title: Two-dimensional second-order quadrupolar exchange powder spectra for nuclei with half-integer spins. Calculations and an experimental example using oxygen NMR.
abstract: Two-dimensional chemical exchange spectra are determined for powders containing half-integer quadrupolar nuclei that evolve under the second-order quadrupolar interaction. For simple exchange processes it is shown that the calculated exchange patterns depend sensitively on the jump angles, the tensor parameters, and the rotation axes characterizing the geometry of the underlying molecular motion. The inclusion of other interactions is discussed. To demonstrate the feasibility of the experimental method a two-dimensional second-order quadrupolar exchange spectrum was recorded for a clathrate hydrate using oxygen NMR. Simulations based on a motional model involving a six-site jump capture the essential features of the experimental results.
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Adjei-Acheamfour
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Storek
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Beerwerth
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany. Electronic address: roland.bohmer@tu-dortmund.de.
authors.forename: R
authors.initials: R
authors.lastname: Böhmer
keywords: Central line; Oxygen NMR; Second-order quadrupole coupling; THF clathrate; Two-dimensional spectroscopy