Dissociation Time, Quantum Yield, and Dynamic Reaction Pathways in the Thermolysis of trans-3,4-Dimethyl-1,2-dioxetane

Abstract

The thermolysis of trans-3,4-dimethyl-1,2-dioxetane is studied by trajectory surface hopping. The significant difference between long and short dissociation times is rationalized by frustrated dissociations and the time spent in triplet states. If the C–C bond breaks through an excited state channel, then the trajectory passes over a ridge of the potential energy surface of that state. The calculated triplet quantum yields match the experimental results. The dissociation half-times and quantum yields follow the same ascending order as per the product states, justifying the conjecture that the longer dissociation time leads to a higher quantum yield, proposed in the context of the methylation effect. The populations of the molecular Coulomb Hamiltonian and diagonal states reach equilibrium, but the triplet populations with different S z components fluctuate indefinitely. Certain initial velocities, leading the trajectories to given product states, can be identified as the most characteristic features for sorting trajectories according to their product states.

Mechanistic Investigation into Chemiluminescence from 1,4-Benzoquinone

“…It is not clear whether the mechanism remains applicable to unexplored TFBQ and TIBQ. Second, the dissociation stage is crucial for the generation of a light emitter. , The anionic DHD – formed by the oxidation could interconvert with neutral DHD in the phosphate buffer solution (PBS), but the dissociation mechanism of DHD – and DHD has not been clearly explored in our previous studies. Additionally, we do not know what is the effect of the relative proportions of DHD / DHD – in the solution on the CL.…”

Quantum simulation of conical intersections

“…These processes are ubiquitous in nature and have been studied extensively in diverse areas such as spectroscopy, solar energy conversion, chemiluminescence, photosynthesis, and photostability of biomolecules. 1–17 Different potential energy surfaces can intersect at regions that exhibit a conical-shaped topography, known as conical intersections (CIs). 18–21 In the vicinity of CIs, the Born–Oppenheimer approximation which assumes adiabaticity breaks down.…”