Speaker
Description
Photodissociation of methyl iodine in its A band is a classical example of a fast reaction mediated with by a conical intersection. The arrival time to this conical intersection was first estimated using theoretical simulations using semiclassical [1, 2, 3] and quantum [4, 5, 6, 7, 8, 9, 10] dynamics over pre-existent potential energy surfaces [1, 2, 5]. From the experimental point of view, the confirmation of the arrival time of the system at the conical intersection was first measured by means of Coulomb explosion [3] and afterwards using Attosecond Transient Absorption [11]. In both cases, combining the measurement with theoretical models based on semiclassical dynamics using the SHARC method [12]. However, the duration of the pump pulse in these
experiments is longer than the estimated arrival time, and the conical pass would be affected. In
fact, in similar experimental setups and for this type of molecules, dumping of the population was
observed [13].
In this work [14], we are going to use a few fs (4.2) pump laser so that during the pass through the conical intersection the laser pulse is not acting. From the theoretical side (where this presentation will focus), this implies the consideration of a broad range of excitation energies and the propagation of a large number of trajectories using state-of-the-art electronic structures methods in combination with surface hopping methodology. In this scheme, strong spin-orbit coupling and fast photodissociation dynamics, is where the combination of the SHARC method [12] with high level ab initio methodology (XMS-CASPT2) brights giving a very good accuracy that agrees with the experimental results.
Notes and References
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14 Colaizzi L. et al. Nat. Commun. 2024, 15, 9196