Reshaping, Fragmentation, and Assembly of Gold Nanoparticles Assisted by Pulse Lasers

Abstract

ConspectusThe vast majority of the outstanding applications of metal nanoparticles (NPs) developed during the last two decades have arisen from their unique optical properties. Within this context, rational synthesis and assembly of gold NPs have been the main research focus, aiming at the design of nanoplasmonic devices with tailored optical functionalities. The progress made in this field is thus to be ascribed to the understanding of the origin of the interaction between light and such gold nanostructures, the dynamics of which have been thoroughly investigated with significant contributions from short and ultrashort pulse laser technologies.We focus this Account on the potential of pulse lasers to provide new fundamental insights into the electron dynamics involved in the interaction of light with the free conduction electrons of Au NPs, that is, localized surface plasmon resonances (LSPRs). The excitation of LSPRs with a femtosecond pulse laser is followed by thermalization of the Au NP electrons and the subsequent relaxation of the nanocrystal lattice and the surrounding environment, which generally results in surface melting. By contrast, nanosecond irradiation usually induces AuNP fragmentation and uncontrolled melting due to overlapping excitation and relaxation phenomena. These concepts have been exploited toward the preparation of highly monodisperse gold nanospheres via pulse laser irradiation of polyhedral nanocrystal colloids, or in the fabrication of nanostructures with “written-in” optical properties. The applicability of pulsed coherent light has been extended toward the direct synthesis and manipulation of Au NPs. Through ablation of a gold target in a liquid with pulse lasers, spherical Au NPs can be synthesized with no need of stabilizing ligands, which is a great advantage in terms of reducing toxicity, rendering these NPs particularly suitable for medical applications. In addition, femtosecond laser irradiation has been proven a unique tool for the controlled welding of plasmonic gold nanostructures by electromagnetic field enhancement at the hot spots of assembled Au NPs. The combination of such nanostructures with pulse lasers promises significant chemical and biochemical advances, including the structural determination of organic reaction intermediates, the investigation of phase transitions in inorganic nanomaterials at mild reaction conditions, or the efficient photothermal destruction of cancer cells avoiding damage of surrounding tissue.

Optimising gold nanorods for photoacoustic imaging in vitro

“…75 The photostability of AuNRs can be affected by a number of factors, including photothermal conversion efficacy, thermal conductivity, surface diffusion, AuNR defects, thermodynamic stability, and the coating surrounding the AuNRs. 76,77 Furthermore, the optical absorption of the particles can have a signicant effect on the reshaping of AuNRs. As the AuNR size decreases, the optical absorption of the particle will also decrease.…”

Strongly Coupled CoO Nanoclusters/CoFe LDHs Hybrid as a Synergistic Catalyst for Electrochemical Water Oxidation

“…LAL has been recognized as a powerful technique for preparing various nanomaterials . In this study, the underlying chemical processes for the formation of CoO/LDHs composite have not been well understood.…”

“…LAL has been recognized as a powerful technique for preparing various nanomaterials. [30][31][32][33] In this study, the underlying chemical processes for the formation of CoO/LDHs composite have not been well understood. However, generally speaking, when a focused nanosecond pulsed laser (usually 1064 nm in wavelength) irradiates a metal target in liquid, the irradiated spot will be heated and evaporate to a plasma state for sufficiently high beam energy, and the plasma will then evaporate the surrounding liquid to plasma.…”

Colloid‐Interface‐Assisted Laser Irradiation of Nanocrystals Superlattices to be Scalable Plasmonic Superstructures with Novel Activities

“…Benefited from unique light-matter physical properties, as one of the typical light-matter interactions, the strong interaction between laser radiation and Au NCs has given a rise for the applications ranging from the materials characterization to NCs architecture and to device fabrications. [27][28][29] When Au NCs assemblies are irradiated by a light beam, the optical fields can be enhanced and the light is confined and localized at subwavelength dimensions by plasmons, which is termed hot spots and occurred directly within the gaps. [30,31] Such hot spots generation is originated from the coupling of Au NCs conduction band electron oscillation with the incident electromagnetic radiation, known as localized surface plasmon resonance (LSPR).…”