Journal of Physical Chemistry, Vol.99, No.22, 9230-9235, 1995
Direct Evidence for Silver Film Deposition Below Room-Temperature on Pt(111) from the ((CH3)(3)Ccochcoc3F7)Agpet(3) Precursor
The study of the adsorption of 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione (fodH), and (1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato) (triethylphosphine)silver(I) ([(fod)AgPEt(3)]) on Pt(111) has been carried out by reflection absorption IR spectroscopy (RAIRS) and temperature-programmed desorption (TPD) techniques. Both molecules adsorb molecularly on Pt(111) at 90 K with their COCHCO skeleton parallel to the surface at low coverage and with random orientation at high coverage. When the Pt(111) sample is heated, the chemisorbed states of fodH and [(fod)AgPEt(3)] dissociate below room temperature. Molecular desorption of fodH and [(fod)AgPEt(3)] occurs at 275 and 340 K, respectively. Thermally induced dissociation of fodH leads to the generation and the desorption of a ketone species at 187 K, which we tentatively attribute to the C4H9COCH3 molecule. The remaining intermediates dissociate and desorb in the form of the CF3 radical at 215 K and CO between 400 and 600 K. Larger and more stable intermediates are generated following fodH decomposition than those generated from hexafluoroacetoacetone (hfacH) dissociation. More importantly, this study showed that the [(fod)AgPEt(3)] precursor releases Ag atoms at very low temperature, the lowest yet reported. Thermal desorption of the deposited Ag atoms takes place at 1035 and 940 K from the monolayer and the multilayer, respectively. The main byproduct desorbing at low temperature upon precursor dissociation is fodH at 236 K. We also observed the thermal desorption of HF and CO at 236, 340, 616, and 948 K.
Keywords:CHEMICAL-VAPOR-DEPOSITION;BETA-DIKETONATE COMPOUNDS;THIN-FILM;COPPER;ADSORPTION;CHEMISTRY;CF3I;(BETA-DIKETONATE)CULN;DECOMPOSITION;MONOLAYER