2006.     KUMMER, J. T., AND EMMETT, P. H.  Chemisorption of Carbon Monoxide and the Heterogeneity of the Surface of Iron Catalysts.  Jour. Am. Chem. Soc., vol. 73, 1951, pp. 2886-2889.

        Radioactive and nonradioactive samples of CO have been added in succession as two separate fractions to a reduced Fe synthetic NH₃ catalyst at –195° or –78°.  The chemisorbed CO layer has then been removed by pumping and analyzed for C¹⁴O.  The results show that 2d fraction of added CO tends to desorb first.  However, the results also show that a partial rapid exchange equivalent to a coverage of about 50% of the Fe surface occurs between the 2 added fractions of chemisorbed CO even if both fractions are added at –195°.