CHARACTERIZATION OF THE 2 RUBIDIUM SITES IN RB2CRO4 BY RB-87 SINGLE-CRYSTAL NMR

The two crystallographically distinct sites in Rb2CrO4 are characteriz ed in terms of their Rb-87 quadrupole coupling and chemical shielding anisotropy (CSA) interactions employing Rb-87 single-crystal NMR. Accu rate values for the quadrupole coupling and CSA parameters are reporte d for both rubidium sites along with the direction cosines describing the orientation of the tensors for the NMR interactions with respect t o the Rb2CrO4 crystal frame. The parameters for site 1 represent the f irst accurate investigation of this site, while the parameters for sit e 2 compare excellently with those previously reported. Some remarkabl e similarities are observed between the present parameters for Rb2CrO4 and the Cs-133 parameters determined from recent magic-angle spinning and single-crystal Cs-133 NMR studies for the isomorphous Cs2CrO4.