Excited-state dynamics and complete transient absorption features of the trimer tris-4,4',4' '-(4-nitrophenyleethynyl)triphenylamine and the monomer 4-N,N-(dimethylamino)-4'-nitrotolane have been obtained from femtosecond pump-probe spectroscopy. The measurements are carried out to understand the mechanism behind enhanced two-photon absorption cross-sections of branched systems over their linear counterparts. Absorption and emission transition dipole moments of monomer and trimer in toluene have suggested that the emitting state of trimer is different from the monomer and probably is arising from the charge-delocalized C(3) symmetry state. Ultrafast transient absorption measurements on these molecules have spectroscopically validated the presence of an initial electron delocalized state with the C(3) symmetry state in the trimer molecule. The results have shown that there is a slower rate of internal conversion from the C(3) symmetry state to intramolecular charge transfer of trimer suggesting a barrier between them. Also, presence of a charge-stabilized state and involvement of a nonemissive state in the excited-state deactivation has been observed for both monomer and trimer.

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp063262hDOI Listing

Publication Analysis

Top Keywords

symmetry state
12
state
9
state excited-state
8
transient absorption
8
monomer trimer
8
state trimer
8
trimer
6
ultrafast excited
4
excited state
4
state relaxation
4

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!