| Abstract
| - We have investigated systematically the effects of various gas adsorbates (H2, N2, O2, and H2O)on the electronic structures and the field emission properties of open edges of single-walled carbonnanotubes by density functional calculations. All of the molecules, except N2, dissociate and chemisorb onopen nanotube edges with large adsorption energies. The Fermi levels are moved toward the valence(conduction) bands for O2 (H2, H2O) adsorption induced by the Mulliken charge transfer on the tube edge.The Fermi level shift for N2 adsorption is negligible. Adsorption of H2O enhances the field emission current,whereas H2 adsorption does not affect the field emission current much because of the absence of thedensity of states near the Fermi level. The correlation of the electronic structures and the field emissioncurrent is further discussed.
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