کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5373222 | 1504210 | 2015 | 6 صفحه PDF | دانلود رایگان |
- fs-transient absorption spectra of emeraldine base of polyaniline pumped at 700Â nm.
- Kinetic master equations for experimental data.
- Formation of charge transfer states within 50Â fs. Non-radiative decay (0.5Â ps).
- Phenyl rings relaxation (2.1Â ps).
- Formation of long-lived polarons (â¼ns).
Using femtosecond pump-probe transient absorption spectroscopy (wavelengths 330-800Â nm), we observed and explained excited state, charge transfer and polaron state dynamics in emeraldine base form of polyaniline in dimethyl sulfoxide solution. The excited state created by a pump pulse (700Â nm) in the quinoid absorption Q-band loses its initial symmetry by subsequent energy transition to a charge transfer state within 50Â fs. The hot charge transfer state either recombines non-radiatively into the ground state with decay time constant 0.55Â ps or transfers into a relaxed state corresponding to the relaxed phenyl geometry during ca 2.1Â ps. This relaxed state shows a prolonged lifetime of about 6.5Â ps before its recombination to the ground state. However, a small amount of long-lived polarons with lifetime of about 2Â ns in air and with lifetime longer than 6Â ns in the solution bubbled with dry N2 was detected.
Journal: Chemical Physics - Volume 456, 29 July 2015, Pages 79-84