Laser-Induced Formation and Disintegration of Gold Nanopeanuts and Nanowires

Abstract

We report the laser-induced formation of peanut-shaped gold nanoparticles (Au nanopeanuts) and gold nanowires (AuNWs), and their morphological properties. Pulsed laser irradiation of citrate-capped gold nanoparticles at 532 nm induces fragmentation, spherical growth, the formation of Au nanopeanuts, and the formation of AuNWs, sequentially. High-resolution transmission electron microscopy images reveal that the Au nanopeanuts are formed by instantaneous fusion of spherical nanoparticles in random orientation by laser heating. Furthermore, Au nanopeanuts are bridged in a linear direction to form AuNWs by an amorphous accumulation of gold atoms in the junction. The laser-produced Au nanopeanuts and AuNWs slowly disintegrate, restoring the spherical shape of the original Au nanoparticles when the laser irradiation is stopped. The addition of citrate effectively prevents them from transforming back to the nanospheres.

Ultrasonic-Enhanced Fabrication of Metal Nanoparticles by Laser Ablation in Liquid

“…From the above result, we can see that ultrasound has considerable potential in the synthesis of smaller nanoparticles in the process of LAL. The chain-like morphology of metal nanoparticle structures fabricated by LAL in distilled water has been observed by many researchers. , During the ablation process, the nanoparticles are ejected and condensed from the high-temperature and high-pressure plasma plume formed by high-energy pulsed laser irradiation . The formation of chains can be explained by the primary nanoparticles adhering to each other during plume expansion, which can form different types of nanoparticles ranging from spherical particles to line-style nanostructures .…”

Size and Shape Homogenization of Ag Nanoparticles by Laser Irradiation

“…This process is consistent with the previously observed photoprocess of AuNPs. 21 The inset in Figure 2 shows that, upon irradiation for 10 s, the surface plasmon absorption band decreases and blueshifts, indicating that AgNPs are crumbled to smaller Ag nanoparticles and Ag atoms. Further irradiation up to 1 min leads to a continuing decrease and blueshift of the SPR band.…”

“…As was observed for AuNPs, the rise in the long wavelength region is attributed to the formation of nanowires. 21 TEM images show that nanowire networks are formed by the irradiation of 355 nm for 5 min (Supporting Information). We believe that the uneven distribution of surface capping agents (i.e., citrate anions) on the fragmented AgNPs causes dipole-induced asymmetric growth.…”

Spatially Controlled SERS Patterning Using Photoinduced Disassembly of Gelated Gold Nanoparticle Aggregates

“…Further irradiation past 1 min leads to the decrease and slight blue-shift of the SPR band at 525 nm, suggesting that smaller, fragmented nanoparticles are produced (Supporting Information). We focus on the disassembly process in this study because the fragmentation of dispersed AuNPs has been extensively investigated in previous studies. − …”