AN EVALUATION OF THE EXCITED-STATE ABSORPTION-SPECTRUM OF RU(BPY)3(2+) IN AQUEOUS AND ACETONITRILE SOLUTIONS

Three pulsed laser techniques have been used to evaluate the absorption spectrum of *Ru(bpy)3(2+) in H2O, CH3CN and H2O/CH3CN mixtures: complete conversion of the ground state, energy transfer to anthracene, and benzophenone actinometry. The three techniques give reliable and reproducible values of epsilon450=4.6(+/-0.4) X 10(3) M-1 cm-1, independent of the solution medium. The ground state spectrum is virtually the same in H2O and CH3CN with epsilon452 = 1.46 x 10(4) M-1 cm-1; the value of DELTAepsilon450, the difference in the epsilon values of the excited and the ground states at 450 nm, is -1.0(+/-0.09) X 10(4) M-1 cm-1. Ru(bpy)3(2+) can serve as a reliable actinometer for the 532 nm frequency doubled Nd:YAG pulsed laser line and, with appropriate corrections for the inner filter effect, for the 355 nm frequency tripled line.