Quantitative Raman spectroscopy: Principles and application to potassium silicate glasses

A mathematical approach was developed to interpret Raman spectra of binary silicate glasses and melts without the necessity of external calibration, e.g., from NMR spectroscopy. The developed approach is based on Principal Component Analysis (PCA), linear combinations of partial Raman spectra and a linear optimization technique. In order to apply and to test this approach, we developed an experimental method to collect a large number of Raman spectra efficiently. We applied the quantification and the experimental approaches to investigate potassium silicate glasses with compositions from 17.4 to 38 mol% K2O. The equilibrium constant for the reaction 2Q3 ⇄ Q2 + Q4 was found log K3 = −2.37 ± 0.07, in excellent agreement with NMR studies for the same glasses.