Identification of Posttranslational Modifications For Sample Prep.
Sample Preparation or Sample Prep. Always Handle samples with GLOVED HANDS!
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Transcript of Sample Preparation or Sample Prep. Always Handle samples with GLOVED HANDS!
Sample Preparation or Sample Prep
Always Handle samples with
GLOVED HANDS!
Best Case Scenario Samples are solid
conducting samples
When samples are not conductive they can be made conductive Au/Pd coating
Carbon Coating does not have to be thick to be
effective
MRC Au/Pd Coater
Carbon Rod attachment for carbon coating
Sample Stubs
There are several types of sample stubs available for mounting samples
Mounting samples to stubs Affix the sample to the stub using appropriate media
Carbon or Silver Paint Double Stick Carbon Tape or dots Double Stick Copper Tape Super Glue* Double Stick Tape*
*Not recommened for use in the S4700
Grounding Samples
Although a sample might be coated it might not be grounded.
Provide a good “path to ground” to reduce charging effects
Silver Paint Carbon Paint Copper, Nickel, Silver, or Aluminum tape
Sample Types
Metals Ceramics – Porous, Insulating Thin Films – Break immediately prior to mounting Geological – Mount and polish Glass – Insulating, Amorphous Polymers – Interaction with electron beam Nano samples Circuits – Insulating and conducting Wafers – Insulating Mounted Samples – Out gassing Particles or particulates
Metals
Polished and etched – Grains Cleaned of excess oils Typically does not need assistance with
grounding unless mounted in epoxy
Ceramics Insulating need
coating and good path to ground
Porous samples need to be in vacuum prior to SEM examination to reduce out gassing
Polishing and etching to see grains
Thin Films
Break prior to SEM examination to avoid contamination
Thin Au/Pd coating Better if not on a
glass substrate
Si Wafers and Glass
Scribe across the back or at the edges
Break prior to SEM examination
Coating and good path to ground
Epoxy Mounted Samples Polished to a mirror finish Polishing scratches detract from desired
images. Methodology is sample dependant Use Optical Microscope to view polishing
progress Kept under vacuum to reduce amount of
out gassing
Particles or Particulates Use appropriate mounting media Ensure the particles are attached firmly to
the stub Blow off excess particles prior to coating Coat, if possible use a moving stage
Shielding
In some cases the sample surface can be shielded with a metal foil can reduce charging effects.
A piece of metal foil is placed on the sample allowing only a small amount of the surface to show
Sample Mount
Put the sample stub on the “Sample Mount” the correct way.
The bottom of the mount should be the widest part
Adjust the height with the “preset height jig”
Lock washer Height screws Mount base Correct sample mount
Preset Height Jig
Sample Prep Summary
All samples need to be handled with gloved hands – even in the processing lab!
Proper sample prep cuts down on analysis time and insures better data collection
Clean all stubs after use and store in appropriate place
GLOVES
Storage and Work Bench