総説

高磁場−高周波数電子スピン共鳴測定
（多周波数ESR測定）

High Field-High Frequency Electron Spin Resonance Spectroscopy
(Multi-Frequency ESR Spectroscopy )

加藤 立久
Tatsuhisa KATO

高磁場−高周波数電子スピン共鳴(ESR)測定を用いて金属内包フラーレンの分子磁性を明らかにした。X-band ESR 測定に加えてW-band 測定を行うと、高磁場化によるg因子の高分解能分離ばかりでなくスピンハミルトニアン中の磁場に比例しない項を容易に分離出来る利点がある。複数のマイクロ波周波数を用いた測定を組み合わせることで、対象スピン系のESR パラメータ決定を見通し良くし、曖昧さのない決定が可能となる。

High field-high frequency electron spin resonance (esr) spectroscopy is applied to the determination of spin parameters for metallofullerenes. The esr measurements combined with multi-frequency microwave are indispensable for unambiguous determination of the parameters. The magnetic field independent terms in the spin Hamiltonian can be easily distinguished from the dependent ones by using the multi-frequency esr measurements. The orientation-dependent g-tensor of La@C₈₂ can be determined by W-band measurements. The fine structures in the high spin system of Eu@C₈₂ are clearly analyzed by the combination of W-band spectroscopy with X-band one. In Gd@C₈₂ there are two spin sites within a molecule, the high spin site on the Gd³⁺ ion and the other radical site on the fullerene cage. The exchange interaction is valued by the temperature dependent W-band measurements. The large hyperfine interaction due to La₂ dimer nuclei within C₈₀ is investigated for La₂@C₈₀ anion.