Phase-Modulated Rotating-Frame NQR Techniques for Spatial Encoding

✍ Scribed by F. Casanova; H. Robert; D. Pusiol

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 68 KB
• Volume: 141
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1999.1874

✦ Synopsis

The rotating-frame method of localization for spatially resolved spectroscopy and imaging in the pure quadrupole regime relies on a gradient B 1 field in which spins experience a flip angle dependent on their position in the B 1 field strength. So far, the techniques have been implemented as amplitude-modulated methods, i.e., the spatial nuclear quadrupole distribution is encoded in the amplitude of the free-induction decay signals. In this work, we describe the implementation of phase-modulated variants of both two-dimensional and rapid rotating-frame imaging techniques. The experiments are discussed for both single crystalline and powder samples. The phasemodulated experiment offers some advantages over the amplitudeencoding technique: It enables one to distinguish the sign of the spatial coordinate and the signal-to-noise ratio is higher than for the simplest amplitude-encoding method.