Spin‐Polarized Photoluminescence in Au 25 (SC 8 H 9 ) 18 Monolayer‐Protected Clusters
Spin‐Polarized Photoluminescence in Au 25 (SC 8 H 9 ) 18 Monolayer‐Protected Clusters
复制标题
Au 25 (SC 8 H 9 ) 18 单层保护团簇中的自旋偏振光致发光
DOI：
10.1002/smll.202004431
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发表时间：
2021
期刊：
影响因子：
13.3
通讯作者：
Knappenberger, Jr., Kenneth L.
中科院分区：
文献类型：
--
作者：
Herbert, Patrick J.;Knappenberger, Jr., Kenneth L.
本文报道了Au 25（SC 8H 9）18单分子层保护团簇（MPC）的自旋极化辐射的观测结果.变温变场磁圆光致发光（VTV-MCPL）测量与VT-PL光谱相结合，以提供Au 25（SC 8H 9）18的瞬态电子结构和自旋极化电子空穴复合动力学的状态分辨表征。通过对VTV-MCPL测量结果的分析，低能（1.64 eV）发射峰被分配给核心金属局域超原子-D到-P轨道之间的带内弛豫。两个更高能量的带间分量（1.78 eV，1.94 eV）被分配给从超原子-D轨道到无机半环局域态的弛豫。对于带内超原子或带间弛豫机制，自旋极化的程度，量化为圆极化度（DOCP），由状态特定的电子振动耦合强度和亮和暗电子精细结构能级的能量分离决定。在低温（<60 K）下，基于金属-金属超原子的带内跃迁主导了全局PL发射。在较高温度（>60 K）下，基于带间配体的发射占主导地位。在低温PL区，样品温度升高会导致整体PL强度增大。在高温状态下，升高的温度淬灭带间辐射复合。每种PL机制的相对强度根据特定状态的电子振动耦合强度进行讨论，并与由Landég因子量化的总角动量相关。
Here, the observation of spin‐polarized emission for the Au25(SC8H9)18monolayer‐protected cluster (MPC) is reported. Variable‐temperature variable‐field magnetic circular photoluminescence (VTV‐MCPL) measurements are combined with VT‐PL spectroscopy to provide state‐resolved characterization of the transient electronic structure and spin‐polarized electron‐hole recombination dynamics of Au25(SC8H9)18. Through analysis of VTV‐MCPL measurements, a low energy (1.64 eV) emission peak is assigned to intraband relaxation between core‐metal‐localized superatom‐D to ‐P orbitals. Two higher energy interband components (1.78 eV, 1.94 eV) are assigned to relaxation from superatom‐D orbitals to states localized to the inorganic semirings. For both intraband superatom‐based or interband relaxation mechanisms, the extent of spin‐polarization, quantified as the degree of circular polarization (DOCP), is determined by state‐specific electron‐vibration coupling strengths and energy separations of bright and dark electronic fine‐structure levels. At low temperatures (<60 K), metal–metal superatom‐based intraband transitions dominate the global PL emission. At higher temperatures (>60 K), interband ligand‐based emission is dominant. In the low‐temperature PL regime, increased sample temperature results in larger global PL intensity. In the high‐temperature regime, increased temperature quenches interband radiative recombination. The relative intensity for each PL mechanism is discussed in terms of state‐specific electronic‐vibrational coupling strengths and related to the total angular momentum, quantified by Landég‐factors.