Investigating the Role of Plasmonics in Electrospun Fibers by Combined Photothermal Heterodyne Imaging and Raman Measurements.

The addition of plasmonic nanoparticles into electrospun polymer fibers can have significant impact on their properties relevant to applications in sensing, catalyst, and energy conversion. A Raman spectrometer incorporated into a photothermal heterodyne imaging system was used to study the hot electron transfer mechanism generated through excitation of a localized surface plasmon resonance (LSPR) of gold and silver nanoparticles in polyacrylonitrile films and nanofibers. The ratio of anion nitrile radicals to neutral nitriles of polyacrylonitrile, provides a measure of the ionization capabilities of the nanoparticles, was found to follow a Boltzmann distribution, indicating that the LSPR mediated hot electron transfer mechanism is dependent on temperature. Silicon nanoparticles were used as a control for temperature and showed that heating itself, using 405 nm and 532 nm pump lasers, was not sufficient to ionize polyacrylonitriles, even at relatively high temperatures. The results provide insight into the roles of heating and electron transfer arising from nanoparticles additives in electrospun polymer fibers and other materials.