Laser ablation of nanoscale particles with 193 nm light

Abstract

Laser interaction with nanoscale particles is distinct and different from laser-bulk material interaction, where a hot plasma is normally created. Here, we review our studies on 193 nm laser ablation of various nanoscale particles including NaCl, soot, polystyrene, and gold. The 20 ns laser beam with fluences up to 0.3 J/cm 2 irradiates nanoparticles in a gas stream at laser repetition rates from 10 to 100 Hz. The particle size distributions before and after irradiation are measured with a scanning mobility particle sizer (SMPS), and particle morphology is examined with electron microscopy. All the nanomaterials studied exhibit a similar disintegration pattern and similar particle formation characteristics. No broadband emission associated with particle heating or optical breakdown is observed. The nanoparticles formed after irradiation have a smaller mean diameter and an order of magnitude higher number concentration with a more spherical shape compared to the original particles. We use the photon-atom ratio (PAR) to interpret the laser-particle interaction energetics.

The mechanism of ArF laser-induced fluorescence of dense plume matter

“…55 The same ArF pulse can then vaporize the sample and excite the dense plume. 21,24 While the interpulse delay of this single pulse scheme is zero, the glare is still very dim because the uence needed to vaporize sub-mm size particulates is low. 55 These tiny plumes disperse extremely fast to produce sharp analyte spectral lines instantaneously.…”

“…Excimer lasers are generally used and no tunable source is required. [21][22][23][24] Multi-analyte detection is also possible if suitable precursor molecules are present. 23 LA-PFF features a good signal-to-noise ratio, no plasma background emissions, no tunable laser, and multi-analyte detection.…”