标题： 非轴化效应和低能激发态在高频EPR探测下对五角双锥型铒(III)配合物慢磁弛豫的相关性研究 显示英文标题

标题： The Relevance of Non-axiality and Low-lying Excited States for Slow Magnetic Relaxation in Pentagonal-bipyramidal Erbium(III) Complexes Probed by High-frequency EPR

摘要： 高频/高场电子顺磁共振研究了一系列七配位五角双锥形（PBP）铒（III）配合物Er(DAPMBH/H$_2$DAPS)X (H$_2$DAPMBH = 2,6-二乙酰吡啶双-4-甲氧基苯甲酰腙, H$_4$DAPS = 2,6-二乙酰吡啶双-(水杨酰腙))，展示了不同顶端配体（X = (H$_2$O)Cl (1)，(CH$_3$OH)N$_3$ (2)，Cl$_2$ (3)）对中心Er(III)离子局部磁各向异性的影响。 特别是，我们报告了有效$g$值和能量上较低的克勒默双能级零场分裂的直接实验测定。 我们对磁各向异性的定量确定突显了轴向$g$张量对于单分子磁体行为的相关性，并表明快速磁弛豫主要由通过低能激发态的热辅助量子隧穿过程驱动。 显示英文摘要

摘要： High-frequency/high-field electron paramagnetic resonance studies on a series of seven-coordinate pentagonal-bipyramidal (PBP) erbium(III) complexes Er(DAPMBH/H$_2$DAPS)X (H$_2$DAPMBH = 2,6-diacetylpyridine bis-4-methoxy benzoylhydrazone, H$_4$DAPS = 2,6-diacetylpyridine bis-(salicylhydrazone)) demonstrate the effects of different apical ligands (X = (H$_2$O)Cl (1), (CH$_3$OH)N$_3$ (2), Cl$_2$ (3)) on the local magnetic anisotropy of the central Er(III) ions. In particular, we report direct experimental determination of the effective $g$-values and zero field splittings of the energetically low-lying Kramers doublets. Our quantitative determination of the magnetic anisotropy highlights the relevance of an axial $g$-tensor for SMM behaviour and suggests that fast magnetic relaxation is mainly driven by a thermally assisted quantum tunnelling process via low-lying excited states.