Many scanning electron microscope (SEM) laboratories use double sticky carbon tape applied directly to SEM stubs as samplers for small particles. The SEM samplers used by law enforcement to test the hands of a suspect for gunshot residue (GSR) are constructed in this manner.

A few years ago, during a presentation at a professional meeting, I presented spectra of particles that were mounted on carbon double sticky tape that was applied directly to the aluminum- alloy SEM stubs. After the presentation a colleague posited that small peaks of copper, which appeared in some of my spectra, were due to a copper support frame for the backscatter detector at the top of the SEM chamber and not the particles. Indeed, I have frequently noticed small peaks of copper in spectra of particles where these should not be present.