We report experimental results of 139La pulse NMR studies in LaOs4As12. Measurements have been performed on a powder sample obtained from high quality single crystals. For the first time the pattern of quadrupole echoes for 139La nuclei (I=7/2) was obtained. All the allowed quadrupolar echoes expected for spin I=7/2 were observed at times t=(4/3)tau, (3/2)tau, (5/3)tau, 2tau, (5/2)tau, 3tau, 4tau. The presence of quadrupolar echoes is the fingerprint of the deviation from perfect cubic symmetry of the structure and can be used as a simple and fast test of the sample quality.
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