University of Illinois Urbana-Champaign

NMR studies of acetylene absorbed on supported platinum catalysts

Sakaie, Ken Earl

This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.

Permalink

https://hdl.handle.net/2142/18847

Description

Title
NMR studies of acetylene absorbed on supported platinum catalysts
Author(s)
Sakaie, Ken Earl
Issue Date
1996
Doctoral Committee Chair(s)
Slichter, C.P.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • Nuclear magnetic resonance (NMR)
  • acetylene
  • platinum catalysts
Language
en
Abstract
"This thesis describes NMR measurements involving carbon-13, deuterons, and protons in acetylene (C2H2) adsorbed at room temperature on supported platinum catalysts. Measurements from 77""K to 158°K of the spin-lattice relaxation behavior of carbon-13 reveal multiple-exponential behavior. Calculations rule out an anisotropic T 1 as an explanation for the multiple-exponential behavior. Carbon-proton SEDOR measurements indicate that each time constant, T 1, in the spin-lattice relaxation of carbon corresponds to a mixture of adsorbate structures. The T 1 seems to exhibit a linear temperature dependence, indicating interaction with conduction electrons of the platinum . clusters. However, the spectrum measurements indicate no Knight shift, a deviation from the Korringa relation. Such a deviation implies that electronic states at the Fermi energy involve hybrids of the platinum conduction band with adsorbate molecular orbitals with no spatial density at the carbon nucleus. Measurements of the deuterium spectrum reveal no obvious features that would prove useful in identifying different adsorbate structures. Spectrum and spin-locking measurements indicate no motion of deuteron groups at 77°K The deuterium spin-lattice relaxation rate exhibits multiple-exponential behavior. Measurements of the coupling between the magnetic dipole moments of deuterons determine bond angles and internuclear distances. A single-resonance ""slow beat"" measurement finds, in deuterated ethylidyne (CCD3) , a distance between deuterons ofr00 = 1.673±0.004A. A double resonance method, demonstrated in a test sample ofD20 in gypsum, can provide bond angle and internuclear distance information. Coherence transfer between carbon and deuterium indicates that deuterium NMR measurements at lower temperatures may offer significant advantages in terms of signal to noise ratios."
Type of Resource
text
Permalink
http://hdl.handle.net/2142/18847
Copyright and License Information
1996 Ken Earl Sakaie

Owning Collections

Dissertations and Theses - Physics
Dissertations in Physics
Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois