Anregung von UV-Strahlung in Stickstoff und Wasserstoff durch einen Elektronenschwarm

Abstract

The radiation excited in nitrogen and hydrogen by an electron swarm moving in a uniform electric field is investigated. In nitrogen the bands of the 2^nd positive group in the region from 3400 to 3800 Å are the dominating part of the radiation. In hydrogen the main part of the radiation is lying in the far ultraviolet (1000 to 1200 Å) due to the excitation of the state 2¹ II _u . The coefficientδ describing the intensity of the radiation is measured with a photomultiplier device as a function of the electric fieldE and the pressurep in the range from about 10 to 100 Torr. Besides the dependence ofδ onE/p a pressure dependence is found which is explained as a quenching process of the excited molecules by collisions. The pressurep ₀ for equal probability of radiating and non-radiating decay of the states involved is 60 Torr in N₂ and 20 Torr in H₂. The theoretical interpretation of the dependence onE/p supports the excitation energy of the state C³ II _u of N₂ for electron impact to be equal to the spectroscopical value of 11·04 eV and yields 0·9·10⁻¹⁶ cm² for the maximum of the excitation cross section. The results of the measurements in H₂ can be described assuming a cross section of 0·55·10⁻¹⁶ cm² for the excitation of the state 2¹ II _u by electron impact.