ADSORPTION AND DECOMPOSITION OF HYDRAZINE ON RU(001)

The adsorption and decomposition of hydrazine on Ru(001) have been inv estigated in the temperature range 150-1000 K utilizing HREELS, therma l desorption and reaction spectroscopy, LEED and DELTAPHI measurements . N2H4 multilayers desorb in one peak at almost-equal-to 190 K. After desorption of these multilayers, a chemisorption layer consisting main ly of molecular hydrazine remains. Decomposition of monolayer hydrazin e starts approximately at 220 K. The thermal evolution of this reactiv e 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 N2, NH3 and H-2, but not N2H4, are observed. In the course of the complex N2H 4 thermal decomposition, several intermediate species can be identifie d in different temperature ranges, among them surface NH2 (220 ... 280 K) and surface NH (280 ... almost-equal-to 480 K). The latter is the last intermediate containing an N-H bond. The final decomposition prod uct on the surface is atomic N for T>480 K which desorbs recombinative ly between 570 and 1000 K. The decomposition routes and reaction mecha nisms leading to these intermediate and final products are discussed.