Quantitative analysis of the concentration of interstitial O2 molecules in SiO2 glass using luminescence and Raman spectrometry

The Raman band of the stretching vibration of interstitial oxygen molecules in glassy ${\mathrm{SiO}}_{\mathrm{2}}$ is found at $\text{1548.5±1\hspace{0.17em}}{\mathrm{cm}}^{\mathrm{-1}}.$ By comparison with the Raman spectrum of gaseous ${\mathrm{O}}_{\mathrm{2}}$ ($Q$ band at $\text{1555.5\hspace{0.17em}}{\mathrm{cm}}^{\mathrm{-1}}$ ), the concentration of the interstitial ${\mathrm{O}}_{\mathrm{2}}$ molecules in Suprasil W1 synthetic fused silica is estimated as ${\text{(8±3.5)×10}}^{17}$ ${\mathrm{(molecules\hspace{0.17em}O}}_{\mathrm{2}}{\mathrm{)/cm}}^{\mathrm{3}}.$ This value is further used to calibrate the intensity of the Nd-YAG laser-excited ${\mathrm{O}}_{\mathrm{2}}$ $\mathrm{a\to X}$ infrared photoluminescence band at 1272.2 nm against the intensity of the fundamental Raman bands of glassy ${\mathrm{SiO}}_{\mathrm{2}}.$ In this way, quantitative measurements of ${\mathrm{O}}_{\mathrm{2}}$ concentrations in ${\mathrm{SiO}}_{\mathrm{2}}$ down to at least ${\text{≈10}}^{16}\hspace{0.17em}{\mathrm{molecules/cm}}^{\mathrm{3}}$ are possible.