IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Thursday Sessions
       Session SS3-ThP

Paper SS3-ThP13
The Chemistry of 1,1-Dichloroethene on Pd(111) Investigated by TDS, LITD-FTMS, STM and FTRAIRS

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Surface Reactions Poster Session
Presenter: D.E. Hunka, University of California, Davis
Authors: D.E. Hunka, University of California, Davis
D.C. Herman, University of North Carolina, Chapel Hill
K.D. Lormand, University of California, Davis
A. Loui, University of California, Davis
S. Chiang, University of California, Davis
D.P. Land, University of California, Davis
Correspondent: Click to Email
Chloroethene contamination in ground water is a concern from both an environmental and health standpoint. All six chloroethenes are contained in over half of the sites listed on the EPA’s National Priorities List as well as possible carcinogens. One promising method of remediating these pollutants is using zero valent metals to degrade these halocarbons. Both iron and iron palladium bimetallic clusters have been shown to effectively decompose several small chlorocarbons, including dichloroethenes (DCEs). However, no systematic studies on palladium alone have been performed to date. In this study, the chemistry of 1,1-dichloroethene on clean Pd(111) has been investigated using thermal desorption spectrometry (TDS), laser induced thermal desorption Fourier transform mass spectrometry (LITD/FTMS), scanning tunneling microscopy (STM) and Fourier transform reflection absorption infrared spectroscopy (FTRAIRS). TDS and LITD-FTMS results indicate a coverage dependent decomposition mechanism. Coverages above 0.32 L show a stepwise decomposition initiated by C-Cl bond scission in which two successive stable surface intermediates are produced. These intermediates are proposed to be monochloroethylidyne and chlorovinylidene, respectively. The decomposition of 1,1-DCE in coverages below 0.32 L are initiated by C-H bond cleavage, and produce one stable surface intermediate, proposed to be dichloroethylidyne. All surface intermeidiates will be investigated and confirmed by FTRAIRS. Finally, STM reveals that adsorption and decomposition of 1,1-DCE happens preferentially at step edges.