Re: What are the best materials for secondary electron emission?

Hi Ethan,

I've never had to deal with these materials personally, so I apologize if this answer is not too helpful.

In a nutshell, your choice of SE-emitting material will depend on what you want to do with it. Different materials have different advantages. You mentioned CsI (cesium iodide)---that indeed has the highest-SEE yield among materials in common use. For example, it is commonly used to coat the dynodes of a photomultiplier tube, as in this abstract. This abstract mentions a possible disadvantage of CsI---it can't be heated up without damaging it. (To learn more about photomultiplier tubes, click here.)

Beyond that---well, *anything* will emit secondary electrons under different circumstances. Any metal will work---higher atomic numbers tend to have higher yields, so try platinum or gold. Any "alkali halide" (CsI, CsBr, RbCl, etc.) will work, although CsI is probably the best. If you need your material to absorb a lot of radiation, get hot, and not melt, perhaps Al2O3 is better. If you want to detect low-energy, visible-light photons via SEE, you need a material with a low "work function"---there is a table of work functions at this page, and more in the CRC Handbook of Chemistry and Physics.

To be any more specific, you have to know exactly what you are using the material for. Electron, ion, or x-ray detection? At what energies and angles? I wish I could point you towards a simple table of SEE data, but such a table seems not to exist on the Web. The data is too complicated to sum up easily. I can recommend a few books, though, which we have here in the MIT library---you may be able to get it through a university library, or interlibrary loan.

"Secondary electron spectra from charged partical interactions."
Bethesda, Md. : International Commission on Radiation Units and
Measurements, 1996.
ICRU report ; 55
ISBN             0913394548
 
"Secondary emission and structural properties of solids. "
Edited by U. A. Arifov. Translated from Russian by Geoffry D. Archard.
New York, Consultants Bureau, 1971.
ISBN             030610864X

Hope this helps,

-Ben