The Chemisorption of Nitrogen on Polycrystallin Tungsten Wires

Desorption spectra have been obtained for successively increasing amounts of nitrogen adsorbed on three polycrystalline tungsten wires at room temperature. Two β phases were desorbed, β 1 with first-order kinetics and an activation energy of 73 kcal/mole and β 2 with second-order kinetics and an activation energy of 75 kcal/mole. Surface impurities such as carbon or thorium reduced the size of the β 1 phase. Mass spectrometric evidence showed that the small α phase was adsorbed as molecules, and the β 1 and β 2 phases were adsorbed as atoms.