Alignment Echo of Spin-3/29Be Nuclei: Detection of Ultraslow Motion

✍ Scribed by X.-P Tang; Y Wu

• Book ID: 102596483
• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 242 KB
• Volume: 133
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1998.1451

✦ Synopsis

It is demonstrated that the alignment echo of 9 Be is quite useful for detecting ultraslow atomic motions in the metallic glass Zr 46.75 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 . The time scale of detectable atomic motion is between T 2 ‫؍‬ 1.5 ms and T 1 of a few seconds. Similar to previous works of 2 H NMR, the Jeener-Broekaert sequence is used to create quadrupolar order for spin-3 2 nuclei upon nonselective excitations. Since the chemical and Knight shift distributions are not negligible for 9 Be, the proper choice of the dephasing time between the first and the second pulses is essential for achieving pure quadrupolar order. It is demonstrated experimentally that slow atomic motions contribute significantly to the decay of the alignment echo near the glass transition temperature.