Probing the Surface of a Heterogeneous Catalyst: Double Resonance of Carbon Monoxide Chemisorbed on Highly Dispersed Platinum

Spin Echo Double Resonance (SEDOR) is observed at 77 K for small Pt particles on which ('13)CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% ('13)C. The ('13)C NMR is observed indirectly through its effect on the ('195)Pt spin echo. SEDOR allows the NMR of the surface ('195)Pt nuclei to be observed underneath the resonance of the nonsurface nuclei from which the surface nuclei are ordinarily unresolved. The position (1.096 kG/MHz)a and width (500 G at 80 kG) of the ('195)Pt SEDOR signal confirms the assignment by Rhodes et al. of a peak in the ('195)Pt NMR line shapes to the surface layer of platinum atoms. No surface nuclei are detected at any other locations in the ('195)Pt NMR line shape. Though the ('195)Pt NMR line shapes for the two dispersions are very different, the SEDOR line shapes are identical. SEDOR shows that the bonding of the CO is to the clean Pt surface through the carbon and that the Pt-C J coupling is similar to that in Pt carbonyls.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Makowka, Claus Dieter

• Physics, Condensed Matter

Language dc:language

eng

Identifier

(UMI)AAI8218517

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/77347