六核的光谱和光物理性质 ((III) 石灰集群
Thomas G Gray1, Christina M Rudzinski, Emily E Meyer
1Department of Chemistry, Massachusetts Institute of Technology 6-335, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|April 17, 2003
概括
六核 ((III) 石灰集群表现出可调节的发光. 连接物选择显著影响量子产量和寿命,在潜在应用中以能量差距定律为指导.
科学领域:
- 无机化学 无机化学
- 材料科学 材料科学 材料科学
- 摄影化学的使用.
背景情况:
- 六核 (III) 石灰集群 ([Re(6) ((mu(3) -Q) ((8))) ((2+)) 是异电子的,具有独特的电子和光学特性.
- 了解它们的兴奋状态特性对于开发新的发光材料至关重要.
研究的目的:
- 研究[Re(6) Q(8) ](2+) 星团 (Q = S, Se) 的电子,振动和兴奋状态属性.
- 阐明控制发光的因素,包括量子产量和寿命.
- 探索基于发光的应用的潜力.
主要方法:
- 光谱方法 (UV-Vis激发,发光光谱学).
- 理论计算 (哈特里-福克,DFT,正常坐标分析).
- 温度依赖的排放实验和非辐射衰变建模.
主要成果:
- 发光最大范围在12,500-15,100厘米 (-1) 之间,量子产量为1-24%和寿命为2.6-22.4微秒.
- 非辐射衰变和发光最大值与能量差距定律 (EGL) 相对应.
- 外集群配体,特别是以氧或为基础的顶端配体,提高量子产量和寿命.
结论:
- 激发状态衰变主要是由以核心为中心的振动模式驱动的,这是理论计算所支持的.
- 能量差距定律有效地预测了集群行为,配体修饰提供了对发光的控制.
- 这些发现为设计基于团的发光材料奠定了基础.
相关概念视频
04:00Periodic Classification of the Elements
The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their electron configurations are added to the table, a periodic recurrence of similar electron configurations in the outer shells of these elements is observed. Because they are in the outer shells of an atom, valence electrons play the most important role in chemical reactions. The outer electrons have the highest energy of the electrons in an atom...
02:58Properties of Transition Metals
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:24The Seven Crystal Systems: Overview
Crystals with various point group symmetries belong to different crystal classes, which are synonymous terms. Despite being in the same class, crystals may have distinct shapes, like cubes and octahedra. There are 32 three-dimensional point groups, all of which are systematically divided into seven crystal systems.The basic cubic crystal system, exemplified by NaCl, features orthogonal vectors (α = β = �� = 90°) of equal lengths (a = b = c). When specific requirements are not imposed on the...
01:29Crystallographic Point Groups
Crystallographic point groups represent the various symmetry operations that can occur within crystals. They are unique in that at least one point will always remain unchanged during these actions. For instance, consider the triclinic system. This system, devoid of any axis or plane of symmetry, aligns with the C1 and Ci point groups.where Cᵢ is characterized solely by a center of inversion.Contrastingly, the monoclinic system introduces an element of symmetry. This system with one plane and...