1P-36 PDF
Ion-molecule reactions of atmospheric ions involving ozone and hydrogen radical
We established an atmospheric pressure corona discharge ionization mass spectrometer (APCDI MS) coupled with an ozone (O3 ) and hydrogen radical (H.) generators, and investigated ion-molecule reactions occurring in the atmosphere with and without the flow of O3 and H.. Ionic species generated by APCDI can be controlled by varying needle angle and voltage which determine the electric field strength on the needle tip surface. The lowest field strength in normal air led to the dominant formation of HO- at m/z 17 and O2- at m/z 32. In contrast, its discharge condition with O3 brought about abundant HO2- at m/z 33, CO3- at m/z 60 and various different negative ions including carbonic acid (H2CO3). Addition of H. under these discharge condition resulted in the dominant generation of hydrogen peroxide (H2O2) and formic acid (HCOOH).