Nanoparticle enhanced blue emission

PHYS 215

Xichen Cai, xichenc@bgsu.edu, Kelechi C Anyaogu, akelech@bgnet.bgsu.edu, and Douglas C. Neckers, neckers@photo.bgsu.edu. Center for Photochemical Sciences, Bowling Green State University, 132 Overman Hall, Bowling Green, OH 43403
5-Mercapto-2,2'-bithiophene functionalized copper, silver, and gold nanoparticles (NPs) of various diameters were synthesized. Emission with a peak around 450 nm was detected on irradiation with UV light. The emission intensity increases with increasing nanoparticle size. Among metal NPs of similar size, the strongest emission was observed with silver, followed by gold then copper. This emission however, disappears upon photopolymerization of the NPs. The absorption and emission spectra of 5-mercapto-2,2'-bithiophene in various solvents at room and low temperatures indicated that the trans-isomer should be dominant when attached onto the surface of the metal nanoparticle. The electronic interaction between the ligand molecule and nanoparticle core likely restricts the isomerization of 5-mercapto-2,2'-bithiophene. Such nanoparticle enhanced blue emission is expected to have potential applications in various fields.