NMR偶合常数2) coupling constant 偶合常数 1. The coupling constants between 19 F and 1H/ 13 C were determined accurately. 用1 H ,1 3CNMR和多种二维核磁共振谱表征了本系列化合物的结构 ,完成了1 H和1 3CNMR谱带的归属 ,测定了氟原子对各质子和碳原子的偶合常数 ,探讨了影响偶合常数大小的因素...
Manatt, S L
The Value of the Gravitation Constant and Its Relation to Cosmic Electrodynamics Two central problems in cosmology are addressed in the context of the GEMS theory: (1) the value of the ratio of coupling constants of EM and gravity... Brandenburg,E John - 《IEEE Transactions on Plasma Science...
Determines the quadrupole coupling constant of the invisible aluminum spins in zeolite HY with 1H/27Al transfer of populations in double resonance (TRAPDOO... Grey,Clare,P.,... - 《Journal of the American Chemical Society》 被引量: 129发表: 1995年 1H/27Al TRAPDOR NMR studies on aluminum ...
NMR spin-spin coupling constants are calculated by means of the extended H眉ckel molecular orbital theory (EHMO). The contributions to the coupling constant from orbital, spin-dipolar, and Fermi-contact interactions are included. By use ... FAAM De Leeuw,CAG Haasnoot,C Altona - 《Journal of...
The magnitude of the interaction is given by the dipolar coupling constant, d, as shown in eqn [5]: 5d=−μ04πγIγSħrIS3 where r is the distance between the point-magnetic dipoles. The manifestation of the dipole–dipole coupling in the NMR signal is orientation-dependent, related ...
where γI, γS, ħ, and μ0 are the geomagnetic ratio of the I and S spins, the plank constant, and the magnetic permeability of a vacuum, respectively. If the molecular motion is sufficiently slower than the NMR timescale, the interatomic distance can be directly calculated from Eq. ...
On the other hand, the coupling constant for a two‐center two‐electron boron–boron bond is predicted to be invariably positive in sign. Results show that the positive sign must also be attributed to 1 J(BH), irrespective of the bridged or normal nature of the boron–hydrogen bond....
The Dirac vector model for the sign of the spin–spin coupling constant ( J) between a pair of atoms states that one-bond coupling constants are positive, two-bond negative, three-bond positive, etc. However, this rule is often violated. In an attempt to understand the sign of J, we ...
In high-resolution NMR, i.e., high frequency NMR, each peak is often split into multiple (or) cluster of peaks due to magnetic interactions between nonequivalent protons on adjacent carbons; the process is called spin–spin splitting or spin–spin coupling. The coupling constant J (usually in...