STM - conductive coating for insulators. Pd, Os, Au, ...?

Don Chernoff posted on Wed, Oct 16 2013 5:10 PM

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Various conductive coatings are used in SEM of insulating samples.  The materials include Au, Pd, C, Os.

Pd and Os are thought to have very tiny particle size.

I wonder whether a native oxide exists on Pd or Os that might be transparent to the high energy electrons in SEM but might interfere with STM at a bias of 1V in air.

Please share your experience with these materials. Which ones are suitable for STM?

Thanks.

Don Chernoff