Abstract
The spectroscopic characterization of a cationic dye, Nile Blue A (NB), in negatively charged SnO2 and SiO2 colloidal suspensions has been carried out. The results show that NB, in the presence of these colloidal suspensions, forms aggregates of H-type which are nonfluorescent and have blue-shifted absorption compared to the NB monomer in aqueous solution. Laser photolysis experiments have been carried out to study the excited-state dynamics of the NB aggregates. The transient absorption measurements of NB adsorbed on SiO2 colloids (inert support) show that the H-aggregates of NB have a relatively short-lived excitonic singlet state (τ = 40 ps); the lifetime of the excited singlet of the monomer in aqueous solution is ∼390 ps. On a reactive semiconductor support like SnO2, the NB aggregates also inject electrons into SnO2. This is characterized by the formation of the cation radical, (NB)2•+, of the NB aggregates and by the trapping of electrons the in SnO2 nanocrystallites. The monophotonic dependence of...
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
