Shielding of nuclei

The results of research on the NMR spectra of elements with different isotopic composition have been reported. (95) The particular interest of these investigations lies in the possibility of applying perturbation theory to account for the contribution of vibrational states to the shielding of nuclei. (96, 97) In addition, the measurement of nuclear g factors of isotopic pairs, with great accuracy, is required for evaluating small hyperfine structure anomalies. (39,98)... 

Numerical ab initio calculations for selected examples with polarized basis sets and Cl of reasonably size confirmed that the size of the matrix elements within the active space matrix is negligible. In contrast, the elements of that involve both the active and inner shells are large, since is primeuily due to the shielding of nuclei by inner-shell electrons [11]. It is therefore common practice in many semiquantitative applications, to account for the effect of the fixed-core electrons by replacing the factor gPgZ r in by the empirical value of the atomic spin-orbit coupling constant valence p orbitals on... 

Sex hormones, 1040—1042, 1044 Shared-electron pair bond. See Covalent bond Shielding of nuclei in NMR spectroscopy, 493—495. See also Chemical shift Sickle-cell anemia, 1089—1090, 1100 Sigma bond, 32... 

In the opening chapter, An Introduction to Solution, Solid-State, and Imaging NMR Spectroscopy Leslie Butler (Louisiana State University) introduces the fundamental structure parameters in the NMR experiment through a discussion on solution state H NMR. The shielding of nuclei by core and valence electrons, gives rise to those structure-pregnant numbers called chemical shifts, d, that have been accrued and correlated since the earliest days of NMR. Scalar coupling,... 

Thus, NMR speetroseopy and cryoporometry are effective methods to study the interfacial phenomena especially at a carbon surface because of an additional factor such as jr-electron clouds at the carbon sheets affeeting electron shielding of nuclei of adsorbed compounds depending on the pore size and strueture of the pore walls. 

N. F. Ramsey. Dependence of Magnetic Shielding of Nuclei upon Molecular Orientation. Phys. Rev., 83(3) (1951) 540-541. 

The shielding of nuclei by y-substituents in a gauche arrangement (y-gauche effect) enables us to both complete and simplify the conformational connection between the microstructures and NMR spectra of polymers. 

Theory of magnetic shielding of nuclei in Lamb, Phys. Rev. 60 817... 

Comparison of the magnetic moments for alkali metal cations purely surrounded by water molecules with the results of atomic beam magnetic resonance experiments yields the shielding of nuclei by water molecules around the ions. This shielding, which for instance for ions is worth -0.1052 x 10 , is a nearly linear function of the atomic number (62). 

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