Picosecond dynamics of excitations studied in three generations of new 4,4′-bis(diphenylamino)stilbene-based dendrimers

Cooperative enhancement of two-photon absorption based on electron coupling in triphenylamine-branching chromophore

“…This cooperative enhancement effect can also be confirmed by time-resolved fluorescence decay curves, presented in Fig. 5, wherein monobranch 1 gives rise to quasi-monoexponential fit and exhibits the lifetime of 1.67 ns, which is close to the BDPAS lifetime [38]. Meanwhile, multibranch 2 gives rise to dual exponential fit and exhibits the dual lifetimes of 1.56 and 6.47 ns.…”

“…Meanwhile, multibranch 2 gives rise to dual exponential fit and exhibits the dual lifetimes of 1.56 and 6.47 ns. The presence of the faster component (content of 64%) is comparable to the decay time of BDPAS [38], while the presence of a slow decay component (content of 36%) is clear evidence of the presence of interactions (i.e., electron coupling) among the individual branch segments. The fact that the long time component appears with concomitance of short time component decreasing implies the existence of more delocalized relaxed state or interaction state between individual branches.…”

One-, two- and three-photon spectroscopy of π-conjugated dendrimers: cooperative enhancement and coherent domains

“…We have recently performed detailed picosecond time-resolved measurements of fluorescence decay kinetics in this series of dendrimers, and have observed a complex non-exponential behavior, which changes both with the size of the molecule, as well as with the wavelength of emission. We attribute this to several different energy relaxation processes occurring in the excited electronic state, including picosecond energy transfer to more delocalized states [42].…”

“…The value s 3 /N p (last column) represents a 3PA enhancement factor, relative to BDPAS. dynamics taking place on picosecond time scale [42]. Even if we could measure transient excited state absorption, then establishing viable quantitative value for M fi , which is relevant to formula (3), will still be less than straightforward.…”

Synthesis, structure and nonlinear optical properties of two novel two-photon absorption chromophores

“…The quantum yields (Φ) of 1 and 2 in different solvents were determined by using Coumarin as standard. Seen from the Table 2, 2 shows high quantum yields in solutions comparing with 1, respectively, which indicated that the quenching effect of fluorin atoms are significant [24] . Table 2 Single-and two-photon-related photophysical properties of chromophores 1 and 2 in several different polar solvents Compounds Solvents a) Peak position of the longest absorption band; b) peak position of SPEF, exited at the absorption maximum; c) quantum yields determined by using coumarin as standard; d) Stokes' shift in cm −1 ; e) TPEF peak position in nm.…”