scholarly journals Surface Nuclear Magnetic Resonance (SNMR) - A new method for exploration of ground water and aquifer properties

2009 ◽  
Vol 43 (6) ◽  
Author(s):  
U. Yaramanci
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ground Water ◽  
New Method ◽  
Aquifer Properties ◽  
Nuclear Magnetic

Frequency cycling for compensation of undesired off-resonance effects in surface nuclear magnetic resonance

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. WB33-WB48 ◽  
Author(s):  
Denys Grombacher ◽  
Mike Müller-Petke ◽  
Rosemary Knight
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Larmor Frequency ◽  
Forward Model ◽  
Resonance Excitation ◽  
Entire Volume ◽  
Resonance Effects ◽  
Aquifer Properties ◽  
The Impact ◽  
Nuclear Magnetic

To produce reliable estimates of aquifer properties using surface nuclear magnetic resonance (NMR), an accurate forward model is required. The standard surface NMR forward model assumes that excitation occurs through a process called on-resonance excitation, which occurs when the transmit frequency is set to the Larmor frequency. However, this condition is often difficult to satisfy in practice due to the challenge of accurately determining the Larmor frequency within the entire volume of investigation. As such, in situations where an undesired offset is present between the assumed and true Larmor frequency, the accuracy of the forward model is degraded. This is because the undesired offset leads to a condition called off-resonance excitation, which impacts the signal amplitude, phase, and spatial distribution in the subsurface, subsequently reducing the accuracy of surface NMR estimated aquifer properties. Our aim was to reduce the impact of an undesired offset between the assumed and true Larmor frequency to ensure an accurate forward model in the presence of an uncertain Larmor frequency estimate. We have developed a methodology where data are collected using two different transmit frequencies, each an equal magnitude above and below the assumed Larmor frequency. These data are combined, through a method we refer to as frequency cycling, in a manner that allow the component well-described by our estimate of the Larmor frequency to be stacked coherently, whereas the component related to the presence of an undesired offset is combined destructively. In synthetic and field studies, we have determined that frequency cycling is able to mitigate the influence of an undesired offset providing more accurate estimates of aquifer properties. Furthermore, the frequency-cycling method stabilized the complex inversion of surface NMR data, allowing advantages associated with complex inversion to be exploited.

scholarly journals Identification of Ambergris from the New Bedford Whaling Museum by Nuclear Magnetic Resonance Spectroscopy

1996 ◽  
Vol 79 (2) ◽  
pp. 423-425 ◽  
Author(s):  
George A Moniz ◽  
Gerald B Hammond
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Adsorption Chromatography ◽  
New Method ◽  
Major Constituent ◽  
Resonance Spectroscopy ◽  
Nuclear Magnetic

Abstract A new method for the separation and identification of ambrein in ambergris using adsorption chromatography and 1H and 13C Fourier transform nuclear magnetic resonance spectroscopy (FT-NMR) is presented. We demonstrated the effectiveness of this method by analyzing an approximately 85-year-old sample of suspected ambergris from the New Bedford Whaling Museum (New Bedford, MA). Results prove that ambrein remains a major constituent of ambergris even after 85 years of storage under ordinary conditions.

scholarly journals C-S-H Pore Size Characterization Via a Combined Nuclear Magnetic Resonance (NMR)–Scanning Electron Microscopy (SEM) Surface Relaxivity Calibration

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1779 ◽  
Author(s):  
Christoph Naber ◽  
Florian Kleiner ◽  
Franz Becker ◽  
Long Nguyen-Tuan ◽  
Christiane Rößler ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ion Beam ◽  
New Method ◽  
Sem Images ◽  
Surface Relaxivity ◽  
Scanning Electron ◽  
Nuclear Magnetic

A new method for the nuclear magnetic resonance (NMR) surface relaxivity calibration in hydrated cement samples is proposed. This method relies on a combined analysis of 28-d hydrated tricalcium silicate samples by scanning electron microscopy (SEM) image analysis and 1H-time-domain (TD)-NMR relaxometry. Pore surface and volume data for interhydrate pores are obtained from high resolution SEM images on surfaces obtained by argon broad ion beam sectioning. These data are combined with T2 relaxation times from 1H-TD-NMR to calculate the systems surface relaxivity according to the fast exchange model of relaxation. This new method is compared to an alternative method that employs sequential drying to calibrate the systems surface relaxivity.

The measurement of frequency separations in high resolution nuclear magnetic resonance spectra using a frequency modulated observing field

1972 ◽  
Vol 25 (6) ◽  
pp. 1207 ◽  
Author(s):  
AG Moritz
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Line Profile ◽  
New Method ◽  
Side Band ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

A new method for the measurement of frequency separations in high resolution nuclear magnetic resonance spectra is presented. The method, which involves comparison of two points on the line profile, is shown to be capable of an internal precision of at least 2 mHz. Line separations measured in this way are shown to give results consistent with those obtained using a double-lock spectrometer and a nuclear double side-band oscillator.

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