman effect in a plasmonic nanocavity
Jaculbia, R.B.; Imada, H.; Miwa, K.; Iwasa, T.; Takenaka, M.; Yang, B.; Kazuma, E.; Hayazawa, N.; Taketsugu, T.; Kim, Y.
Nature Nanotechnology, 2020, [Peer-reviewed]
Scientific journal

Combined Automated Reaction Pathway Searches and Sparse Modeling Analysis for Catalytic Properties of Lowest Energy Twins of Cu 13
Takeshi Iwasa; Takaaki Sato; Makito Takagi; Min Gao; Andrey Lyalin; Masato Kobayashi; Ken Ichi Shimizu; Satoshi Maeda; Tetsuya Taketsugu
Journal of Physical Chemistry A, 123, 1, 210, 217, Oct. 2019, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal

Roles of silver nanoclusters in surface-enhanced Raman spectroscopy
Takao Tsuneda; Takeshi Iwasa; Tetsuya Taketsugu
The Journal of Chemical Physics, 151, 9, 094102, 094102, AIP Publishing, 07 Sep. 2019, [Peer-reviewed]
Scientific journal

Low-Lying Excited States of hqxcH and Zn-hqxc Complex: Toward Understanding Intramolecular Proton Transfer Emission
Ebina, M.; Kondo, Y.; Iwasa, T.; Taketsugu, T.
Inorganic Chemistry, 58, 7, 4686, 4698, 01 Apr. 2019, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Ammonia-rich combustion and ammonia combustive decomposition properties of various supported catalysts
Takeshi Iwasa
Catalysis Communications, 123, 64, 68, 01 Apr. 2019, [Peer-reviewed]
English, Scientific journal

First Principles Calculations Toward Understanding SERS of 2,2′-Bipyridyl Adsorbed on Au, Ag, and Au–Ag Nanoalloy
Takenaka, M.; Hashimoto, Y.; Iwasa, T.; Taketsugu, T.; Seniutinas, G.; Bal?ytis, A.; Juodkazis, S.; Nishijima, Y.
Journal of Computational Chemistry, 40, 8, 925, 932, 30 Mar. 2019, [Peer-reviewed], [Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal

Photoluminescence Properties of [Core+ exo]-Type Au6 Clusters: Insights into the Effect of Ligand Environments on the Excitation Dynamics
Yukatsu Shichibu; Mingzhe Zhang; Takeshi Iwasa; Yuriko Ono; Tetsuya Taketsugu; Shun Omagari; Takayuki Nakanishi; Yasuchika Hasegawa; Katsuaki Konishi
Journal of Physical Chemistry C, 123, 11, 6934, 6939, 21 Mar. 2019, [Peer-reviewed]
Scientific journal

Structural and Electronic Properties, Isomerization, and NO Dissociation Reactions on Au, Ag, Cu Clusters
Takeshi Iwasa
Journal of Computer Chemistry, Japan, 18, 1, 64, 69, Jan. 2019, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Insights into Geometries, Stabilities, Electronic Structures, Reactivity Descriptors, and Magnetic Properties of Bimetallic NimCun-m (m=1, 2; n=3-13) Clusters: Comparison with Pure Copper Clusters
Singh, Raman K.; Iwasa, Takeshi; Taketsugu, Tetsuya
Journal of Computational Chemistry, 39, 23, 1878, 1889, 05 Sep. 2018, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
Scientific journal

Time-Dependent Density Functional Theory Study on Higher Low-Lying Excited States of Au25(SR)18 -
Masanori Ebina; Takeshi Iwasa; Yu Harabuchi; Tetsuya Taketsugu
Journal of Physical Chemistry C, 122, 7, 4097, 4104, American Chemical Society, 22 Feb. 2018, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Twist of C=C Bond Plays a Crucial Role in the Quenching of AIE-Active Tetraphenylethene Derivatives in Solution
Kenta Kokado; Takashi Machida; Takeshi Iwasa; Tetsuya Taketsugu; Kazuki Sada
Journal of Physical Chemistry C, 122, 1, 245, 251, American Chemical Society, 11 Jan. 2018, [Peer-reviewed]
English, Scientific journal

