title: 14N NMR echo in NH4ClO4 after the pulse sequence (theta1)x-tau-(theta2)y-t.
abstract: We have derived a closed-form expression for the solid echo signal of quadrupolar I = 1 nuclei after the pulse sequence (theta1)x-tau-(theta2)y-t for arbitrary values of the RF nutation frequency omega1 = gammaB1 and the quadrupolar frequency omegaQ. In the case of single crystals both the true echo term of this expression and its induction-signal-like terms are important as shown by experiments on 14N nuclei in NH4ClO4 crystal. Conditions for obtaining the maximal echo in powder samples are presented. A very low B1 field together with long RF pulses may distort even the central part of the spectrum, resulting in strange looking apparent spectra.
authors.affiliation: Department of Physics, University of Turku, Turku, FIN-20014, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Punkkinen
authors.forename: A H
authors.initials: AH
authors.lastname: Vuorimäki
authors.forename: E E
authors.initials: EE
authors.lastname: Ylinen
authors.forename: A
authors.initials: A
authors.lastname: Kaikkonen
mesh_terms: D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D008958:Models, Molecular; D009584:Nitrogen; D010472:Perchlorates / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D010472:Perchlorates; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen; C053506:ammonium perchlorate