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Early stage of laser induced breakdown spectroscopy
A. De Giacomo1,2, M. Dell’Aglio2, O. De Pascale2, R. Gaudiuso2, A. Santagata2, G.S. Senesi2
1. Department of Chemistry, University of Bari-Italyand
2. Institute of Inorganic Methodologies and Plasmas-National Council of Research (IMIP-CNR)
e.mail:[email protected]
LIBS:Planetary exploration;Meteorites;Cultural heritage;Environment: soils, water;Industrial process monitoring;
RF-discharge assistedPulsed Laser Deposition
Modeling
Laser propulsion
Nano Technology
Laser Induced Plasma
Experimental set-up
Triax550(1800)
Nd:Yag532nm
PG ICCD
PG Laser
ICCD
lens
lens
Optical fibre
mirror
Experimental set-up
Triax550(1800)
Nd:Yag532nm
PG ICCD
PG Laser
ICCD
lens
lens
Optical fibre
mirror
Experimental set-up
Nd:Yag532nm
Dichroicmirror1Dichroic
mirror2
Triax550(1800)
Nd:Yag532nm
PG ICCD
PG Laser
ICCD
lens
lens
Optical fibre
mirror
Experimental set-up
Nd:Yag532nm
Dichroicmirror1Dichroic
mirror2
Triax550(1800)
Nd:Yag532nm
PG ICCD
PG Laser
ICCD
lens
lens
Optical fibre
mirror
LIP spectral characteristics
As an experimental example, the spectrum of Hydrogen LIP has been reported at two different delays from the laser pulse. The plasma has been induced focusing the laser directly in a vacuum chamber filled with pure H2 at 150 Torr (total atomic density of about 1 1019 cm-3). The temperature was estimated by the line ratio approach and found to vary between 8,500 and 5,000 K in the observed temporal window. Let’s consider the delay times 0 and 100 ns from the laser pulse and the corresponding electron number density 8.0 1018 and 7.5 1017 cm-3 , respectively, as calculated by Stark broadening of the Ha line. D-H equation is applied to these experiments, in perfect agreement with the experimental spectrum, the maximum principal quantum number is nc= 3 at 0 ns and nc = 6 at 100 ns, corresponding to the lines Ha at 656 nm and Hd at 410 nm, respectively.
Experimental example: H-LIP
A. De Giacomo, R. Gaudiuso, M. Dell’Aglio, A. Santagata, The role of Continuum radiation in Laser Induced Plasma Spectroscopy, Spectrochimica Acta Part B 65/5 (2010) 385-394.
The analysis based on LTE (CF-LIBS)
REF: M. Dell’Aglio et al., Laser Induced Breakdown Spectroscopy applications to meteorites: Chemical analysis and composition profiles. Geochimimica and Cosmochimica. Acta (2010), 74 (2010) 7329-7339.
Δt(µs) =
10 35 60 100 150 20020 Laser-Induced Plasma/Bubble Evolution
(a) (b) (c)2 mm
DP- and SP-LIBS on submerged solid DP-LIBS in bulk sea water
REF: A. De Giacomo, M. Dell’Aglio, O. De Pascale, M. Capitelli, From single pulse to double pulse ns-Laser Induced Breakdown Spectroscopy under water: elemental analysis of aqueous solutions and submerged solid samples, Spectrochimica Acta Part B Review 62/ (2007) 721-737.
Analytical performance of DP-LIBS under water
REF: A. De Giacomo, M. Dell’Aglio, O. De Pascale, M. Capitelli, From single pulse to double pulse ns-Laser Induced Breakdown Spectroscopy under water: elemental analysis of aqueous solutions and submerged solid samples, Spectrochimica Acta Part B Review 62/ (2007) 721-737.
focusing lens
optical windowfor plasma analysis
10 mm axial movement &rotating target holder
spacer tube
HPLC PUMP
solvent reservoir
purgechannel
pumpchannel
relief valve
water drain pipe
HIGH PRESSURE CHAMBER
LASER SYSTEM
laser pathNd-YAG
Nd-YAG
dichroic mirrors
ICCDmonochromator
pulse generator
biconvex lens
optical fibercomputerSPECTROSCOPIC SYSTEM
pulse generator
148 atm
70 atm
57 atm1 atm
P/P
ex
REF: A. De Giacomo et al. Laser Ablation of Graphite in water in a range of pressure from 1 to 146 atm using single and double pulse techniques for the production of carbon nanostructures, Journal of Physical Chemistry C, in press.
Conclusion
Thanks to:
•Emission spectroscopy is a powerful tool for studying Laser induced plasma (LIP).
• LIP at the initial stage is characterized by high density effects.
•LIP can be confined selecting the external environment conditions.
•The possibility of controlling the LIP temporal evolution allows to employ LIP in a wide range of applications from chemical analysis to material production.
•G. Colonna for theoretical support•L.D. Pietanza for CR models•F. Taccogna for cavitation bubble modeling•D. Bruno for fluidynamics modeling•M. Capitelli for general supervision