Supported binary CuO x -Pt catalysts with high activity and thermal stability for the combustion of NH 3 as a carbon-free energy source
Kiritoshi, S.; Iwasa, T.; Araki, K.; Kawabata, Y.; Taketsugu, T.; Hinokuma, S.; Machida, M.
RSC Advances, 8, 72, 41491, 41498, 01 Jan. 2018, [Peer-reviewed]
English, Scientific journal

Spiral Eu(iii) coordination polymers with circularly polarized luminescence
Hasegawa, Y.; Miura, Y.; Kitagawa, Y.; Wada, S.; Nakanishi, T.; Fushimi, K.; Seki, T.; Ito, H.; Iwasa, T.; Taketsugu, T.; Gon, M.; Tanaka, K.; Chujo, Y.; Hattori, S.; Karasawa, M.; Ishii, K.
Chemical Communications, 54, 76, 10695, 10697, 01 Jan. 2018, [Peer-reviewed]
Scientific journal

Optical readout of hydrogen storage in films of Au and Pd
Yoshiaki Nishijima; Shogo Shimizu; Keisuke Kurihara; Yoshikazu Hashimoto; Hajime Takahashi; Armandas Balcytis; Gediminas Seniutinas; Shinji Okazaki; Jurga Juodkazyte; Takeshi Iwasa; Tetsuya Taketsugu; Yoriko Tominaga; Saulius Juodkazis
OPTICS EXPRESS, 25, 20, 24081, 24092, Oct. 2017, [Peer-reviewed]
English, Scientific journal

Development of Integrated Dry-Wet Synthesis Method for Metal Encapsulating Silicon Cage Superatoms of M@Si-16 (M = Ti and Ta)
Hironori Tsunoyama; Hiroki Akatsuka; Masahiro Shibuta; Takeshi Iwasa; Yoshiyuki Mizuhata; Norihiro Tokitoh; Atsushi Nakajima
JOURNAL OF PHYSICAL CHEMISTRY C, 121, 37, 20507, 20516, Sep. 2017, [Peer-reviewed]
English, Scientific journal

A designer ligand field for blue-green luminescence of organoeuropium(II) sandwich complexes with cyclononatetraenyl ligands
Kenshiro Kawasaki; Rion Sugiyama; Takashi Tsuji; Takeshi Iwasa; Hironori Tsunoyama; Yoshiyuki Mizuhata; Norihiro Tokitoh; Atsushi Nakajima
CHEMICAL COMMUNICATIONS, 53, 49, 6557, 6560, Jun. 2017, [Peer-reviewed]
English, Scientific journal

Luminescent Mechanochromic 9-Anthryl Gold(I) Isocyanide Complex with an Emission Maximum at 900 nm after Mechanical Stimulation
Tomohiro Seki; Noriaki Tokodai; Shun Omagari; Takayuki Nakanishi; Yasuchika Hasegawa; Takeshi Iwasa; Tetsuya Taketsugu; Hajime Ito
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 139, 19, 6514, 6517, May 2017, [Peer-reviewed]
English, Scientific journal

Multiple-decker and ring sandwich formation of manganese-benzene organometallic cluster anions: Mn(n)Bz(n)(-) (n=1-5 and 18)
Tsugunosuke Masubuchi; Takeshi Iwasa; Atsushi Nakajima
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 18, 37, 26049, 26056, Oct. 2016, [Peer-reviewed]
English, Scientific journal

Generalized theoretical method for the interaction between arbitrary nonuniform electric field and molecular vibrations: Toward near-field infrared spectroscopy and microscopy
Takeshi Iwasa; Masato Takenaka; Tetsuya Taketsugu
JOURNAL OF CHEMICAL PHYSICS, 144, 12, Mar. 2016, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Heterodimerization via the Covalent Bonding of Ta@Si-16 Nanoclusters and C-60 Molecules
Masato Nakaya; Takeshi Iwasa; Hironori Tsunoyama; Toyoaki Eguchi; Atsushi Nakajima
JOURNAL OF PHYSICAL CHEMISTRY C, 119, 20, 10962, 10968, May 2015, [Peer-reviewed]
English, Scientific journal

Formation of a superatom monolayer using gas-phase-synthesized Ta@Si16 nanocluster ions
Masato Nakaya; Takeshi Iwasa; Hironori Tsunoyama; Toyoaki Eguchi; Atsushi Nakajima
Nanoscale, 6, 24, 14702, 14707, Royal Society of Chemistry, 21 Dec. 2014, [Peer-reviewed]
English, Scientific journal

Experimental and theoretical studies of the structural and electronic properties of vanadium benzene sandwich clusters and their anions: V(n)Bz(n)(0/-) (n=1-5) and V(n)Bz(n-1)(0/-) (n=2-5)
Tsugunosuke Masubuchi; Takeshi Iwasa; Atsushi Nakajima
JOURNAL OF CHEMICAL PHYSICS, 141, 21, Dec. 2014, [Peer-reviewed]
English, Scientific journal

Formation and Control of Ultrasharp Metal/Molecule Interfaces by Controlled Immobilization of Size- Selected Metal Nanoclusters onto Organic Molecular Films
Masato Nakaya; Takeshi Iwasa; Hironori Tsunoyama; Toyoaki Eguchi; Atsushi Nakajima
ADVANCED FUNCTIONAL MATERIALS, 24, 9, 1202, 1210, Mar. 2014, [Peer-reviewed]
English, Scientific journal

Physical properties of mononuclear organoeuropium sandwich complexes ligated by cyclooctatetraene and bis(trimethylsilyl) cyclooctatetraene
Takashi Tsuji; Suguru Fukazawa; Rion Sugiyama; Kenshiro Kawasaki; Takeshi Iwasa; Hironori Tsunoyama; Norihiro Tokitoh; Atsushi Nakajima
CHEMICAL PHYSICS LETTERS, 595, 144, 150, Mar. 2014, [Peer-reviewed]
English, Scientific journal

Liquid-Phase Synthesis of Multidecker Organoeuropium Sandwich Complexes and Their Physical Properties
Takashi Tsuji; Natsuki Hosoya; Suguru Fukazawa; Rion Sugiyama; Takeshi Iwasa; Hironori Tsunoyama; Hirofumi Hamaki; Norihiro Tokitoh; Atsushi Nakajima
JOURNAL OF PHYSICAL CHEMISTRY C, 118, 11, 5896, 5907, Mar. 2014, [Peer-reviewed]
English, Scientific journal

Electronic and optical properties of vertex-sharing homo- and hetero-biicosahedral gold clusters
Takeshi Iwasa; Katsuyuki Nobusada; Atsushi Nakajima
Journal of Physical Chemistry C, 117, 46, 24586, 24591, 21 Nov. 2013, [Peer-reviewed], [Lead author]
English, Scientific journal

Geometric, electronic, and optical properties of monomer and assembly of endohedral aluminum superatomic clusters
Takeshi Iwasa; Atsushi Nakajima
Journal of Physical Chemistry C, 117, 41, 21551, 21557, 17 Oct. 2013, [Peer-reviewed], [Lead author]
English, Scientific journal

Geometric, electronic, and optical properties of a boron-doped aluminum cluster of B2Al21-: A density functional theory study
Takeshi Iwasa; Atsushi Nakajima
CHEMICAL PHYSICS LETTERS, 582, 100, 104, Sep. 2013, [Peer-reviewed], [Lead author]
English, Scientific journal

Experimental and theoretical studies on the electronic properties of vanadium-benzene sandwich cluster anions, V(n)Bz(n+1)(-) (n=1-5)
Tsugunosuke Masubuchi; Katsuya Ohi; Takeshi Iwasa; Atsushi Nakajima
JOURNAL OF CHEMICAL PHYSICS, 137, 22, Dec. 2012, [Peer-reviewed]
English, Scientific journal

Geometric, Electronic, and Optical Properties of a Superatomic Heterodimer and Trimer: Sc@Si-16-V@Si-16 and Sc@Si-16-Ti@Si-16-V@Si-16
Takeshi Iwasa; Atsushi Nakajima
JOURNAL OF PHYSICAL CHEMISTRY C, 116, 26, 14071, 14077, Jul. 2012, [Peer-reviewed], [Lead author]
English, Scientific journal

