Spatio-temporal inhomogeneities of laser induced plasma on surface solutions

Abstract

A transient plasma created by focusing a nanosecond laser pulse on the surface of ionic solutions of Ca++ and Mg++ is studied spectroscopically. This kind of plasma has a properties which vary significantly with time and over its extended volume. The emissions of ionic and atomic line of calcium and magnesium are analyzed to get information on the electronic temperature, the electronic density and on the kinetics of the population of low atomic and ionic states: 4P1 of CaI, 5S1/2 of CaII, 3P1 of MgII and 3P1/2 of MgII. The temperature is maximal at the plasma center and it drops at the edges. The study of the term T(r ≠ 0)/T(r = 0) as a function of time, where r is the radial position, shows a continue decreasing with time, which implies that the inhomogeneity of the temperature develops with time. On the another side, the electronic density deceases exponentially with time and does not vary significantly with space. These measurements allow us to follow the kinetics of the transformation of calcium (magnesium) from Ca++Mg++ to Ca+(Mg+) to give at the end Ca (Mg) and to understand the behavior of self-absorption phenomena which is observed in the resonance line of CaII at t ≈ 2000 ns to increase with time. The experimental results are simulated by a kinetics model of LTE laser induced plasma in its late relaxation period.

Temporal and Spatial Characterizations of Zn Ions in Plasma by Pulsed-Laser Ablation of Zinc Metal in Vacuum Condition

“…Pulsed-laser ablated plasma emission spectroscopy (PLAPES) has long been used as a very promising technique for real-time detection of multiple elements and determining the composition of materials in any physical state, including solids, liquids and aerosols [1][2][3][4]. Moreover, the deposition parameters of high quality films prepared using pulsed laser deposition (PLD) method can also be effectively controlled by PLAES [2][3][4][5][6].…”

“…Pulsed-laser ablated plasma emission spectroscopy (PLAPES) has long been used as a very promising technique for real-time detection of multiple elements and determining the composition of materials in any physical state, including solids, liquids and aerosols [1][2][3][4]. Moreover, the deposition parameters of high quality films prepared using pulsed laser deposition (PLD) method can also be effectively controlled by PLAES [2][3][4][5][6]. Despite its versatility and wide applicability, however, it is well known that the plasma emission spectroscopy is not sensitive to accuracy, precision, limit of detection, etc., compared to some other established methods of chemical analysis.…”

“…The improvement of these applications has been proposed at the region of higher temperature and density plasma, which is highly related to the ablation process, the aerosol transport and the vaporization, atomization and ionization within the plasma. The enhancement of spectral lines, especially the spectral emission from multi-charged ions can be obtained at this region [4][5][6]. Recently, detailed characterization of ions in plasma by laser beam ablated metal has been provided to give very important and useful information for improving the analytical sensitivity and capability of PLAPES [3][4][5][6][7].…”

“…The enhancement of spectral lines, especially the spectral emission from multi-charged ions can be obtained at this region [4][5][6]. Recently, detailed characterization of ions in plasma by laser beam ablated metal has been provided to give very important and useful information for improving the analytical sensitivity and capability of PLAPES [3][4][5][6][7].…”