Formations of negative ions in Sf6/N2 mixtures and their transport at atmospheric pressure

Formation of negative ions initiated by interaction of thermal electrons and in the corona discharge (CD) in N-2 with small admixture of SF6; was studied using the ion mobility spectrometry-orthogonal acceleration time-of-flight mass spectrometry (IMS-oaTOF) at atmospheric pressure. The negative ions have been analyzed by the ion mobility spectrometry and mass spectrometry (IMS-MS) and two-dimensional spectra (2D IMS-MS) have been recorded. We discuss the mechanisms of the negative ion formation in the N-2/SF6 mixtures (0.003-0.018%) as well as the transport parameters of the ions in these mixtures. The values of the reduced ion mobilities of negative ions formed in these mixtures were determined (2.43 cm(2)/V s for HF2- (HF)(n), 2.32 cm(2)/V s for NO3-(HF)(n), 2.08 cm(2)/V s for SF5-, 2.01 cm(2)/V s for SOF5-, 2.00 for SOF4- 1.99 cm(2)/V s for SF6-, 1.83 cm(2)/V s for SOF5-(H2O)n and 1.73 for SOF5-(H2O)(n)(HF)(m)). The assignment of the ion mobility peaks was performed on the basis of the 2D IMS-MS spectra.