Mechanically induced generation of highly reactive excited-state oxygen molecules in cluster scattering

Abstract

Molecular electronic excitation in (O(2))(n) clusters induced by mechanical collisions via the "chemistry with a hammer" is investigated by a combination of molecular dynamics simulations and quantum chemistry calculations. Complete active space self-consistent field augmented with triple-zeta polarizable basis set quantum chemistry calculations of a compressed (O(2))(2) cluster model in various configurations reveal the emergence of possible pathways for the generation of electronically excited singlet O(2) molecules upon cluster compression and vibrational excitation, due to electronic curve-crossing and spin-orbit coupling. Extrapolation of the model (O(2))(2) results to larger clusters suggests a dramatic increase in the population of electronically excited O(2) products, and may account for the recently observed cluster-catalyzed oxidation of silicon surfaces, via singlet oxygen generation induced by cluster impact, followed by surface reaction of highly reactive singlet O(2) molecules. Extensive molecular dynamics simulations of (O(2))(n) clusters colliding onto a hot surface indeed reveal that cluster compression is sufficient under typical experimental conditions for nonadiabatic transitions to occur. This work highlights the importance of nonadiabatic effects in the "chemistry with a hammer."

Structure, Energy, and Vibrational Frequencies of Oxygen Allotropes On (n ≤ 6) in the Covalently Bound and van der Waals Forms: Ab Initio Study at the CCSD(T) Level

“…However, it was performed at a moderate theory level CAS(4,4)CI/6-311G(d) and only for the H-shaped conformer. Recently, the potential energy curves for all of the proposed conformers of the dimer in 13 electronic states were revised in refs and .…”

“…37,38 The giant clusters (O 2 ) N with several thousands of O 2 molecular units are potentially important for future technologies based on a relatively new concept called "chemistry with a hammer." 34,39,40 A polymeric form of oxygen (θ-O 4 phase based on a polymeric chain structural motif) was predicted in ref 41 on the basis of DFT calculations.…”

“…It was observed experimentally both in the low-temperature matrix , and in the molecular beams . The most recent theoretical studies of intermolecular complexes (O 2 ) 2 , (O 2 ) 4 , and (O 2 ) 3 are presented in refs − where high-level ab initio and quantum Monte Carlo methods are applied in the investigations for material sciences. The clusters (O 2 ) 4 are of particular importance for the oxygen solid state at extremely high pressure. , The giant clusters (O 2 ) N with several thousands of O 2 molecular units are potentially important for future technologies based on a relatively new concept called “chemistry with a hammer.” ,, A polymeric form of oxygen (θ-O 4 phase based on a polymeric chain structural motif) was predicted in ref on the basis of DFT calculations.…”

Reaction dynamics within a cluster environment

“…50 This concept still retains computational attention. 51 3 The pick-up, a dedicated technique to add reactants to clusters and nanodroplets Most of the experiments reported in this perspective use the pick-up technique for adding reactants (atoms or molecules) to free clusters or nanodroplets. This elegant and versatile method was introduced by Scoles and coworkers in the 1980s.…”