title: Benzene at 1GHz. Magnetic field-induced fine structure.
abstract: The deuterium NMR spectrum of benzene-d6 in a high field spectrometer (1GHz protons) exhibits a magnetic field-induced deuterium quadrupolar splitting Δν. The magnitude of Δν observed for the central resonance is smaller than that observed for the (13)C satellite doublets Δν'. This difference, Δ(Δν)=Δν'-Δν, is due to unresolved fine structure contributions to the respective resonances. We determine the origins of and simulate this difference, and report pulse sequences that exploit the connectivity of the peaks in the (13)C and (2)H spectra to determine the relative signs of the indirect coupling, JCD, and Δν. The positive sign found for Δν is consonant with the magnetic field biasing of an isolated benzene molecule-the magnetic energy of the aromatic ring is lowest for configurations where the C6 axis is normal to the field. In the neat liquid the magnitude of Δν is decreased by the pair correlations in this prototypical molecular liquid.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Heist
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA.
authors.forename: C-D
authors.initials: CD
authors.lastname: Poon
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA. Electronic address: et@unc.edu.
authors.forename: E T
authors.initials: ET
authors.lastname: Samulski
authors.affiliation: Department of Materials Science, University of Patras, Patras 26504, Greece.
authors.forename: D J
authors.initials: DJ
authors.lastname: Photinos
authors.affiliation: NMR Research Group, University of Oulu, 90014 Oulu, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Jokisaari
authors.affiliation: NMR Research Group, University of Oulu, 90014 Oulu, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Vaara
authors.affiliation: Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: J W
authors.initials: JW
authors.lastname: Emsley
authors.affiliation: Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Mamone
authors.affiliation: Centre de RMN à Très Hauts Champs, Institut de Sciences Analytiques (CNRS/ENS Lyon/UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France.
authors.forename: M
authors.initials: M
authors.lastname: Lelli
keywords: Magnetic orientation; Quadrupole coupling; Sign of quadrupolar splitting