Abstract
The electronic properties of diphenylphthalide dicarboxylic acid (DPDA) are studied under gas-phase conditions using dissociative electron attachment spectroscopy and in the condensed environment by means of total current spectroscopy. The experimental features are assigned with the support of density functional theory calculations of the energies of the lowest-lying anion states to describe both resonances responsible for low-energy (0-15 eV) electron attachment to the isolated molecule and the maxima in the density of unoccupied electronic states in the condensed ultrathin (up to 10 nm) films. Resonance electron attachment to DPDA is found to be followed by the opening of the γ-lactone ring in the molecular negative ions, an unusual mechanism leading to their stabilization. A similar mechanism is expected to be responsible for the unique properties of phthalide-based materials in the condensed state.
Highlights
The field of nonadiabatic dynamics is rich and well traversed
We examine the many open questions that arise for nonadiabatic dynamics in the presence of degenerate electronic states, e.g., for singletto-triplet intersystem crossing where a minimal Hamiltonian must include four states
One can wonder: Is spin merely a bystander during the electron transfer process? Or during relaxation after photoexcitation? This question has been taken up recently by several leading chemists, especially Mai et al.38 and Granucci et al.39 who have focused on intersystem crossing (ISC) dynamics with spin– orbit coupling (SOC) between a singlet and a triplet
Summary
The field of nonadiabatic dynamics is rich and well traversed. Dating back to the basic Marcus/Hush/Bixon/Jortner theory of electron transfer, chemists have continuously explored how electron transfer and electronic dynamics are intimately intertwined with nuclear motion and nuclear relaxation. Assuming that one can treat decoherence correctly, one can construct meaningful theories of chemical reaction rates with either Ehrenfest or surface-hopping dynamics Both of these methods can be employed to calculate slow thermal rate processes. This question has been taken up recently by several leading chemists, especially Mai et al. and Granucci et al. who have focused on intersystem crossing (ISC) dynamics with spin– orbit coupling (SOC) between a singlet and a triplet In this Perspective, we will argue that the presence of spin–orbit coupling and/or degenerate systems dramatically increases the complexity of nonadiabatic dynamics in not subtle ways that fundamentally reflect new and very rich physics and that modeling nonadiabatic dynamics with spin degrees of freedom and/or electronic degeneracy represents a key opportunity for future discovery in physical chemistry
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