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Observations of CO adsorption on {100} nickel made previously by Park and Farnsworth have been repeated with a combined LEED and mass spectrometer (MS) system. The results confirm the previous observations and are in disagreement with those of Lichtman, Kirst, and McQuistan. Possible causes of the discrepancy are indicated. CO adsorption on the surface subsequent to prolonged heat treatment was greatly reduced due to diffusion of contamination from the bulk. No desorption of O2 or O was observed even when a CO-covered surface was exposed to O2 and heated subsequently, but only large desorptions of CO2 and CO with a c2 × 2-O structure remaining on the surface. Also, heating a surface, which had been exposed to O2 only, produced desorption of CO but no trace of O2 or O was found.

Results were obtained with combined LEED and Mass Spectrometer equipments. On first admission of N2O to the outgassed system in the pressure range 2 to 5 × 10−8 Torr, nitrogen was formed by decomposition but no oxygen was observed. In addition to some dissociation of N2O on (100) Ni, some adsorption of N2O occurred in a lattice structure similar to that of the nickel substrate. Subsequent heating at 200–300°C caused weak desorptions of CO and N2O, the oxygen being removed as CO. The adsorbed N2O was easily replaced by CO at room temperature. The work function of the clean surface was increased 0.1 eV by exposure to N2O, probably due to adsorbed oxygen as a decomposition product of N2O as well as adsorbed N2O. On first admission of NO, substitutional desorption of CO from tube components occurred and the resulting CO adsorbed on the crystal surface was later substitutionally desorbed by NO. NO was strongly adsorbed on the crystal surface primarily in an amorphous form but with some lattice structure similar to that of the nickel substrate. The adsorbed NO was removed as CO and N2 by heating. NO was strongly adsorbed on both clean and slightly contaminated surfaces. There was no evidence of a surface reaction between adsorbed NO and oxygen atoms to form NO2. Adsorption of NO caused a maximum decrease in work function of 0.38 eV. Admission of CO2 to the system caused no substitutional desorption of CO. Adsorbed CO2 molecules were dissociated on the clean crystal surface at room temperature to form adsorbed CO and O when the exposure reached a rather critical value of about 10−6 Torr-min, as indicated by both sharp decreases in LEED intensity and increases in work function. Heating the crystal at 200 to 300°C caused desorption of both CO and CO2. A slightly contaminated surface, produced by heating the crystal at 850°C for a few hours, was very inactive for CO2 adsorption or dissociation.

LEED experiments on the adsorption of CO on {100} nickel have been repeated with the addition of a quadrupole mass spectrometer. The results confirm earlier observations that CO does adsorb on this clean surface and further indicate that such a surface cannot be cleaned by heating alone. CO adsorption on the surface subsequent to prolonged heat treatment is greatly reduced due to diffusion of contamination from the bulk.

The angular distribution of Auger electrons from clean Fe(100) surface and from Fe(100) surfaces having various adsorbed structures has been investigated by means of a simple new method of Auger electron spectroscopy using a combined LEED and scanning photoelectron multiplier system. The experimental results indicate that the typical three types of angular distribution of Auger electrons are existed; 1) the lobular distribution due to the diffraction effect in the case of the 45 eV Fe Auger electron emission from well-ordered surfaces, 2) the cosine squared distribution in the case of the 598 eV Fe Auger electron emission, 3) the cosine distribution in the case of Auger electron emission from adatoms located at the outermost surface, for example, S Auger electrons from the Fe(100) c(2×2)–S and the Fe(100)–disordered–H2S structures.