Ultrafast energy flow in the wake of solution-phase bimolecular reactions.
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-C(6)H(12) → HCN + c-C(6)H(11) in CH(2)Cl(2), 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.
School of Chemistry, University of Bristol, Bristol BS8 1TS, UK. david.r.glowacki@bristol.ac.uk
David R
DR
Glowacki
Rebecca A
RA
Rose
Stuart J
SJ
Greaves
Andrew J
AJ
Orr-Ewing
Jeremy N
JN
Harvey
D004735:Energy Transfer; D005740:Gases / Q000737:chemistry; D006856:Hydrogen Cyanide / Q000737:chemistry; D007700:Kinetics; D008752:Methylene Chloride / Q000737:chemistry; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D012996:Solutions / Q000737:chemistry*; D013997:Time Factors; D014732:Vibration
D005740:Gases; D012996:Solutions; D006856:Hydrogen Cyanide; D008752:Methylene Chloride