To detect the amount of Oxygen (O₂), existing in conventional incandesent lamps as impurity, we have investigated light spectra with discharging them. The total pressure is 93000 Pa (Ar90%, N₂10%) and O₂ content is iess than 250PPM.
Though any significant dependence of spectrum decaytime on the O₂ content is not found from Ar and N₂ gas, large dependence on the O₂ is found from O (¹S) Ar excimer formed in the discharge, i. e., while 0₂ content is less than 50 PPM, R (R; attenuation constant [1/sec]) of the spectrum from the excimer increases in proportion to O₂ content. The measured decaytime fits a calculaion using the equation of Welge and Atkinson. While O₂ content becomes more than 50 PPM, R increases with the third power of O₂ content. The reason of this higher rate may be related to production of 0₃.
With checking time dependent behaviour of the excimer spectrum, it becomes possible to detect the amount of O₂ in conventional incandescent lamps without destruction of envelopes.