Powder of the S = 1/2 triangular lattice system with c-axis chains, BaVS3,
was investigated by inelastic neutron scattering. Strongly temperature-depe
ndent spin-gap-like inelastic excitations were observed below the metal-ins
ulator transition point T-MI approximate to 70 K Q-spectra suggest that the
inter-chain antiferromagnetic coupling plays a role for the spin-singlet f
ormation. Other low-energy excitations were found within the spin-gap at a
certain momentum transfer. (C) 1999 Elsevier Science Ltd. All rights reserv
ed.