P-31 two-dimensional (2D) nuclear magnetic resonance (NMR) is proposed
as a powerful tool for direct investigation of the connectivities bet
ween like or different Q(n) units in glasses or the medium-range order
. The entire experiment was carried out under conditions of fast magic
angle sample spinning (MAS). The magnetization transfer was obtained
by recoupling of the dipole-dipole interaction despite the fast MAS. T
he mixing time dependence of the 2D spectra for a binary Na2O-P2O5 gla
ss suggests an almost regular alternation of Q2 and Q3 units for that
glass.