Spectroscopic study of 50 Hz pulsed Ar–O2 mixture plasma

• Ar–O2 mixture plasma can be used for sterilization.
• Optimum conditions have been suggested.
• Atomic oxygen density is measured using classical actinometry method.
• Dissociation fraction has been evaluated which is based on different rate coefficients.

Plasma sterilization is widely used to disinfect the heat sensitive materials. In this study, we have investigated 50 Hz pulsed capacitively coupled plasma (CCP) system operated in Ar–O2 mixture. Optical emission spectroscopy (OES) is used to identify the optimum conditions suitable for plasma based sterilization. Explicitly, excitation temperature of Ar-I lines, atomic oxygen density, dissociation fraction and UV radiation intensity are measured as a function of discharge parameters. The excitation temperature is calculated using Boltzmann plot method whereas OES has also been employed to evaluate the ground state atomic oxygen density and dissociation fraction. Similarly the normalized UV radiation intensity is determined from UV spectrum in 200–400 nm range. The results show that the total UV emission has optimum value at 20% oxygen, 2 mbar pressure and 2.68 mA/cm2 current density in the mixture. While excitation temperature, atomic oxygen density and dissociation fraction increase with the current density. A comparison with the literature suggests 50 Hz CCP system operated in Ar–O2 mixture has the potential of a cheap and reliable system for plasma sterilization.