Effect of adsorbates on field emission from carbon nanotubes.
Recent experiments indicate that water molecules adsorbed on carbon nanotube tips significantly enhance field-emission current. Through first-principles density-functional theory calculations we show that the water-nanotube interaction is weak in zero electric field. However, under emission conditions large electric field present at the tube tip: (a) increases the binding energy appreciably, thereby stabilizing the adsorbate; and (b) lowers the ionization potential (IP), thereby making it easier to extract electrons. Lowering of IP is enhanced further through the formation of a water cluster on the nanotube tip.
Maiti
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Accelrys Inc., 9685 Scranton Road, San Diego, California 92121, USA. amaiti@accelrys.com
Andzelm
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J
Tanpipat
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N
von Allmen
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P