Measurement of negative ion mobilities at atmospheric pressure in O2/O3 mixtures

In a previous work, we measured the negative ion mobilities in O2 at atmospheric pressure. The obtained zero‐field mobility of O⁻₂ in O2 agreed well with the results of Snuggs and co‐workers. However, we mentioned that the apparent zero‐field mobility tended to small values with increase of the drift length. This paper describes experimental results for the negative ion mobilities in O2/O3 mixtures. Ozone was generated in a silent discharge tube and the ozone concentration was varied from 10 ppm up to 1200 ppm. It was found that the negative ion mobilities become smaller with increases of the ozone concentration. When ozone was mixed above 10 ppm in O2, the mobility decreased rapidly. The apparent zero‐field mobility was 1.69 cm2/V·s at 300 ppm O3 and 1.52 cm2V·s at 1200 ppm O3. Within this range from 300 to 1200 ppm O3, the apparent zero‐field mobility decreased linearly with increases of the ozone concentration. This suggests that cluster ions are formed by some ion‐molecule reactions in the drift space.