Magnetic susceptibility shielding

Magnetic susceptibility and nuclear magnetic shielding of a chosen nucleus I, in the presence of an external weak, homogeneous electric field E may be expanded as (3)... 

The third-rank diamagnetic and paramagnetic contributions to electric field dependent magnetic susceptibility and nuclear magnetic shielding, to first order in... 

The magnetic properties used to probe aromaticity arise from the presence of a diatropic ring current which tends to push an aromatic molecule out of a magnetic field (calculated property magnetic susceptibility, /). and which exerts NMR shielding on a proton at or above the ring center (calculated property nucleus-independent chemical shift, NICS). NICS values are obtained from the... 

Calculations of the dependence of the nuclear shielding on bond length in H2 appeared some years ago,56 and the authors have recently calculated the magnetic susceptibility using their wavefunction and compared it with the KW function.57 Several important predictions of this work remain to be experimentally verified. 

The constants / and g are functions of the magnetic susceptibility of the molecule when the magnetic field is aligned perpendicular or parallel to the intemuclear axis. They are very small in magnitude and were only included in the analysis of the high field spectra. We will discuss these quantities at length in section 8.2.2. They are closely related to the shielding parameter [Pg.380]

In general, where the proton in question does not lie on one of the principal axes of magnetic susceptibility, the shielding varies according to both distance and angle ... 

A demonstration of the efficacy of MBER spectroscopy is the recent experiments on HF carried out by Bass, DeLeon, and Muenter [14]. In an effort to obtain Stark, Zeeman, and hyperfine properties, measurements were made that gave accurate values for both the ground and first excited vibrational levels of HF. Conventional resonance experiments can be done if the D = 1 state can be sufficiently populated. Using a color center IR laser to excite HF to u = 1, J = 1 levels, all the properties measured for the u = 0 and V = 1 states had essentially identical precision. The results included dipole moments, magnetic shielding anisotropies, rotational magnetic moments, magnetic susceptibilities, transition moments, and first and second derivatives with respect to internuclear separation of the properties. 

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