Relativity of Electron and Energy Transfer Contributions in Nanoparticle-Induced Fluorescence Quenching

• Published in: Journal of physical chemistry. C Vol. 119; no. 48; pp. 27145 - 27155
• Main Authors: Rahman, Dewan S, Deb, Sanhita, Ghosh, Sujit Kumar
• Format: Journal Article
• Language: English
• Published: American Chemical Society 03.12.2015
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b08466

Metallic nanostructures are known to drastically modify the spontaneous emission of molecular probes placed in their vicinity. The main critical parameters that modify the spontaneous rate of emission of organic fluoroprobes near metallic nanostructures are the location of the fluoroprobes around the particle, its separation from the metal surface, and the molecular dipole orientation with respect to the particle surface. Depending on its relative position and orientation with respect to the nanostructures, the fluoroprobe may experience an enhanced or suppressed electric field, leading to a higher or lower excitation rate, respectively, in comparison to a fluoroprobe in free space. The fluorescence of molecules in direct contact with the metal is completely quenched. Possible deactivation pathways of the photoexcited fluoroprobes near metal nanostructures could be enunciated as the intermolecular interactions, electron transfer, energy transfer, and the emission from the molecular probes near the metal surface. Under optimal conditions, both electron and energy transfer processes are considered to be major deactivation pathways for excited fluoroprobes on metal surface, and therefore it has remained difficult to separate their cumulative effects in nanoparticle-induced fluorescence quenching. On the basis of these perspectives, pyrene and its derivatives and four different sizes of silver nanoparticles have, judiciously, been selected in such a way that eventually paves a substantial avenue in realizing electron and energy transfer contributions in nanoparticle-induced fluorescence quenching.