The excited-state relaxation dynamics of the protein-labeling dye acrylodan in solution and attached to human serum albumin has been studied by femtosecond transient absorption spectroscopy. Time?resolved spectra and kinetics of stimulated emission and excited-state absorption in the wavelength region from 400 to 800 nm were studied in ethanol and dimethylformamide. The excited-state solvation dynamics is characterized by multiexponential behavior in both solvents. In ethanol solution, the time dependence of the transient spectra is interpreted in terms of fast solvent relaxation followed by excited?state isomerization of the dye. Acrylodan attached to the protein shows a relaxation component of 3 ps that is attributed to the solvation dynamics of water in the neighborhood of the fluorescent label.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry