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

1998; Elsevier BV; Volume: 133; Issue: 1 Linguagem: Inglês

10.1006/jmre.1998.1451

1096-0856

Xiaoping Tang, Yue Wu,

Phase-change materials and chalcogenides

It is demonstrated that the alignment echo of9Be is quite useful for detecting ultraslow atomic motions in the metallic glass Zr46.75Ti8.25Cu7.5Ni10Be27.5. The time scale of detectable atomic motion is betweenT2= 1.5 ms andT1of a few seconds. Similar to previous works of2H NMR, the Jeener–Broekaert sequence is used to create quadrupolar order for spin-32nuclei upon nonselective excitations. Since the chemical and Knight shift distributions are not negligible for9Be, 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.