The relation betwen the 129Xe NMR chemical shifts of xenon in the zeolites NaX, NaY and CuNaY
Abstract
The adsorption isotherms and 129Xe NMR chemical shifts of xenon in the voids of zeolite Y with 0%, 53%, 75%, and 95% exchange of copper (II) for sodium ions were determined. With increasing copper content the shifts go upfield. The local chemical shifts of xenon at a crystallographic SII site with and without the charge compensating sodium ion are condluced to be 60 and 32 ppm, respectively.
References (15)
- J. Fraissard et al.
Zeolites
(1988) - B. Boddenberg et al.
Zeolites
(1988) - A. Gedeon et al.
Zeolites
(1988) - D.W. Breck(1974)
- I.E. Maxwell et al.
J. Phys. Chem.
(1975) - T. Ichikawa et al.
J. Phys. Chem.
(1983) - A. Gedeon et al.
J. Phys. Chem.
(1989)
Cited by (21)
Nuclear Data Sheets for A = 129
2014, Nuclear Data SheetsThe experimental nuclear spectroscopic data for known nuclides of mass number 129 (Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm) have been evaluated and presented together with adopted properties for levels and γ rays. This evaluation represents a revision of the previous one 18 years ago by Y. Tendow (1996Te01). Extensive new data have become available for many nuclides in the intervening years, although, no data are available for excited states in 129Pm and 129Sm, and for 129Ag and 129Cd, only limited information is available for the g.s. and isomers. The decay schemes of 129Ag, 129Pm and 129Sm are unknown, and those for 129Cd, 129In, 129Ce, 129Pr and 129Nd are incomplete. Many γ rays and extended level schemes have been reported for the ground state and isomer decays of 129Ba to 129Cs, yet the adopted set of intensities in this evaluation originate from a brief paper in an annual laboratory report. There remain several unplaced gamma rays, coupled with ambiguity about division of intensities amongst the two activities of 129Ba with nearly the same half-lives. Isomerism is expected in 129Pr, but there is no confirmed identification. Low-lying level structure in 129Nd, including identification of a possible third long-lived isomer in this nuclide, remains uncertain.
The spin-parity assignments of (5/2+) for the ground state and (7/2−) for an isomer at 107.6 keV in 129Ce are assigned based on strong support from systematics and band configurations, yet this result is in contradiction with the quadrupole interaction hyperfine structure measurement which favors 9/2− over 7/2− for the isomer, consequently 7/2+ for the ground state. Direct measurements of spins of ground state and isomer of 129Ce are needed to settle this issue. Confirmed spins and parities of the ground state and isomer of 129La are also lacking. Assignments in this work are mainly based on systematics of decoupled structures. A direct measurement of ground state spin of 129La will also be desirable.
Recommended data presented in this work supersede those in previous NDS evaluations of A=129 nuclides published by 1996Te01, 1983Ha46 and 1972Ho55.
Enhancement of <sup>13</sup>C NMR signals in solid C<inf>60</inf> and C<inf>70</inf> using laser-polarized xenon
1998, Chemical Physics LettersNMR signals emanating from surface nuclei of solids may be enhanced by the transfer of spin polarization from laser-polarized noble gases via SPINOE (spin polarization induced nuclear Overhauser effect). The present contribution describes experiments in which the spin polarization is transferred under magic angle spinning (MAS) from laser-polarized to , a nuclear spin with a low gyromagnetic ratio in the fullerenes C60 and C70, polycrystalline materials with a low surface area. In C70, differential enhancement of the NMR is observed for the different atomic sites in the molecule.
