Transcript Characterization-Update-CNM

Characterization: CNM Proposal
Slade J. Jokela, Igor V. Veryovkin,
Alexander V. Zinovev
Purpose
• Our goal is to determine what is responsible
for the ageing of secondary electron emissive
materials.
– Will examine changes in surface composition and
structure under electron exposure
– This experiment will not perfectly emulate normal
MCP ageing as it must be carried out in a limited
time. High electron flux must be used to complete
experiment in the allotted time.
Equipment
• Four-point non-destructive
probe (can be used as STM)
• SEM for positioning of
probe can be used for surface
examination
• Gemini column for high
resolution (energy and
spatial) mapping of surface
chemical composition using
Ager Electron Spectroscopy
(AES).
Procedure
• Examine sample under SEM, STM, and AES
• Determine Secondary Emissive Yield (LEED
System)
• Expose small sample area to some fluence of
electrons from (LEED System)
– Start with large fluence to see if there is a
detectable change, then perform smaller fluence
exposures to determine dynamics
• Repeat…
Variations
• Sample heating up to 500 °C for examination
of thermal desorption/diffusion .
– Especially carbon
• Gas exposure for examining effects on
composition and morphology.
– Primarily interested in atmospheric gasses
What needs to be done
• Equipment needs to be checked out by CNM
– Voltage Sources
• Plan on starting measurements in July or
August.
– Still need to check calendar at CNM
Vacuum Transfer System
• This is for the characterization instrument
(XPS, UPS, LEED) in building 200-D110.
• Discussion with Hau Wang and Larry Curtis
(Li-ion Battery) have resulted in shared costs
for this hardware
– Some items remain to be purchased
• Vacuum Chamber ($1840)
• Machining (Estimates must be made - $5000 to $10000)