Atmospheric Pressure Corona Discharge Ionisation and Ion Mobility Spectrometry/Mass Spectrometry study of the negative corona discharge in high purity oxygen and oxygen/nitrogen mixtures

Negative ions formed in negative corona discharge in high purity O2 and O2/N2 mixtures have been studied using the Atmospheric Pressure Corona Discharge Ionisation Mass spectrometry (APCDI/MS) and Ion Mobility Spectrometry/Mass Spectrometry techniques (IMS/MS). The primary negative ions have been detected and identified using APCDI/MS technique. The primary ions are fast transformed via ion-molecule reaction with N2O into ions with m/z = 60 (N2O2−). The N2O is formed in the negative corona discharge in the reaction of O with N2 (∼5 ppm). In the case of N2 admixtures to O2 from 10 to 80%, additional negative ion m/z = 62, NO3− appears in the IMS and MS spectra. The mobilities of the negative ions were determined from IMS and mass selected IMS spectra. The m/z = 60 (N2O2−) has reduced ion mobility of 2.52 ± 0.05 cm2 V−1 s−1. In O2/N2 mixtures, additionally to m/z = 60, negative ion with reduced ion mobility of 2.14 ± 0.05 cm2 V−1 s−1 and m/z = 62 have been detected and assigned to NO3−. Formation of this ion was associated with the presence of NO2 generated in the negative corona discharge in O2/N2 mixtures.

Negative ions formed in negative corona discharge in high purity O2 and O2/N2 mixtures have been studied using the Atmospheric Pressure Corona Discharge Ionisation Mass spectrometry (APCDI/MS) and Ion Mobility Spectrometry/Mass Spectrometry techniques (IMS/MS).Figure optionsDownload high-quality image (69 K)Download as PowerPoint slide