Towards realization of reactive gas amount of substance standards through spectroscopic measurements

This paper discusses the use of high-precision direct absorption spectroscopy to realize the amount of substance standards for ozone (O-3), a reactive species which cannot be delivered through traditional gravimetrically based gas cylinder standards. The O-3 amount of substance is linked to the known concentrations of nitric oxide (NO) and nitrogen dioxide (NO2) through a gas-phase titration reaction and spectroscopic measurements using room-temperature pulsed quantum-cascade lasers. Ultimately, this approach will allow the determination of an O-3 transition line strength linked to the primary gravimetric standards of NO and NO2. The line strength can be used in future measurements to determine O-3 concentrations of unknown samples.