Identification of Negative Ion at 20 Produced by Atmospheric Pressure Corona Discharge Ionization under Ambient Air.

The negative ion at 20 observed at atmospheric pressure corona discharge ionization mass spectra has been identified by supplying the vapors of deuterium oxide (DO) and HO. From the mass shifts of the ion at 20 observed with DO and HO, it was suggested that the chemical composition of the ion at 20 is to be HO. Further mass shift from 20 to 22 was observed by supplying the vapor of perfluorokerocene, suggesting the chemical composition of HF. The chemical compositions of the negative ions HO and HF were consistence with the dipole-bound complex states between hydrogen H and polar molecules such as HO and hydrogen fluoride (HF) having dipole moments beyond a critical dipole moment of 1.625 D, theoretically proposed by Skurski and Simons. The ionic chemical compositions and structures of HO and HF obtained with density functional theory calculations implied that both dipole-bound complex HO…H and HF…H can be formed by exothermic reactions by which H molecule is complexing with negative ions HO and HF, respectively.