Plasmonic vesicle consists of multiple gold nanocrystals within a polymer coating or around a phospholipid core. As a multifunctional nanostructure, it has unique advantages of assembling small nanoparticles (<5 nm) for rapid renal clearance, strong plasmonic coupling for ultrasensitive biosensing and imaging, and near‐infrared light absorption for drug release. Thus, understanding the interaction of plasmonic vesicles with light is critically important for a wide range of applications. In this paper, a combined experimental and computational study is presented on the nanocrystal transformation in colloidal plasmonic vesicles induced by the ultrafast picosecond pulsed laser. Experimentally observed merging and transformation of small nanocrystals into larger nanoparticles when treated by laser pulses is first reported. The underlying mechanisms responsible for the experimental observations are investigated with a multiphysics computational approach featuring coupled electromagnetic/molecular dynamics simulation. This study reveals for the first time that combined nanoparticle heating and laser‐enhanced Brownian motion is responsible for the observed nanocrystal merging. Correspondingly, laser fluence, interparticle distance, and presence of water are identified as the most important factors governing the nanocrystal transformation. The guidelines established from this study can be employed to design a host of biomedical and nanomanufacturing applications involving laser interaction with plasmonic nanoparticles.
The carrier excitation, relaxation, energy transport, and conversion processes during light‐nanocrystal (NC) interactions have been intensively investigated for applications in optoelectronics, photocatalysis, and photovoltaics. However, there are limited studies on the non‐equilibrium heating under relatively high laser excitation that leads to NCs sintering. Here, the authors use femtosecond laser two‐pulse correlation and in‐situ optical transmission probing to investigate the non‐equilibrium heating of NCs and transient sintering dynamics. First, a two‐pulse correlation study reveals that the sintering rate strongly increases when the two heating laser pulses are temporally separated by <10 ps. Second, the sintering rate is found to increase nonlinearly with laser fluence when heating with ≈700 fs laser pulses. By three‐temperature modeling, the NC sintering mechanism mediated by electron induced ligand transformation is suggested. The ultrafast and non‐equilibrium process facilitates sintering in dry (spin‐coated) and wet (solvent suspended) environments. The nonlinear dependence of sintering rate on laser fluence is exploited to print sub‐diffraction‐limited features in NC suspension. The smallest feature printed is ≈200 nm, which is ≈¼ of the laser wavelength. These findings provide a new perspective toward nanomanufacturing development based on probing and engineering ultrafast transport phenomena in functional NCs.
more » « less- NSF-PAR ID:
- 10448300
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 17
- Issue:
- 50
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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