Adsorption and decomposition of hydrazine on Ru(001)

Abstract

The adsorption and decomposition of hydrazine on Ru(001) have been investigated in the temperature range 150–1000 K utilizing HREELS, thermal desorption and reaction spectroscopy, LEED and ΔΦ measurements. N 2H 4 multilayers desorb in one peak at ≈ 190 K. After desorption of these multilayers, a chemisorption layer consisting mainly of molecular hydrazine remains. Decomposition of monolayer hydrazine starts approximately at 220 K. The thermal evolution of this reactive chemisorption layer has been investigated in detail. NN bond and NH bond scission proceed essentially in parallel, with the first being complete at lower T. In monolayer TPD, the desorption products N 2, NH 3 and H 2, but not N 2H 4, are observed. In the course of the complex N 2H 4 thermal decomposition, several intermediate species can be identified in different temperature ranges, among them surface NH 2 (220…280 K) and surface NH (280…≈480 K). The latter is the fast intermediate containing an NH bond. The final decomposition product on the surface is atomic N for T > 480 K which desorbs recombinatively between 570 and 1000 K. The decomposition routes and reaction mechanisms leading to these intermediate and final products are discussed.