NMR Spectroscopy of Xenon in Confined Spaces: Clathrates, Intercalates, and Zeolites

Dybowski, Cecil; Bansal, Navin; Duncan, T. M.

doi:10.1146/annurev.pc.42.100191.002245

Cited by 159 publications

(117 citation statements)

References 38 publications

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“…Starting from the first publications [1,2], the use of 129Xe NMR has proved to be very valuable in the study of porous materials. There ate already several reviews on the subject [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

129Xe NMR studies of the dynamics of xenon in siliceous ZSM-12 zeolite

1996

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The adsorption of xenon in siliceous zeolite ZSM-12 has been studied by static, magic angle spinning and 2D-EXSY 129Xe NMR. Anisotropic lines were observed with parameters dependent on the Xe loading and the temperature of the experiment. The observed dependence of the isotropic chemical shift is at variance with the predictions of the mean-free-path model, which casts further doubt on the applicability of this model to the interpretation of Xe NMR data in porous systems. Based on the continuous changes of anisotropic parameters with the loading, we conclude that there are several adsorption sites for xenon in the pores. A qualitative model for the distribution and rapid exchange of the xenon atoms between several sites is discussed. The observed lines arise from a dynamic average of the chemical shift tensors for the different types of site weighted by their populations. 2D-EXSY spectra show two kinds of slow exchange of Xe: (a) particle to particle and, (b) particle to interparticle gas phase.

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Section: Introductionmentioning

confidence: 99%

129Xe NMR studies of the dynamics of xenon in siliceous ZSM-12 zeolite

1996

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“…In vivo MRI of airways with hp 129 Xe as a contrast agent (19)(20)(21) suffers from a lower sensitivity compared with hp 3 He. However, 129 Xe adds a further parameter not available by 3 He, namely, the chemical shift that allows for insights into the local environment of the xenon atoms (22)(23)(24)(25)(26)(27). The 129 Xe chemical shift has been used extensively for research in materials science, engineering, and xenon dissolved in liquids including human blood (3,5,6,8,9,12,28).…”

mentioning

confidence: 99%

Hyperpolarized krypton-83 as a contrast agent for magnetic resonance imaging

Pavlovskaya

Cleveland

Stupic

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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For the first time, magnetic resonance imaging (MRI) with hyperpolarized (hp) krypton-83 ( 83 Kr) has become available. The relaxation of the nuclear spin of 83 Kr atoms (I ‫؍‬ 9͞2) is driven by quadrupolar interactions during brief adsorption periods on surrounding material interfaces. Experiments in model systems reveal that the longitudinal relaxation of hp 83 Kr gas strongly depends on the chemical composition of the materials. The relaxationweighted contrast in hp 83 Kr MRI allows for the distinction between hydrophobic and hydrophilic surfaces. The feasibility of hp 83 Kr MRI of airways is tested in canine lung tissue by using krypton gas with natural abundance isotopic distribution. Additionally, the influence of magnetic field strength and the presence of a breathable concentration of molecular oxygen on longitudinal relaxation are investigated.NMR ͉ optical pumping ͉ pulmonary ͉ MRI ͉ xenon H igh nuclear spin polarization in noble gasses can be generated through rubidium vapor spin exchange optical pumping (RbSEOP) (1) and allows for NMR signal enhancements of many orders of magnitude (2). Hyperpolarized (hp) 3 He and hp 129 Xe (both I ϭ 1͞2) have both been used in a wide range of NMR and magnetic resonance imaging (MRI) experiments that are otherwise impossible (3-15). In particular hp 3 He has been applied for medical MRI diagnosis of pulmonary diseases (16)(17)(18)(19). One of the fundamental parameters with high diagnostic value for hp 3 He MRI is the spin-density that is a result of the helium concentration in a particular volume. Spin-density mapping of hp 3 He can be applied to visualize ventilation in lungs. Other useful parameters are 3 He diffusion that provides information about alveolar size distributions in lung tissue and hp 3 He relaxation that depends on oxygen partial pressure in lungs. In vivo MRI of airways with hp 129 Xe as a contrast agent (19-21) suffers from a lower sensitivity compared with hp 3 He. However, 129 Xe adds a further parameter not available by 3 He, namely, the chemical shift that allows for insights into the local environment of the xenon atoms (22-27). The 129 Xe chemical shift has been used extensively for research in materials science, engineering, and xenon dissolved in liquids including human blood (3,5,6,8,9,12,28). The chemical shift obtained from hp 129 Xe can be used to generate an in vivo MRI contrast that is a probe for gas perfusion in lungs (i.e., exchange of the gaseous xenon with the lung parenchyma) (29).3 He and 129 Xe are the only spin I ϭ 1͞2 stable isotopes of the noble gas group, but there are three more NMR active isotopes in this group with higher spin that possess a nuclear electric quadrupole moment. The three quadrupolar isotopes are 21 Ne (I ϭ 3͞2, natural abundance 0.27%), 83 Kr (I ϭ 9͞2, natural abundance 11.5%), and 131 Xe (I ϭ 3͞2, natural abundance 21%). Quadrupolar interactions in these noble gas atoms cause spin relaxation and coherent spin evolution that are probes for the shape, size, and symmetry of void spaces as well as the ...

