Influence of electron dynamics on the enhancement of double-pulse femtosecond laser-induced breakdown spectroscopy of fused silica

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy Vol. 141; pp. 63 - 69
• Main Authors: Cao, Zhitao, Jiang, Lan, Wang, Sumei, Wang, Mengmeng, Liu, Lei, Yang, Fan, Lu, Yongfeng
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01-03-2018; Elsevier BV
• Subjects: Ablation; Analytical methods; Delay; Dielectric breakdown; Dielectrics; Double pulse; Dynamics; Electron dynamics; Electrons; Emission analysis; Femtosecond laser; Femtosecond pulses; Fused silica; Ionization; Irradiation; Laser induced breakdown spectroscopy; Lasers; Morphology; Phase transitions; Removal; Silica; Silicon dioxide; Spatial discrimination; Spatial resolution; Spectroscopy; Spectrum analysis; Thermodynamics; Femtosecond laser; Electron dynamics; Laser-induced breakdown spectroscopy; Double pulse
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/j.sab.2018.01.010

Femtosecond laser pulse train induced breakdown of fused silica was studied by investigating its plasma emission and the ablated crater morphology. It was demonstrated that the electron dynamics in the ablated fused silica play a dominant role in the emission intensity of induced plasma and the volume of material removal, corresponding to the evolution of free-electron, self-trapped excitons, and the phase change of the fused silica left over by the first pulse. For a fluence of 11 J/cm2, the maximum plasma intensity of double-pulse irradiation at an interpulse delay of 120 ps was about 35 times stronger than that of a single-pulse, while the ablated crater was reduced by 27% in volume. The ionization of slow plume component generated by the first pulse was found to be the main reason for the extremely high intensity enhancement for an interpulse delay of over 10 ps. The results serve as a route to simultaneously increase the spatial resolution and plasma intensity in laser-induced breakdown spectroscopy of dielectrics.
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•High enhancement of ~35 times is achieved in collinear double pulse femtosecond LIBS.•The ablated volume is the smallest when the plasma intensity reaches the maximum.•The slow plume component ionization is proved to be the main mechanism for the results.