Probing strain on graphene flake using polarized Raman spectroscopy

We presented an approach to measure the strain on graphene by using the polarized Raman spectroscopy with two excited sources and lineshape analysis, and studied the strain effect due to golden nanoparticles on graphene flake with it. The surface enhanced Raman spectroscopy (SERS) can effectively enhance Raman signals, but depositing metallic films or nanoparticles on graphene is needed. We compared the Raman signal intensity using Raman spectroscopy and SERS, and fitted the lineshape into the combined Lorentzian profiles. The strain effect due to golden nanoparticles can be neglected in our experimental design. The distribution of golden nanoparticles can be regarded as random. The technique of SERS can enhance Raman signal and not cause strain changing. At the same time, the Raman signal intensity of graphene flake with 532-nm laser excitation is larger than one with 632-nm laser approximately 10 times. Expectedly, we used the way of 532-nm excited laser and technique of SERS to greatly enhance measuring efficiency.