Anomalous nitrogen-metal bonding on Cr(110) and Cr/W(110) overlayers

Journal Article · Tue May 01 04:00:00 EDT 1990 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)

DOI:https://doi.org/10.1116/1.576713· OSTI ID:6879459

Shinn, N D; Tsang, K ^[1]

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1. Sandia National Laboratories, Division 1114, Albuquerque, NM (USA)

Valence and core-level synchrotron photoemission studies of molecular nitrogen chemisorption on Cr(110) and Cr/W(110) overlayers have revealed unusual metal:molecule bonding. On Cr(110), a single molecular adsorption state ({alpha}-N{sub 2}) is populated via a mobile precursor at 90 K and characterized by valence orbital peaks at binding energies of 12.7 (weak), 8.4, and 7.1 eV with respect to the Fermi level. This is indicative of highly perturbed {alpha}-N{sub 2} valence orbitals and a molecular electronic structure similar to that of {pi} bonded'' {alpha}-N{sub 2} on Fe(111). Nitrogen (1{ital s}) core-level spectra are used to identify three co-existing nitrogen species on the monolayer and bilayer Cr/W(110) surfaces at 80 K: weakly chemisorbed molecules ({gamma}-N{sub 2}), a stronglychemisorbed molecular dissociation intermediate ({alpha}-N{sub 2}), and atomic nitrogen ({beta}-N). A multiply coordinated species, Cr {sup N=N} Cr, is proposed for the {alpha}-N{sub 2} binding states, in spite of the absence of deep hollow sites usually invoked to account for this anomalous metal:nitrogen bonding. However, a high-symmetry local binding site requires a reconsideration of the ultraviolet photoelectron spectroscopy (UPS) peak assignments for {alpha}-N{sub 2}.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6879459
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA) Vol. 8:3; ISSN JVTAD; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALLOYS
BONDING
CHEMICAL REACTIONS
CHEMISORPTION
CHROMIUM
CHROMIUM ALLOYS
ELEMENTS
EMISSION
FABRICATION
JOINING
METALS
NITROGEN
NONMETALS
PHOTOEMISSION
SECONDARY EMISSION
SEPARATION PROCESSES
SORPTION
TRANSITION ELEMENTS
TUNGSTEN ALLOYS