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.
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Photothermal behaviour of titanium nitride nanoparticles evaluated by transient X-ray diffraction
The photothermal properties of metal nitrides have recently received significant attention owing to diverse applications in solar energy conversion, photothermal therapies, photoreactions, and thermochromic windows. Here, the photothermal response of titanium nitride nanoparticles is examined using transient X-ray diffraction, in which optical excitation is synchronized with X-ray pulses to characterize dynamic changes in the TiN lattice. Photoinduced diffraction data is quantitatively analyzed to determine increases in the TiN lattice spacing, which are furthermore calibrated against static, temperature-dependent diffraction patterns of the same samples. Measurements of 20 nm and 50 nm diameter TiN nanoparticles reveal transient lattice heating from room temperature up to ∼175 °C for the highest pump fluences investigated here. Increasing excitation intensity drives sublinear increases in lattice temperature, due to increased heat capacity at the higher effective temperatures achieved at higher powers. Temporal dynamics show that higher excitation intensity drives not only higher lattice temperatures, but also unexpectedly slower cooling of the TiN nanoparticles, which is attributed to heating of the solvent proximal to the nanoparticle surface.
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- Award ID(s):
- 1808590
- PAR ID:
- 10293389
- Date Published:
- Journal Name:
- Nanoscale
- Volume:
- 13
- Issue:
- 4
- ISSN:
- 2040-3364
- Page Range / eLocation ID:
- 2658 to 2664
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0NR08202C
