We introduce combined vibrational multipolar decompositions of IR, polarized Raman and hyper-Raman spectra as a powerful way to study isotropic materials. This new procedure has been applied to the molecular liquid
and to silica glass, which are made of elementary structural units (ESU) weakly interacting and covalently 3Dlinked, respectively. Through the vibrational multipolar analyses of these two different isotropic media, new structural and dynamical insights have been drawn. In particular, for silica we propose an ESU which fits the multipolar spectral activity. It is derived from the α-Cristoballite structure, with an octupolar
symmetry, which consists of a central
tetrahedron embedded in a super
tetrahedron with bent Si-O-Si bonds.