  Acetyl salicylic acid, deuterated at the methyl group, was investigated using
2H-NMR in its supercooled and glassy states. Just above the glass transition
temperature the molecular reorientations were studied using stimulated-echo
spectroscopy and demonstrated a large degree of similarity with other glass
formers. Deep in the glassy phase the NMR spectra look similar to those
reported for the crystal [A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z.
Olejniczak, Z. T. Lalowicz, Z. Naturforsch. A 50 (1995) 95] and below 20 K they
are indicative for rotational tunneling with a relatively large tunneling
frequency. Measurements of the spin-lattice relaxation times for temperatures
below 150 K reveal a broad distribution of correlation times in the glass. The
dominant energy barrier characterizing the slow-down of the methyl group is
significantly smaller than the well defined barrier in the crystal.
