Achieving ultranarrow absorption linewidths in the condensed phase enables optical state preparation of specific non-thermal states, a prerequisite for quantum-enabled technologies. The 4f orbitals of lanthanide(III) complexes are often referred to as “atom-like,” reflecting their isolated nature, and are promising substrates for the optical preparation of specific quantum states. To better understand the photophysical properties of 4f states and assess their potential for quantum applications, theoretical building blocks are required for rapid screening. In this study, an atomic-level perturbative calculation (i.e., spin-orbit crystal field, SOCF) is applied to various Yb(III) complexes to investigate their linear absorption and emission through a fitting mechanism of their experimentally determined transition energies and oscillator strengths. In particular, the optical properties of (thiolfan)YbCl(THF) (thiolfan = 1,1′-bis(2,4-di-tert-butyl-6-thiomethylenephenoxy)ferrocene), a recently reported complex with a ultranarrow optical linewidth, are computed and compared to those of other Yb(III) compounds. Through a transition energy sampling study, major contributors to the optical linewidth are identified. We observe particularly isolated f-f transitions and narrow linewidths, which we attribute to two distinct factors. Firstly, the ultra-high atomic similarity of the orbitals involved in the optical transition, along with the presence of an anisotropic crystal field, collectively contribute to the observed narrow transitions. Secondly, we note highly correlated excited-ground energy fluctuations that serve to greatly suppress inhomogeneous line-broadening. This article illustrates how SOCF can be used as a low-cost method to probe the influence of crystal field environment on the optical properties of Yb(III) complexes to assist the development of novel lanthanide series quantum materials.

中文翻译：

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阐明镱 (III) 配合物中的超窄 2F7/2 至 2F5/2 吸收


在凝聚相中实现超窄吸收线宽可以实现特定非热态的光学态制备，这是量子技术的先决条件。镧系元素 (III) 配合物的 4f 轨道通常被称为“类原子”，反映了它们的孤立性质，并且是用于特定量子态光学制备的有前途的底物。为了更好地了解 4f 态的光物理性质并评估其量子应用潜力，需要理论构建模块来进行快速筛选。在这项研究中，将原子级微扰计算（即自旋轨道晶体场，SOCF）应用于各种 Yb(III) 配合物，通过实验确定的跃迁能量和振荡器强度的拟合机制来研究它们的线性吸收和发射。特别是 (thiolfan)YbCl(THF) (thiolfan = 1,1′-bis(2,4-di-tert-丁基-6-thiommethylphenoxy)ferrocene) 的光学性质，这是最近报道的一种具有超窄光学线宽的配合物，计算并与其他 Yb(III) 化合物进行比较。通过跃迁能量采样研究，确定了光学线宽的主要贡献者。我们观察到特别孤立的 f-f 跃迁和窄线宽，我们将其归因于两个不同的因素。首先，光学跃迁涉及的轨道的超高原子相似性，以及各向异性晶体场的存在，共同促成了观察到的窄跃迁。其次，我们注意到高度相关的激发基能量涨落，有助于极大地抑制不均匀谱线展宽。 本文阐述了如何利用SOCF作为一种低成本方法来探究晶体场环境对Yb(III)配合物光学性质的影响，以协助新型镧系量子材料的开发。