Nanocomposites and nanomaterials
Spectroscopy of Underwater Electric Spark Discharge between Metal Granules
Murmantsev O.O.1, Veklich A.M.1, Boretskij V.F.1
1 Faculty of Radio Physics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska str., Kyiv, 01601, Ukraine
E-mail: murmantsev.aleksandr@gmail.com

The study of underwater discharge plasma is of great importance to increase efficient of its practical use in electrochemistry, biology, agriculture etc. Specifically, such discharge is widely used in some kind of treatment (water or surface), plasma sterilization and synthesis of solutions with micro- and nanoparticles. It is well-known that such substances have great bactericidal, antiviral, antifungal and antiseptic properties, what makes them essential biocide products [1-3].
The plasma spectral emission of the underwater electric spark discharge between metal granules is investigated in spectral range of 440-910 nm. The emission of silver, copper, molybdenum and iron spectral lines were understudy in the frame of this work.
The specially developed pulse power source is used to initiate a discharge between granules immersed into the deionized water. Typical values of voltage vary from 40 to 200 V, current is up to 150 A and pulse frequency is in the range of 0.2–2 kHz. The voltage, applied to electrodes, caused a current flow along the chain of closely arranged granules in the stochastic switching mode.
Optical emission spectroscopy methods are used to determine main plasma parameters. Namely, the excitation temperature is determined by the Boltzmann plots and the relative intensity of spectral lines techniques. The electron density is obtained from width of Hα and certain metal spectral lines exposed to the Stark mechanism of spectral lines’ broadening. 

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