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Nuclear magnetic resonance studies of simple molecules on metal surfaces
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http://hdl.handle.net/2142/23785
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| Title: | Nuclear magnetic resonance studies of simple molecules on metal surfaces |
| Author(s): | Klug, Christopher Aaron |
| Doctoral Committee Chair(s): | Slichter, Charles P. |
| Department / Program: | Physics, Condensed Matter |
| Discipline: | Physics, Condensed Matter |
| Degree Granting Institution: | University of Illinois at Urbana-Champaign |
| Degree: | Ph.D. |
| Genre: | Dissertation |
| Subject(s): | Physics, Condensed Matter |
| Abstract: | We have used NMR to study the structure and reactions of acetylene and ethylene adsorbed on small catalyst particles. By monitoring $\sp{13}$C-$\sp{13}$C and $\sp{13}$C-$\sp1$H dipolar couplings we found the carbon-carbon bond length to be 1.44 $\pm$ 0.02A for acetylene adsorbed on Rh clusters at room temperature and the surface species to consist mostly of CCH$\sb2$ with a small amount of CCH. Using $\sp2$H NMR we studied the conversion of ethylene adsorbed at low temperatures on Pt clusters to the stable room temperature species (CCH$\sb3$) and also the hydrogen-deuterium exchange in this CCH$\sb3$ species. We found an activation energy of 15.2 $\pm$ 2.0 kcal/mole and preexponential factor of 10$\sp{7{\pm}1.7}$ sec$\sp{-1}$ for the conversion reaction and an activation energy of 14.3 $\pm$ 2.5 kcal/mole and preexponential factor of 4 $\times$ 10$\sp{7{\pm}2}$ sec$\sp{-1}$ for the exchange reaction. We compare these results with those obtained by other researchers. We also studied the formation of CCH$\sb3$ from the stable room temperature species of acetylene adsorbed on Pt (CCH$\sb2$) and found an activation energy of 9.3 $\pm$ 2.5 kcal/mole and a preexponential factor of 10$\sp{3{\pm}2}$ sec$\sp{-1}$torr$\sp{-1}$. In addition, we used measurements of $\sp{13}$C-$\sp1$H dipolar couplings to monitor the hydrogen population for the surface species formed from acetylene adsorbed on Pt and Ir. We were able to show that the CCH$\sb2$ species do not lose hydrogen prior to carbon-carbon bond scission on Ir but that there is a gradual dehydrogenation below the temperature of carbon-carbon bond scission for CCH$\sb2$ species on Pt. |
| Issue Date: | 1990 |
| Type: | Text |
| Language: | English |
| URI: | http://hdl.handle.net/2142/23785 |
| Rights Information: | Copyright 1990 Klug, Christopher Aaron |
| Date Available in IDEALS: | 2011-05-07 |
| Identifier in Online Catalog: | AAI9114301 |
| OCLC Identifier: | (UMI)AAI9114301 |
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Dissertations and Theses - Physics
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Graduate Theses and Dissertations at Illinois
Graduate Theses and Dissertations at Illinois
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