Theoretical Investigation of a Titanium-Aniline Complex with and without an Alkyl Chain
Takeshi Iwasa; Kazuki Horiuchi; Masaya Shikishirna; Yuji Noguchi; Shuhei Nagaoka; Atsushi Nakajima
JOURNAL OF PHYSICAL CHEMISTRY C, 115, 33, 16574, 16582, Aug. 2011, [Peer-reviewed], [Lead author]
English, Scientific journal

Near-field-induced optical force on a metal particle and C-60: Real-time and real-space electron dynamics simulation
Takeshi Iwasa; Katsuyuki Nobusada
PHYSICAL REVIEW A, 82, 4, Oct. 2010, [Peer-reviewed], [Lead author]
English, Scientific journal

Isolation, structure, and stability of a dodecanethiolate-protected Pd1Au24 cluster
Yuichi Negishi; Wataru Kurashige; Yoshiki Niihori; Takeshi Iwasa; Katsuyuki Nobusada
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 12, 23, 6219, 6225, 2010, [Peer-reviewed]
English, Scientific journal

Nonuniform light-matter interaction theory for near-field-induced electron dynamics
Takeshi Iwasa; Katsuyuki Nobusada
PHYSICAL REVIEW A, 80, 4, Oct. 2009, [Peer-reviewed], [Lead author]
English, Scientific journal

Oligomeric gold clusters with vertex-sharing bi- and triicosahedral structures
Katsuyuki Nobusada; Takeshi Iwasa
JOURNAL OF PHYSICAL CHEMISTRY C, 111, 39, 14279, 14282, Oct. 2007, [Peer-reviewed]
English

Thiolate-induced structural reconstruction of gold clusters probed by Au-197 Mossbauer spectroscopy
Kazuhiro Ikeda; Yasuhiro Kobayashi; Yuichi Negishi; Makoto Seto; Takeshi Iwasa; Katsuyuki Nobusada; Tatsuya Tsukuda; Norimichi Kojima
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 129, 23, 7230, +, Jun. 2007, [Peer-reviewed]
English, Scientific journal

Gold-thiolate core-in-cage cluster Au-25(SCH3)(18) shows localized spins in charged states
Takeshi Iwasa; Katsuyuki Nobusada
CHEMICAL PHYSICS LETTERS, 441, 4-6, 268, 272, Jun. 2007, [Peer-reviewed], [Lead author]
English, Scientific journal

Theoretical investigation of optimized structures of thiolated gold cluster [Au-25(SCH3)(18)](+)
Takeshi Iwasa; Katsuyuki Nobusada
JOURNAL OF PHYSICAL CHEMISTRY C, 111, 1, 45, 49, Jan. 2007, [Peer-reviewed], [Lead author]
English, Scientific journal

特集： 分光・イメージングの最前線
理論化学会会誌「フロンティア」, 5, 3, Jul. 2023

[Ag23Pd2(PPh3) 10Cl7]0 の合成と幾何構造：形成可能な 超原子分子の種類とその形成要因の解明に向けて
宮嶋 小百合; Sakiat Hossain; 岩佐 豪; 川脇 徳久; 武次 徹也; 根岸 雄一, ナノ学会刊行和文誌, 20, 2, 59, 64, Mar. 2022, [Peer-reviewed]
Introduction scientific journal

特集：光と分子の相互作用
理論化学会誌「フロンティア」, 3, 4, 205, 257, 31 Oct. 2021
理論化学会

第一原理計算による近接場光と分子の相互作用
岩佐豪, 光学, 50, 3, 120, 126, Mar. 2021

低コストNi_1-xCu_xCo₂O₄触媒のN₂O分解反応特性と分光・理論解析
日隈 聡士; 岩佐 豪
アグリバイオ 2026年8月臨時増刊号・北陵館, 05 Aug. 2026, 46315025;46315024;30404718, [Joint work]

密度汎関数法による量子化学計算
常田貴夫; 武次徹也; 小林正人; 岩佐豪; Andrey Lyalin; 斉田謙一郎; 小野ゆり子; 堤拓朗; 和田諒; 赤間知子, 2.2 振動スペクトル
講談社サイエンティフィク, 28 May 2025, 9784065396780, 256, 51-63, [Contributor]

