在Cs2NaBiCl6双矿中使用磁共振光谱进行三角测量
Abhoy Karmakar1, Guy M Bernard1, Arkadii Pominov1
1Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Journal of the American Chemical Society
|February 14, 2023
概括
这项研究使用磁共振来研究含的无双矿. 在位发生 doping,影响材料
科学领域:
- 材料科学
- 固态化学
- 光谱学
背景情况:
- 无金属化物双矿对光电子具有前景.
- 使用过渡金属调节光学带隙.
- 在低兴奋剂水平下,Mn (II) 在Cs2NaBiCl6的结合部位尚不清楚.
研究的目的:
- 在Cs2NaBiCl6中确定Mn(II) 的原子层结构.
- 了解高级光电子应用的结构-属性关系.
- 通过磁共振技术阐明Mn(II) 的插入位置.
主要方法:
- 结合固态核磁共振 (NMR),动态核极化 (DNP) 和电子偏磁共振 (EPR) 光谱的多技术方法.
- 多核核核磁共振 (Na23,Cl35,Cs,209),用于探测当地环境.
- 通过EPR和HYSCORE分级CORrelation光谱识别二氧化状态,对称性和相互作用.
主要成果:
- 检测到低水平的Mn (II) 结合,受影响的旋转显示了对磁放松增强 (PRE).
- 在HYSCORE中证实了Mn (II) 的八面对称性,没有Bi相关性,表明Bi位点的替代.
- 在室温下,NMR和EPR显示立方体结构,偏差低于30K. DNP NMR支持均的Mn{\displaystyle Mn}
结论:
- 在Cs2NaBiCl6双矿结构中替代Bi.
- 这种材料在室温下保持立方对称性,但在低温下会出现偏差.
- 磁共振技术成功阐明了2的结合部位和分布,为光电子应用提供了更深入的理解.
相关概念视频
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.1K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.1K
02:42Valence Bond Theory
8.9K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.9K
01:13¹H NMR: Complex Splitting
1.3K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.3K
03:02Colors and Magnetism
12.1K
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...
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...
12.1K
01:17Chemical Shift: Internal References and Solvent Effects
705
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
705
01:15NMR Spectroscopy: Chemical Shift Overview
1.6K
The position of the absorption signal of a sample is reported relative to the position of the signal of tetramethylsilane (TMS), which is added as an internal reference while recording spectra. The difference between the absorption frequencies of the sample and TMS (in Hz) is divided by the spectrometer operating frequency (in MHz) to obtain a dimensionless quantity called the chemical shift. It is reported on the δ (delta) scale and expressed in parts per million.
For instance, the proton...
For instance, the proton...
1.6K