No abstract

Ultraviolet (UV) and vacuum ultraviolet (VUV) spectral irradiance is determined in low-pressure microwave-produced plasma, which is regularly used for polymer surface treatment. The re-emitted fluorescence in the UV/VIS spectral range from a sodium salicylate layer is measured. This fluorescence is related to VUV/UV radiation in different spectral bands based on cut-off filters. The background produced by direct emitted radiation in the fluorescence spectral region is quantified using a specific background filter, thus enabling the use of the whole fluorescence spectral range. A novel procedure is applied to determine the absolute value of the VUV/UV irradiance on a substrate. For that, an independent measurement of the absolute spectral emissivity of the plasma in the UV is performed. The measured irradiances on a substrate from a 25 Pa Ar/O2-produced plasma are in the range of 1015–1016 These values include the contribution from impurities present in the discharge.

We report the in situ measurement of the ultraviolet/vacuum-ultraviolet (UV/VUV) emission from a plasma produced by high power impulse magnetron sputtering with aluminum target, using argon as background gas. The UV/VUV detection system is based upon the quantification of the re-emitted fluorescence from a sodium salicylate layer placed in a housing inside the vacuum chamber at 11 cm from the center of the cathode. The detector is equipped with filters that allow for differentiating various spectral regions, and with a front collimating tube that provides a spatial resolution ≈ 0.5 cm. Using various views of the plasma, the measured absolutely calibrated photon rates enable to calculate emissivities and irradiances based on a model of the ionization region. We present results that demonstrate that Al + ions are responsible for most of the VUV irradiance. We also discuss the photoelectric emission due to irradiances on the target~ 2 × 10 s • cm produced by high energy photons from resonance lines of Ar + .