A hollow cathode discharge with a copper nickel cathode (Cu50Ni50) was operated in an Ar/H2/N2 gas mixture. Optical emission spectroscopy revealed the formation of NH radicals, which serve as precursors for NH3 formation. Ion mass spectrometry showed the formation of NH3 + and NH4 + ions indicating NH3 formation. Gas samples taken at the exhaust of the vacuum system were analyzed by Fourier transform infrared spectroscopy. Clear evidence for NH3 formation was obtained from these measurements.

Institut für Physik Universität Greifswald Felix Hausdorff Strasse 6 17489 Greifswald Germany

Institute of Physics Czech Academy of Sciences Na Slovance 2 18200 Prague Czech Republic

J Heyrovsky Institute of Physical Chemistry Czech Academy of Sciences Dolejskova 2155 3 18223 Prague Czech Republic

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