Investigations on atomisation mechanisms of volatile hydride-forming elements in a heated quartz cell. Part 1. Gas-phase and surface effects; decomposition and atomisation of arsine

The atomisation of gaseous hydrides in a heated quartz cell is not caused by a thermal decomposition but by collision with free hydrogen radicals. These radicals are formed in a reaction with oxygen at temperatures above 600 °C. In a “clean” environment, the concentration of radicals is well above the equilibrium concentration because their formation is a much faster process than their recombination. Several materials, however, can catalyse radical recombination and therefore have a depressing effect on the observed signal. In the absence of hydrogen, arsine is not atomised but thermally decomposed, probably with the formation of As2 and As4.