Time-dependent Chemiluminescence from the Surface-catalyzed Recombination of O and NO on Polycrystalline Ni

DOI: 10.1039/ft9918702877

Source and publish data:

Journal of the Chemical Society - Faraday Transactions p. 2877 - 2885 (1991)

Update date:2022-08-11

Topics:

Authors:

Ardebili, M. H. Parviz

Grice, Roger

Hughes, Christopher J.

Whitehead, J. Christopher

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Article abstract of DOI:10.1039/ft9918702877

The near-infrared chemiluminescence produced by the surface-catalyzed recombination of nitric oxide with a supersonic beam of atomic oxygen on polycrystalline nickel has been studied.The dependence of the luminescence on time, substrate temperature, O and NO fluxes and pre-exposure to the O atom beam has been investigated.The spectrum of the luminescence has also been determined.Strong initial luminescence was observed decaying with time to a steady state.The use of argon-ion bombardement to clean the sample prior to each experiment was essential to the observation of this time-dependent luminescence.The initial luminescence shows a strong dependence on the substrate temperature, increasing by a factor of 80 when the substrate temperature is reduced from 300 to 195 K.The luminescence showed an initial first-order dependence on the atomic oxygen and nitric oxide fluxes, before levelling off at higher fluxes.The spectrum of the luminescence shows intensity rising from a threshold of 530 nm to a maximum at 800 nm, which is shifted significantly towards longer wavelengths compared to that from the termolecular gas-phase recombination of O and NO.Pre-exposure of the substrate to the O-atom beam suggests that a monolayer of chemisorbed oxygen, which reduces both the binding energy and dissociative adsorption of NO on the substrate, is resposible for the production of a weakly bound electronically excited NO2 which may leave the surface and emit light.A mechanism involving surface poisoning by NO2 product molecules has been suggested.