NUCLEAR QUADRUPOLE RESONANCE SPECTRUM OF B¹¹ IN KERNITE

Abstract

The pure quadrupole resonance frequencies of B 11 nuclei at two different sites (denoted by E and F) in a single crystal of kernite (Na 2 B 4 O 7. 4H 2 O) have been determined both by observing the B 11 resonances in zero external magnetic field, and also by investigating their Zeeman splitting in magnetic fields up to 30 gauss. The values obtained are 1281.1 ± 2 and 1287.0 ± 1 kc./sec. for the E and F sites respectively. These frequencies agree within experimental error with the values 1286 ± 4 and 1287 ± 3 kc./sec. predicted on the basis of studies in a magnetic field of 7000 gauss. The agreement for the F site is much better than for the E site. These zero field resonances have also been observed in a polycrystalline sample. The observed weak field Zeeman splitting for the single crystal agrees very well with that calculated from high field data for F sites, but at present disagrees with the corresponding calculation for E sites. A Na 23 pure quadrupole resonance in kernite has also been measured at 1560.0 ± 1 kc./sec. The second Na 23 resonance expected from high field work has not been observed to date.