Principles & Protocols

Protocols - Using Carbon Thread in Edwards 306

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You will need:

• Carbon thread
• Thread holder
• Screwdriver
• Filled LN2 trap

Setup

• Vent jar by pressing vent
  • If "Vent" is not allowed (red light on key not lit), press "Start" then press Vent
• When vented (2MB), remove jar by first disconnecting hinge, then lifting and rotating away
• Secure carbon thread in holder (cut a ~4cm piece, place between screws and screw down)
• Attach the holder to rod B&D and grounded rod 7cm from grid
• Insert sample
• If desired, fold a piece of filter paper and place near sample -- this will let you see the carbon shadow
• Hold in place with microscope slide or pennies
• Lower jar and press "Process"

• Move stop over sample to prevent C from coating during step 10
• Pump down to 10-4
• Turn dial to #0 (L)
• Switch LT selector to D (30V)
• Switch on LT
• Turn the selector up to # 2 to make the thread glow a few seconds and off gas contamination slowly
  • if thread does not glow, his "Reset" button to allow current to flow
• Remove stop to coat with C
• Insert LN2 trap into hole on left side of pumping station. Trap is stored in drawer below station.
• Add liquid nitrogen to the LN2 trap
• Allow vacuum to recover to 5x10-6 - may need to be restarted
• Trip the LT (this prevent current from flowing when you increase the current value in next step)
• Set selector to 6
• Press reset & look away
• Thread will glow brightly until it burns out, leaving a thick layer of carbon on sample.
• Turn off LT

• Vent bell jar

• Close jar again and pump down
• When it reaches fine pumping, press "seal"

7cm from grid and 1cm of thread gives about 6 nm carbon coat

This method is very reproducible

Visit Cryo EM Web site at http://www.nysbc.org/facilities/CEM

-- DavidStokes - 18 Mar 2005

• Set ALLOWTOPICCHANGE = CemfacGroup