Analytical characterization of O₃ samples prepared for investigation of tropospheric heterogeneous reactions

In this study, ozone (O₃) samples were prepared for investigating the heterogeneous reactions between O₃ and tropospheric aerosols and were characterized by spectroscopic methods. O₃ generated from an ozone generator was purified by selective adsorption on refrigerated silica gel, followed by transfer to a sample bulb. The amount of UV light (λ = 256 nm) absorbed by O₃ was measured as a function of time at two different temperatures (room temperature and 50 °C) and under different irradiation conditions. A correlation plot of 1/[O₃ ] versus time showed that O₃ decomposition follows the 2 order reaction rate under a steady-state^nd approximation. The initial concentration of O₃, observed rate constants (k_obs), and the half-life of O₃ in the sample stored at room temperature were determined to be 2.74 [±0.14] × 10 molecules·cm, 4.47 [±0.64]^{16 −3} ×10 molecules^−1·cm3·s, and 9.5 [±1.4] days, respectively. The evaluation of O^{−23 −1}₃ stability under various conditions indicated that special care should be taken to prevent the exposure of the O₃ samples to high-temperature environment and/or UV radiation. This study established a protocol for the preparation of highly purified O₃ samples and confirmed that the O₃ samples can be stored for a day after preparation for further experiments.