Nanosecond UV Laser Ablation of Gold Nanoparticles: Enhancement of Ion Desorption by Thermal-Driven Desorption, Vaporization, or Phase Explosion

Abstract

The phase transition of surface-assisted laser desorption/ionization (SALDI) substrates has been identified as a driving process for ion desorption in many previous SALDI fundamental studies. Here, the effects of various phase transition stages, including substrate melting, vaporization, and phase explosion, on SALDI ion desorption efficiency and extent of heat transfer were investigated. We employed molecular dynamics to simulate the phase transition (from melting, vaporization, to phase explosion) of gold nanoparticles (AuNPs, ⌀: 2.5 nm) upon laser-induced heating and experimentally probed the corresponding SALDI ion desorption efficiency and extent of heat transfer to a chemical thermometer, benzylpyridinium (BP) salt (using 355 nm solid-state laser, pulse width: 6 ns, laser fluence range: 21.3 to 125.9 mJ/cm2). The results showed that substrate phase explosion has the most significant effect on enhancing the ion desorption efficiency and lowering the extent of heat transfer, which were reflected by an...