Adsorption Spectrum of Nitrogen on Tungsten

Abstract

IT has recently been shown¹ that even at low coverages of a fraction of a monolayer, nitrogen is simultaneously adsorbed on tungsten in different states of binding, of which three have so far been isolated. The temperatures above which these individual species are unstable have been estimated semi-quantitatively as 800° K. for state α, 2,000° K. for β and 200° K. for γ. In order to define the spectrum of binding energies of the molecular species adsorbed on the surface, it is necessary to measure the concentration of adsorbed entities as a function of sorbent temperature. We have now been able to do this by a simultaneous recording of the rise in pressure and the increase in electrical resistance when the tungsten wire sample is heated in a flash-filament cell. Since the variation of electrical resistance of tungsten with temperature is known, the flash filament can be used both as adsorption sample and resistance thermometer.