%0 Journal Article %J European Physical Journal-Special Topics %D 2008 %T Photothermally excited coherent lattice phonon oscillations in plasmonic nanoparticles %A Huang, Wenyu %A El-Sayed, Mostafa A %X The photothermal property of (Ag and Au) plasmonic nanoparticles has brought about many important discoveries and applications in nanoscience and nanotechnology. In this review, we briefly summarize a photothermal effect, the coherent phonon oscillation, of plasmonic nanoparticles irradiated with ultrafast laser pulses of low power density. The coherent phonon oscillation is created in the nanoparticle by the ultrafast impulsive photothermal heating. The effects of size, shape, thickness, and interparticle interaction on the period of coherent phonon oscillations are discussed. The detection of the coherent lattice oscillation of metallic nanoparticles provides a powerful tool to characterize the mechanical and structural properties of nanostructures. %B European Physical Journal-Special Topics %V 153 %P 325-333 %8 Jan %@ 1951-6355 %G eng %M WOS:000254041300075 %R 10.1140/epjst/e2008-00456-x %0 Journal Article %J European Physical Journal-Special Topics %D 2008 %T Pulsed laser photothermal annealing and ablation of plasmonic nanoparticles %A Huang, Wenyu %A El-Sayed, Mostafa A %X In this review, we briefly summarize the photothermal properties of plasmonic nanoparticles. Several photothermal effects of plasmonic nanoparticles irradiated with ultrafast laser pulses of various powers are introduced. Plasmonic nanoparticles have been synthesized by pulsed laser ablation of bulk materials. Melting and ablation of nanoparticles have also been used to modify the shape and the size distribution of plasmonic nanoparticle samples. Under certain circumstances, another interesting observation using high power femtosecond laser irradiation of plasmonic nanoparticles is also included in this review, namely the flying, by propulsion of the plasmonic nanoparticles. %B European Physical Journal-Special Topics %V 153 %P 223-230 %8 Jan %@ 1951-6355 %G eng %M WOS:000254041300051 %R 10.1140/epjst/e2008-00432-6 %0 Journal Article %J Journal of Applied Physics %D 2005 %T Photothermal reshaping of prismatic Au nanoparticles in periodic monolayer arrays by femtosecond laser pulses %A Huang, Wenyu %A Qian, Wei %A El-Sayed, Mostafa A %X Prismatic gold nanoparticles in the periodic monolayer arrays prepared with nanosphere lithography technique can be reshaped with femtosecond laser pulses at different powers and wavelengths. As the power density of 400 nm femtosecond laser increases, the prismatic particle tips begin to round and the overall particle shape changes from a prism to a sphere with a tripodal intermediate. The formation of the tip-rounded nanoprisms is probably due to the dewetting properties of gold on quartz surface and the low melting temperature at the tips. The formation of the tripodal nanoparticles is attributed to the inhomogeneous heating and lattice rearrangement of the as-deposited nanoparticles to a metastable state, which is more stable than the prismatic shape but less stable than the spherical shape. With 800 nm femtosecond laser irradiation, only tip-rounded nanoprisms are observed and no spherical nanoparticles are formed at the laser powers used. This is most likely due to the blueshift of the plasmon absorption band for the transformed particles, so that they cannot absorb the required energy to overcome the barrier to make the spherical shape. With 700 nm femtosecond laser irradiation, the tip-rounded and the tripodal nanoparticles are formed and few spherical particles are observed at the higher laser power density. From the results of this work, it is shown that by changing the wavelength and power density of the femtosecond laser, one can control the final shape of the particles formed from the original prismatic nanoparticles. %B Journal of Applied Physics %V 98 %8 Dec %@ 0021-8979 %G eng %M WOS:000234119600067 %] 114301 %R 10.1063/1.2132515