Synthesis of superatomic metal clusters by microdroplet chemistry and its application to photoelectron imaging

2024 Fiscal Year Final Research Report

• Project/Area Number: 22K19009
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Kyushu University
• Principal Investigator: Horio Takuya 九州大学, 理学研究院, 准教授 (40443022)
• Project Period (FY): 2022-06-30 – 2025-03-31
• Keywords: 金属クラスター / 光電子イメージング / 微小液滴 / 超原子 / 量子サイズ効果

Outline of Final Research Achievements

This study aims to develop a novel, cost-effective method to synthesize gas-phase superatomic metal clusters via reduction reactions in microdroplets and analyze their electronic structures using a highly efficient photoelectron imaging technique. Through investigations of clusters such as Ag18－, Ag15Sc－, Ag12M－ (M=V, Nb, Ta), and Ag3－, we successfully visualized their occupied molecular orbitals and characterize the discrete energy levels and the angular momenta. The findings were supported by quantum chemical calculations and ezDyson simulations, enabling the identification of orbital types (e.g., 1S, 1P, 1D，2S) and structural symmetries. Notably, the work includes the first angular-momentum-resolved measurements for binary clusters, providing experimental insights into electron behavior in complex quantum systems. These achievements offer a foundation for further advancement in superatom-based material science and quantum nanostructure research.

Free Research Field

物理化学

Academic Significance and Societal Importance of the Research Achievements

本研究では、物理化学とクラスター科学を専門とする研究代表者により、超原子金属クラスターに形成される価電子軌道の軌道エネルギーならびに軌道角運動量状態を明らかにしました。量子サイズ効果の産物であるこれら価電子軌道の特性を明らかにした本成果は，量子論の学理構築に貢献するとともに，超原子物質科学や量子材料研究に資する基礎物理化学的知見を与えた点に，学術的かつ社会的意義があります。さらに，繰返し周波数100 kHzという前例の無い効率で光電子可視化計測を実現した点も当該分野において画期的です。今後，超原子金属クラスターを基盤とする機能性物質の開発や量子材料設計への発展が期待されます。