Schematic representation of the FEM used to examine MWCNTs. Scanning electron micrograph of the nanotube ( protrusion length) used in these experiments (inset).
FEM micrograph and current vs time of a beam from a single MWCNT. Bright spots corresponding to emission through adsorbates appear against the pentagonal rings from the clean nanotube surface.
A schematic representation of the energy analyzer/DFEA system. Scanning electron micrograph showing nanotip detail for a diamond field emitter (inset).
Phosphor screen image of beams from individual diamond emitters in a sparse ( pitch) array. Each beam consists of multiple beamlets that fluctuate in space and time (Ref. 15).
The current collected from an individual CVD-diamond field emitter fluctuates between discrete, stable levels. Periods of stability can range from fractions of a second to many minutes depending on the operating conditions.
Measured spectra for a diamond field emitter for fixed experimental conditions. The spectrum fluctuates between a variety of stable configurations coincident with the emitted current fluctuations.
Measured spectrum for what is believed to be a clean diamond field emitter. It is located near the estimated Fermi energy and has a spectral width of .
Measured energy spectrum before and after a single adsorbate event. The emission current increased by more than an order of magnitude without affecting the spectral width or shape.
The measured spectrum during a period of stable emission for various applied voltages. The anode-cathode gap in this case was . Significant spectral changes were observed as the electric field was changed by small amounts.
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