We report spectroscopic studies of laser-induced plasma (LIP) produced by ns-IR-Nd:YAG laser light pulses of different energies onto four different oxides of vanadium (VO, V2O3, VO2, and V2O5) in air under atmospheric pressure. For each oxide with a different oxidation state of vanadium, both electron density and plasma temperature were calculated for different time delays and laser pulse energies. The plasma temperature was determined from Boltzmann plot method, whereas the electron number density was estimated from the Saha equation. The decay rates for plasma temperature as well as electron density were observed to follow power law and were independent of the nature of vanadium oxide. These investigations provide an insight to optimize various parameters during LIBS analysis of vanadium-based matrices. 1. Introduction Laser-induced breakdown spectroscopy (LIBS) is an elemental analysis technique based on the excitation of atoms present on the sample surface, by focusing a pulsed laser beam. Material amounts ranging from ng to g are ablated in this process producing a microplasma which can be characterized by several of parameters. After the creation of the plasma, electromagnetic radiation is emitted as a consequence of several processes, namely, bremsstrahlung, recombination and de-excitation of atoms and ions occurring inside the plume [1]. De-excitation of atoms and ions leads to emission of light of characteristic frequency which can be used for both qualitative and quantitative determinations. LIBS has several attractive features like the ability to analyze nonconducting and conducting material in any phase (solids, gases, and liquids) as well as refractory materials which are difficult to digest or dissolve (ceramics, superconductors, etc.). The rapidness of analysis and multielemental analyzing capability make LIBS a highly useful technique for trace elemental determination. Several experimental parameters are reported to affect the LIBS analysis. These include the effect of laser wavelength [2], pulse energy [3], pulse duration and shape [4, 5], and the acquisition time delay. Cabalin and Laserna studied the effect of thermal property of material on threshold laser fluence variation [6]. The different phases of iron oxide were found to have different plasma characteristics [7]. To the best of our knowledge, the effect of different oxidation states of an element present in the sample on the plasma characteristics has not been reported. Theoretically, the information regarding laser-induced plasma (LIP) can be obtained by solving a complex
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