14N NMR Echo in NH4ClO4after the Pulse Sequence (θ1)x–τ–(θ2)y–t
✍ Scribed by M. Punkkinen; A.H. Vuorimäki; E.E. Ylinen; A. Kaikkonen
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 181 KB
- Volume
- 130
- Category
- Article
- ISSN
- 1090-7807
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✦ Synopsis
We have derived a closed-form expression for the solid echo of NH 4 ClO 4 and in a corresponding polycrystalline sample. signal of quadrupolar I Å 1 nuclei after the pulse sequence ( u 1 ) x -In the single crystal also the induction-signal-like terms of t -(u 2 ) y -t for arbitrary values of the RF nutation frequency v 1 the echo are important and their effect is studied in detail.
Å gB 1 and the quadrupolar frequency v Q . In the case of single For the polycrystalline sample the conditions which produce crystals both the true echo term of this expression and its inducthe maximum echo amplitude are found. Some manifestation-signal-like terms are important as shown by experiments tions of spectral distortion are also shown. on 14 N nuclei in NH 4 ClO 4 crystal. Conditions for obtaining the maximal echo in powder samples are presented. A very low B 1 THEORY field together with long RF pulses may distort even the central part of the spectrum, resulting in strange looking apparent spectra. ᭧ 1998 Academic Press
We calculate the free induction and echo signals for I Å 1 nuclei by using the time-dependent Schro ¨dinger equation. The state of the spin system is described by the wavefunction 287