Photochemistry of Dimethyl Cadmium on Quartz and Silicon Surfaces
Abstract
The photochemistry of adsorbed dimethyl cadmium at submonolayer levels on a fused quartz and a Si(111) single crystal surface has been investigated at 193 and 248 nm using a rare-gas fluoride excimer laser. The desorbed gaseous products, which include CH2, CH3, CH4, C2H4, C2H5, C2H6, Cd, CH3Cd and (CH3)2Cd, have been detected by time-of-flight mass spectrometry by means of either electron impact or resonance-enhanced multiphoton ionization. The translational energies of these desorption products could be characterized in terms of Maxwell-Boltzmann temperatures, TMB's, which depend strongly on sample dosage (surface coverage), laser fluence, photon energy and the nature of the substrates employed. The TMB's of the C1- and C2-hydrocarbon species were found to be much lower than those of Cd, CH3Cd and (CH3)2Cd, suggesting that the electronic excitation/relaxation mechanism may be involved in the desorption of these metal/metal-containing species. A similar mechanism is not available for the desorption of the hydrocarbon products. A realistic mechanism is proposed for the UV-photochemistry of adsorbed (CH3)2Cd.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 26, 1991
- Accession Number
- ADA237261
Entities
People
- Lin Ming-chang
- S. P. Lee
Organizations
- Emory University