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In a new study published in Spectrochimica Acta Part B: Atomic Spectroscopy, researchers are investigating nanoparticle-enhanced laser produced plasma (NELPP) for nanoparticle-enhanced laser-induced breakdown spectroscopy (NELIBS), to understand the expansion dynamics of traditional laser-produced plasma (LPP) in the presence of nanoparticles (NPs).
NELIBS has gained prominence in various analytical fields, including microscopy, biomedicine, electrochemical and biosensors, laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), archaeology, and wastewater treatment. The use of NPs as spectroscopic enhancers bolsters the intensity of emission signals, enhancing LIBS sensitivity. This has been extensively studied through spectroscopy, with notable works reporting signal enhancements of 1–2 orders of magnitude (102) for various samples under normal atmospheric pressure.
However, the current research goes beyond the conventional spectroscopic studies and delves into the plume dynamics of laser-produced plasma in the presence of NPs. The researchers conducted a systematic investigation, exploring the influence of laser pulse energy on the expansion dynamics of NELPP for copper (Cu) and aluminum (Al) samples in different ambient conditions.
Using a fast-gated plume imaging technique, the team comprehensively analyzed the temporal evolution of the plume front and plume diameter for both LPP and NELPP at different laser energies. The study extended to lower pressures and various ambient conditions, providing a detailed comparison of plume propagation parameters for NELPP and LPP.
The results revealed that the plasma formation in the case of NELPP differs significantly from conventional LPP due to the presence of NPs on the surface. However, despite this difference, no major changes were observed in various plume propagation parameters between the two cases. The study compared the plume evolution at different energies under normal atmospheric pressure, highlighting the independence of fitting parameters on pulse energy.
The researchers also compared NELPP and LPP under different pressure regimes (10-2 mbar, 1 mbar, and 1000 mbar), finding reasonably good agreement with existing plume propagation models such as the drag, blast wave, and adiabatic free expansion models.
This study provides a comprehensive understanding of the influence of laser pulse energy and pressure on the expansion dynamics of NELPP. The findings contribute valuable insights to the field of LIBS and open avenues for further exploration of nanoparticle-enhanced analytical techniques.
Soumyashree, S.; Kumar, P. Influence of Pressure and Pulse Energy on the Expansion Dynamics of Nanoparticle-Enhanced Laser Produced Plasma. Spectrochim Acta Part B At Spectrosc. 2023, 208, 106761. DOI: 10.1016/j.sab.2023.106761.