Takeshi Iwasa

Graduate School of Science, Hokkaido University
Assistant professor
A02
Research AreasQuantum Chemistry, Molecular Physics
Participating Group (2020-2021)

Excited States and Emission Mechanisms of Molecular Crystals

Keywords
Molecular Crystal, Few-Body Systems, Quantum Chemistry Calculations, Intermolecular interactions
Co-Researcher
Co-Researcher: Tetsuya Taketsugu (Graduate School of Science, Hokkaido University, Professor)

Research Outline

Weak macroscopic stimulations can induce structural phase transitions for some molecular systems changing their luminescent properties. To understand the excited states and optical properties of these systems, one has to study the relaxation pathways for their excited states of a molecule or few-molecule under surroundings because the luminescence properties of a molecule depend on the crystal structure. In this study, we will develop a method that can study the relaxation pathway of these systems that includes explicit inter-molecular interactions in a condensed phase toward full understandings on the excited states and therefore the crystal structure-dependent luminescence properties.

Development of a method for emission mechanisms of molecular crystals
Participating Group (2018-2019)

Theoretical Study of Excited States and Emission Mechanisms of Molecular Crystals

Keywords
Molecular Crystal, Few-Body Systems, Quantum Chemistry Calculations, Excited States Molecular Dynamics, Non-adiabatic transitions
Co-Researcher
Co-Researcher: Tetsuya Taketsugu (Graduate School of Science, Hokkaido University, Professor)

Research Outline

Weak macroscopic stimulations can induce structural phase transitions for some molecular systems changing their luminescent properties. To understand the excited states and optical properties of these systems, one has to study the relaxation pathways for their excited states of a molecule or few-molecule under surroundings because the luminescence properties of a molecule depend on the crystal structure. In this study, we will develop a method that can study the relaxation pathway of these systems that includes explicit inter-molecular interactions in a condensed phase toward full understandings on the excited states and therefore the crystal structure-dependent luminescence properties.

Development of a methods for luminescent properties of molecular crystals

Publications

Academic papers/reviewed

A02-11

  1. "Theoretical method for near-field Raman spectroscopy with multipolar Hamiltonian and real-time-TDDFT: Application to on- and off-resonance tip-enhanced Raman spectroscopy" M. Takenaka, T. Taketsugu, *T. Iwasa, J. Chem. Phys., 154, 024104 (2021).
    DOI: 10.1063/5.0034933
  2. “[Ag23Pd2(PPh3)10Cl7]0: A New Family of Synthesizable Bi-icosahedral Superatomic Molecules” S. Hossain, S. Miyajima, *T. Iwasa, R. Kaneko, T. Sekine, A. Ikeda, T. Kawawaki, T. Taketsugu, and *Y. Negishi, J. Chem. Phys., 155, 024302 (2021).
    DOI: 10.1063/5.0057005
  3. “A Comparative Study of Structural, Electronic, and Optical Properties of Thiolated Gold Clusters with Icosahedral vs Face-Centered Cubic Cores” M. Miyamoto, T. Taketsugu, *T. Iwasa, J. Chem. Phys., 155, 094304 (2021).
    DOI:  10.1063/5.0057566
  4. “Barium Oxide Encapsulating Cobalt Nanoparticles Supported on Magnesium Oxide: Active Non-noble Metal Catalyst for Ammonia Synthesis under Mild Reaction Conditions” *K. Sato, S. Miyahara, K. Tsujimaru, Y. Wada, T. Toriyama, T. Yamamoto, S. Matsumura, K. Inazu, H. Mohri, T. Iwasa, T. Taketsugu, *K. Nagaoka, ACS Catal., 11, 13050-13061 (2021).
    DOI: 10.1021/acscatal.1c02887
  5. “Photoluminescence of Doped Superatoms M@Au12 (M = Ru, Rh, Ir) Homoleptically Capped by (Ph2)PCH2P(Ph2): Efficient Room-Temperature Phosphorescence from Ru@Au12” S. Takano, H. Hirai, T. Nakashima, T. Iwasa, T. Taketsugu, and *T. Tsukuda, J. Am. Chem. Soc. (Communication), 143, 10560-10564 (2021).
    DOI: 10.1021/jacs.1c05019
  6. ”Single-molecule laser nanospectroscopy with micro–electron volt energy resolution” *H. Imada, M. Imai-Imada, K. Miwa, H. Yamane, T. Iwasa, Y. Tanaka, N. Toriumi, K. Kimura, N. Yokoshi, A. Muranaka, M. Uchiyama, T. Taketsugu, Y. K. Kato, H. Ishihara, *Y. Kim, Science, 373, 95-98 (2021).
    DOI: 10.1126/science.abg8790
  7. "Combined Automated Reaction Pathway Searches and Sparse Modeling Analysis for Catalytic Properties of Lowest Energy Twins of Cu13" T. Iwasa, T. Sato, M. Takagi, M. Gao, A. Lyalin, M. Kobayashi, K. Shimizu, S. Maeda, T. Taketsugu, J. Phys. Chem. A, 2019, 123, 210-217.
    DOI: 10.1021/acs.jpca.8b08868
  8. "Low-lying Excited States of hqxcH and Zn-hqxc Complex: Toward Understanding Intramolecular Proton Transfer Emission" M. Ebina, Y. Kondo, T. Iwasa, T. Taketsugu, Inorg. Chem., 2019, 58, 4686-4698.
    DOI: 10.1021/acs.inorgchem.9b00410
  9. "Photoluminescence Properties of [Core+exo]-Type Au6 Clusters: Insights into the Effect of Ligand Environments on the Excitation Dynamics" Y. Shichibu, M. Zhang, T. Iwasa, Y. Ono, T. Taketsugu, S. Omagari, T. Nakanishi, Y. Hasegawa, K. Konishi, J. Phys. Chem. C, 2019, 123, 6934-6939.領域内共同研究　A03公募 長谷川靖)
    DOI: 10.1021/acs.jpcc.9b01810

International conferences

A02-11

  • ”First principles studies for optical near-field spectroscopy and photochemistry beyond the dipole approximation”, T. Iwasa (Invited), Pacifichem2021 (Online, Dec. 20, 2021).
Related Website(s)
Contact
tiwasa[at]sci.hokudai.ac.jp