Decay Lifetimes of Para-Substituted Polystyrene in Solid Films and in Dichloromethane
Titel:
Decay Lifetimes of Para-Substituted Polystyrene in Solid Films and in Dichloromethane
Auteur:
Al-Ani, Khalid E. Akasheh, Talal Yousef, Yaser A.
Verschenen in:
International journal of polymeric materials
Paginering:
Jaargang 56 (2007) nr. 4 pagina's 387-396
Jaar:
2007-04-01
Inhoud:
The fluorescence decay times of polystyrene, poly(4-bromostyrene), poly(4-chlorostyrene), poly(4-methylstyrene), poly(α-methylstyrene), poly(4-methoxystyrene), and poly(4-tert butylstyrene) were measured in solid films and in dichloromethane solution. A detailed analysis of the emission profile performed by nanosecond time resolved fluorescence spectroscopy confirmed the presence of monomer fluorescence as well as excimer fluorescence in both media. Monomer fluorescence decay times gave shorter times compared with that of excimer decay times in dichloromethane solution. Fluorescence from substituted polystyrene was mainly excimer fluorescence with shift of maximum emission to longer wavelength. The ratio of monomer to excimer contributions was found to be dependent on the emission wavelength, but was not affected by polymer concentration. Both monomer and excimer fluorescence lifetimes as well as excimer intensity increase with increasing emission wavelength. An accompanying decrease in monomer contribution is also observed is solution in comparison with that in solid films.