Zeeman Effect of the Nuclear Quadrupole Resonance Spectrum in Crystalline Powder

Abstract

The Zeeman effect of the nuclear quadrupole resonance spectrum for spin $\mathrm{I=}\frac{3}{2}$ in crystalline powder has been studied. Theoretical considerations have predicted that, in a nonaxial electric field gradient, the absorption line should be broadened with a characteristic envelope by a weak static magnetic field. When a radio‐frequency (rf) field is applied parallel to the static field, one pair of sharp minima should be produced on the envelope at the frequencies shifted by $\text{±γH/2π}$ from the unperturbed quadrupole resonance line, and two pairs of sharp maxima at $\text{±(1−η)γH/2π}$ and at $\text{±(1+η)γH/2π}$ . Resonance spectra of Cl³⁵ nuclei in p‐dichlorobenzene and cyanuryl chloride have clearly displayed the predicted shape of envelopes on a recorder at room temperature. Analysis of them has resulted in determining the asymmetry parameters of electric field gradients with considerable accuracy; 0.07₀±0.01 for the α‐modification of p‐dichlorobenzene, and 0.22±0.03 for ν₁ line, and 0.23±0.04 for ν₂ line of cyanuryl chloride.