Spectra of Molecules Adsorbed on Unsupported Metals

Spectrum of Carbon Monoxide on Evaporated Platinum Films 

Evaporated metal films represent a type of sample which is of major interest in fundamental catalysis research. Moreover, these samples are not subject to the wavelength limitations imposed by the presence of silicious carriers. Therefore, development of infrared techniques suitable for observing spectra of molecules adsorbed on evaporated films is of vital 

Spectrum of carbon monoxide chemisorbed on films of evaporated plat inum. 

On the basis of the intensity of the 4.9 n band in Fig. 31, it was calculated that the sample contained the equivalent of 20-40 monolayers of carbon monoxide. A value of 300 X 10 20 cm.2/mol. was used as the extinction coefficient for the chemisorbed CO. The range of 20-40 monolayers results from the uncertainty as to what crystal faces are exposed. Since there were four films in the sample, each film chemisorbed the equivalent of 5-10 monolayers. 

The idea of obtaining emission spectra of molecules adsorbed on metal was suggested by French and Wadsworth (58). They indicated that they had used the method to obtain spectra of surface complexes but did not give specific details of these spectra. 

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