Albert Zens - Academia.edu (original) (raw)

Papers by Albert Zens

Journal of Magnetic Resonance, Feb 1, 2023

Journal of Magnetic Resonance

PURPOSE: To reduce a perturbation by the magnetic field caused by the inherent structure in the p... more PURPOSE: To reduce a perturbation by the magnetic field caused by the inherent structure in the probe of an NMR spectrometer in an analytical measuring device based on a magnetic resonance phenomenon. CONSTITUTION: The RF probe for a gyroscopic magnetic resonance spectrometer has a coil cage for supporting a probe coil and pref. supported within a cage formed by a, large number of rod-shaped members 62, 64, 66, 68, 70, 72 placed at positions parallel to the axial line of the coil and separated by a definite distance from the axial line. The passage to the coil passing through the slot extending in the axial direction or a slot like structure removes the nonequality in the axial direction of magnetization by separating the hole of a coil frame.

Journal of Magnetic Resonance, 2019

Shielding of the NMR sample by a thin coating of metal between the sample and the rf coil arises ... more Shielding of the NMR sample by a thin coating of metal between the sample and the rf coil arises in some geometries. The shielding may be used for rf heating of the sample tube or for a high infrared reflectivity coating in cryoprobe applications. An important application is for a shield that prevents noise from entering the rf probe circuit while allowing pulsed magnetic field gradients or field modulation to pass. We show by simple, approximate derivations that the criterion for shielding is not whether the coating exceeds the classical electromagnetic skin depth δ at the operating frequency (as is often stated), but whether the geometric mean between the thickness and an appropriate radius r exceeds δ. Thus, because r is typically much larger than δ, conducting layers substantially thinner than δ may still be good shields. Measurements are performed at high audio frequencies to confirm the calculations, using geometries relevant to rf saddle coils and to rf solenoids. Measurements of the slowing of the edges of a pulsed field gradient are also in accord with the calculations.

Chemischer Informationsdienst, 1976

Journal of Magnetic Resonance, 2015

We report on a method of measuring the high-field susceptibilities of paramagnetic and diamagneti... more We report on a method of measuring the high-field susceptibilities of paramagnetic and diamagnetic materials using only a standard NMR system equipped with pulsed field gradients. We demonstrate the accuracy and sensitivity of the technique by measuring a series of 99.9% copper wires with diameters between 0.16 mm and 0.79 mm. We measured the volumetric susceptibility of the copper to be χ=-9.5±0.2·10(-6), which agrees with the literature value of pure copper, -9.6·10(-6). In addition to making quantitative measurements, this technique can also be used to evaluate the effectiveness of compensation schemes used to produce "zero-susceptibility" materials needed for construction of high-resolution NMR probes.

Journal of the American Chemical Society, 1975

The Journal of Organic Chemistry, 1985