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Issue 32, 2012
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Nitrogen adsorption and desorption at iron pyrite FeS2{100} surfaces

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We have investigated the interaction of nitrogen with single-crystal iron pyrite FeS2{100} surfaces in ultra-high vacuum. N2 adsorbs molecularly at low temperatures, desorbing at 130 K, but does not adsorb dissociatively even at pressures up to 1 bar. Atomic surface N can, however, be obtained with nitrogen ions and/or excited neutral species, generated by passing N2 through an ion gun. Substantial nitrogen-induced disorder is seen with both ions and neutrals, and no ordered N overlayers form; a decrease in the S/Fe ratio is seen when exposing to nitrogen ions. Recombinative desorption leads to temperature-programmed desorption peaks at 410 and 520–560 K which we associate with interstitial atomic N and substitutional ionic N, respectively, in the surface regions. Thermal repair of sputter damage necessitates segregation of bulk S to the surface, which, over repeated experiments, leads to gross cumulative damage to the bulk crystal. The desorption temperatures associated with recombinative desorption of atomic N from FeS2{100} are significantly lower than those measured for Fe surfaces. This is linked to the inability of FeS2{100} to dissociate N2, but suggests that Nads will be significantly more able to react with other species than it is on Fe surfaces.

Graphical abstract: Nitrogen adsorption and desorption at iron pyrite FeS2{100} surfaces

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The article was received on 14 May 2012, accepted on 02 Jul 2012 and first published on 02 Jul 2012

Article type: Paper
DOI: 10.1039/C2CP41549F
Citation: Phys. Chem. Chem. Phys., 2012,14, 11491-11499
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    Nitrogen adsorption and desorption at iron pyrite FeS2{100} surfaces

    T. Liu, I. Temprano, S. J. Jenkins, D. A. King and S. M. Driver, Phys. Chem. Chem. Phys., 2012, 14, 11491
    DOI: 10.1039/C2CP41549F

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