INCOHERENT DYNAMICAL STRUCTURE FACTOR OF THE COMPRESSED FRAGILE LIQUID ORTHOTERPHENYL

We present first results of inelastic neutron scattering experiments o n the glass transition of Orthoterphenyl under pressure. The quasielas tic broadening decreases as pressure is increased at a given temperatu re. The spectral line shape for the structural relaxation does not cha nge under isoviscous conditions. The obtained alpha-relaxation times s cale with viscosity. The scattering law of the beta-process obeys a fa ctorisation S(Q,omega) = (H) over cap(Q)G(omega). Comparison of correl ation functions under isochoric conditions shows that the density alon e cannot be the only relevant parameter for the liquid-glass transitio n.