Existence of Phase Explosion during Laser Ablation and Its Effects on Inductively Coupled Plasma-Mass Spectroscopy

Abstract

A sudden increase in crater depth was observed during high irradiance (> 10 10 W/cm 2 ) laser ablation of silicon, and it is attributed to the phenomena of phase explosion.The threshold irradiance for phase explosion showed a dependence on two laser parameters; laser beam spot size and wavelength. For a larger beam size and longer incident wavelength, a higher laser irradiance was required to generate phase explosion.The rapid increase of crater depth above the phase explosion threshold irradiance correlated with a significant increase in the ICP-MS signal intensity. The ratio of crater volume to ICP-MS intensity, which represents entrainment efficiency, remained the lowest at laser irradiances slightly above the phase explosion threshold. However, this ratio increased at irradiances well above the threshold (> 10 11 W/cm 2 ). Chemical analysis using laser ablation at irradiance above 10 11 W/cm 2 provides increased sensitivity via improved entrainment and transport efficiency and increased ablation rate.

Influence of spot size on propagation dynamics of laser-produced tin plasma

“…It should be remembered that a change in the spot size can significantly influence the amount of ablated mass and, hence, the crater volume. 36 Depending on the laser irradiance and target material, mass removal can occur through desorption, thermal evaporation, exfoliation, phase explosion, and other mechanisms. The threshold for the occurrence of the earlier processes strongly depended on the laser wavelength and the laser spot size at the target surface.…”

“…The threshold for the occurrence of the earlier processes strongly depended on the laser wavelength and the laser spot size at the target surface. For example, Yoo et al 36 reported the laser irradiance threshold for the phase explosion is roughly one order higher with 532 nm than 266 nm. They have not observed any rapid change in the crater volume with 1064 nm in the studied laser irradiance range ͑1-10 3 GW/ cm 2 ͒ and explained it is due to stronger plasma shielding and deeper optical penetration depth with the increasing wavelength.…”

Laser ablation in analytical chemistry—a review

“…Yoo et al [92] found increased entrainment efficiency at even higher irradiance during laser ablation of silicon (figure 13). They proposed that strong absorption of the incident laser light by the plasma could create a high temperature and pressure region through which the particulates must traverse.…”

Improved Analytical Characterization of Solid Waste-Forms by Fundamental Development of Laser Ablation Technology

“…F or high-density alloys, thermal vaporization may dominate the formation of small particles. For ablation of single crystal silicon and NIST glass, we discovered a phase explosion process that produced large particle (~ 5 -20 micron) (44)(45)(46)(47).…”

“…Time-resolved particle ejection (particle velocity) and changes in particle size can be measured using this system (44)(45)(46)(47). Particle sizes equal to and greater than the wavelength of the probe light (532nm) can be measured.…”