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“…60,61 The production of hp 83 Kr, in contrast, requires prolonged periods of optical pumping. 38 Similar to 3 He, 24 long RbSEOP times are required for the production of hp 83 Kr because the relevant spin exchange cross-sections for the rubidium-krypton system 24,36 are much smaller than those in the rubidium-xenon system. 62 Additionally, quadrupolar relaxation on pump cell walls slows the polarization buildup rate.…”

Section: Longitudinal Relaxation In Hp 83 Krmentioning

confidence: 99%

Studying porous materials with krypton-83 NMR spectroscopy

Cleveland

Meersmann

2007

Magn. Reson. Chem.

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This report is the first review of (83)Kr nuclear magnetic resonance as a new and promising technique for exploring the surfaces of solid materials. In contrast to the spin I = 1/2 nucleus of (129)Xe, (83)Kr has a nuclear spin of I = 9/2 and therefore possesses a nuclear electric quadrupole moment. Interactions of the quadrupole moment with the electronic environment are modulated by surface adsorption processes and therefore affect the (83)Kr relaxation rate and spectral lineshape. These effects are much more sensitive probes for surfaces than the (129)Xe chemical shielding and provide unique insights into macroporous materials in which the (129)Xe chemical shift is typically of little diagnostic value. The first part of this report reviews the effect of quadrupolar interactions on the (83)Kr linewidth in zeolites and also the (83)Kr chemical shift behavior that is distinct from that of its (129)Xe cousin in some of these materials. The second part reviews hyperpolarized (hp) (83)Kr NMR spectroscopy of macroporous materials in which the longitudinal relaxation is typically too slow to allow sufficient averaging of thermally polarized (83)Kr NMR signals. The quadrupolar-driven T(1) relaxation times of hp (83)Kr in these materials are sensitive to surface chemistry, surface-to-volume ratios, coadsorption of other species on surfaces, and surface temperature. Thus, (83)Kr T(1) relaxation can provide information about surfaces and chemical processes in macroscopic pores and can generate surface-sensitive contrast in hp (83)Kr MRI.

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NMR Spectroscopy of Xenon in Confined Spaces: Clathrates, Intercalates, and Zeolites

Cited by 159 publications

References 38 publications

129Xe NMR studies of the dynamics of xenon in siliceous ZSM-12 zeolite

129Xe NMR studies of the dynamics of xenon in siliceous ZSM-12 zeolite

Hyperpolarized krypton-83 as a contrast agent for magnetic resonance imaging

Studying porous materials with krypton-83 NMR spectroscopy

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