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CED 030

Carbon thread evaporationdevice

Overview

CED 030 Carbon Thread Evaporation Device

The carbon thread evaporation process requires a special carbon thread which is flash evaporated under vacuum conditions. This produces films suitable for SEM specimens without carbon particles that can be deposited on the samples when using carbon rods.

Key Features

  • Compact bench-top unit
  • Cost effective
  • Gentle coating
  • Easy film thickness determination
  • Uniform, cohesive carbon films
  • Exactly reproducible film thickness
  • Easy and clean loading
  • Very easy operation

Carbon thread coating

Up to now carbon films have usually been applied to SEM and TEM specimens by evaporation from suitably sharpened carbon rods under high vacuum conditions. Resistance, arc or electron beam heating have all been used. However, the carbon rods could not be completely degassed, which often led to specimen damage when the degassing carbon rods splashed material onto them. And the films produced under high vacuum do not envelop the structures on the specimen surface (shadowing), which is a problem when using SEM.

The carbon thread evaporation process requires a special carbon thread which is flash evaporated under vacuum conditions to produce films suited for SEM specimens.

The carbon thread is stretched between two high current electrodes using a quick mounting holder. It is completely degassed under fore vacuum conditions by heating to a red glow. The source is covered during this degassing process by a shutter which protects the specimen both from unacceptable heating and from being coated with impure carbon. After degassing, a predetermined level of high current is run through the carbon thread to “flash“ evaporate it. Many collisions occur between the carbon atoms thus released into the vacuum chamber atmosphere and the relatively large number of residual gas molecules still present since the chamber has only been pumped to fore vacuum. These collisions cause the carbon atoms to scatter widely and a diffuse “cloud“of atoms forms, which then condense evenly on the specimen, impinging from all directions.