Heating of liquid substrate by low-pressure sputtering plasma

The heating of the liquid substrate by low-pressure (∼1 Pa) sputtering plasma has been investigated by in situ temperature measurements. The combination of "green"non-toxic solvent, castor oil, copper target, and direct current magnetron sputtering was chosen as a model system. The temperature increase induced by plasma was registered with two thermocouples placed immediately under the liquid surface and in the bulk solution. The effect of the working gas pressure and sputter power was studied. It was shown that the liquid temperature increases at a rate of up to 1 °C/min, depending on the sputtering conditions. The experimental data were compared with numerical calculations and COMSOL simulation. Provided information is essential data for the detailed explanation of the formation of nanoparticles during sputtering onto liquids, a clean approach for production of colloidal solutions of "naked"nanoparticles.