Plasma temperature clamping in filamentation laser induced breakdown spectroscopy

Area of Science:

• Physics
• Materials Science
• Spectroscopy

Background:

• Ultrafast laser filament induced breakdown spectroscopy (LIBS) is a key technique for remote material analysis.
• Understanding plasma characteristics is crucial for optimizing LIBS performance.

Purpose of the Study:

• To investigate the properties of plasmas generated in metal targets using laser filaments in ambient air.
• To elucidate the factors influencing emission intensity and spectral characteristics in fs LIBS.

Main Methods:

• Generation of plasma in metal targets using femtosecond (fs) laser filaments.
• Characterization of plasma properties, including temperature and species emission, along the filament channel.
• Analysis of atomic and ionic emission spectra.

Main Results:

• Plasma temperature remains clamped along the filament channel due to intensity clamping.
• Significant variations in radiation intensity are observed, primarily driven by changes in the number density of emitting atoms.
• A notable absence of ion emission and a strong presence of atomic neutral emission are observed in plumes generated by fs LIBS in air.

Conclusions:

• The study clarifies plasma behavior in fs LIBS, highlighting the role of intensity clamping on temperature.
• It explains the dominance of atomic neutral emission over ion emission, attributed to variations in particle density.
• These findings contribute to the advancement of remote material detection using LIBS technology.