Velocity and damping of thermal phonons in isomeric alcohols

Polarized Mandelstam-Brillouin scattering data in isomeric pentanols (normal-pentanol and 2-methyl-2-butanol) are presented. Hypersonic velocity ν s and absorption α/f 2 are measured as a function of temperature in the liquid phase. The experimental results indicate, for both the alcohols, a shear relaxation phenomenon in the GHz region. The shear relaxation times τ s and the shear moduli G ∞ , evaluated in the framework of visco-elastic theories, show a temperature dependence characteristic of strongly associated liquids in n-pentanol, whereas a more molecular behaviour is evidenced for 2-methyl-2-butanol.