Beta-detected NQR in zero field with a low energy beam of 8Li+

AbstractBeta-detected nuclear quadrupole resonances (β-NQR) at zero field are observed using a beam of low energyhighly polarized radioactive 8 Li + . The resonances were detected in SrTiO 3 , Al 2 O 3 and Sr 2 RuO 4 single crystals bymonitoring the beta-decay anisotropy as a function of a small audio frequency magnetic field. The resonances showclearly that 8 Li occupies one site with non-cubicsymmetry in SrTiO 3 ,two in Al 2 O 3 andthree sites in Sr 2 RuO 4 . Theresonance amplitude and width are surprisingly large compared to the values expected from transitions betweenthe |± 2i ↔ |± 1i spin states, indicating a significant mixing between the |± mi quadrupolar split levels. Key words: Zero field, quadrupole resonance, β-NQR, β-NMR. 1. IntroductionRecently, we have constructed two spectrome-ters for beta-detected nuclear magnetic resonance[1] (β-NMR) and nuclear quadrupole resonance [2](β-NQR), usingalowenergyhighlypolarized 8 Li + beam. We report here on the first results obtainedfromtheβ-NQRspectrometeratzeroappliedmag-netic field. The β-NQR spectra were obtained for