Quantitative infrared spectroscopic measurement of hydroxyl concentrations in silica glass

Infrared (IR) spectroscopic analysis of high hydroxyl content silica glasses was compared with both weight loss measurements and nuclear reaction analysis (Helmich and Rauch, 1993) to obtain the molar absorptivity of the 3673 cm(-1) hydroxyl band in silica glass. Agreement between the resulting molar absorptivity values (76.4+/-2.8 and 77+/-6 l(glass)/mol(OH)cm(glass) for weight loss and nuclear reaction the experiments, respectively) and those from the literature gives a best estimate of the molar absorptivity to be 77.5+/-1.5 l(glass)/mol(OH)cm(glass). Proportionality between the amplitudes of the fundamental OH stretching band at 3673 cm(-1) and the combination SiOH bending-OH stretching band at 4522 cm(-1) allowed the molar absorptivity of the combination band to be determined (1.53+/- 0.03 I-glass/mol(OH)cm(glass)) and comparison of the amplitudes and areas for both the 3673 and 4522 cm(-1) bands gives the integrated molar absorptivities to be 10,100+/-200 and 232+/-5 l(glass)/mol(OH) cm(glass)(2), respectively. Nonlinear absorbance loss versus weight loss per surface area curves observed for some batches of type III silica glass suggest that hydroxyl can be simultaneously removed via multiple mechanisms.