NEW ASPECT OF THE Q(2)-CDW PHASE-TRANSITION OF NBSE3

We present an x-ray study of the q(2)-pretransitional structural fluct uations of the low temperature T-2=59 K Peierls transition of the tric halcogenure NbSe3. These fluctuations are less anisotropic than the q( 1)-ones of the high temperature Peierls transition. We present evidenc e that close to T-2 the q(2)-fluctuations exhibit two length scales. T he longer one appears 3 K above T-2 and diverges at T-2 while the shor ter one is not critical. These features recall those observed in magne tic systems and perovskites.