Transient absorption spectroscopy of a heteroaromatic donor–acceptor-π-conjugated 2,2′-bipyridine dye

摘要: Abstract We report on a study of the excited state dynamics heteroaromatic 4,4′-π-conjugated 2,2′-bipyridine dye, bearing conjugated π-excessive and π-deficient rings as donor acceptor substituents, by means steady transient absorption spectroscopy in EtOH solutions room temperature. The ground shows an intense intramolecular charge transfer band visible region with maximum at 515 nm. Excited is measured pumping 480 nm shorter wavelengths from probing specific corresponding to bleaching, stimulated emission absorption. spectral evolution also evaluated frequency domain function delay between pump probe pulses. By SVD analysis two components time constants around 2 ps 150 ps are identified. In addition relevant dynamical Stokes shift occurs first 60 ps which attributed solvent dynamics. Ab initio calculations allows assign features conformation. geometry optimized both cisoid transoid forms. latter results more stable about 0.4 eV.