Surface structures from the interaction of ammonia with tungsten

Thesis/Dissertation · Mon Apr 01 04:00:00 EDT 1974

OSTI ID:4323915

Summers, D L

Thesis. LEED was used to investigate surface structures resulting from the interaction of NH/sub 3/ and N/sub 2/ with W (100) and (111) single crystal faces. At 1000 deg K and 10/sup -6/ torr, the steady-state interaction of NH/sub 3 with W(100) results in a (6 x 6) diffraction pattern. The same structure is formed by molecular nitrogen under the same conditions. At lower temperatures the diffraction patterns indicate that a nearly 1/5 order structure is formed. N/ sub 2/ or NH/sub 3/ interaction with W(111) at 1200 deg K and 10/sup -5/ torr result in a (3 x 3) LEED pattern. At ~1000 deg K, NH/sub 3/ forms a 1/5 order pattern on W(111) which is also observed at pressures as high as 10/sup -3/ torr. All results were interpreted in terms of reconstructed surface layers of nearly hexagonal geometry. A qualitative explanation was given to correlate the proposed structures with recent kinetic results of NH/sub 3/ decomposition on W single-crystal faces. (19 fig, 53 references)

• Research Organization: Ames Lab., Iowa (USA)
• DOE Contract Number: W-7405-ENG-82
• NSA Number: NSA-29-030045
• OSTI ID: 4323915
• Report Number(s): IS-T--618
• Country of Publication: United States
• Language: English

Related Subjects

AMMONIA
ELECTRON DIFFRACTION
MONOCRYSTALS
N50210* --Metals
Ceramics
& Other Materials--Metals & Alloys--Corrosion & Erosion & Surface Phenomena
NITROGEN
SURFACES