129Xe NMR – highly polarized thin films

Gerhard, Peter; Koch, Matthias; Jänsch, H.J.

doi:10.1016/j.crhy.2004.02.007

Cited by 6 publications

(5 citation statements)

References 20 publications

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“…For a thin film the shift has an angular dependence of (3 cos 2 ( ) Ϫ 1)͞2 as has been shown for highly polarized 3 He films (26,27) or 129 Xe films (28). Here, the shift and anisotropy are in the order of 10-20 ppm even for highest nuclear polarization (21). Therefore, this also does not serve as an explanation of the experimental anisotropy.…”

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confidence: 83%

“…The analysis showed an anisotropy of ⌬ ϭ 15 ppm due to the substrate susceptibility. This effect is well understood quantitatively (19,21). It is not discussed further in this article because 15 ppm is very small compared with the monolayer ⌬ of 437 ppm.…”

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confidence: 96%

“…This high polarization is the prime reason for achieving the necessary sensitivity gain that allows the present experiments. The polarization can be monitored in situ in the ultrahigh vacuum chamber by observing the bulk xenon NMR line shift because of the nuclear magnetization (19,21).…”

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confidence: 99%

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¹²⁹Xe on Ir(111): NMR study of xenon on a metal single crystal surface

Jänsch

Gerhard

Koch

2004

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

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NMR experiments of 129 Xe adsorbed on an iridium single crystal surface are reported. Very high nuclear polarization (P z Ϸ 0.7) makes the experiment possible. A coverage of less then one monolayer is investigated on the Ir(111) surface with an area of 0.8 cm 2 . The observed resonance line shifts are very large and highly anisotropic. We find iso ‫؍‬ 1,032 ؎ 11 ppm and an ‫؍‬ 291 ؎ 33 ppm, which are far above the typical range of physisorption. The highly ordered substrate leads to homogeneous conditions for the xenon atoms, as seen in the narrow linewidth of 20 ppm. Chemical shifts under physisorption conditions are not large enough to totally explain the results. Knight shift can clearly be identified as the cause of the findings. This shift shows the presence of conduction electrons of the metallic substrate at the xenon nucleus and thus the mixing of metallic and atomic states at the Fermi level. Such mixing is in accordance with recent Hartree-Fock and density functional calculations of similar van der Waals adsorption systems. Quantitative comparisons, however, fail completely. The size and ratio of an and iso are pure ground-state properties in a structurally simple system. They are accessible to theory and provide detailed local information that can serve as a benchmark for theory.

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confidence: 83%

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confidence: 96%

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¹²⁹Xe on Ir(111): NMR study of xenon on a metal single crystal surface

Jänsch

Gerhard

Koch

2004

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

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“…To correct the xenon signal decay for the effect of the flip angle ϑ and to determine the exact xenon longitudinal self-relaxation time T 1 , a series of xenon NMR spectra with short interscan delay (<1 s) and the same flip angle ϑ was acquired. The exploitation of the latter allowed the extraction of the xenon signal decrease factor (cos ϑ) for each acquisition . Using this value and a home-written C program, the xenon decay curves as a function of time t n were fitted to the function cos n -1 ϑ exp(− t n / T 1 ) with n the spectrum number.…”

Section: Methodsmentioning

confidence: 99%

Dynamics of Xenon Binding Inside the Hydrophobic Cavity of Pseudo-Wild-type Bacteriophage T4 Lysozyme Explored through Xenon-Based NMR Spectroscopy

et al. 2005

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Wild-type bacteriophage T4 lysozyme contains a hydrophobic cavity with binding properties that have been extensively studied by X-ray crystallography and NMR. In the present study, the monitoring of 1H chemical shift variations under xenon pressure enables the determination of the noble gas binding constant (K = 60.2 M(-1)). Although the interaction site is highly localized, dipolar cross-relaxation effects between laser-polarized xenon and nearby protons (SPINOE) are rather poor. This is explained by the high value of the xenon-proton dipolar correlation time (0.8 ns), much longer than the previously reported values for xenon in medium-size proteins. This indicates that xenon is highly localized within the protein cavity, as confirmed by the large chemical shift difference between free and bound xenon. The exploitation of the xenon line width variation vs xenon pressure and protein concentration allows the extraction of the exchange correlation time between free and bound xenon. Comparison to the exchange experienced by protein protons indicates that the exchange between the open and closed conformations of T4 lysozyme is not required for xenon binding.

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“…In addition, we could detect weak perturbations such as the spin-rotation (SR) interaction and chemical shift anisotropy (CSA) [10][11][12][13], which would otherwise be hidden by the above relaxations in a finitesized cell. Spin relaxation on solid surfaces has been reported for cross-relaxation of gaseous and liquid 129 Xe nuclei with protons of coating material [14,15], relaxation of gaseous 3 He nuclei due to magnetic sites in the glass [16], and relaxation of a thin 129 Xe film on metal [17]. For Xe atoms in solution, we need to develop a better understanding of wall relaxation as well as the weak perturbation due to the solvent such as a straight-chain molecule.…”

Section: Introductionmentioning

confidence: 98%