A comparative study of enhanced emission in double pulse laser induced breakdown spectroscopy

• Single and dual pulse LIBS by Nd:YAG Laser.
• Collinear and orthogonal configuration of double pulse laser induced breakdown spectroscopy.
• Signal intensity enhancement mechanism in double pulse LIBS.
• Laser pulses energy ratio.

We are presenting a comparative study of laser induced breakdown spectroscopy (LIBS) of copper, in single pulse and dual pulse collinear and orthogonal (re-heating) configurations, using fundamental (1064 nm) and second harmonics (532 nm) of two Nd:YAG lasers. The double pulse collinear configuration yields about fifty times and the orthogonal (re-heating) configuration yields fifteen times, signal intensity enhancement in the neutral copper lines. The difference in emission enhancements in both LIBS techniques (Collinear and orthogonal double pulse) provides an experimental evidence about the enhancement mechanism in double pulse LIBS. The effect of inter pulse delay between the two laser pulses and the ratio of their pulse energies in the double pulse spectra are reported. The variation of electron temperature with different interpulse delays, different laser pulse energies ratio and along the plume axis has been studied.