An atmospheric-pressure argon plasma-jet is generated, and optical emission spectroscopy of the argon plasma-jet is carried out. It is found that the emission lines of Ar, OH, N2 and O are observed in the emission spectra, and that the emission line of NO is also found only when room-air is mixed into the plasma-jet. The emission intensities of Ar, OH and N2 with mixing the room-air monotonously decrease toward the downstream, but those of OH and N2 without mixing the room-air reach those maximum in the mid-stream of the plasma-jet and then decrease. Deionised-water is exposed to the argon plasma-jet, and dissolved ions in deionised-water after the exposure of the argon plasma-jet are investigated. It is found that H2O2, NO2- and NO2- are dissolved, and that those concentration increase with the increase of the exposure time.
