There are four 29 Si NMR experimental studies published for glasses containing ~40 mol% Na 2 O and the reported Q species abundances are remarkably consistent. These results have been used to determine accurate Raman Q 3 and Q 2 cross sections for a 40.1 mol% Na 2 O glass. The Q 3 and Q 2 cross sections are respectively 1.10 and 0.95 (±0.03). The Q 2 band of the Raman spectrum is dominantly Lorentzian in shape whereas the Q 3 band is asymmetric and based on other studies, the asymmetry increases with alkali content, due primarily to alkali-BO interactions. As explanation, increase in alkali content enhances preferentially electron density over Si atoms of tetrahedra, thereby weakening Si-O coulombic interactions (i.e., force constants), which shifts the symmetric stretch of the Q 3 species to lower frequencies, producing asymmetric Q 3 line shapes. With Q 2 and Q 3 cross sections established, the high resolution of Raman spectroscopy now can be used to provide highly accurate estimates of Q species in silicate glasses and melts.