Ultrafast dynamics of formation and autodetachment of a dipole-bound state in an open-shell pi-stacked dimer anion

Download
Author
Bull, JN; West, CW; Verlet, JRRDate
2016-01-01Source Title
Chemical SciencePublisher
ROYAL SOC CHEMISTRYUniversity of Melbourne Author/s
Bull, JamesAffiliation
School of ChemistryMetadata
Show full item recordDocument Type
Journal ArticleCitations
Bull, J. N., West, C. W. & Verlet, J. R. R. (2016). Ultrafast dynamics of formation and autodetachment of a dipole-bound state in an open-shell pi-stacked dimer anion. CHEMICAL SCIENCE, 7 (8), pp.5352-5361. https://doi.org/10.1039/c6sc01062h.Access Status
Open AccessAbstract
Isolated π-stacked dimer radical anions present the simplest model of an excess electron in a π-stacked environment. Here, frequency-, angle-, and time-resolved photoelectron imaging together with electronic structure calculations have been used to characterise the π-stacked coenzyme Q0 dimer radical anion and its exited state dynamics. In the ground electronic state, the excess electron is localised on one monomer with a planar para-quinone ring, which is solvated by the second monomer in which carbonyl groups are bent out of the para-quinone ring plane. Through the π-stacking interaction, the dimer anion exhibits a number of charge-transfer (intermolecular) valence-localised resonances situated in the detachment continuum that undergo efficient internal conversion to a cluster dipole-bound state (DBS) on a ∼60 fs timescale. In turn, the DBS undergoes vibration-mediated autodetachment on a 2.0 ± 0.2 ps timescale. Experimental vibrational structure and supporting calculations assign the intermolecular dynamics to be facilitated by vibrational wagging modes of the carbonyl groups on the non-planar monomer. At photon energies ∼0.6-1.0 eV above the detachment threshold, a competition between photoexcitation of an intermolecular resonance leading to the DBS, and photoexcitation of an intramolecular resonance leading to monomer-like dynamics further illustrates the π-stacking specific dynamics. Overall, this study provides the first direct observation of both internal conversion of resonances into a DBS, and characterisation of a vibration-mediated autodetachment in real-time.
Export Reference in RIS Format
Endnote
- Click on "Export Reference in RIS Format" and choose "open with... Endnote".
Refworks
- Click on "Export Reference in RIS Format". Login to Refworks, go to References => Import References