| prov:value
| - It can be done in various ways, for example by heating, e.g. by means of a glowing metal surface, e.g., a Ta- or W-wire, -tube, or net with corresponding high temperature, by gas discharges at sub-pressure started by direct or alternating currents, by the use of a cold plasma, made by electromagnetic waves, preferably in the mega- and gigahertz range, by ultra sonic and pressure change, respective
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