ALIGNMENT ECHO OF SPIN-3 2 BE-9 NUCLEI - DETECTION OF ULTRASLOW MOTION/

It is demonstrated that the alignment echo of Be-9 is quite useful for detecting ultraslow atomic motions in the metallic glass Zr46.75Ti8.2 5Cu7.5Ni10Be27.5. The time scale of detectable atomic motion is betwee n T-2 = 1.5 ms and T-1 of a few seconds. Similar to previous works of H-2 NMR, the Jeener-Broekaert sequence is used to create quadrupolar o rder for spin-3/2 nuclei upon nonselective excitations. Since the chem ical and Knight shift distributions are not negligible for Be-9, the p roper choice of the dephasing time between the first and the second pu lses is essential for achieving pure quadrupolar order. It is demonstr ated experimentally that slow atomic motions contribute significantly to the decay of the alignment echo near the glass transition temperatu re. (C) 1998 Academic Press.