UV light sources with microwave excited molecular gas plasmas

Molecular gas discharge plasma has long kept a higher potential to use as ultraviolet light source. The value of it should be rising to replace the common UV lightning using by toxic mercury. Our 3-years-work of this JST project has been founded as the following UV candidates, i.e., carbon monoxide (CO), nitrogen oxide (N₂O₂), water vapor (H₂O), and its with rare gases. First, the CO has many of vacuum UV peaks from A¹Pi to X¹Sigma⁺ in wide range 150-210 nm. Among the peaks, we can choose and enhance few peaks. For example, a peak of 156 nm was enlarged twice as compare with maximum peak of pure CO at 173 nm. Second, the nitric oxide peaks (NO) have been optimized as through oxygen contents (10-20%). The many peaks are emitted from NO within a range of the germicidal effect (210-315 nm). Finally, the water vapor microwave discharge plasma has a peak at 310 nm from the OH radicals. It shows the most intense and concentrated UV emission at the saturated water vapor pressure at RT. We report the previous suggested gases but they are small parts of many of possible molecular gases as a UV light source.