Homogeneity radiofrequency

Link, J. The Design of Resonator Probes with Homogeneous Radiofrequency Fields. Vol. 26, pp. 1-32... 

Nuclear magnetic resonance is another characterisation technique of great practical importance, and yet another that became associated with a Nobel Prize for Physics, in 1952, jointly awarded to the American pioneers, Edward Purcell and Felix Bloch (see Purcell et at. 1946, Bloch 1946). In crude outline, when a sample is placed in a strong, homogeneous and constant magnetic field and a small radiofrequency magnetic field is superimposed, under appropriate circumstances the... 

Fig. 6 Schematic of a FTICR MS instrument. This type of MS consists of an ion cyclotron resonance (ICR) analyzer cell that is situated in the homogeneous region of a large magnet. The ions introduced into the ICR analyzer are constrained (trapped) by the magnetic field to move in circular orbits with a specific frequency that corresponds to a specific mass-to-charge ratio (m/z). Mass analysis occurs when radiofrequency (rf) potential is applied (pulsed) to the ICR analyzer so that all ions are accelerated to a larger orbit radius. After the pulse is turned off, the transient image current is acquired and a Fourier transform separates the individual cyclotron frequencies. Repeating this pulsing process to accumulate several transients is used to improve the signal-to-noise ratio. (Courtesy of Bruker Daltonics, Billerica, MA.)...

Total through-bond correlation technique using adiabatic pulses and fast MAS has been suggested by Hardy et al It has been shown that above a certain threshold, the polarisation transfer achieved with these sequences is largely insensitive to the amplitude and homogeneity of the radiofrequency field employed. An experimental transfer efficiency of up to 76 /o was achieved in a two-spin system. Applications to resonance assignments in the dipeptide L-Val-... 

The shape of NMR lines in a homogeneous magnet is dictated by the decay of the transverse magnetization, which is detected as the free induction decay (FID) following a radiofrequency pulse. If the observed nucleus remains in the same environment (associated to the same characteristic resonance frequency), the NMR lines will have a Lorentzian shape with a width at half height given by the effective transverse relaxation time T2). The faster the transverse relaxation, the broader will be the line (1) ... 

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