Fluorescence Spectroscopy of All-trans-anhydrorhodovibrin and Spirilloxanthin:  Detection of the 1B_u^- Fluorescence

Abstract

Fluorescence spectra of all-trans-anhydrorhodovibrin and spirilloxanthin having the number of conjugated double bonds n ) 12 and 13 were recorded in n-hexane solution. The optically forbidden 2A gf 1A gfluorescence was observed for carotenoids having such a long conjugated chain, and the optically forbidden 1B uf 1A gfluorescence was identified for the first time. The proposed energies of the 2A g -, 1B u -, and 1B u + fluorescence origins are 12 500, 14 900, and 19 200 cm -1 for anhydrorhodovibrin and 11 900, 13 600, and 18 900 cm -1 for spirilloxanthin (at 295 K). The estimated transition dipole moments for fluorescence from the 2A g -, 1B u -, and 1B u + states to the ground 1A gstate are 1.24, 4.76, and 17.4 D for the former and 1.37, 3.72, and 16.8 D for the latter.

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

“…[186][187][188] It was assigned to a signal on the higher-energy side of the S 0 !S n transition in transient absorption studies. [186,189,190] Additional experimental evidence for this state was obtained by stationary fluorescence [191] and resonance Raman spectroscopy. [179,182,192] The S* state was suggested to be either the 1B u À state [182,191,192] as predicted by Tavan and Schulten [177,193] or the 3A g À state.…”

“…[186,189,190] Additional experimental evidence for this state was obtained by stationary fluorescence [191] and resonance Raman spectroscopy. [179,182,192] The S* state was suggested to be either the 1B u À state [182,191,192] as predicted by Tavan and Schulten [177,193] or the 3A g À state. [179] In light-harvesting complexes, the S* state was proposed to be a 1B u À state which acts as precursor for triplet-state formation.…”

Orbital optimization in the density matrix renormalization group, with applications to polyenes and β-carotene

“…Recent studies using resonance Raman excitation profiles and electronic absorption spectroscopy on substituted polyenes in the carotenoid family have indicated the presence of additional dark states below the 1B u + state. [68][69][70][71][72] In particular, for the all-trans-carotenoids with ͑the number of double bonds͒ n = 9 -11, Sashima et al 67 and Cerullo et al 73 72 The assignment was made by extrapolating from the earlier Pariser-ParrPople multi-reference doubles configuration interaction calculations by Tavan and Schulten on short polyenes ͑n =2-8͒, which had predicted the existence of these additional states. 56 To better understand the electronic structure of these low-lying states, we would ideally like to be able to carry out an ab initio multireference calculation using the complete -valence space.…”

Ultrafast Energy‐Transfer Pathway in a Purple‐Bacterial Photosynthetic Core Antenna, as Revealed by Femtosecond Time‐Resolved Spectroscopy

“…A likely donor state for Bchl!Spx EET upon excitation of the Q x band of Bchl is the Q x band, because the S 1 energy of Spx in solution has been reported to be 1.48 eV, [18] a value that is slightly higher than the Q y energy of 1.40 eV. Moreover, if Q y is assumed to be the donor for the EET to S 1 of Spx, it is expected that at least part of the transient absorption of Q y would be rapidly quenched with a time constant of 30 fs.…”