Effect of ammonia on atmospheric pre-nucleation clusters containing the common atmospheric ion HSO4- and highly oxidized organic species containing nitrogen

In the present study, the role of ammonia playing in the formation of atmospheric clusters containing sulfuric acid, highly oxidized organic molecule containing N and the impact of the common atmospheric ion HSO4 have been investigated. Our findings indicate cluster stabilization due to the presence of ammonia is moderate when compared to the same clusters without ammonia present. At later stages of cluster growth, the sulfuric acid affinity is observed to be enhanced by -2 kcal mol−1 due to ammonia molecule in the studied clusters. Similarly, when the clusters of (H2SO4)m(HSO4)(C10H15O10N)(NH3) are compared to (H2SO4)m(HSO4−)(NH3), as the value of m increases so does the ammonia affinity to a given cluster with the exception of m=3, where no more bonds to the ammonia molecule are possible. This comparison indicates the potential role ammonia can play in nucleation of the atmospheric clusters studied here. These results lead us to conclude that the presence of ammonia in the larger negatively charged (H2SO4)2-3(HSO4-)(C10H15O10N)(NH3) clusters is favorable for the new particle formation (NPF).