Nuclear magnetic resonance studies of simple molecules on metal surfaces
Klug, Christopher Aaron
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/2142/23785
Description
Title
Nuclear magnetic resonance studies of simple molecules on metal surfaces
Author(s)
Klug, Christopher Aaron
Issue Date
1990
Doctoral Committee Chair(s)
Slichter, C.P.
Department of Study
Physics, Condensed Matter
Discipline
Physics, Condensed Matter
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Condensed Matter
Language
eng
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.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
