Spin signature of photoexcitations in sexithiophene

Long-lived photoexcited states in polydiacetylenes: The photoinduced-absorption spectra of PDA-4BCMU

“…As the pump intensity increases, the traps are filled and the efficiency to create long-living states that give rise to PA signals, is reduced. Such a process can be described by the following rate equation 38 dn dt…”

“…This kind of rate equation was proposed in the study of steady-state PA in oligothiophenes 38 and multiple quantum wells 40 to explain the observed steady-state saturation of the signal with increasing pump intensity. In the limit n 0 →ϱ, Eq.…”

Absorption-detected magnetic-resonance studies of photoexcitations in conjugated-polymer/C60composites

“…This is true because spindependent recombination of polarons is enhanced at resonance, leading to a decrease of polar population for polaron pairs ( p ϩ -p Ϫ , p ϩ -p ϩ , and p Ϫ -p Ϫ ) and resulting in an increase of bipolaron population due to p ϩ ϩ p ϩ →BP ϩϩ and p Ϫ ϩ p Ϫ →BP ϪϪ . 19 We also made efforts to separate the 0-0 and 0-1 transitions at LE and HE PA bands of MEH-PPV/C 60 using the ADMR spectroscopy. H-ADMR spectra using resonant microwave frequencies of 3 and 16 GHz, respectively, were measured ͑Fig.…”

Long-lived photoexcited states in polydiacetylenes with different molecular and supramolecular organization

“…29,42,43 A possible explanation for this discrepancy may be given in terms of the saturation of either the excited-state populations as proposed for a polydiacetylene 44 or of the sites available for the trapping of the photogenerated excitations. 45,46 We would like to stress at this point the similarity in the behavior of the 1.4-eV signal of the red form and the 1.45-eV peak of the blue form 29 upon changing the parameters associated with the PA experiments. For this reason it seems reasonable to assign the 1.4-eV signal of the red form to a triplet-to-triplet transition, as already proposed for the 1.45-eV peak of the blue form.…”