Improving correlated SERS measurements with scanning electron microscopy: an assessment of the problem arising from the deposition of amorphous carbon

For surface-enhanced Raman scattering (SERS) substrates with nonspherical symmetry, it is critical to correlate spectroscopy measurements with imaging by scanning electron microscopy (SEM). However, the deposition of carbon resulting from e-beam exposure during SEM imaging contaminates the surface of nanoparticles, potentially preventing their further functionalization with Raman probe molecules. In addition, the deposited carbon leads to unwanted background SERS signals. In this study, we systematically investigated the deposition of carbon during SEM imaging and examined how it affects the functionalization of nanoparticles with probe molecules and impacts the detection of SERS signals. Significantly, we found that the carbon could be removed or replaced from the surface of Ag nanoparticles through chemical or physical means, rendering the nanoparticles the capability for correlated SEM/SERS studies.