129Xe chemical shift measurements on a single crystal surface

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

doi:10.1016/s0009-2614(03)00384-1

Cited by 10 publications

(6 citation statements)

References 24 publications

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“…A good estimate of this contribution can be taken from our experiments on xenon adsorbed on CO-covered Ir(111) (11). Here, the metallic interaction is strongly shielded by the molecular CO spacer.…”

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confidence: 98%

“…Conceptually, this adsorption system constitutes a simple enough situation to be treated by theory. Experimentally, it is a long-sought-after goal (9) that is not so easily reached (10,11).…”

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confidence: 99%

“…Recently, a breakthrough was achieved when it was shown that NMR experiments of xenon adsorbed in monolayer quantities on a 1-cm 2 nonmetallic surface are possible (11). This method has now been further developed and adapted to metallic surfaces.…”

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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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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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“…The present results are part of an endeavor to study the 1 cm 2 area of a highly polished, oriented and cleaned metal single crystal surface. First results have been obtained on 129 Xe adsorbed on CO-or CH 3 C-coated Ir(111) [6]. Chemical shift differences between the two preparations demonstrate the usefulness of 129 Xe atom as a probe.…”

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confidence: 98%

129Xe NMR – highly polarized thin films

Gerhard

Koch

Jänsch

2004

Comptes Rendus. Physique

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“…The utility and relative inertness of hyperpolarized xenon has created the opportunity for a wide variety of applications, including gas-phase MRI imaging − as well as NMR studies of high-surface-area substrates and zeolites, blood, and crystallites or crystals. − With the connection of magic angle spinning to optical pumping experiments, , a wide variety of surface studies can now be conducted with the advantage of improved spectral resolution. To date, the SPINOE method of polarization transfer has been the most popular and has been examined under many conditions.…”

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confidence: 99%

Substrate and Field Dependence of the SPINOE Transfer to Surface ¹³C from Hyperpolarized ¹²⁹Xe

2005

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The substrate and field dependencies of surface SPINOE enhancements using optical pumping and magic angle spinning NMR were monitored. Relaxation rates and enhancements were examined to gain an understanding of the parameters that determine the SPINOE enhancement. (13)C-labeled deuterated methanol was adsorbed on three different substrates (SnO(2), TiO(2), Ti/SiO(2)) with heats of adsorption for xenon ranging from 14.2 to 22.6 kJ/mol. The different heats of adsorption led to a range of xenon coverages and xenon relaxation rates. Using a simple model along with experimental values for the xenon surface polarization and cross- and self-relaxation rates, the (13)C signal enhancement could be predicted and compared with experimental enhancement values. Magnetic field dependence studies were also made by monitoring the (13)C enhancements via SPINOE from hyperpolarized xenon at fields of 0.075, 4.7, and 9.4 T. The pertinent parameters necessary to achieve maximum SPINOE enhancement are discussed.

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129Xe chemical shift measurements on a single crystal surface

Cited by 10 publications

References 24 publications

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

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

129Xe NMR – highly polarized thin films

Substrate and Field Dependence of the SPINOE Transfer to Surface ¹³C from Hyperpolarized ¹²⁹Xe

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129Xe chemical shift measurements on a single crystal surface

Cited by 10 publications

References 24 publications

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

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

129Xe NMR – highly polarized thin films

Substrate and Field Dependence of the SPINOE Transfer to Surface 13C from Hyperpolarized 129Xe

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

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

Substrate and Field Dependence of the SPINOE Transfer to Surface ¹³C from Hyperpolarized ¹²⁹Xe