Ablation and plasma emission produced by dual femtosecond laser pulses

Journal Article · Mon Dec 01 04:00:00 EST 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3040082· OSTI ID:21179995

Singha, Sima; Gordon, Robert J ^[1]; Zhan, Hu ^[2]

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1. Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061 (United States)
2. Institute of Atomic and Molecular Physics, Jilin University, Changchun 130021 (China)

Pairs of 80 fs, 800 nm laser pulses were used to ablate Si, Cu, and CaF{sub 2} in air. The spectrally resolved plasma emission was measured as a function of laser fluence and pulse delay. After an initial dip, the fluorescence was found to increase monotonically with pulse delay, reaching a plateau after some tens of picoseconds, depending on the material and fluence. The enhancement ratio (defined as the ratio of the fluorescence produced by the pulse pair to that produced by a single pulse of the same total fluence) reaches a maximum value of 6 and 11 at a fluence of {approx}6 J/cm{sup 2} for Si and Cu, respectively, and declines to a value below 2 at higher fluences. In contrast, the enhancement for CaF{sub 2} increases slowly from zero near threshold to a broad maximum value of 2 near 50 J/cm{sup 2}. Using reflectivity and atomic force microscopy measurements as diagnostics, we interpret the Si and Cu behavior in terms of a two phase mechanism, in which the first pulse melts the surface of the crystal and the second pulse ablates the resulting liquid film. A qualitatively different mechanism initiated by multiphoton absorption is involved in CaF{sub 2} ablation.

• OSTI ID: 21179995
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 104; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABLATION
ABSORPTION
AIR
ATOMIC FORCE MICROSCOPY
CALCIUM FLUORIDES
COPPER
CRYSTALS
FLUORESCENCE
LASERS
MULTI-PHOTON PROCESSES
PLASMA
PLASMA DIAGNOSTICS
PLASMA PRODUCTION
PULSES
REFLECTIVITY
SILICON