Mobile single-sided NMR

Progress in Nuclear Magnetic Resonance Spectroscopy (Impact Factor: 7.24). 05/2008; 52(4):197-269. DOI: 10.1016/j.pnmrs.2007.10.002


The development of NMR instrumentation, methods, and applications of mobile NMR, with particular attention to single-sided NMR is discussed. Inside-out NMR is a form of single-sided or unilateral NMR, where an NMR sensor much smaller than the object is placed near the object to acquire signals from the object volume near the sensor. Mobile NMR holds great promise in a variety of fields, in particular in medicine, materials science, chemical engineering and space science. A very promising area of application of mobile NMR is process control by sensors installed in the production line. The development of NMR methods for mobile NMR is driven by two sources. One is the need for more information from, and better accuracy of, well-logging instruments. The other is scientific curiosity about doing NMR in low and inhomogeneous fields with inexpensive instrumentation and with it the drive for expanding the range of applications of NMR.

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    • "In an inhomogeneous magnetic field, such as in NMR MOUSE devices, the NMR signal (FID) decays very quickly and, thus, cannot be directly detected. Therefore, signal decay is generally recovered in single-sided NMR devices by applying Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence [10]. Usually, the first echoes obtained are removed and the decay of the echo amplitudes is fitted using an exponential function. "
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    ABSTRACT: Single-sided NMR devices, like NMR MOUSE (MObile Universal Surface Explorer), are designed to allow NMR surface measurements to be conducted on arbitrarily large samples, and are therefore valuable tools to evaluate non-invasively moisture content ‘‘inside’’ a planar object. In this work, we aim to perform “in situ” studies of moisture transport in building materials during drying experiments with NMR MOUSE. The local moisture content was monitored over time and mapped over sample thickness with a depth resolution of 0.5 mm and a maximum penetration depth of 25 mm. In addition, NMR MOUSE allows measuring longitudinal and transverse relaxation time (T1 and T2) and 2D relaxation spectra, as well as self-diffusion coefficient. Experimental results show that moisture content is homogeneously distributed over the thickness, which indicates that moisture is transferred through capillary processes. Furthermore, transverse relaxation time distribution measurements revealed that the drainage of pore water occurs sequentially from larger pores to smaller pores.
    6th International Building Physics Conference, Torino; 06/2015
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    • "Because the number and the amount of samples collected from precious artifacts must be reduced to a minimum , multi-analytical studies where micro-destructive, non-destructive, and possibly non-invasive techniques are 0935-1221/15/0027-2453 $ 6.30 DOI: 10.1127/ejm/2015/0027-2453 eschweizerbart_xxx combined, are advisable. Within this framework, a breakthrough for the NMR application to cultural heritage has been the development of portable unilateral NMR sensors (Mitchell et al., 2006, 2014; Blümich et al., 2008; Perlo et al., 2011). These instruments, combining open magnets and surface radiofrequecy (RF) coils to generate a sensitive volume external to the sensor and inside the object under investigation, allow one to study non-invasively and in situ variably sized objects (Eidmann et al., 1996). "
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    ABSTRACT: Nuclear Magnetic Resonance (NMR) can be successfully applied to a wide number of organic, inorganic, and hybrid materials regarding cultural heritage. High-resolution solid-state NMR provides information on the structure of materials, and portable NMR devices allow non-destructive and non-invasive in situ investigation of variably sized objects. This result is possible by combining open magnets and surface radiofrequency coils to generate a sensitive volume external to the sensor and inside the object under investigation. In this paper we focus on the application of NMR to investigate inorganic porous materials such as pottery, plasters, and stones from cultural heritage sites. 27Al MAS and 3QMAS, and 29Si MAS high-resolution solid-state NMR along with spectral deconvolution allowed for the investigation of the chemical structure of ancient pottery. Portable unilateral NMR was used to investigate, in a non-invasive and non-destructive way, the porous structure of pottery. The effect of protective-consolidating treatments on plaster was carefully investigated by 1H NMR depth profiles that allowed for scanning with micrometric resolution of plaster specimens. Changes occurring in the total open porosity after treatments were also evaluated. NMR diffusion measurements provided information on the restricted geometry of the porous structure of two types of biocalcarenite and tuff. A suitable processing of collected data enabled us to define the average pore radius and pores’ interconnection in these materials.
    European Journal of Mineralogy 06/2015; 27 (3)(3):297-310. DOI:10.1127/ejm/2015/0027-2453 · 1.48 Impact Factor
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    • "There are several factors responsible for that. Most importantly, the inhomogeneous B 0 and B 1 fields lead to a distribution of RF pulses across the sensitive volume [15] [29], producing multiple magnetization pathways and reducing the contribution of the ideal (90–180–180–. . .) pathway to the total NMR signal with every subsequent echo. "
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    ABSTRACT: An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an “effective” square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR.
    Journal of Magnetic Resonance 10/2014; 248:1-7. DOI:10.1016/j.jmr.2014.09.003 · 2.51 Impact Factor
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