局在した光と分子
岩佐豪
カーボン・エネルギーコントロール社会協議会 (CanApple), 05 Jan. 2024, Others

計算化学研究におけるスパースモデリングの応用
岩佐豪; 小林正人; 武次徹也
技術情報協会, 28 Apr. 2023

ナノの光を使った化学反応 STM 探針先端のプラズモン場に光を閉じ込める
岩佐豪
Oct. 2020

温和な条件下でのアンモニア合成を目指したCo/MgO触媒へのBaO添加効果
佐藤勝俊; 佐藤勝俊; 宮原伸一郎; 毛利広野; 岩佐豪; 岩佐豪; 武次徹也; 武次徹也; 永岡勝俊; 永岡勝俊
触媒討論会討論会A予稿集(CD-ROM), 2021
2021 - 2021

クラスターモデルでの酸化物担持金属クラスター触媒の電子物性
岩佐豪; 武次徹也; 岩佐豪; 武次徹也
ナノ学会大会講演予稿集, 10 May 2017, Japanese
10 May 2017 - 10 May 2017

チオール分子で保護された金クラスターの励起状態と発光機構の解明
蝦名昌徳; 原渕祐; 原渕祐; 岩佐豪; 岩佐豪; 武次徹也; 武次徹也
ナノ学会大会講演予稿集, 10 May 2017, Japanese
10 May 2017 - 10 May 2017

Specifying primary factors in the catalytic activity of metal clusters based on quantum chemical calculations and machine learning
Kobayashi Masato; Iwasa Takeshi; Gao Min; Takagi Makito; Maeda Satoshi; Taketsugu Tetsuya
Proceedings of the Symposium on Chemoinformatics, 2016, Division of Chemical Information and Computer Sciences The Chemical Society of Japan, Japanese
2016 - 2016, Because catalytic activities of metal nano clusters depend on the composition, size, environment, and structural isomers of the cluster, it has been difficult to elucidate the primary factors in their catalytic activities. In this study, we attempted to extract the factors in the catalytic activity using the sparse modeling techniques and the systematic quantum chemical calculations assisted by the automatic search of reaction pathways. In particular, the transition state energies for NO dissociation on Cu13 clusters were modeled with the orbital energies and local indices by the LASSO, SCAD, and MC+ regressions. It was found that the transition state energy negatively correlates with the LUMO energy. The SCAD and MC+ regressions could generate more compact and better models with higher correlation factors than the LASSO regression.

22pBG-13 Theoretical method for the interaction between non-uniform near-field and molecular vibrations
Iwasa T; Taketsugu T
Meeting Abstracts of the Physical Society of Japan, 2015, The Physical Society of Japan (JPS), Japanese
2015 - 2015

分子化学Ａ（分子理論化学）, 2024年, 修士課程, 総合化学院

一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育

理学共通演習Ⅱ, 2024年, 学士課程, 理学部

Theoretical Chemistry Analysis of Superatomic Materials
Grants-in-Aid for Scientific Research
01 Apr. 2026 - 31 Mar. 2031
武次 徹也; 岩佐 豪
Japan Society for the Promotion of Science, Grant-in-Aid for Transformative Research Areas (A), Hokkaido University, 26H00397

Advancing Interfacial Photofunctional Molecular Science via Operando Microscopy Integrated with Theory
Grants-in-Aid for Scientific Research
01 Apr. 2026 - 31 Mar. 2031
杉本 敏樹; 岩佐 豪
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Institute for Molecular Science, 26K21748

一酸化二窒素の低温分解を可能にするHigh-entropy Spinel触媒の開発と反応機構解明
科学研究費助成事業
01 Apr. 2026 - 31 Mar. 2029
日隈 聡士; 岩佐 豪
日本学術振興会, 基盤研究(C), 国立研究開発法人産業技術総合研究所, 26K15228

Development of multi-excitation transient spectroscopy for analyzing multi-step photo-reduction processes of CO2
Grants-in-Aid for Scientific Research
01 Apr. 2023 - 31 Mar. 2026
宮田 潔志; 倉持 悠輔; 岩佐 豪
Japan Society for the Promotion of Science, Grant-in-Aid for Transformative Research Areas (B), Kyushu University, 23H03833

一酸化二窒素分解触媒の基礎開発と特性解明
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2026
日隈 聡士; 岩佐 豪
日本学術振興会, 基盤研究(C), 国立研究開発法人産業技術総合研究所, 23K04833

