Quantitative evaluation of low-concentration OH impurities in quartz glass by infrared photothermal deflection spectroscopy

Abstract

Abstract. Impurity control in materials is of great importance to achieve excellent performance, yet the quantitative determination of trace impurities, especially OH, is extremely difficult using today’s characterization techniques. Here we report the determination of trace amounts of OH in quartz glass plates by photothermal deflection spectroscopy (PDS) extended to the IR region. PDS detects trace OH based on the amount of heat generated during non-radiative processes during light irradiation. IR absorption spectra of quartz glasses with five different OH concentrations were investigated. In addition to the standard OH band around 3640 cm−1, we find that there are combination modes, overtones, and water-induced IR features. The presence and OH concentration dependence of these species reveal the role of impurities in quartz glass. The PDS is effective in quantifying OH concentrations below 1 ppmw (parts per million weight) in quartz glass plates.