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Negative Ion Formation by Thermal Surface Ionization of Sulfur Dioxide
Author(s) -
Marciszuk Karolina,
Pieńkos Tomasz,
Gontarz Patryk,
Pelc Andrzej
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000388
Subject(s) - chemistry , ion , electron affinity (data page) , molecule , dissociation (chemistry) , ionization , electron ionization , thermal ionization , ionization energy , analytical chemistry (journal) , inorganic chemistry , organic chemistry
The generation of negative ions from SO 2 in the gas phase was studied using the thermal surface ionization method. Six anion types were measured: O − , S − , SO − , and SO 2 − and anions with m/z=96 and m/z=128. The most abundant anion formed was S − and the formation routes are discussed for each of the six anions. O − , S − , and SO − are formed via dissociative electron attachment to the molecule, whereas the generation of SO 2 − and anions with m/z=96 and m/z=128 are probably associated with the formation of H 2 SO 4 in the gas inlet system and the ion source. Using statistical thermodynamics the dissociation temperatures of SO 2 and SO in the gas phase are calculated and values of above 1800 °C are obtained for both molecules. We also estimated the optimal filament temperatures for the formation of all anions measured, indicating that for SO 2 the optimal temperature is related to the electron affinity of the molecules: the optimal temperature increases with decreasing value of the electron affinity for the molecule corresponding to the respective anion.