近接場光と分子の磁気的相互作用の理論研究
科学研究費助成事業 基盤研究(C)
01 Apr. 2023 - 31 Mar. 2026
岩佐 豪
日本学術振興会, 基盤研究(C), 北海道大学, 23K04671

Elucidation of selection rules in nano-optics and development of new energy conversion pathways
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
05 Apr. 2021 - 31 Mar. 2025
今田 裕; 安藤 康伸; 久間 晋; 今井 みやび; 岩佐 豪
実験面では、計測システムの改良を継続して行ってきており、徐々に分光計測の高精度化と分光データ取得が進んでいる。近接場光学の実験においては、スピン選択則や項間交差の詳細解明を目指して、りん光材料であるプラチナフタロシアニン分子の単一分子分光計測を実施した。STMのトンネル電流および近接場光という異なる二つの励起源を組み合わせて用いることで、単一分子で項間交差のナノ計測に成功した。また、近接場分光のさらなる高精度化を目指して、STMだけではなく原子間力顕微鏡（AFM）と光を組み合わせた光STM/AFM装置の立ち上げを行った。光STMとしては単一分子のエレクトロルミネッセンス分光ができるまで装置の整備が進み、AFM機能もqPlusセンサーを用いた力計測とAFM像取得ができることを確認した。超流動He液滴実験では、液滴に内包されたフタロシアニン分子の分光計測を進めている。精密な励起スペクトルに加えて、発光分散スペクトル測定の計測系立ち上げを行い、調整・改良を継続して行っている。データ解析においては、任意の数のピークを含むスペクトルデータに対し客観的なピーク本数の推定方法や使い易いインターフェースの検討を進めている。近接場光学の理論に関しては、実験で使用するフタロシアニン系やその他特徴的な対称性を有するモデル分子において、近接場中での分子の遷移モーメントの計算を実施した。近接場分光の実験結果と比較することで近接場内での特徴的相互作用の理解を進めている。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Institute of Physical and Chemical Research, 21H04644

近接場光による励起状態制御の理論
戦略的な研究開発の推進 戦略的創造研究推進事業 さきがけ
Nov. 2020 - Mar. 2025
岩佐 豪
量子力学では、基底状態の波動関数に外場を作用させて励起状態を重ね合わせることができます。本研究では、「物質近傍に局在する近接場光を用いて励起状態をどのように制御できるか」に理論的に挑戦します。具体的には、近接場光と分子の相互作用を記述するための双極子近似を超えた第一原理計算手法を開発し、電磁場の空間構造を設計して、狙いの電子励起状態へと励起し、分子の反応性を能動的に制御する仕組みを打ち立てます。
科学技術振興機構, 北海道大学, Principal investigator

Theoretical study for near-field induced photochemistry beyond the dipole approximation
Grants-in-Aid for Scientific Research
01 Apr. 2020 - 31 Mar. 2023
Iwasa Takeshi
In this study, we developed a theoretical method beyond the dipole approximation to elucidate the mechanism of photochemical reactions induced by localized near-field and clarified the difference between far-field and near-field excisions, as well as the selection rule for a photo-STM experiment. Furthermore, using a cluster model, we investigated the excited states of the supported molecules in consideration of the interaction between the metal substrate and the molecules, and found that the excited states of the supported molecules become broadly distributed according to the interaction with the metal, and that the higher excited states are dipole-allowed, but there are many dipole-forbidden states in the low energy region. Although the transition probabilities were also investigated using near-field light, but the reaction mechanism was not fully elucidated, and we intend to improve the metal model in the future.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 20K05412

Development of new nitrogen-fixing reactions
Grants-in-Aid for Scientific Research
01 Apr. 2020 - 31 Mar. 2023
Hinokuma Satoshi
Catalysts are indispensable in the production of chemical products, and heterogeneous reactions using solid catalysts are "low environmental load" because continuous production of chemical products and recovery and reuse of catalysts are possible. However, solid catalyst reactions are more stable (inert) and have lower surface energy than homogeneous reactions using molecular catalysts. In this research, we challenged the production of valuable substances (organic amines, amino acids, etc.) from nitrogen (N2) using catalysts with the surface energy of solid materials raised to the limit. If this research can produce valuable materials from N2, it will become a "dream nitrogen circulation technology." Furthermore, it has become a technology that can be manufactured with "low environmental impact" and contributes to the "Sustainable Development Goals (SDGs)" that promote human health and welfare.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), National Institute of Advanced Industrial Science and Technology, 20K05592

