“…To our knowledge, no comprehensive and generally accepted explanation for the effect exists yet, though several studies have addressed issues related to the subject. For example, SO 3 ·H 2 O complexes have been studied by several groups, most recently by Morokuma and Muguruma [74], Meijer and Sprik [75], Larson et al [76,77], Loerting and Liedl [42,78], Ida et al [79], Standard et al [80] and Fliegl et al [81]. (Note that most of these studies do not explicitly focus on atmospheric nucleation mechanisms.)…”