title: Ultrafast dynamical study of pyrene-N,N-dimethylaniline (PyDMA) as an organic molecular diode in solid state.
abstract: Femtosecond optical pump-probe spectroscopy has been employed for studying the directly linked electron donor-acceptor system pyrene-N,N-dimethylaniline (PyDMA) in solid state. This DMA-pyrene derivative discussed is being applied as a molecular diode system switching on an ultrafast time scale. Our ultrafast solid-state studies reveal a complex photochemistry of this molecular crystal system. Strong couplings of the optically induced charge-transfer state with the radical ion pair state allow a femtosecond transition of the latter. One could see on the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) description that a pure optical transition switches the system from a conducting to a blocked system because the molecular orbitals (MOs) of DMA moiety lie in a node plane of the LUMO. Within 800 fs the system relaxes back to the ground state and/or forms a radical ion pair, which is the surprising result of our study; when the system was probed further, the system underwent vibrational cooling and enhanced population inversion of the radical ion pair.
authors.affiliation: FS-SCS, Deutsches Elecktronen-Synchrotron (DESY), Notkestr.85, 22607 Hamburg, Germany.
authors.forename: Sreevidya
authors.initials: S
authors.lastname: Thekku Veedu
authors.forename: Dirk
authors.initials: D
authors.lastname: Raiser
authors.forename: Reza
authors.initials: R
authors.lastname: Kia
authors.forename: Mirko
authors.initials: M
authors.lastname: Scholz
authors.forename: Simone
authors.initials: S
authors.lastname: Techert
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D004579:Electron Transport; D008958:Models, Molecular; D055096:Optical Devices; D010777:Photochemistry; D011721:Pyrenes / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D011721:Pyrenes; C015157:N,N-dimethylaniline; C030984:pyrene