Formation and desorption of SiI2 molecules

The chemical etching of Si(100)−(2×1) in I₂ ambient is considered. The desorption activation energy of SiI₂ molecules is evaluated from experimental data. It is found that the desorption activation energy of SiI₂ molecules is equal to . This corresponds to a value of the mean lifetime of adsorbed molecules on the surface of at temperature .     

Ion-molecule reactions in mixtures of methane with carbon tetrafluoride

Ion-molecule reactions have been measured for methane-carbon tetrafluoride mixtures of different composition using a quadrupole mass spectrometer with a high-pressure ion source. Concentration of methane in these mixtures ranged from 10% to 90% (at 10% increment). Primary ions , , F⁺, CF⁺ and were produced by electrons with energy of 300 eV. Secondary ions , , , , and were observed as the result of ion-molecule reactions. Relative current intensities for primary and secondary ions are presented as a function of both total mixture pressure and concentration of methane in the mixture. Potential of repeller electrode inside the ion source collision chamber was fixed at 5 V for all measurements. Total mixture pressure was changed from 0.7 to 33.3 Pa. Schemes of ion-molecule reactions were proposed.     

Surface reactions between CO2 and H over K-modified Cu(0 0 1)

Low temperature (115-160 K) adsorption of CO on clean Cu(0 0 1), CO₂ on potassium modified Cu(0 0 1) and surface reactions between H₂ and CO₂ were studied. Pre-adsorption of K leads to strong interaction of the interface with arriving carbon dioxide molecules and linear CO₂(phys), bent , CO and are observed as adsorbed species. Annealing of the CO₂/K/Cu(0 0 1) interface causes, successively, desorption of the reaction products. Pre-adsorbed hydrogen on the alkali-modified substrate changes the surface reaction channels, mainly with no presence of CO and creation of surface formate species. Details of surface reactions are compared with results for thick potassium film on a copper substrate.