Powder Zeeman NQR Study on 123Sb in Sb(C6H5)3

Powder Zeeman NQR spectra of Sb in Sb(C6H5)3 were studied by means of a computer simulation and an experiment. TheSb nucleus has spin 7/2. There are two non-equivalentSb atoms in the crystal of Sb(C6H5)3, so that there are two series of three transition lines (higher series: 1h, 2h, 3h; lower series: 1l, 2l, 3l). The powder Zeeman spectra for 1h, based on the transition between the levels mI = 1/2 and 3/2, were observed at 77 K under the two conditions that i) the oscillation coil and the static magnetic coil were set coaxially and parallel, and ii) they were set perpendicular to each other. The powder line shapes for 1h, which is the lowest line of the higher series due to Sb nuclei, were in good agreement with those from a computer simulation under the conditions i) and ii), showing that the asymmetry parameter of the field gradient is very small ( = 0). The line shape from i) exhibits two shoulders (saddle type), as it appeared for nuclear spin 5/2 and = 0. The quadrupole coupling constant for 1h, calculated from the resonance frequency 47.820 MHz and the observed , is 669.480 MHz at 77 K.