Excited states and emission mechanisms of molecular crystals
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
01 Apr. 2020 - 31 Mar. 2022
岩佐 豪
ソフトクリスタルを構成する分子の多くは、多彩な分子間相互作用を有する。分子間相互作用は、励起状態からの緩和経路の変調や、複数の分子間に広がる新たな電子励起状態の形成をもたらすため、ソフトクリスタルの発光機構の解明には、複数種の分子間相互作用を適切に考慮した理論手法が必要になる。本研究では、金属間相互作用と配位子間相互作用の競合する分子結晶の発光過程の学理を構築することを目指して、計算手法の開発と応用を行ってきた。
本年度は、QM/MM法の独自実装を進めた。QM計算には高速なRI-DFT計算が可能なTURBOMOLEを利用し、MM領域は点電荷とLennard-Jones（LJ）ポテンシャルとして扱った。SCF計算を行う際に、MM原子の位置にDFTから求めた自然電荷を考慮した。その後、エネルギー勾配を計算した出力ファイルに、各QM原子がMM原子から受けるLJポテンシャルからの力を追加するルーチンを作成し、これらの力を用いて構造最適化を行うようにした。金イソシアニド錯体10分子を結晶構造から切り出し、そのうちの2分子をQM領域、残りの8分子をMM領域とした構造最適化を基底状態、および第一励起一重項状態に対して行い、MM領域の有無で最適化構造に違いがでることを確認した。今後は、実験結果の解析に向けた計算を進めて行く。
また、前年に引き続きクラスター錯体の研究も進めた。今年度は、同じAu25SR18（SRはチオール）で表される2つの構造異性体の光物性の解明に取り組み、コアになるクラスターが対称性のよいコンパクトな形状を取ると原子が密に集まり電子密度が上がる。その結果、HOMOが不安定化してHOMO-LUMO gapエネルギーの低下と吸収ピークの低エネルギー化をもたらすことを明らかにした。関連して、異種原子ドープによる金・銀クラスター錯体の発光機能の向上などについての共同研究も行なった。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Hokkaido University, 20H04652

Theoretical study on the excited states and emission mechanisms of molecular crystals
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
01 Apr. 2018 - 31 Mar. 2020
岩佐 豪
配位化合物は、金属間相互作用と配位子間の相互作用の兼ね合いによって複数の結晶構造を取り得る。このような系の励起状態を調べようとすると、複数の種類の分子間相互作用を考慮したモデルを踏まえて適切な近似が必要になる。分子間相互作用によって発光量子収率の向上、あるいは場合によって単分子では蛍光を示す分子が凝集することによって燐光を示すようになることも知られている。分子間の相互作用が強く、単なる構造緩和の経路を変えるだけでなく、2分子あるいは数分子間に広がった新たな電子励起状態を形成することもある。このように分子結晶の発光を調べる場合には、分子間相互作用を適切に考慮した励起状態からの緩和経路を調べる必要がある。
本年度は、励起状態プロトン移動を示す亜鉛錯体の励起状態における分子間相互作用の効果、励起状態でのプロトン移動に伴う構造変化を調べた結果を論文にまとめた。また領域内外のメンバーと共同研究を行った。Eu錯体の励起状態をTDDFT計算とPopulation解析の結果を組み合わせて金属-金属、金属-配位子1、金属-配位子2、配位子中心の遷移に分類してエネルギー緩和過程を実験と比較した。ホスフィン保護金クラスターに対しては励起状態からの緩和過程を明らかにした。
一方で、DFT法は汎関数依存性もあり、長距離相関や分子間力などの弱い相互作用の記述に難しさがあるため、必ずしも適切ではない。そこで、高精度量子化学計算手法のMP2法やCC2法を用いて分子間相互作用や励起状態の計算を進めており、現在までに金-アントシアニン錯体の単分子の励起状態は電荷移動状態があり、その波長はDFT法では実験と合わないがCC2計算では実験との良い一致を示す事が分かった。今後は、二量体の励起状態における緩和過程において分子間相互作用が果たす役割について解明を進めて行く予定である。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Hokkaido University, 18H04496

