Spectroscopy and electron dynamics of polynuclear lanthanide and transition metal complexes (multi-lanthanide) (C05)

多核稀土元素和过渡金属配合物（多稀土元素）的光谱学和电子动力学（C05）

• 批准号: 189483018
• 金额: --
• 依托单位: Institut für Nanotechnologie (INT)
• 依托单位国家: 德国
• 项目类别: CRC/Transregios
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/189483018?language=en
• 关键词: Spectroscopy; electron; dynamics; polynuclear; lanthanide

The aim of the project in the second funding period is to synthesise an unprecedented family of [2x2] metalgrid complexes, to investigate their spin-dependent electron dynamics by spectroscopic methods, and toachieve active control over their cooperative magnetic properties. For this purpose, we will develop a newtype of grid-ligand that is stabilizing the metal ions - either a transition metal or a lanthanide - on their specificpositions. In particular, the backbone of the employed ligand family will allow controlling the overall-charge ofthe resulting grid complex and therefore also the number of counter ions. This may lead to neutral unchargedgrid complexes which potentially will be suitable for sublimation processing. Moreover, for FeII the ligandsystem is designed to access different conformational isomers, allowing to investigate and to compare theintrinsic cooperativity of the spin state switching process. We will separate the resulting two grid-types eitherby fractionated crystallization or more promising by ¿freezing¿ the two conformational isomers by chemicalsynthesis. This will prevent isomerisation allowing the separation of the isomers using columnchromatography. The control over the cooperative magnetic properties of these compounds will be achievedby following two main strategies:(i) Deposition of the complexes on magnetic substrates;(ii) Control of the spin state transition by optical triggers.The first approach (i) is to choose various ferromagnetic substrates (Fe, Co, Ni, magnetic oxides), to modifythe strength of the magnetic coupling with the spin centres of the deposited complexes. Different strengths ofthe magnetic coupling will inevitably influence the transition temperature of the high-spin (HS) and low-spin(LS) state transition, giving us control over the overall spin transition process. The second approach (ii) willtarget the selective optical excitation of the HS-LS transition in dynamical pump-probe spin-resolvedphotoemission experiments. Here, the wavelength of the optical pump pulse will be tuned to excite the HSLStransition, while the probe pulse will be selective to the specific spin state of the grid complexes depositedon the various ferromagnetic surfaces. Such experiments will thus give access to the fundamentaltimescales involved in the HS-LS transition, opening the way to the active control of the spin transition inmetal grid complexes deposited on magnetic surfaces by tailored optical excitation.

该项目在第二个资助期的目标是合成一个史无前例的[2x2]金属格栅配合物家族，用光谱方法研究它们与自旋相关的电子动力学，并实现对它们的协同磁性的主动控制。为此，我们将开发一种新型的网格配体，它可以稳定金属离子--无论是过渡金属还是稀土--在它们的特定位置上。特别是，所使用的配位体家族的主干将允许控制生成的网格络合物的总电荷，因此也可以控制反离子的数量。这可能导致中性的不带电荷的网格络合物，这将潜在地适合于升华处理。此外，对于FeII，配体系统被设计为访问不同的构象异构体，从而允许研究和比较自旋态转换过程的内在协同性。我们将通过分步结晶或更有希望的通过化学合成冻结两种构象异构体来分离得到的两种格子类型。这将防止异构化，允许使用柱层析法分离异构体。对这些化合物的协同磁性的控制将通过以下两个主要策略来实现：(I)将络合物沉积在磁性衬底上；(Ii)通过光学触发控制自旋态转变。第一种方法是选择不同的铁磁性衬底(Fe，Co，Ni，磁性氧化物)，以改变与沉积的络合物的自旋中心的磁耦合强度。不同的磁耦合强度将不可避免地影响高自旋(HS)和低自旋(LS)态转变的转变温度，使我们能够控制整个自旋转变过程。第二种方法(II)将针对动态泵浦-探测自旋分辨光电子能谱实验中HS-LS跃迁的选择性光激发。这里，光抽运脉冲的波长将被调谐以激发HSL跃迁，而探测脉冲将对沉积在各种铁磁表面上的网格络合物的特定自旋态具有选择性。这样的实验将获得HS-LS跃迁所涉及的基本时间尺度，从而为主动控制通过定制的光激发沉积在磁性表面上的金属格子络合物的自旋跃迁开辟了道路。