Xenon Nmr
1998, Annual Reports on NMR SpectroscopyThis chapter presents an attempt to cover the entire scientific literature of xenon NMR, encompassing physical, chemical and biological applications involving both spectroscopy and imaging, from the earliest days of NMR to the new opportunities afforded by hyperpolarized Xe. The large, polarizable, electron cloud of the Xe atom endows it with a great sensitivity to its local environment, which is reflected in its chemical shift and electric field gradient. Thus the NMR of Xe(O) largely concerns the physical interaction of the Xe atom with other atoms (including other Xe) through collision and overlap, in the gas and in condensed materials including liquids, polymers, clathrates, porous materials and surfaces. Xe NMR has been used extensively to probe pore spaces and other species present in them, such as metal clusters and paramagnetic centres. Much has also been learned in recent years about the dynamics of Xe in porous media, especially through the use of 2D exchange spectroscopy and diffusion experiments. Particular attention has been focused on efforts to understand the origins and to calculate the chemical shift in microporous materials from first principles, and thus go beyond a qualitative picture. The 104 gain in sensitivity of hyperpolarized Xe has been exploited for studies of low-surface-area materials, in low-concentration and time resolution experiments, for polarization transfer to other nuclei, and for imaging. 129Xe NMR has also played a very major role in the investigation of Xe chemistry (which is now quite extensive), particularly in following chemical reactions and determining structure and bonding characteristics. An extensive updated tabulation of chemical shifts and J-coupling constants is given.
The role of polarization of Xe by di- and monovalent cations in <sup>129</sup>Xe NMR studies in zeolite A
1997, Solid State Nuclear Magnetic ResonanceWe consider the role of polarization in the adsorption of Xe in zeolites of type A by direct comparative analysis of the adsorption isotherms, distributions of occupancies, and 129Xe NMR chemical shifts of Xen in cages containing CaxNa12 −2x ions per alpha cage (x = 0, 1, 2, 3, 5). We find that the qualitative trends in the adsorption isotherms, and in the progressions of Xen chemical shifts (for n = 0–8 in cages with x = 0, 1 Ca2+ ions and for n = 0–5 in cages with x = 2, 3 Ca2+ ions) upon increasing the level of Ca2+ ion for Na+ ion substitution could only be accounted for by including polarization of the Xe atom by the zeolite framework and its ions. This system, which permits observation of individual Xen peaks and of directly comparable adsorption isotherms in several cage types, provides a good model system for the interpretation of the more general case in which only the overall average 129Xe NMR chemical shift is observed in open network zeolites, arising from free exchange of Xe among cavities of variable occupancy and variable cation distribution.
An ab initio study of the chemical bond and the <sup>129</sup>Xe NMR chemical shifts in M<sup>+</sup> -Xe compounds, M = Li, Na, K, Cu, Ag
1995, Chemical PhysicsQuantum chemical ab initio calculations have been performed for the interaction between ground state Xe atoms and the monopositive metal cations Li+, Na+, K+, Cu+, and Ag+. Potential energy curves have been calculated at the SCF and CEPA (coupled electron pair approach) levels. The mechanism of the bonding between Xe and the cation has been analyzed. For the alkali ions Li+, Na+, and K+ the bonds are rather weak (0.367, 0.210, 0.112 eV, respectively) and are caused mainly by inductive forces. In Cu+ −Xe and Ag+−Xe the binding energies are slightly larger (0.632 and 0.380 eV) and contain small contributions of genuine chemical effects and dispersion. 129Xe NMR chemical shifts have been calculated at the SCF level by means of the IGLO method. Only the paramagnetic part of the magnetic shielding constant σ of Xe is affected by the interaction with the cation, the diamagnetic part remains unchanged. For the alkali ions a small downfield shift is obtained which is attributed to the polarization of the Xe wave function by the charge of the cation. For the noble metal cations Cu+ and Ag+ an additional upfield shift is found which is caused by a mixing of the 54p, 4p, 3p orbitals at Xe with the 3d or 4d orbitals at the noble metals in the magnetic response function. This leads to an increased magnetic shielding. Comparison with 129Xe NMR data in X and Y zeolites is made.
Application of <sup>129</sup>Xe nuclear magnetic resonance to the study of CuY zeolites: Dehydration and redox effects
1995, Solid State Nuclear Magnetic ResonanceCopper-exchanged sodium Y zeolites have been studied by using 129Xe nuclear magnetic resonance (NMR) spectroscopy. The oxidation state as well as the location of copper in the zeolite have been determined for different samples at various levels of exchange (λ = 15, 35, 58%) and hydration, and at different stages of redox treatment. Information about the nature of XeCu+ or XeCu2+ interactions has been obtained by a combination of electron spin resonance (ESR) and 129Xe NMR measurements on CuY and Cu-Rho zeolites.