Chemical shift factors determining position

If the two radicals were identical, the precession frequency of the two electrons would be precisely the same, and a particular radical pair would remain in whichever of the four states it found itself initially. But if the two radicals are different, the two electrons will have slightly different precession frequencies. The precession frequency of an electron is characterized by a quantity called the g factor. If one were to observe just one of the radicals of the pair in an electron paramagnetic resonance spectrometer, the value of its g factor would determine the position of the resonance line in the spectrum g of an electron in a radical is thus analogous to chemical shift of a proton. 

The L2,3 edges of the 4th period transition metals are marked by prominent "white line" features due to excitations of the 2p3/2 (L3) and 2pi/2 (L2) levels, following the allowed dipole transitions, to unoccupied d states. On the basis of the (2j + 1) degeneracy in a one electron model, the L3/L2 intensity ratio should be 2 1, but wide departures from this ratio have been observed in transition metals and their oxides [21, 22, 29, 30]. Even though no single factor has been found to account for these observations, these extensive studies form the basis of an empirical catalogue of L3/L2 ratios to be used in future determinations of the oxidation states. Further, positive chemical shifts are also observed as a function of oxidation states for Tj 3+- Ti4+ (2 eV), Mn2+ - Mn4+ (2 eV), Fe2+... 

The peak position or chemical shift of an NMR peak within the phosphorus spectrum is determined by the electron cloud around the nucleus. When the electron cloud is altered, the peak will shift position. Binding of an ion to an NMR visible compound changes the electron cloud and produces a position proportional to the concentration of the ion. Different ion concentrations are used to generate a titration curve from which a particular position can be converted into an ion concentration. To be an effective method in tissue spectroscopy, the physiological concentration of the ion must be within a factor of 10 of the pK of the binding of the ion and must be the predominant ion binding to the compound. This means that Pj, with a pK of 6.77 (Kushmerick etal., 1986), is useful in monitoring tissue... 

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