title: Single photon triggered dianion formation in TCNQ and F4TCNQ crystals.
abstract: Excited state dynamics in two strong organic electron acceptor systems, TCNQ and F4TCNQ single crystals, was studied. After absorption of a single photon, dianions are formed in both crystals on ultrashort timescale: TCNQ τ < 50 fs, F4TCNQ τ = 4 ps. By use of transient absorption spectroscopy, we demonstrate that the dianion formation in F4TCNQ is mediated by the radical anion precursor which is described by a two-step model. Our measurements show the phenomenon that in this quinoid acceptor crystals in the absence of additional donor molecule, it is possible to resolve the two step formation of a doubly charged anion upon absorption of a single low energy photon (2.6 eV).
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
authors.forename: Peng
authors.initials: P
authors.lastname: Hu
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
authors.forename: Hui
authors.initials: H
authors.lastname: Jiang
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
authors.forename: Christian
authors.initials: C
authors.lastname: Kloc
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Handong
authors.initials: H
authors.lastname: Sun
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Cesare
authors.initials: C
authors.lastname: Soci
authors.affiliation: Instituciό Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain.|Institut de Química Computacional i Catàlisi (IQCC), Universitat de Girona, Campus de Montilivi 17071 Girona, Spain.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Voityuk
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Michel-Beyerle
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.|Institute of Artificial Photosynthesis, State Key Laboratory of Fine Chemicals F-209, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Gagik G
authors.initials: GG
authors.lastname: Gurzadyan