Primary processes in photophysics and photochemistry of complex studied by femtosecond pump–probe spectroscopy

Ultrafast pump–probe spectroscopy (λpump = 420 nm) was applied to study the photoaquation of PtBr 6 2 - complex. The excitation to d–d excited 1T1g state was followed by the formation of an intermediate absorption decaying with characteristic times of 370 fs, 2.2 and 15.2 ps. Two shorter times were attributed to the formation of the lower excited state (3T1g) and its vibrational cooling accompanied by solvent relaxation. The longest time was interpreted as 3T1g transition to the hot ground state (1A1g) and the dissociation product (PtBr5(H2O)− complex). The scheme is consistent with the independence of the photoaquation quantum yield on the excitation wavelength.