Ultrafast energy flow in the wake of solution-phase bimolecular reactions

Abstract

Vibrational energy flow into reactants, and out of products, plays a key role in chemical reactivity, so understanding the microscopic detail of the pathways and rates associated with this phenomenon is of considerable interest. Here, we use molecular dynamics simulations to model the vibrational relaxation that occurs during the reaction CN + c-C6H12 → HCN + c-C6H11 in CH2Cl2, which produces vibrationally hot HCN. The calculations reproduce the observed energy distribution, and show that HCN relaxation follows multiple timescales. Initial rapid decay occurs through energy transfer to the cyclohexyl co-product within the solvent cage, and slower relaxation follows once the products diffuse apart. Re-analysis of the ultrafast experimental data also provides evidence for the dual timescales. These results, which represent a formal violation of conventional linear response theory, provide a detailed picture of the interplay between fluctuations in organic solvent structure and thermal solution-phase chemistry. The flow of vibrational energy into reactants and out of products plays a critical role in nearly every chemical reaction. Here, a time-resolved ultrafast microscopic map of energy flow is provided for a thermal bimolecular chemical reaction that takes place in dichloromethane, a typical organic solvent.

Cite this article

Glowacki, D., Rose, R., Greaves, S. et al. Ultrafast energy flow in the wake of solution-phase bimolecular reactions. Nature Chem 3, 850–855 (2011). https://doi.org/10.1038/nchem.1154

View full text

>> Full Text:   Ultrafast energy flow in the wake of solution-phase bimolecular reactions