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Vacuum ultraviolet (VUV) radiation emitted by microwave driven argon plasmas has been investigated at low-pressure conditions (0.36 mbar). A classical surface-wave sustained discharge at 2.45 GHz has been used as plasma source. VUV radiation has been detected by emission spectroscopy in the 30–125 nm spectral range. The spectrum exhibits atomic and ionic argon emissions with the most intense spectral lines corresponding to the atomic resonance lines, at 104.8 nm and 106.7 nm, and to the ion lines, at 92.0 nm and 93.2 nm. Emissions at lower wavelengths were also detected, including lines with no information concerning level transitions in the well-known NIST database (e.g., the atomic line at 89.4 nm). The dependence of the lines' intensity on the microwave power delivered to the launcher was investigated. The electron density was estimated to be around 1012 cm−3 using the Stark broadening of the hydrogen Hβ line at 486.1 nm. The main population and loss mechanisms considered in the model for the excited a...

The vacuum ultraviolet (VUV) radiation emitted by hydrogen surface-wave-driven plasmas operating at microwave frequency (2.45 GHz) and low-pressure conditions (0.1–2 mbar) was investigated, in particular the influence of microwave power and gas pressure on the intensity of the emissions. The strong emission of Lyman H2 and Werner H2 molecular bands in the 80–125 nm spectral range was detected, while the most intense atomic emissions observed correspond to Lyman-α and Lyman-β lines at 121.6 nm and 102.6 nm respectively. An increase of the atomic lines and molecular bands intensities with increasing microwave power at pressure 0.1 mbar was observed. At 2 mbar the VUV spectra are entirely dominated by molecular bands. Theoretical predictions, as obtained from a collisional-radiative model, were validated by the experimental results.

The extreme ultraviolet radiation emitted by helium microwave-driven (2.45 GHz) plasmas operating at low-pressure conditions was investigated. Novel data regarding emitted spectral lines of excited helium atoms and ions in the 20–33 nm wavelength range and their intensity behavior with variation of discharge operational conditions are presented. The intensity of all the spectral emissions was found to strongly increase with the microwave power delivered to the plasma. Furthermore, the intensity of the ionic spectral emissions decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar.

Vacuum ultraviolet emission from Ar-H2 wave driven microwave (2.45 GHz) plasmas operating at low pressures (0.1–1 mbar) has been investigated. The emitted spectra show the presence of the Ar resonance lines at 104.8 and 106.7 nm and of the Lyman-α,β atomic lines at 121.6 nm and 102.6 nm, respectively. The increase of the hydrogen amount in the mixture results in an abrupt increase of the Werner and Lyman molecular bands intensity. The Lyman-β intensity shows little changes in the range of 5%–30% of hydrogen in the mixture while the Lyman-α intensity tends to decrease as the percentage of hydrogen increases.