Ab initio molecular dynamics with the multipolar interaction for near-field photoexcitation
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
01 Apr. 2017 - 31 Mar. 2020
Iwasa Takeshi
Near field, a highly localized non-uniform light field around a surface, can excite a molecule to dipole-forbidden excited states and can induce unexpected photo chemical reactions. To understand the interactions between the near-field and molecule, a theoretical method beyond the widely used dipole approximation is required. We have developed a theory starting from the original form of the Hamiltonian before the dipole-approximation. The theory is applied to an Ehrenfest molecular dynamics. In addition, we studied structural and electronic properties and relaxation pathways in dipole-forbidden excited states of pure and adsorbed molecules relevant to the near-field excitations. Near-field vibrational excitations including near-field IR and Raman spectroscopic experiments have also been studied by means of an integrated computational chemistry and computational electrodynamics technique. In the future, a diabatic method for near-field photochemistry will be developed.
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 17K14428

Optical response theory based on the interaction between nonuniform electric field and molecular vibrations
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
01 Apr. 2013 - 31 Mar. 2015
IWASA Takeshi
A theoretical method for the interaction between an electric nearfield in close proximity of a nanomaterial and molecular vibrations has been developed. Nearfields can hardly be described in the dipole approximation due to sharp intensity gradient and their lines of electric force whose distribution depend strongly on the structure of a nanomaterial, the source of nearfield. Here the interaction between an arbitrary shape of electric fields and molecular vibrations is formulated starting from the multipole Hamiltonian and a program code that utilizes the outputs of electronic structure codes is developed. Using this program, vibrational excitations by nearfields for single molecules in the gas phase or adsorbed on a metal cluster are studied and the effects of the near-fields such as the intensity gradients and field distributions are discussed.
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), 25810008

空間構造を取り入れた光学応答の時間領域での展開:近接場光の探索と局所励起問題
科学研究費助成事業 特別研究員奨励費
2008 - 2009
岩佐 豪
局在性を持つ近接場光と物質の相互作用から多種多様な物理現象が期待されている。20年度に開発を終えた電場の空間構造の効果を取り込んだ定式化と時間依存の密度汎関数理論を組み合わせた手法を、実在分子やナノ構造系へと適用し、近接場光の局在性を利用した局所分光と、近接場光の急峻な強度勾配を利用した力学操作の可能性を研究した。まず異方性を持つ1nmサイズの板状の金属ナノ構造体をジェリウムモデルで、近接場光は双極子放射で近似した系での近接場光励起問題を調べた。高調波スペクトルが、ナノ構造体と近接場光の光源の相対位置や相対角度に強く依存することから、局所分光へと展開できることを明らかにした。局所分光の一例として、少数Naクラスターの近接場光励起に対する吸収スペクトル(線形光学応答)と高調波スペクトル(非線形光学応答)を、近接場光光源位置の関数として求めた。Na_2の分子軸方向に偏光した近接場光による局所吸収スペクトルにおいて、分子中心、あるいは各原子上にピークを持つ2つの吸収成分を示すことを明らかにし、特に各原子上での吸収成分は近接場光の強度勾配の作用によるものと帰属した。また直線状とリング状のNa_6での近接場光誘起の高調波強度が、分子の形状を反映した実空間分布を示すことを明らかにし、高調波の次数によって分解能が大きく変わることを明らかにした。
最後に、近接場光から受ける力をジェリウムモデルによる直径1nmの金属粒子とC_<60>分子に置いて時間領域、エネルギー領域の両面から調べた。力のエネルギー依存性の図において振動構造を持つ事がわかり、これは近接場光励起により発生する不均一な分極を、誘起電荷とそれを遮蔽する成分に分けて考えることで説明した。また、双極子あるいは四極子励起には見られないより高次の多重極子の効果を含んだ近接場光励起特有の励起状態が力を大きく弱めることを明らかにした。
日本学術振興会, 特別研究員奨励費, 08J03281

ヘテロ接合積層体及び受光素子
Patent right, 中嶋敦; 角山寛規; 岩佐豪; 赤塚紘己
特願2012-88325, 09 Apr. 2012