Combination of transient 2D-IR experiments and AB initio computations sheds light on the formation of the charge-transfer state in photoexcited carbonyl carotenoids (Articolo in rivista)

Type
Label
  • Combination of transient 2D-IR experiments and AB initio computations sheds light on the formation of the charge-transfer state in photoexcited carbonyl carotenoids (Articolo in rivista) (literal)
Anno
  • 2014-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/jp505473j (literal)
Alternative label
  • Di Donato, Mariangela; Segado Centellas, Mireia; Lapini, Andrea; Lima, Manuela G.; Ávila, Francisco José; Santoro, Fabrizio; Cappelli, Chiara; Righini, Roberto (2014)
    Combination of transient 2D-IR experiments and AB initio computations sheds light on the formation of the charge-transfer state in photoexcited carbonyl carotenoids
    in The journal of physical chemistry. B
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Di Donato, Mariangela; Segado Centellas, Mireia; Lapini, Andrea; Lima, Manuela G.; Ávila, Francisco José; Santoro, Fabrizio; Cappelli, Chiara; Righini, Roberto (literal)
Pagina inizio
  • 9613 (literal)
Pagina fine
  • 9630 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url
  • http://www.scopus.com/record/display.url?eid=2-s2.0-84906093683&origin=inward (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 118 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo
  • 32 (literal)
Note
  • ISI Web of Science (WOS) (literal)
  • Scopu (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • LENS European Laboratory for Non-Linear Spectroscopy; cNR - Istituto Nazionale di Ottica; Universita degli Studi di Firenze, DIP. DI CHIMICA; Scuola Normale Superiore di Pisa; Universita di Pisa, Dip. di Chimica; CNR ICCOM, UOS Pisa; Universidad de Malaga (literal)
Titolo
  • Combination of transient 2D-IR experiments and AB initio computations sheds light on the formation of the charge-transfer state in photoexcited carbonyl carotenoids (literal)
Abstract
  • The excited state dynamics of carbonyl carotenoids is very complex because of the coupling of single- and doubly excited states and the possible involvement of intramolecular charge-transfer (ICT) states. In this contribution we employ ultrafast infrared spectroscopy and theoretical computations to investigate the relaxation dynamics of trans-8'-apo-beta-carotenal occurring on the picosecond time scale, after excitation in the S-2 state. In a (slightly) polar solvent like chloroform, one-dimensional (TID-IR) and two-dimensional (T2D-IR) transient infrared spectroscopy reveal spectral components with characteristic frequencies and lifetimes that are not observed in nonpolar solvents (cyclohexane). Combining experimental evidence with an analysis of CASPT2//CASSCF ground and excited state minima and energy profiles, complemented with TDDFT calculations in gas phase and in solvent, we propose a photochemical decay mechanism for this system where only the bright single-excited 1B(u)(+) and the dark double-excited 2A(g)(-) states are involved. Specifically, the initially populated 1B(u)(+) relaxes toward 2A(g)(-) in 200 fs. In a nonpolar solvent 2A(g)(-) decays to the ground state (GS) in 25 ps. In polar solvents, distortions along twisting modes of the chain promote a repopulation of the 1B(u)(+) state which then quickly relaxes to the GS (18 Ps in chloroform). The 1B(u)(+) state has a high electric dipole and is the main contributor to the charge-transfer state involved in the dynamics in polar solvents. The 2A(g)(-) -> 1B(u)(+) population transfer is evidenced by a cross peak on the T2D-IR map revealing that the motions along the same stretching of the conjugated chain on the 2A(g)(-) and 1B(u)(+) states are coupled. (literal)
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