Abstract
The effect of moisture on the chemical formation of air ions produced by corona discharge in clean air, and the formation of large clusters were mainly discussed in this paper. We measured the composition of positive and negative air ions generated by corona discharge in clean air using an atmospheric pressure lonization mass spectrometer (APIMS). The positive ions were composed of H+(H2O)n (n= 1 , 2 , 3 , ……), and the negative ions of CO3-(H2O)n, O2-(H2O)n, NO3-, NO2-(H2O)n, O-, and O3-. The degree of hydration, n, in those hydrate ions increased with a moisture increase. Ultra-fine particles of nanometer size were detected in the ionized clean air with a CNC, and the number of them also increased with the moisture increase. Large hydrate ions which have high degrees of hydration, probably constitute those ultra-fine particles.
