Atmospheric-PLD as a New Trend for Nanofabrication in Nanotechnology

In this short letter, a new method is introduced, which is recently emerged and provides a sound and feasible route to make plasmonic nanomaterials. The method is based on the pulsed laser ablation in gas at atmospheric pressure. At these conditions, the hydrodynamic expansion of a laser produced plasma plume is significantly different from its expansion in vacuum or lowpressure gas. In vacuum or low-pressure gas (< 0.1mbar), ablation plume expands freely away from the target compared atmospheric pressure where ambient gas severely restricts the plume expansion to 1-3mm. To efficiently utilize the ablation process at atmospheric pressure, a novel method of atmospheric PLD (APLD) was recently introduced and applied to produce NP film [1,2]. The films produced by this method were effective SERS substrates used in surface enhanced Raman spectroscopy (SERS) [1]. Initially, the method was used with ablation in confined geometry, where the plasma plume was artificially confined in a small region (gap) between the target and the deposited surface to produce a longlived dense plasma. The method so called confined geometry showed strong potential to make a layer of NPs with a single laser shot [3]. APLD is alternative to classical vacuum PLD and marks the upper end of the pressure domain of vacuum PLD examined to date. At atmospheric pressure, the laser produced ablation plume dose not expand freely and is restricted above the target surface to form a NP aerosol by collisional condensation [4]. The produced NP aerosol is entrained in a gas flow or flowing atmospheric plasma to a substrate and build up a NP film. The newly introduced APLD method is technologically feasible with strong potential for industrial scale application. The method is constantly under investigation in direction of understanding to develop this method. The method will open a new fabrication route of new plasmonic materials to feed nanotechnology in various sectors.

In conclusion, the newly and recently emerged APLD method was briefly discussed. The method is under hot debate and successfully applied to make plasmonic nanomaterials. The method is based on flowing gas or flowing atmospheric plasma to transport NP aerosol to a deposited surface to make NP film. The method is relatively fast and has strong potential for industrial scale application.

1. Khan TM, Mujawar MA, Siewerska KE, Pokle A, Donnelly T, et al. (2017) Atmospheric pulsed laser deposition and thermal annealing of plasmonic silver nanoparticle films. Nanotechnology 28(44): 445601.
2. Khan TM, Pokle A, Lunney JG (2018) Atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver with flowing gas and flowing atmospheric plasma. Appl Phys A 124: 336.
3. Donnelly T, Lunney JG (2013) Confined laser ablation for single-shot nanoparticle deposition of silver. Appl Surf Sci 282: 133-137.
4. Itina TE, Voloshko A (2013) Nanoparticle formation by laser ablation in air and by spark discharges at atmospheric pressure. Appl Phys B 113: 473-478.