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. 2000 Jul 5;97(14):7687–7691. doi: 10.1073/pnas.97.14.7687

Figure 3.

Figure 3

(a) Comparison of absorbance (ΔA) − time (t) changes in the assembly [co-PS-CH2NHCO-(RuII(RC)3RuII17)](PF6)46 (4) and homopolymer [co-PS-CH2NHCO-(RuII16)](PF6)32 (5). At the monitoring wavelength of 401 nm, unquenched antenna excited states do not contribute to the observed signal. The observed absorbance change is associated with the appearance of MV+. in the RS state. The large value of ΔAmax shows that a considerable fraction of the RS state forms during the laser pulse. There is also clear evidence for both rapid and slow decay processes after the laser pulse. Experimental conditions as in Fig. 2. (b) Transient absorbance change at the bleach (450 nm) obtained after 500 nm excitation, 1.82 mJ/pulse⋅cm2 with the excitation beam defocused to 3.85 cm2. The smaller ΔAmax change for 4 compared with 5 is consistent with a rapid quenching process or processes that occur within the laser flash. The enhanced decay kinetics for 4 compared with 5 occur because of energy migration and quenching by sensitization of the RC. Fitting the decay traces to Eq. 3 gives for 4 k1 = 6.7 × 107 s−1 (ΔA1 = 10.10 mOD), k2 = 9.0 × 106 s−1 (ΔA2 = 8.47 mOD), k3 = 1.3 × 106 s−1 (ΔA3 = 6.67 mOD) and for 5 k1 = 3.7 × 107 s−1 (ΔA1 = 14.08 mOD), k2 = 3.8 × 106 s−1 (ΔA2 = 8.42 mOD), k3 = 7.8 × 105 s−1 (ΔA3 = 10.91 mOD). With use of Eq. 4, this gives the average decay rate constants <k (4)> = 4 × 106 s−1 and <k (5)> = 2 × 106 s−1.