Abstract
Anisotropic shapes of gold nanoparticles are prepared using a modified seed method in the presence of silver ions or clusters in order to study the thermal stability and the dynamics of the hot carriers induced by femtosecond laser pulses. Although gold nanospheres are stable towards thermal treatment, the decomposition of the gold nanorods into spherical nanoparticle aggregates upon thermal treatment is mechanistically different from the case of nanoprisms. Great enhancement of thermal stability is achieved by modifying the surface of the nanoparticles by adding specific amounts of polyvinyl pyrrolidone (PVP) after preparation of gold particles of different shapes capped with cetyltrimethylammonium bromide (CTAB). The surface plasmon resonance spectra of the gold nanostructures are used to monitor their morphological changes. In regards to the hot carrier dynamics, it is found that the phonon-phonon (ph-ph) coupling is much slower in dots than in rods and prisms while electron-phonon (e-ph) coupling is almost the same in these particles.
Highlights
One of the desired goals is to overcome the challenge of controlling the morphology of the nanoparticles, and to be able to fabricate and stabilize them in the desired form
A new proposed mechanism for the formation of anisotropic gold nanoparticles was published that takes into account the reduction of Ag ions by ascorbic acid forming intermediate small Ag clusters, which can act as a catalyst for the formation of gold nanoparticles by their adsorption onto the surface of the gold seeds [34] [36]-[38]
Thermal Stability of Gold Nanoparticles The prepared gold nanoparticles are capped with only one surfactant (CTAB), and the anisotropic shape resulted by adding Ag+ ions or clusters during particle growth [34]
Summary
One of the desired goals is to overcome the challenge of controlling the morphology of the nanoparticles, and to be able to fabricate and stabilize them in the desired form. (2015) Thermal Stability and Hot Carrier Dynamics of Gold Nanoparticles of Different Shapes. Controlling the shape, morphology, and size can be useful in understanding of the electron dynamics and the relaxation processes in gold nanoparticles, which is required because of their fast optical response. This is very important for many potential applications such as optical switching, electronic devices, and biomedical sensing and diagnostics applications [8]-[14]. Better understanding of properties such as electrical and thermal conductivity and superconductivity of metal nanoparticles could be achieved by studying the relaxation dynamics
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